More json refactoring towards System.Text.Json (#244)

Directory.Build.props

@@ -131,8 +131,8 @@
   <Choose>
     <When Condition="'$(IsTestProject)' != 'true' and '$(IsSampleProject)' != 'true' and '$(IsDesignProject)' != 'true'">
       <ItemGroup>
-        <PackageReference Include="Microsoft.VisualStudio.Threading.Analyzers" Version="15.8.168" PrivateAssets="all" />
-        <PackageReference Include="StyleCop.Analyzers" Version="1.1.1-beta.61" PrivateAssets="all" />
+        <PackageReference Include="Microsoft.VisualStudio.Threading.Analyzers" Version="16.5.132" PrivateAssets="all" />
+        <PackageReference Include="StyleCop.Analyzers" Version="1.1.118" PrivateAssets="all" />
 
         <!-- <EmbeddedResource Include="**\*.rd.xml" />
         <Page Include="**\*.xaml" Exclude="**\bin\**\*.xaml;**\obj\**\*.xaml" SubType="Designer" Generator="MSBuild:Compile" />

Lottie-Windows/Lottie-Windows.csproj

@@ -31,18 +31,19 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.UI.Xaml">
-      <Version>2.2.190917002</Version>
+      <Version>2.3.200213001</Version>
       <Generator>MSBuild:Compile</Generator>
       <SubType>Designer</SubType>
     </PackageReference>
     <PackageReference Include="Newtonsoft.Json">
-      <Version>12.0.2</Version>
+      <Version>12.0.3</Version>
     </PackageReference>
     <PackageReference Include="System.Memory" Version="4.5.3" />
     <PackageReference Include="System.Numerics.Vectors">
       <Version>4.5.0</Version>
     </PackageReference>
-    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="4.6.0" />
+    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="4.7.0" />
+    <PackageReference Include="System.Text.Json" Version="4.7.1" />
     <PackageReference Include="System.ValueTuple">
       <Version>4.5.0</Version>
     </PackageReference>

LottieGen/LottieGen.csproj

@@ -23,14 +23,10 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Newtonsoft.Json" Version="12.0.2" />
-    <PackageReference Include="StyleCop.Analyzers" Version="1.1.1-beta.61">
-      <PrivateAssets>all</PrivateAssets>
-      <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
-    </PackageReference>
+    <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
     <PackageReference Include="System.Memory" Version="4.5.3" />
     <PackageReference Include="System.Numerics.Vectors" Version="4.5.0" />
-    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="4.6.0" />
+    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="4.7.0" />
   </ItemGroup>
 
   <Import Project="..\source\LottieData\LottieData.projitems" Label="Shared" />

LottieViewer/LottieViewer.csproj

@@ -224,16 +224,19 @@
       <Version>6.2.9</Version>
     </PackageReference>
     <PackageReference Include="Microsoft.UI.Xaml">
-      <Version>2.2.190917002</Version>
+      <Version>2.3.200213001</Version>
     </PackageReference>
     <PackageReference Include="Newtonsoft.Json">
-      <Version>12.0.2</Version>
+      <Version>12.0.3</Version>
     </PackageReference>
     <PackageReference Include="System.Memory">
       <Version>4.5.3</Version>
     </PackageReference>
     <PackageReference Include="System.Runtime.CompilerServices.Unsafe">
-      <Version>4.6.0</Version>
+      <Version>4.7.0</Version>
+    </PackageReference>
+    <PackageReference Include="System.Text.Json">
+      <Version>4.7.1</Version>
     </PackageReference>
     <PackageReference Include="Win2D.uwp">
       <Version>1.24.0</Version>

dlls/LottieReader/LottieReader.dll.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <TargetFramework>netcoreapp2.2</TargetFramework>
@@ -11,6 +11,7 @@
 
   <ItemGroup>
     <PackageReference Include="Newtonsoft.Json" Version="12.0.2" />
+    <PackageReference Include="System.Text.Json" Version="4.7.1" />
   </ItemGroup>
 
   <ItemGroup>

source/Lottie/LottieVisualSource.cs

@@ -676,7 +676,9 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie
             await task;
             await Task.Delay(_checkedDelayMs);
 #else
+#pragma warning disable VSTHRD003 // Avoid awaiting foreign Tasks
             return task;
+#pragma warning restore VSTHRD003 // Avoid awaiting foreign Tasks
 #endif
         }
 

source/LottieReader/LottieReader.projitems

@@ -13,17 +13,15 @@
     <Compile Include="$(MSBuildThisFileDirectory)Serialization\Enums.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Serialization\Exceptions.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Serialization\Fonts.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Serialization\JCArray.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Serialization\JCObject.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Serialization\JCObjectExtensions.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Serialization\JsonToGenericData.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Serialization\JTokenExtensions.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Serialization\Layers.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Serialization\LottieCompositionReader.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Serialization\LottieCompositionReaderException.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Serialization\LottieJsonArrayElement.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Serialization\LottieJsonElement.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Serialization\LottieJsonObjectElement.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Serialization\Markers.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Serialization\ParsingIssues.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Serialization\Primitives.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Serialization\Reader.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Serialization\ShapeLayerContents.cs" />
   </ItemGroup>

source/LottieReader/Serialization/Animatables.cs

@@ -5,7 +5,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using Newtonsoft.Json.Linq;
+using System.Text.Json;
 
 using PathGeometry = Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Sequence<Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.BezierSegment>;
 
@@ -15,79 +15,108 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
 #pragma warning disable SA1601 // Partial elements should be documented
     sealed partial class LottieCompositionReader
     {
-        static readonly AnimatableParser<double> s_animatableFloatParser = CreateAnimatableParser(ReadFloat);
-        static readonly AnimatableParser<Opacity> s_animatableOpacityParser = CreateAnimatableParser(ReadOpacity);
-        static readonly AnimatableParser<PathGeometry> s_animatableGeometryParser = CreateAnimatableParser(ReadGeometry);
-        static readonly AnimatableParser<Rotation> s_animatableRotationParser = CreateAnimatableParser(ReadRotation);
-        static readonly AnimatableParser<Trim> s_animatableTrimParser = CreateAnimatableParser(ReadTrim);
-        static readonly AnimatableParser<Vector3> s_animatableVector3Parser = CreateAnimatableParser(ReadVector3);
+        static readonly Sequence<GradientStop> s_defaultGradientStops =
+            new Sequence<GradientStop>(new[] { new ColorGradientStop(0, Color.Black) });
+
+        static readonly Animatable<double> s_animatableDoubleZero = CreateNonAnimatedAnimatable(0.0);
+        static readonly Animatable<Color> s_animatableColorBlack = CreateNonAnimatedAnimatable(Color.Black);
+        static readonly Animatable<Opacity> s_animatableOpacityOpaque = CreateNonAnimatedAnimatable(Opacity.Opaque);
+        static readonly Animatable<PathGeometry> s_animatableGeometryEmpty = CreateNonAnimatedAnimatable(Sequence<BezierSegment>.Empty);
+        static readonly Animatable<Rotation> s_animatableRotationNone = CreateNonAnimatedAnimatable(Rotation.None);
+        static readonly Animatable<Sequence<GradientStop>> s_animatableGradientStopsSingle = CreateNonAnimatedAnimatable(s_defaultGradientStops);
+        static readonly Animatable<Trim> s_animatableTrimNone = CreateNonAnimatedAnimatable(Trim.None);
+        static readonly AnimatableVector3 s_animatableVector3Zero = new AnimatableVector3(Vector3.Zero, null);
+        static readonly AnimatableParser<double> s_animatableFloatParser =
+            CreateAnimatableParser((in LottieJsonElement element) => element.AsDouble() ?? 0);
+
+        static readonly AnimatableParser<Opacity> s_animatableOpacityParser = CreateAnimatableParser(ParseOpacity);
+        static readonly AnimatableParser<PathGeometry> s_animatableGeometryParser = CreateAnimatableParser(ParseGeometry);
+        static readonly AnimatableParser<Rotation> s_animatableRotationParser = CreateAnimatableParser(ParseRotation);
+        static readonly AnimatableParser<Trim> s_animatableTrimParser = CreateAnimatableParser(ParseTrim);
+        static readonly AnimatableParser<Vector3> s_animatableVector3Parser = CreateAnimatableParser(ParseVector3);
         readonly AnimatableParser<Color> _animatableColorParser;
 
+        static Animatable<T> CreateNonAnimatedAnimatable<T>(T value)
+            where T : IEquatable<T>
+            => new Animatable<T>(value, null);
+
         static Animatable<T> CreateAnimatable<T>(T initialValue, IEnumerable<KeyFrame<T>> keyFrames, int? propertyIndex)
             where T : IEquatable<T>
             => keyFrames.Any()
                 ? new Animatable<T>(keyFrames, propertyIndex)
                 : new Animatable<T>(initialValue, propertyIndex);
 
-        static SimpleAnimatableParser<T> CreateAnimatableParser<T>(Func<JToken, T> valueReader)
+        static SimpleAnimatableParser<T> CreateAnimatableParser<T>(LottieJsonElementReader<T> valueReader)
             where T : IEquatable<T>
              => new SimpleAnimatableParser<T>(valueReader);
 
-        Animatable<T> ReadAnimatable<T>(AnimatableParser<T> parser, JCObject obj)
+        Animatable<T> ReadAnimatable<T>(AnimatableParser<T> parser, in LottieJsonObjectElement obj)
             where T : IEquatable<T>
         {
             parser.ParseJson(this, obj, out var keyFrames, out var initialValue);
-            return CreateAnimatable(initialValue, keyFrames, ReadInt(obj, "ix"));
+            return CreateAnimatable(initialValue, keyFrames, obj.Int32OrNullProperty("ix"));
         }
 
-        Animatable<Color> ReadAnimatableColor(JCObject obj)
+        Animatable<Color> ReadAnimatableColor(in LottieJsonObjectElement? obj)
+            => obj is null
+                ? s_animatableColorBlack
+                : ReadAnimatable(_animatableColorParser, obj.Value);
+
+        Animatable<double> ReadAnimatableFloat(in LottieJsonObjectElement? obj)
+            => obj is null
+                ? s_animatableDoubleZero
+                : ReadAnimatable(s_animatableFloatParser, obj.Value);
+
+        Animatable<PathGeometry> ReadAnimatableGeometry(in LottieJsonObjectElement? obj)
+            => obj is null
+                ? s_animatableGeometryEmpty
+                : ReadAnimatable(s_animatableGeometryParser, obj.Value);
+
+        Animatable<Sequence<GradientStop>> ReadAnimatableGradientStops(in LottieJsonObjectElement? obj)
+            => obj is null
+                ? s_animatableGradientStopsSingle
+                : ReadAnimatableGradientStops(obj.Value);
+
+        Animatable<Sequence<GradientStop>> ReadAnimatableGradientStops(in LottieJsonObjectElement obj)
         {
-            if (obj is null)
+            // If the "k" doesn't exist, we can't parse.
+            var kObj = obj.ObjectOrNullProperty("k");
+
+            if (kObj is null)
             {
-                return new Animatable<Color>(Color.Black, null);
+                return s_animatableGradientStopsSingle;
+            }
+            else
+            {
+                // Get the number of color stops. This is optional unless there are opacity stops.
+                // If this value doesn't exist, all the stops are color stops. If the value exists
+                // then this is the number of color stops, and the remaining stops are opacity stops.
+                var numberOfColorStops = obj.Int32OrNullProperty("p");
+                var propertyIndex = obj.Int32OrNullProperty("ix");
+                return ReadAnimatableGradientStops(kObj.Value, numberOfColorStops, propertyIndex);
             }
-
-            _animatableColorParser.ParseJson(this, obj, out var keyFrames, out var initialValue);
-            return CreateAnimatable(initialValue, keyFrames, ReadInt(obj, "ix"));
         }
 
-        Animatable<double> ReadAnimatableFloat(JCObject obj) => ReadAnimatable(s_animatableFloatParser, obj);
-
-        Animatable<PathGeometry> ReadAnimatableGeometry(JCObject obj)
+        Animatable<Sequence<GradientStop>> ReadAnimatableGradientStops(
+                in LottieJsonObjectElement obj,
+                int? numberOfColorStops,
+                int? propertyIndex)
         {
-            s_animatableGeometryParser.ParseJson(this, obj, out var keyFrames, out var initialValue);
-            var propertyIndex = ReadInt(obj, "ix");
-
-            return keyFrames.Any()
-                ? new Animatable<PathGeometry>(keyFrames, propertyIndex)
-                : new Animatable<PathGeometry>(initialValue, propertyIndex);
-        }
-
-        void ReadAnimatableGradientStops(
-            JCObject obj,
-            out Animatable<Sequence<GradientStop>> gradientStops)
-        {
-            // Get the number of color stops. This is optional unless there are opacity stops.
-            // If this value doesn't exist, all the stops are color stops. If the value exists
-            // then this is the number of color stops, and the remaining stops are opacity stops.
-            var numberOfColorStops = ReadInt(obj, "p");
-
             var animatableColorStopsParser = new AnimatableColorStopsParser(numberOfColorStops);
+
             animatableColorStopsParser.ParseJson(
                 this,
-                obj.GetNamedObject("k"),
+                obj,
                 out var colorKeyFrames,
                 out var colorInitialValue);
 
-            var propertyIndex = ReadInt(obj, "ix");
-
             if (numberOfColorStops.HasValue)
             {
                 // There may be opacity stops. Read them.
                 var animatableOpacityStopsParser = new AnimatableOpacityStopsParser(numberOfColorStops.Value);
                 animatableOpacityStopsParser.ParseJson(
                     this,
-                    obj.GetNamedObject("k"),
+                    obj,
                     out var opacityKeyFrames,
                     out var opacityInitialValue);
 
@@ -95,7 +124,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                 {
                     // There are opacity key frames. The number of color key frames should be the same
                     // (this is asserted in ConcatGradientStopKeyFrames).
-                    gradientStops = new Animatable<Sequence<GradientStop>>(
+                    return new Animatable<Sequence<GradientStop>>(
                                             ConcatGradientStopKeyFrames(colorKeyFrames, opacityKeyFrames),
                                             propertyIndex);
                 }
@@ -109,7 +138,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                             "Numbers of key frames in opacity gradient stops and color gradient stops are unequal.");
                     }
 
-                    gradientStops = new Animatable<Sequence<GradientStop>>(
+                    return new Animatable<Sequence<GradientStop>>(
                                             new Sequence<GradientStop>(colorInitialValue.Concat(opacityInitialValue)),
                                             propertyIndex);
                 }
@@ -117,7 +146,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             else
             {
                 // There are only color stops.
-                gradientStops = colorKeyFrames.Any()
+                return colorKeyFrames.Any()
                     ? new Animatable<Sequence<GradientStop>>(colorKeyFrames, propertyIndex)
                     : new Animatable<Sequence<GradientStop>>(colorInitialValue, propertyIndex);
             }
@@ -158,24 +187,38 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             }
         }
 
-        Animatable<Opacity> ReadAnimatableOpacity(JCObject obj) => ReadAnimatable(s_animatableOpacityParser, obj);
+        Animatable<Opacity> ReadAnimatableOpacity(in LottieJsonObjectElement? obj)
+            => obj is null
+                ? s_animatableOpacityOpaque
+                : ReadAnimatable(s_animatableOpacityParser, obj.Value);
 
-        Animatable<Rotation> ReadAnimatableRotation(JCObject obj) => ReadAnimatable(s_animatableRotationParser, obj);
+        Animatable<Rotation> ReadAnimatableRotation(in LottieJsonObjectElement? obj)
+            => obj is null
+                ? s_animatableRotationNone
+                : ReadAnimatable(s_animatableRotationParser, obj.Value);
 
-        Animatable<Trim> ReadAnimatableTrim(JCObject obj) => ReadAnimatable(s_animatableTrimParser, obj);
+        Animatable<Trim> ReadAnimatableTrim(in LottieJsonObjectElement? obj)
+            => obj is null
+                ? s_animatableTrimNone
+                : ReadAnimatable(s_animatableTrimParser, obj.Value);
 
-        IAnimatableVector3 ReadAnimatableVector3(JCObject obj)
+        IAnimatableVector3 ReadAnimatableVector3(in LottieJsonObjectElement? obj)
+            => obj is null
+                ? s_animatableVector3Zero
+                : ReadAnimatableVector3(obj.Value);
+
+        IAnimatableVector3 ReadAnimatableVector3(in LottieJsonObjectElement obj)
         {
-            IgnoreFieldThatIsNotYetSupported(obj, "s");
+            obj.IgnorePropertyThatIsNotYetSupported("s");
 
             // Expressions not supported.
-            IgnoreFieldThatIsNotYetSupported(obj, "x");
+            obj.IgnorePropertyThatIsNotYetSupported("x");
 
-            var propertyIndex = ReadInt(obj, "ix");
-            if (obj.ContainsKey("k"))
+            var propertyIndex = obj.Int32OrNullProperty("ix");
+            if (obj.ContainsProperty("k"))
             {
                 s_animatableVector3Parser.ParseJson(this, obj, out var keyFrames, out var initialValue);
-                AssertAllFieldsRead(obj);
+                obj.AssertAllPropertiesRead();
 
                 return keyFrames.Any()
                     ? new AnimatableVector3(keyFrames, propertyIndex)
@@ -184,11 +227,11 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             else
             {
                 // Split X and Y dimensions
-                var x = ReadAnimatableFloat(obj.GetNamedObject("x"));
-                var y = ReadAnimatableFloat(obj.GetNamedObject("y"));
-                AssertAllFieldsRead(obj);
+                var x = ReadAnimatableFloat(obj.ObjectOrNullProperty("x"));
+                var y = ReadAnimatableFloat(obj.ObjectOrNullProperty("y"));
+                obj.AssertAllPropertiesRead();
 
-                return new AnimatableXYZ(x, y, s_animatable_0);
+                return new AnimatableXYZ(x, y, s_animatableDoubleZero);
             }
         }
 
@@ -201,24 +244,33 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                 _ignoreAlpha = ignoreAlpha;
             }
 
-            protected override Color ReadValue(JToken obj)
+            protected override Color ReadValue(in LottieJsonElement element)
+            {
+                var array = element.AsArray();
+
+                // Colors are expected to be arrays.
+                // If we can't parse it at least return a color.
+                return array is null
+                    ? Color.Black
+                    : ReadValue(array.Value);
+            }
+
+            Color ReadValue(in LottieJsonArrayElement array)
             {
-                var colorArray = obj.AsArray();
                 double a = 0;
                 double r = 0;
                 double g = 0;
                 double b = 0;
                 int i = 0;
-                var count = colorArray.Count;
+                var count = array.Count;
                 for (; i < count; i++)
                 {
                     // Note: indexing a JsonArray is faster than enumerating.
-                    var jsonValue = colorArray[i];
+                    var jsonValue = array[i];
 
-                    switch (jsonValue.Type)
+                    switch (jsonValue.Kind)
                     {
-                        case JTokenType.Float:
-                        case JTokenType.Integer:
+                        case JsonValueKind.Number:
                             break;
                         default:
                             if (_ignoreAlpha && i == 3)
@@ -228,10 +280,10 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                                 goto AllColorChannelsRead;
                             }
 
-                            throw UnexpectedTokenException(jsonValue.Type);
+                            throw UnexpectedTokenException(jsonValue.Kind);
                     }
 
-                    var number = (double)jsonValue;
+                    var number = jsonValue.AsDouble() ?? 0;
                     switch (i)
                     {
                         case 0:
@@ -277,15 +329,21 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                 _colorStopCount = colorStopCount;
             }
 
-            protected override Sequence<GradientStop> ReadValue(JToken obj)
+            protected override Sequence<GradientStop> ReadValue(in LottieJsonElement element)
             {
-                var gradientStopsData = obj.AsArray().Select(v => (double)v).ToArray();
+                var array = element.AsArray();
+                return array is null
+                    ? s_defaultGradientStops
+                    : ReadValue(array.Value);
+            }
+
+            Sequence<GradientStop> ReadValue(in LottieJsonArrayElement array)
+            {
+                var gradientStopsData = array.Select((in LottieJsonElement v) => v.AsDouble() ?? 0).ToArray();
 
                 // Get the number of color stops. If _colorStopCount wasn't specified, all of
                 // the data in the array is for color stops.
-                var colorStopsDataLength = _colorStopCount.HasValue
-                    ? _colorStopCount.Value * 4
-                    : gradientStopsData.Length;
+                var colorStopsDataLength = _colorStopCount * 4 ?? gradientStopsData.Length;
 
                 if (gradientStopsData.Length < colorStopsDataLength)
                 {
@@ -344,9 +402,17 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                 _colorStopCount = colorStopCount;
             }
 
-            protected override Sequence<GradientStop> ReadValue(JToken obj)
+            protected override Sequence<GradientStop> ReadValue(in LottieJsonElement element)
             {
-                var gradientStopsData = obj.AsArray().Skip(_colorStopCount * 4).Select(v => (double)v).ToArray();
+                var array = element.AsArray();
+                return array is null
+                    ? s_defaultGradientStops
+                    : ReadValue(array.Value);
+            }
+
+            Sequence<GradientStop> ReadValue(in LottieJsonArrayElement array)
+            {
+                var gradientStopsData = array.Select((in LottieJsonElement v) => v.AsDouble() ?? 0).Skip(_colorStopCount * 4).ToArray();
                 var gradientStops = new OpacityGradientStop[gradientStopsData.Length / 2];
                 var offset = 0.0;
                 for (int i = 0; i < gradientStopsData.Length; i++)
@@ -383,29 +449,33 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             {
             }
 
-            protected abstract T ReadValue(JToken obj);
+            protected abstract T ReadValue(in LottieJsonElement element);
 
-            internal void ParseJson(LottieCompositionReader reader, JCObject obj, out IEnumerable<KeyFrame<T>> keyFrames, out T initialValue)
+            internal void ParseJson(
+                LottieCompositionReader reader,
+                in LottieJsonObjectElement obj,
+                out IEnumerable<KeyFrame<T>> keyFrames,
+                out T initialValue)
             {
-                // Deprecated "a" field meant "isAnimated". The existence of key frames means the same thing.
-                reader.IgnoreFieldIntentionally(obj, "a");
+                // Deprecated "a" property meant "isAnimated". The existence of key frames means the same thing.
+                obj.IgnorePropertyIntentionally("a");
 
                 keyFrames = Array.Empty<KeyFrame<T>>();
                 initialValue = default(T);
 
-                foreach (var field in obj)
+                foreach (var property in obj)
                 {
-                    switch (field.Key)
+                    switch (property.Key)
                     {
                         case "k":
                             {
-                                var k = field.Value;
-                                if (k.Type == JTokenType.Array)
+                                var k = property.Value;
+                                if (k.Kind == JsonValueKind.Array)
                                 {
                                     var kArray = k.AsArray();
                                     if (HasKeyframes(kArray))
                                     {
-                                        keyFrames = ReadKeyFrames(reader, kArray).ToArray();
+                                        keyFrames = ReadKeyFrames(kArray.Value).ToArray();
                                         initialValue = keyFrames.First().Value;
                                     }
                                 }
@@ -428,7 +498,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                             // Do not report it as an issue - existence of "ix" doesn't mean that an expression is actually used.
                             break;
 
-                        // Extremely rare fields seen in 1 Lottie file. Ignore.
+                        // Extremely rare properties seen in 1 Lottie file. Ignore.
                         case "nm": // Name
                         case "mn": // MatchName
                         case "hd": // IsHidden
@@ -439,19 +509,19 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                             reader._issues.Expressions();
                             break;
                         default:
-                            reader._issues.UnexpectedField(field.Key);
+                            reader._issues.UnexpectedField(property.Key);
                             break;
                     }
                 }
             }
 
-            static bool HasKeyframes(JCArray array)
+            static bool HasKeyframes(in LottieJsonArrayElement? array)
             {
-                var firstItem = array[0];
-                return firstItem.Type == JTokenType.Object && firstItem.AsObject().ContainsKey("t");
+                return array?[0].AsObject()?.ContainsProperty("t") == true;
             }
 
-            IEnumerable<KeyFrame<T>> ReadKeyFrames(LottieCompositionReader reader, JCArray jsonArray)
+            IEnumerable<KeyFrame<T>> ReadKeyFrames(
+                LottieJsonArrayElement jsonArray)
             {
                 int count = jsonArray.Count;
 
@@ -478,8 +548,8 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                 //   { startFrame_4 }
                 // ]
                 //
-                // In order to handle the current and old formats, we detect the presence of the endValue field.
-                // If there's an endValue field, the keyframes are using the old format.
+                // In order to handle the current and old formats, we detect the presence of the endValue property.
+                // If there's an endValue property, the keyframes are using the old format.
                 //
                 // We convert these to keyframes that match the Windows.UI.Composition notion of a keyframe,
                 // which is a triple: {endValue, endTime, easingFunction}.
@@ -500,20 +570,25 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                 for (int i = 0; i < count; i++)
                 {
                     var lottieKeyFrame = jsonArray[i].AsObject();
+                    if (lottieKeyFrame is null)
+                    {
+                        throw UnexpectedTokenException(jsonArray[i].Kind);
+                    }
+
+                    var lottieKeyFrameObj = lottieKeyFrame.Value;
 
                     // "n" is a name on the keyframe. It is not useful and has been deprecated in Bodymovin.
-                    reader.IgnoreFieldIntentionally(lottieKeyFrame, "n");
+                    lottieKeyFrameObj.IgnorePropertyIntentionally("n");
 
                     // Read the start frame.
-                    var startFrame = lottieKeyFrame.GetNamedNumber("t", 0);
+                    var startFrame = lottieKeyFrameObj.DoubleOrNullProperty("t") ?? 0;
 
                     if (i == count - 1)
                     {
                         // This is the final key frame.
                         // If parsing the old format, this key frame will just have the "t" startFrame value.
                         // If parsing the new format, this key frame will also have the "s" startValue.
-                        var finalStartValue = lottieKeyFrame.GetNamedValue("s");
-                        if (finalStartValue is null)
+                        if (!lottieKeyFrameObj.TryGetProperty("s", out var finalStartValue))
                         {
                             // Old format.
                             yield return new KeyFrame<T>(startFrame, endValue, to, ti, easing);
@@ -529,21 +604,22 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                     }
 
                     // Read the start value.
-                    var startValue = ReadValue(lottieKeyFrame.GetNamedValue("s"));
+                    lottieKeyFrameObj.TryGetProperty("s", out var startValueToken);
+                    var startValue = ReadValue(startValueToken);
 
                     // Output a keyframe that describes how to interpolate to this start value. The easing information
                     // comes from the previous Lottie keyframe.
                     yield return new KeyFrame<T>(startFrame, startValue, to, ti, easing);
 
                     // Spatial control points.
-                    if (lottieKeyFrame.ContainsKey("ti"))
+                    if (lottieKeyFrameObj.ContainsProperty("ti"))
                     {
-                        ti = ReadVector3FromJsonArray(lottieKeyFrame.GetNamedArray("ti"));
-                        to = ReadVector3FromJsonArray(lottieKeyFrame.GetNamedArray("to"));
+                        ti = lottieKeyFrameObj.AsArrayProperty("ti")?.AsVector3() ?? Vector3.Zero;
+                        to = lottieKeyFrameObj.AsArrayProperty("to")?.AsVector3() ?? Vector3.Zero;
                     }
 
                     // Get the easing to the end value, and get the end value.
-                    if (ReadBool(lottieKeyFrame, "h") == true)
+                    if (lottieKeyFrameObj.BoolOrNullProperty("h") == true)
                     {
                         // Hold the current value. The next value comes from the start
                         // of the next entry.
@@ -555,28 +631,29 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                     else
                     {
                         // Read the easing function parameters. If there are any parameters, it's a CubicBezierEasing.
-                        var cp1Json = lottieKeyFrame.GetNamedObject("o", null);
-                        var cp2Json = lottieKeyFrame.GetNamedObject("i", null);
+                        var cp1Json = lottieKeyFrameObj.ObjectOrNullProperty("o");
+                        var cp2Json = lottieKeyFrameObj.ObjectOrNullProperty("i");
                         if (cp1Json != null && cp2Json != null)
                         {
-                            var cp1 = new Vector3(ReadFloat(cp1Json.GetNamedValue("x")), ReadFloat(cp1Json.GetNamedValue("y")), 0);
-                            var cp2 = new Vector3(ReadFloat(cp2Json.GetNamedValue("x")), ReadFloat(cp2Json.GetNamedValue("y")), 0);
-                            easing = new CubicBezierEasing(cp1, cp2);
+                            var cp1 = cp1Json.Value.AsVector3();
+                            var cp2 = cp2Json.Value.AsVector3();
+                            easing = new CubicBezierEasing(cp1 ?? Vector3.Zero, cp2 ?? Vector3.Zero);
                         }
                         else
                         {
                             easing = LinearEasing.Instance;
                         }
 
-                        var endValueObject = lottieKeyFrame.GetNamedValue("e");
-                        endValue = endValueObject != null ? ReadValue(endValueObject) : default(T);
+                        endValue = lottieKeyFrameObj.TryGetProperty("e", out var endValueObject)
+                            ? ReadValue(endValueObject)
+                            : default(T);
                     }
 
                     // "e" is the end value of a key frame but has been deprecated because it should always be equal
                     // to the start value of the next key frame.
-                    reader.IgnoreFieldIntentionally(lottieKeyFrame, "e");
+                    lottieKeyFrameObj.IgnorePropertyIntentionally("e");
 
-                    reader.AssertAllFieldsRead(lottieKeyFrame);
+                    lottieKeyFrameObj.AssertAllPropertiesRead();
                 }
             }
         }
@@ -586,14 +663,14 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
         sealed class SimpleAnimatableParser<T> : AnimatableParser<T>
             where T : IEquatable<T>
         {
-            readonly Func<JToken, T> _valueReader;
+            readonly LottieJsonElementReader<T> _valueReader;
 
-            internal SimpleAnimatableParser(Func<JToken, T> valueReader)
+            internal SimpleAnimatableParser(LottieJsonElementReader<T> valueReader)
             {
                 _valueReader = valueReader;
             }
 
-            protected override T ReadValue(JToken obj) => _valueReader(obj);
+            protected override T ReadValue(in LottieJsonElement element) => _valueReader(element);
         }
     }
 }

source/LottieReader/Serialization/Assets.cs

@@ -4,7 +4,7 @@
 
 using System;
 using System.Linq;
-using Newtonsoft.Json;
+using System.Text.Json;
 
 namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
 {
@@ -14,7 +14,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
     {
         Asset ParseAsset(ref Reader reader)
         {
-            ExpectToken(ref reader, JsonToken.StartObject);
+            ExpectToken(ref reader, JsonTokenType.StartObject);
 
             int e = 0;
             string id = null;
@@ -28,7 +28,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             {
                 switch (reader.TokenType)
                 {
-                    case JsonToken.PropertyName:
+                    case JsonTokenType.PropertyName:
                         {
                             var currentProperty = reader.GetString();
                             ConsumeToken(ref reader);
@@ -37,20 +37,20 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                             {
                                 case "e":
                                     // TODO: unknown what this is. It shows up in image assets.
-                                    e = ParseInt(ref reader);
+                                    e = reader.ParseInt();
                                     break;
                                 case "h":
-                                    height = ParseDouble(ref reader);
+                                    height = reader.ParseDouble();
                                     break;
                                 case "id":
                                     // Older lotties use a string. New lotties use an int. Handle either as strings.
                                     switch (reader.TokenType)
                                     {
-                                        case JsonToken.String:
+                                        case JsonTokenType.String:
                                             id = reader.GetString();
                                             break;
-                                        case JsonToken.Integer:
-                                            id = ParseInt(ref reader).ToString();
+                                        case JsonTokenType.Number:
+                                            id = reader.ParseInt().ToString();
                                             break;
                                         default:
                                             throw UnexpectedTokenException(ref reader);
@@ -67,7 +67,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                                     imagePath = reader.GetString();
                                     break;
                                 case "w":
-                                    width = ParseDouble(ref reader);
+                                    width = reader.ParseDouble();
                                     break;
 
                                 // Report but ignore unexpected fields.
@@ -81,7 +81,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                         }
 
                         break;
-                    case JsonToken.EndObject:
+                    case JsonTokenType.EndObject:
                         {
                             if (id is null)
                             {

source/LottieReader/Serialization/Chars.cs

@@ -3,7 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System.Collections.Generic;
-using Newtonsoft.Json;
+using System.Text.Json;
 
 namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
 {
@@ -13,7 +13,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
     {
         Char ParseChar(ref Reader reader)
         {
-            ExpectToken(ref reader, JsonToken.StartObject);
+            ExpectToken(ref reader, JsonTokenType.StartObject);
 
             string ch = null;
             string fFamily = null;
@@ -26,7 +26,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             {
                 switch (reader.TokenType)
                 {
-                    case JsonToken.PropertyName:
+                    case JsonTokenType.PropertyName:
                         {
                             var currentProperty = reader.GetString();
                             ConsumeToken(ref reader);
@@ -37,19 +37,19 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                                     ch = reader.GetString();
                                     break;
                                 case "data":
-                                    shapes = ReadShapes(JCObject.Load(ref reader, s_jsonLoadSettings));
+                                    shapes = ReadShapes(LottieJsonObjectElement.Load(this, ref reader, s_jsonLoadSettings));
                                     break;
                                 case "fFamily":
                                     fFamily = reader.GetString();
                                     break;
                                 case "size":
-                                    size = ParseDouble(ref reader);
+                                    size = reader.ParseDouble();
                                     break;
                                 case "style":
                                     style = reader.GetString();
                                     break;
                                 case "w":
-                                    width = ParseDouble(ref reader);
+                                    width = reader.ParseDouble();
                                     break;
                                 default:
                                     _issues.UnexpectedField(currentProperty);
@@ -58,7 +58,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                         }
 
                         break;
-                    case JsonToken.EndObject:
+                    case JsonTokenType.EndObject:
                         {
                             return new Char(ch, fFamily, style, size ?? 0, width ?? 0, shapes);
                         }

source/LottieReader/Serialization/Enums.cs

@@ -8,165 +8,207 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
 #pragma warning disable SA1601 // Partial elements should be documented
     sealed partial class LottieCompositionReader
     {
-        BlendMode BmToBlendMode(double bm)
+        BlendMode BmToBlendMode(double? bm)
         {
-            if (bm == (int)bm)
+            if (bm.HasValue)
             {
-                switch ((int)bm)
+                if (TryAsExactInt(bm.Value, out var intValue))
                 {
-                    case 0: return BlendMode.Normal;
-                    case 1: return BlendMode.Multiply;
-                    case 2: return BlendMode.Screen;
-                    case 3: return BlendMode.Overlay;
-                    case 4: return BlendMode.Darken;
-                    case 5: return BlendMode.Lighten;
-                    case 6: return BlendMode.ColorDodge;
-                    case 7: return BlendMode.ColorBurn;
-                    case 8: return BlendMode.HardLight;
-                    case 9: return BlendMode.SoftLight;
-                    case 10: return BlendMode.Difference;
-                    case 11: return BlendMode.Exclusion;
-                    case 12: return BlendMode.Hue;
-                    case 13: return BlendMode.Saturation;
-                    case 14: return BlendMode.Color;
-                    case 15: return BlendMode.Luminosity;
+                    switch (intValue)
+                    {
+                        case 0: return BlendMode.Normal;
+                        case 1: return BlendMode.Multiply;
+                        case 2: return BlendMode.Screen;
+                        case 3: return BlendMode.Overlay;
+                        case 4: return BlendMode.Darken;
+                        case 5: return BlendMode.Lighten;
+                        case 6: return BlendMode.ColorDodge;
+                        case 7: return BlendMode.ColorBurn;
+                        case 8: return BlendMode.HardLight;
+                        case 9: return BlendMode.SoftLight;
+                        case 10: return BlendMode.Difference;
+                        case 11: return BlendMode.Exclusion;
+                        case 12: return BlendMode.Hue;
+                        case 13: return BlendMode.Saturation;
+                        case 14: return BlendMode.Color;
+                        case 15: return BlendMode.Luminosity;
+                    }
                 }
+
+                _issues.UnexpectedValueForType("BlendMode", bm.ToString());
             }
 
-            _issues.UnexpectedValueForType("BlendMode", bm.ToString());
             return BlendMode.Normal;
         }
 
-        ShapeStroke.LineCapType LcToLineCapType(double lc)
+        ShapeStroke.LineCapType LcToLineCapType(double? lc)
         {
-            if (lc == (int)lc)
+            if (lc.HasValue)
             {
-                switch ((int)lc)
+                if (TryAsExactInt(lc.Value, out var intValue))
                 {
-                    case 1: return ShapeStroke.LineCapType.Butt;
-                    case 2: return ShapeStroke.LineCapType.Round;
-                    case 3: return ShapeStroke.LineCapType.Projected;
+                    switch (intValue)
+                    {
+                        case 1: return ShapeStroke.LineCapType.Butt;
+                        case 2: return ShapeStroke.LineCapType.Round;
+                        case 3: return ShapeStroke.LineCapType.Projected;
+                    }
                 }
+
+                _issues.UnexpectedValueForType("LineCapType", lc.ToString());
             }
 
-            _issues.UnexpectedValueForType("LineCapType", lc.ToString());
             return ShapeStroke.LineCapType.Butt;
         }
 
-        ShapeStroke.LineJoinType LjToLineJoinType(double lj)
+        ShapeStroke.LineJoinType LjToLineJoinType(double? lj)
         {
-            if (lj == (int)lj)
+            if (lj.HasValue)
             {
-                switch ((int)lj)
+                if (TryAsExactInt(lj.Value, out var intValue))
                 {
-                    case 1: return ShapeStroke.LineJoinType.Miter;
-                    case 2: return ShapeStroke.LineJoinType.Round;
-                    case 3: return ShapeStroke.LineJoinType.Bevel;
+                    switch (intValue)
+                    {
+                        case 1: return ShapeStroke.LineJoinType.Miter;
+                        case 2: return ShapeStroke.LineJoinType.Round;
+                        case 3: return ShapeStroke.LineJoinType.Bevel;
+                    }
                 }
+
+                _issues.UnexpectedValueForType("LineJoinType", lj.ToString());
             }
 
-            _issues.UnexpectedValueForType("LineJoinType", lj.ToString());
             return ShapeStroke.LineJoinType.Miter;
         }
 
-        MergePaths.MergeMode MmToMergeMode(double mm)
+        MergePaths.MergeMode MmToMergeMode(double? mm)
         {
-            if (mm == (int)mm)
+            if (mm.HasValue)
             {
-                switch ((int)mm)
+                if (TryAsExactInt(mm.Value, out var intValue))
                 {
-                    case 1: return MergePaths.MergeMode.Merge;
-                    case 2: return MergePaths.MergeMode.Add;
-                    case 3: return MergePaths.MergeMode.Subtract;
-                    case 4: return MergePaths.MergeMode.Intersect;
-                    case 5: return MergePaths.MergeMode.ExcludeIntersections;
+                    switch (intValue)
+                    {
+                        case 1: return MergePaths.MergeMode.Merge;
+                        case 2: return MergePaths.MergeMode.Add;
+                        case 3: return MergePaths.MergeMode.Subtract;
+                        case 4: return MergePaths.MergeMode.Intersect;
+                        case 5: return MergePaths.MergeMode.ExcludeIntersections;
+                    }
                 }
+
+                _issues.UnexpectedValueForType("MergeMode", mm.ToString());
             }
 
-            _issues.UnexpectedValueForType("MergeMode", mm.ToString());
             return MergePaths.MergeMode.Merge;
         }
 
-        TrimPath.TrimType MToTrimType(double m)
+        TrimPath.TrimType MToTrimType(double? m)
         {
-            if (m == (int)m)
+            if (m.HasValue)
             {
-                switch ((int)m)
+                if (TryAsExactInt(m.Value, out var intValue))
                 {
-                    case 1: return TrimPath.TrimType.Simultaneously;
-                    case 2: return TrimPath.TrimType.Individually;
+                    switch (intValue)
+                    {
+                        case 1: return TrimPath.TrimType.Simultaneously;
+                        case 2: return TrimPath.TrimType.Individually;
+                    }
                 }
+
+                _issues.UnexpectedValueForType("TrimType", m.ToString());
             }
 
-            _issues.UnexpectedValueForType("TrimType", m.ToString());
             return TrimPath.TrimType.Simultaneously;
         }
 
-        Polystar.PolyStarType? SyToPolystarType(double sy)
+        Polystar.PolyStarType? SyToPolystarType(double? sy)
         {
-            if (sy == (int)sy)
+            if (sy.HasValue)
             {
-                switch ((int)sy)
+                if (TryAsExactInt(sy.Value, out var intValue))
                 {
-                    case 1: return Polystar.PolyStarType.Star;
-                    case 2: return Polystar.PolyStarType.Polygon;
+                    switch (intValue)
+                    {
+                        case 1: return Polystar.PolyStarType.Star;
+                        case 2: return Polystar.PolyStarType.Polygon;
+                    }
                 }
+
+                _issues.UnexpectedValueForType("PolyStartType", sy.ToString());
             }
 
-            _issues.UnexpectedValueForType("PolyStartType", sy.ToString());
             return null;
         }
 
-        GradientType TToGradientType(double t)
+        GradientType TToGradientType(double? t)
         {
-            if (t == (int)t)
+            if (t.HasValue)
             {
-                switch ((int)t)
+                if (TryAsExactInt(t.Value, out var intValue))
                 {
-                    case 1: return GradientType.Linear;
-                    case 2: return GradientType.Radial;
+                    switch (intValue)
+                    {
+                        case 1: return GradientType.Linear;
+                        case 2: return GradientType.Radial;
+                    }
                 }
+
+                _issues.UnexpectedValueForType("GradientType", t.ToString());
             }
 
-            _issues.UnexpectedValueForType("GradientType", t.ToString());
             return GradientType.Linear;
         }
 
-        Layer.MatteType TTToMatteType(double tt)
+        Layer.MatteType TTToMatteType(double? tt)
         {
-            if (tt == (int)tt)
+            if (tt.HasValue)
             {
-                switch ((int)tt)
+                if (TryAsExactInt(tt.Value, out var intValue))
                 {
-                    case 0: return Layer.MatteType.None;
-                    case 1: return Layer.MatteType.Add;
-                    case 2: return Layer.MatteType.Invert;
+                    switch (intValue)
+                    {
+                        case 0: return Layer.MatteType.None;
+                        case 1: return Layer.MatteType.Add;
+                        case 2: return Layer.MatteType.Invert;
+                    }
                 }
+
+                _issues.UnexpectedValueForType("MatteType", tt.ToString());
             }
 
-            _issues.UnexpectedValueForType("MatteType", tt.ToString());
             return Layer.MatteType.None;
         }
 
-        Layer.LayerType? TyToLayerType(double ty)
+        Layer.LayerType? TyToLayerType(double? ty)
         {
-            if (ty == (int)ty)
+            if (ty.HasValue)
             {
-                switch ((int)ty)
+                if (TryAsExactInt(ty.Value, out var intValue))
                 {
-                    case 0: return Layer.LayerType.PreComp;
-                    case 1: return Layer.LayerType.Solid;
-                    case 2: return Layer.LayerType.Image;
-                    case 3: return Layer.LayerType.Null;
-                    case 4: return Layer.LayerType.Shape;
-                    case 5: return Layer.LayerType.Text;
+                    switch (intValue)
+                    {
+                        case 0: return Layer.LayerType.PreComp;
+                        case 1: return Layer.LayerType.Solid;
+                        case 2: return Layer.LayerType.Image;
+                        case 3: return Layer.LayerType.Null;
+                        case 4: return Layer.LayerType.Shape;
+                        case 5: return Layer.LayerType.Text;
+                    }
                 }
+
+                _issues.UnexpectedValueForType("LayerType", ty.ToString());
             }
 
-            _issues.UnexpectedValueForType("LayerType", ty.ToString());
             return null;
         }
 
+        static bool TryAsExactInt(double value, out int intValue)
+        {
+            intValue = (int)value;
+            return value == intValue;
+        }
+
         enum GradientType
         {
             Linear,

source/LottieReader/Serialization/Fonts.cs

@@ -4,7 +4,6 @@
 
 using System.Collections.Generic;
 using System.Linq;
-using Newtonsoft.Json;
 
 namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
 {
@@ -16,14 +15,22 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
         {
             IList<Font> list = EmptyList<Font>.Singleton;
 
-            var fontsObject = JCObject.Load(ref reader, s_jsonLoadSettings);
-            foreach (JCObject item in fontsObject.GetNamedArray("list"))
+            var fontsObject = LottieJsonObjectElement.Load(this, ref reader, s_jsonLoadSettings);
+
+            foreach (var item in fontsObject.AsArrayProperty("list"))
             {
-                var fName = item.GetNamedString("fName");
-                var fFamily = item.GetNamedString("fFamily");
-                var fStyle = item.GetNamedString("fStyle");
-                var ascent = ReadFloat(item.GetNamedValue("ascent"));
-                AssertAllFieldsRead(item);
+                var element = item.AsObject();
+                if (!element.HasValue)
+                {
+                    continue;
+                }
+
+                var obj = element.Value;
+                var fName = obj.StringOrNullProperty("fName") ?? string.Empty;
+                var fFamily = obj.StringOrNullProperty("fFamily") ?? string.Empty;
+                var fStyle = obj.StringOrNullProperty("fStyle") ?? string.Empty;
+                var ascent = obj.DoubleOrNullProperty("ascent") ?? 0;
+                obj.AssertAllPropertiesRead();
                 if (list == EmptyList<Font>.Singleton)
                 {
                     list = new List<Font>();
@@ -32,7 +39,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                 list.Add(new Font(fName, fFamily, fStyle, ascent));
             }
 
-            AssertAllFieldsRead(fontsObject);
+            fontsObject.AssertAllPropertiesRead();
 
             return list.ToArray();
         }

source/LottieReader/Serialization/JCArray.cs

@@ -1,79 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System;
-using System.Collections;
-using System.Collections.Generic;
-using Newtonsoft.Json;
-using Newtonsoft.Json.Linq;
-
-namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
-{
-    sealed class JCArray : IList<JToken>
-    {
-        internal Newtonsoft.Json.Linq.JArray Wrapped { get; }
-
-        internal JCArray(Newtonsoft.Json.Linq.JArray wrapped)
-        {
-            Wrapped = wrapped;
-        }
-
-        internal static JCArray Load(JsonReader reader, JsonLoadSettings settings)
-        {
-            return new JCArray(Newtonsoft.Json.Linq.JArray.Load(reader, settings));
-        }
-
-        public JToken this[int index] { get => Wrapped[index]; set => throw new NotImplementedException(); }
-
-        public int Count => Wrapped.Count;
-
-        public bool IsReadOnly => throw new NotImplementedException();
-
-        public void Add(JToken item)
-        {
-            throw new NotImplementedException();
-        }
-
-        public void Clear()
-        {
-            throw new NotImplementedException();
-        }
-
-        public bool Contains(JToken item)
-        {
-            throw new NotImplementedException();
-        }
-
-        public void CopyTo(JToken[] array, int arrayIndex)
-        {
-            throw new NotImplementedException();
-        }
-
-        public IEnumerator<JToken> GetEnumerator()
-        {
-            foreach (var value in Wrapped)
-            {
-                yield return value;
-            }
-        }
-
-        public int IndexOf(JToken item) => throw new NotImplementedException();
-
-        public void Insert(int index, JToken item) => throw new NotImplementedException();
-
-        public bool Remove(JToken item) => throw new NotImplementedException();
-
-        public void RemoveAt(int index) => throw new NotImplementedException();
-
-        IEnumerator IEnumerable.GetEnumerator()
-        {
-            return GetEnumerator();
-        }
-
-        public static implicit operator JCArray(Newtonsoft.Json.Linq.JArray value)
-        {
-            return value is null ? null : new JCArray(value);
-        }
-    }
-}

source/LottieReader/Serialization/JCObject.cs

@@ -1,57 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System.Collections;
-using System.Collections.Generic;
-using Newtonsoft.Json;
-using Newtonsoft.Json.Linq;
-
-namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
-{
-    sealed class JCObject : IEnumerable<KeyValuePair<string, JToken>>
-    {
-        internal Newtonsoft.Json.Linq.JObject Wrapped { get; }
-
-        internal HashSet<string> ReadFields { get; } = new HashSet<string>();
-
-        internal JCObject(Newtonsoft.Json.Linq.JObject wrapped)
-        {
-            Wrapped = wrapped;
-        }
-
-        internal static JCObject Parse(string input, JsonLoadSettings loadSettings) => new JCObject(Newtonsoft.Json.Linq.JObject.Parse(input, loadSettings));
-
-        internal bool ContainsKey(string key)
-        {
-            ReadFields.Add(key);
-            return Wrapped.ContainsKey(key);
-        }
-
-        internal bool TryGetValue(string propertyName, out JToken value)
-        {
-            ReadFields.Add(propertyName);
-            return Wrapped.TryGetValue(propertyName, out value);
-        }
-
-        internal static JCObject Load(ref Reader reader, JsonLoadSettings settings)
-        {
-            return new JCObject(Newtonsoft.Json.Linq.JObject.Load(reader.NewtonsoftReader, settings));
-        }
-
-        public IEnumerator<KeyValuePair<string, JToken>> GetEnumerator()
-        {
-            return Wrapped.GetEnumerator();
-        }
-
-        IEnumerator IEnumerable.GetEnumerator()
-        {
-            return Wrapped.GetEnumerator();
-        }
-
-        public static implicit operator JCObject(Newtonsoft.Json.Linq.JObject value)
-        {
-            return value is null ? null : new JCObject(value);
-        }
-    }
-}

source/LottieReader/Serialization/JCObjectExtensions.cs

@@ -1,41 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using Newtonsoft.Json.Linq;
-
-namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
-{
-    static class JCObjectExtensions
-    {
-        internal static JToken GetNamedValue(this JCObject obj, string name, JToken defaultValue = null)
-        {
-            return obj.TryGetValue(name, out JToken value) ? value : defaultValue;
-        }
-
-        internal static string GetNamedString(this JCObject obj, string name, string defaultValue = "")
-        {
-            return obj.TryGetValue(name, out JToken value) ? (string)value : defaultValue;
-        }
-
-        internal static double GetNamedNumber(this JCObject obj, string name, double defaultValue = double.NaN)
-        {
-            return obj.TryGetValue(name, out JToken value) ? (double)value : defaultValue;
-        }
-
-        internal static JCArray GetNamedArray(this JCObject obj, string name, JCArray defaultValue = null)
-        {
-            return obj.TryGetValue(name, out JToken value) ? value.AsArray() : defaultValue;
-        }
-
-        internal static JCObject GetNamedObject(this JCObject obj, string name, JCObject defaultValue = null)
-        {
-            return obj.TryGetValue(name, out JToken value) ? value.AsObject() : defaultValue;
-        }
-
-        internal static bool GetNamedBoolean(this JCObject obj, string name, bool defaultValue = false)
-        {
-            return obj.TryGetValue(name, out JToken value) ? (bool)value : defaultValue;
-        }
-    }
-}

source/LottieReader/Serialization/JTokenExtensions.cs

@@ -1,48 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System;
-using Newtonsoft.Json.Linq;
-
-namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
-{
-    static class JTokenExtensions
-    {
-        internal static JCObject AsObject(this JToken token)
-        {
-            try
-            {
-                return (JCObject)token;
-            }
-            catch (InvalidCastException ex)
-            {
-                var exceptionString = ex.Message;
-                if (!string.IsNullOrWhiteSpace(token.Path))
-                {
-                    exceptionString += $" Failed to cast to correct type for token in path: {token.Path}.";
-                }
-
-                throw new LottieCompositionReaderException(exceptionString, ex);
-            }
-        }
-
-        internal static JCArray AsArray(this JToken token)
-        {
-            try
-            {
-                return (JCArray)token;
-            }
-            catch (InvalidCastException ex)
-            {
-                var exceptionString = ex.Message;
-                if (!string.IsNullOrWhiteSpace(token.Path))
-                {
-                    exceptionString += $" Failed to cast to correct type for token in path: {token.Path}.";
-                }
-
-                throw new LottieCompositionReaderException(exceptionString, ex);
-            }
-        }
-    }
-}

source/LottieReader/Serialization/Layers.cs

@@ -12,23 +12,21 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
 #pragma warning disable SA1601 // Partial elements should be documented
     sealed partial class LottieCompositionReader
     {
-        Layer ParseLayer(ref Reader reader) => ReadLayer(JCObject.Load(ref reader, s_jsonLoadSettings));
+        Layer ParseLayer(ref Reader reader) => ReadLayer(LottieJsonObjectElement.Load(this, ref reader, s_jsonLoadSettings));
 
         // May return null if there was a problem reading the layer.
-        Layer ReadLayer(JCObject obj)
+        Layer ReadLayer(in LottieJsonObjectElement obj)
         {
-            // Not clear whether we need to read these fields.
-            IgnoreFieldThatIsNotYetSupported(obj, "bounds");
-            IgnoreFieldThatIsNotYetSupported(obj, "sy");
-            IgnoreFieldThatIsNotYetSupported(obj, "td");
+            // Not clear whether we need to read these properties.
+            obj.IgnorePropertyThatIsNotYetSupported("bounds", "sy", "td");
 
-            // Field 'hasMask' is deprecated and thus we are intentionally ignoring it
-            IgnoreFieldIntentionally(obj, "hasMask");
+            // Property 'hasMask' is deprecated and thus we are intentionally ignoring it.
+            obj.IgnorePropertyIntentionally("hasMask");
 
             var layerArgs = default(Layer.LayerArgs);
 
             layerArgs.Name = ReadName(obj);
-            var index = ReadInt(obj, "ind");
+            var index = obj.Int32OrNullProperty("ind");
 
             if (!index.HasValue)
             {
@@ -36,12 +34,12 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             }
 
             layerArgs.Index = index.Value;
-            layerArgs.Parent = ReadInt(obj, "parent");
-            layerArgs.Is3d = ReadBool(obj, "ddd") == true;
-            layerArgs.AutoOrient = ReadBool(obj, "ao") == true;
-            layerArgs.BlendMode = BmToBlendMode(obj.GetNamedNumber("bm", 0));
-            layerArgs.IsHidden = ReadBool(obj, "hd") == true;
-            var render = ReadBool(obj, "render") != false;
+            layerArgs.Parent = obj.Int32OrNullProperty("parent");
+            layerArgs.Is3d = obj.BoolOrNullProperty("ddd") == true;
+            layerArgs.AutoOrient = obj.BoolOrNullProperty("ao") == true;
+            layerArgs.BlendMode = BmToBlendMode(obj.DoubleOrNullProperty("bm"));
+            layerArgs.IsHidden = obj.BoolOrNullProperty("hd") == true;
+            var render = obj.BoolOrNullProperty("render") != false;
 
             if (!render)
             {
@@ -50,12 +48,12 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             }
 
             // Warnings
-            if (layerArgs.Name.EndsWith(".ai") || obj.GetNamedString("cl", string.Empty) == "ai")
+            if (layerArgs.Name.EndsWith(".ai") || obj.StringOrNullProperty("cl") == "ai")
             {
                 _issues.IllustratorLayers();
             }
 
-            if (obj.ContainsKey("ef"))
+            if (obj.ContainsProperty("ef"))
             {
                 _issues.LayerEffectsIsNotSupported(layerArgs.Name);
             }
@@ -65,112 +63,109 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             // ----------------------
             var shapeLayerContentArgs = default(ShapeLayerContent.ShapeLayerContentArgs);
             ReadShapeLayerContentArgs(obj, ref shapeLayerContentArgs);
-            layerArgs.Transform = ReadTransform(obj.GetNamedObject("ks"), in shapeLayerContentArgs);
+            layerArgs.Transform = ReadTransform(obj.ObjectOrNullProperty("ks"), in shapeLayerContentArgs);
 
             // ------------------------------
             // Layer Animation
             // ------------------------------
-            layerArgs.TimeStretch = obj.GetNamedNumber("sr", 1.0);
+            layerArgs.TimeStretch = obj.DoubleOrNullProperty("sr") ?? 1;
 
             // Time when the layer starts
-            layerArgs.StartFrame = obj.GetNamedNumber("st");
+            layerArgs.StartFrame = obj.DoubleOrNullProperty( "st") ?? double.NaN;
 
             // Time when the layer becomes visible.
-            layerArgs.InFrame = obj.GetNamedNumber("ip");
-            layerArgs.OutFrame = obj.GetNamedNumber("op");
+            layerArgs.InFrame = obj.DoubleOrNullProperty("ip") ?? double.NaN;
+            layerArgs.OutFrame = obj.DoubleOrNullProperty( "op") ?? double.NaN;
 
             // NOTE: The spec specifies this as 'maskProperties' but the BodyMovin tool exports
             // 'masksProperties' with the plural 'masks'.
-            var maskProperties = obj.GetNamedArray("masksProperties", null);
-            layerArgs.Masks = maskProperties != null ? ReadMaskProperties(maskProperties) : null;
+            var maskProperties = obj.AsArrayProperty("masksProperties");
+            layerArgs.Masks = maskProperties != null ? ReadMaskProperties(maskProperties.Value) : null;
 
-            layerArgs.LayerMatteType = TTToMatteType(obj.GetNamedNumber("tt", (double)Layer.MatteType.None));
+            layerArgs.LayerMatteType = TTToMatteType(obj.DoubleOrNullProperty( "tt"));
 
-            Layer.LayerType? layerType = TyToLayerType(obj.GetNamedNumber("ty", double.NaN));
+            Layer.LayerType? layerType = TyToLayerType(obj.DoubleOrNullProperty( "ty"));
 
             if (!layerType.HasValue)
             {
                 return null;
             }
 
-            switch (layerType)
+            try
             {
-                case Layer.LayerType.PreComp:
-                    {
-                        var refId = obj.GetNamedString("refId", string.Empty);
-                        var width = obj.GetNamedNumber("w");
-                        var height = obj.GetNamedNumber("h");
-                        var tm = obj.GetNamedObject("tm", null);
-                        if (tm != null)
+                switch (layerType)
+                {
+                    case Layer.LayerType.PreComp:
                         {
-                            _issues.TimeRemappingOfPreComps();
+                            var refId = obj.StringOrNullProperty("refId") ?? string.Empty;
+                            var width = obj.DoubleOrNullProperty("w") ?? double.NaN;
+                            var height = obj.DoubleOrNullProperty("h") ?? double.NaN;
+                            var tm = obj.ObjectOrNullProperty("tm");
+                            if (tm != null)
+                            {
+                                _issues.TimeRemappingOfPreComps();
+                            }
+
+                            return new PreCompLayer(in layerArgs, refId, width, height);
                         }
 
-                        AssertAllFieldsRead(obj);
-                        return new PreCompLayer(in layerArgs, refId, width, height);
-                    }
+                    case Layer.LayerType.Solid:
+                        {
+                            var solidWidth = obj.Int32OrNullProperty("sw") ?? 0;
+                            var solidHeight = obj.Int32OrNullProperty("sh") ?? 0;
+                            var solidColor = ReadColorFromString(obj.StringOrNullProperty("sc") ?? string.Empty);
+                            return new SolidLayer(in layerArgs, solidWidth, solidHeight, solidColor);
+                        }
 
-                case Layer.LayerType.Solid:
-                    {
-                        var solidWidth = ReadInt(obj, "sw").Value;
-                        var solidHeight = ReadInt(obj, "sh").Value;
-                        var solidColor = ReadColorFromString(obj.GetNamedString("sc"));
+                    case Layer.LayerType.Image:
+                        {
+                            var refId = obj.StringOrNullProperty("refId") ?? string.Empty;
+                            return new ImageLayer(in layerArgs, refId);
+                        }
 
-                        AssertAllFieldsRead(obj);
-                        return new SolidLayer(in layerArgs, solidWidth, solidHeight, solidColor);
-                    }
+                    case Layer.LayerType.Null:
+                        return new NullLayer(in layerArgs);
 
-                case Layer.LayerType.Image:
-                    {
-                        var refId = obj.GetNamedString("refId", string.Empty);
+                    case Layer.LayerType.Shape:
+                        {
+                            var shapes = ReadShapes(obj);
+                            return new ShapeLayer(in layerArgs, shapes);
+                        }
 
-                        AssertAllFieldsRead(obj);
-                        return new ImageLayer(in layerArgs, refId);
-                    }
+                    case Layer.LayerType.Text:
+                        {
+                            // Text layer references an asset.
+                            var refId = obj.StringOrNullProperty("refId") ?? string.Empty;
 
-                case Layer.LayerType.Null:
-                    AssertAllFieldsRead(obj);
-                    return new NullLayer(in layerArgs);
+                            // Text data.
+                            ReadTextData(obj.ObjectOrNullProperty("t").Value);
+                            return new TextLayer(in layerArgs, refId);
+                        }
 
-                case Layer.LayerType.Shape:
-                    {
-                        var shapes = ReadShapes(obj);
-
-                        AssertAllFieldsRead(obj);
-                        return new ShapeLayer(in layerArgs, shapes);
-                    }
-
-                case Layer.LayerType.Text:
-                    {
-                        // Text layer references an asset.
-                        var refId = obj.GetNamedString("refId", string.Empty);
-
-                        // Text data.
-                        ReadTextData(obj.GetNamedObject("t"));
-
-                        AssertAllFieldsRead(obj);
-                        return new TextLayer(in layerArgs, refId);
-                    }
-
-                default: throw Unreachable;
+                    default: throw Unreachable;
+                }
+            }
+            finally
+            {
+                obj.AssertAllPropertiesRead();
             }
         }
 
-        List<ShapeLayerContent> ReadShapes(JCObject obj)
+        List<ShapeLayerContent> ReadShapes(in LottieJsonObjectElement obj)
         {
-            return ReadShapesList(obj.GetNamedArray("shapes", null));
+            return ReadShapesList(obj.AsArrayProperty("shapes"));
         }
 
-        List<ShapeLayerContent> ReadShapesList(JCArray shapesJson)
+        List<ShapeLayerContent> ReadShapesList(in LottieJsonArrayElement? shapesJson)
         {
             var shapes = new List<ShapeLayerContent>();
             if (shapesJson != null)
             {
-                var shapesJsonCount = shapesJson.Count;
+                var shapesJsonCount = shapesJson.Value.Count;
                 shapes.Capacity = shapesJsonCount;
                 for (var i = 0; i < shapesJsonCount; i++)
                 {
-                    var item = ReadShapeContent(shapesJson[i].AsObject());
+                    var item = ReadShapeContent(shapesJson.Value[i].AsObject().Value);
                     if (item != null)
                     {
                         shapes.Add(item);
@@ -181,7 +176,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             return shapes;
         }
 
-        void ReadTextData(JCObject obj)
+        void ReadTextData(in LottieJsonObjectElement obj)
         {
             // TODO - read text data
 
@@ -197,33 +192,31 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             // "sc":strokeColor
             // "sw":strokeWidth
             // "of":(bool)strokeOverFill
-            IgnoreFieldThatIsNotYetSupported(obj, "d");
+            obj.IgnorePropertyThatIsNotYetSupported("d", "p", "m");
 
-            IgnoreFieldThatIsNotYetSupported(obj, "p");
-            IgnoreFieldThatIsNotYetSupported(obj, "m");
-
-            // Array of animatable text properties (fc:fill color, sc:stroke color, sw:stroke width, t:tracking (float))
-            IgnoreFieldThatIsNotYetSupported(obj, "a");
-            AssertAllFieldsRead(obj);
+            // Array of animatable text properties (fc:fill color, sc:stroke color, sw:stroke width, t:tracking (float)).
+            obj.IgnorePropertyThatIsNotYetSupported("a");
+            obj.AssertAllPropertiesRead();
         }
 
-        IEnumerable<Mask> ReadMaskProperties(JCArray array)
+        IEnumerable<Mask> ReadMaskProperties(LottieJsonArrayElement array)
         {
             foreach (var elem in array)
             {
-                var obj = elem.AsObject();
+                var obj = elem.AsObject().Value;
 
-                // Ignoring field 'x' because it is not in the official spec
+                // Ignoring property 'x' because it is not in the official spec.
                 // The x property refers to the mask expansion. In AE you can
                 // expand or shrink a mask getting a reduced or expanded version of the same shape.
-                IgnoreFieldThatIsNotYetSupported(obj, "x");
+                obj.IgnorePropertyThatIsNotYetSupported("x");
 
-                var inverted = obj.GetNamedBoolean("inv");
+                var inverted = obj.BoolOrNullProperty("inv") ?? false;
                 var name = ReadName(obj);
-                var animatedGeometry = ReadAnimatableGeometry(obj.GetNamedObject("pt"));
+                var animatedGeometry = ReadAnimatableGeometry(obj.ObjectOrNullProperty("pt"));
                 var opacity = ReadOpacityFromO(obj);
-                var mode = Mask.MaskMode.None;
-                var maskMode = obj.GetNamedString("mode");
+                var maskMode = obj.StringOrNullProperty("mode") ?? string.Empty;
+
+                Mask.MaskMode mode;
                 switch (maskMode)
                 {
                     case "a":
@@ -252,7 +245,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                         continue;
                 }
 
-                AssertAllFieldsRead(obj);
+                obj.AssertAllPropertiesRead();
                 yield return new Mask(
                     inverted,
                     name,
@@ -271,9 +264,9 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             }
             else
             {
-                var index = 1; // Skip '#'
+                var index = 1; // Skip '#'.
 
-                // '#AARRGGBB'
+                // '#AARRGGBB'.
                 byte a = 255;
                 if (hex.Length == 9)
                 {

source/LottieReader/Serialization/LottieCompositionReader.cs

@@ -6,7 +6,7 @@ using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
-using System.Runtime.CompilerServices;
+using System.Text.Json;
 using Microsoft.Toolkit.Uwp.UI.Lottie.GenericData;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
@@ -24,8 +24,6 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
 #pragma warning disable SA1601 // Partial elements should be documented
     sealed partial class LottieCompositionReader
     {
-        static readonly Animatable<double> s_animatable_0 = new Animatable<double>(0, null);
-
         static readonly JsonLoadSettings s_jsonLoadSettings = new JsonLoadSettings
         {
             // Ignore commands and line info. Not needed and makes the parser a bit faster.
@@ -147,30 +145,12 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             {
                 switch (reader.TokenType)
                 {
-                    case JsonToken.StartObject:
-                    case JsonToken.StartArray:
-                    case JsonToken.StartConstructor:
-                    case JsonToken.Raw:
-                    case JsonToken.Integer:
-                    case JsonToken.Float:
-                    case JsonToken.String:
-                    case JsonToken.Boolean:
-                    case JsonToken.Null:
-                    case JsonToken.Undefined:
-                    case JsonToken.EndArray:
-                    case JsonToken.EndConstructor:
-                    case JsonToken.Date:
-                    case JsonToken.Bytes:
-                        // Here means the JSON was invalid or our parser got confused. There is no way to
-                        // recover from this, so throw.
-                        throw UnexpectedTokenException(ref reader);
-
-                    case JsonToken.Comment:
+                    case JsonTokenType.Comment:
                         // Ignore comments.
                         ConsumeToken(ref reader);
                         break;
 
-                    case JsonToken.PropertyName:
+                    case JsonTokenType.PropertyName:
                         var currentProperty = reader.GetString();
 
                         ConsumeToken(ref reader);
@@ -184,10 +164,10 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                                 chars = ParseArray(ref reader, ParseChar);
                                 break;
                             case "ddd":
-                                is3d = ParseBool(ref reader);
+                                is3d = reader.ParseBool();
                                 break;
                             case "fr":
-                                framesPerSecond = ParseDouble(ref reader);
+                                framesPerSecond = reader.ParseDouble();
                                 break;
                             case "fonts":
                                 fonts = ParseFonts(ref reader);
@@ -196,13 +176,13 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                                 layers = ParseArray(ref reader, ParseLayer);
                                 break;
                             case "h":
-                                height = ParseDouble(ref reader);
+                                height = reader.ParseDouble();
                                 break;
                             case "ip":
-                                inPoint = ParseDouble(ref reader);
+                                inPoint = reader.ParseDouble();
                                 break;
                             case "op":
-                                outPoint = ParseDouble(ref reader);
+                                outPoint = reader.ParseDouble();
                                 break;
                             case "markers":
                                 markers = ParseArray(ref reader, ParseMarker);
@@ -214,7 +194,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                                 version = reader.GetString();
                                 break;
                             case "w":
-                                width = ParseDouble(ref reader);
+                                width = reader.ParseDouble();
                                 break;
 
                             // Treat any other property as an extension of the BodyMovin format.
@@ -231,9 +211,9 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
 
                         break;
 
-                    case JsonToken.EndObject:
+                    case JsonTokenType.EndObject:
                         {
-                            // Check that the required fields were found. If any are missing, throw.
+                            // Check that the required properties were found. If any are missing, throw.
                             if (version is null)
                             {
                                 throw Exception("Version parameter not found.", ref reader);
@@ -298,6 +278,8 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                             return result;
                         }
 
+                    // Here means the JSON was invalid or our parser got confused. There is no way to
+                    // recover from this, so throw.
                     default:
                         throw UnexpectedTokenException(ref reader);
                 }
@@ -306,64 +288,58 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             throw EofException;
         }
 
-        string ReadName(JCObject obj)
+        string ReadName(in LottieJsonObjectElement obj)
         {
             if (_options.HasFlag(Options.IgnoreNames))
             {
-                IgnoreFieldIntentionally(obj, "nm");
+                obj.IgnorePropertyIntentionally("nm");
                 return string.Empty;
             }
             else
             {
-                return obj.GetNamedString("nm", string.Empty);
+                return obj.StringOrNullProperty("nm") ?? string.Empty;
             }
         }
 
-        string ReadMatchName(JCObject obj)
+        string ReadMatchName(in LottieJsonObjectElement obj)
         {
             if (_options.HasFlag(Options.IgnoreMatchNames))
             {
-                IgnoreFieldIntentionally(obj, "mn");
+                obj.IgnorePropertyIntentionally("mn");
                 return string.Empty;
             }
             else
             {
-                return obj.GetNamedString("mn", string.Empty);
+                return obj.StringOrNullProperty("mn") ?? string.Empty;
             }
         }
 
-        Animatable<Color> ReadColorFromC(JCObject obj) =>
-            ReadAnimatableColor(obj.GetNamedObject("c", null));
+        Animatable<Color> ReadColorFromC(in LottieJsonObjectElement obj)
+            => ReadAnimatableColor(obj.ObjectOrNullProperty("c"));
 
-        Animatable<Opacity> ReadOpacityFromO(JCObject obj)
+        Animatable<Opacity> ReadOpacityFromO(in LottieJsonObjectElement obj)
+            => ReadOpacityFromObject(obj.ObjectOrNullProperty("o"));
+
+        Animatable<Opacity> ReadOpacityFromObject(in LottieJsonObjectElement? obj)
         {
-            var jsonOpacity = obj.GetNamedObject("o", null);
-            return ReadOpacityFromObject(jsonOpacity);
+            return ReadAnimatableOpacity(obj);
         }
 
-        Animatable<Opacity> ReadOpacityFromObject(JCObject obj)
+        static PathGeometry ParseGeometry(in LottieJsonElement element)
         {
-            var result = obj != null
-                ? ReadAnimatableOpacity(obj)
-                : new Animatable<Opacity>(Opacity.Opaque, null);
-            return result;
-        }
-
-        static PathGeometry ReadGeometry(JToken value)
-        {
-            JCObject pointsData = null;
-            if (value.Type == JTokenType.Array)
+            LottieJsonObjectElement? pointsData = null;
+            if (element.Kind == JsonValueKind.Array)
             {
-                var firstItem = value.AsArray().First();
-                var firstItemAsObject = firstItem.AsObject();
-                if (firstItem.Type == JTokenType.Object && firstItemAsObject.ContainsKey("v"))
+                var firstItem = element.AsArray()?[0];
+                var firstItemAsObject = firstItem?.AsObject();
+                if (firstItemAsObject?.ContainsProperty("v") == true)
                 {
                     pointsData = firstItemAsObject;
                 }
             }
-            else if (value.Type == JTokenType.Object && value.AsObject().ContainsKey("v"))
+            else if (element.AsObject()?.ContainsProperty("v") == true)
             {
-                pointsData = value.AsObject();
+                pointsData = element.AsObject();
             }
 
             if (pointsData is null)
@@ -371,31 +347,33 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                 return null;
             }
 
-            var vertices = pointsData.GetNamedArray("v", null);
-            var inTangents = pointsData.GetNamedArray("i", null);
-            var outTangents = pointsData.GetNamedArray("o", null);
-            var isClosed = pointsData.GetNamedBoolean("c", false);
+            var points = pointsData.Value;
+
+            var vertices = points.AsArrayProperty("v");
+            var inTangents = points.AsArrayProperty("i");
+            var outTangents = points.AsArrayProperty("o");
+            var isClosed = points.BoolOrNullProperty("c") ?? false;
 
             if (vertices is null || inTangents is null || outTangents is null)
             {
-                throw new LottieCompositionReaderException($"Unable to process points array or tangents. {pointsData}");
+                throw new LottieCompositionReaderException($"Unable to process points array or tangents. {points}");
             }
 
-            var beziers = new BezierSegment[isClosed ? vertices.Count : Math.Max(vertices.Count - 1, 0)];
+            var beziers = new BezierSegment[isClosed ? vertices.Value.Count : Math.Max(vertices.Value.Count - 1, 0)];
 
             if (beziers.Length > 0)
             {
                 // The vertices for the figure.
-                var verticesAsVector2 = ReadVector2Array(vertices);
+                var verticesAsVector2 = ReadArrayOfVector2(vertices.Value);
 
                 // The control points that define the cubic beziers between the vertices.
-                var inTangentsAsVector2 = ReadVector2Array(inTangents);
-                var outTangentsAsVector2 = ReadVector2Array(outTangents);
+                var inTangentsAsVector2 = ReadArrayOfVector2(inTangents.Value);
+                var outTangentsAsVector2 = ReadArrayOfVector2(outTangents.Value);
 
                 if (verticesAsVector2.Length != inTangentsAsVector2.Length ||
                     verticesAsVector2.Length != outTangentsAsVector2.Length)
                 {
-                    throw new LottieCompositionReaderException($"Invalid path data. {pointsData}");
+                    throw new LottieCompositionReaderException($"Invalid path data. {points}");
                 }
 
                 var cp3 = verticesAsVector2[0];
@@ -425,45 +403,37 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             return new PathGeometry(beziers);
         }
 
-        static Opacity ReadOpacity(JToken jsonValue) => Opacity.FromPercent(ReadFloat(jsonValue));
-
-        static Rotation ReadRotation(JToken jsonValue) => Rotation.FromDegrees(ReadFloat(jsonValue));
-
-        static Trim ReadTrim(JToken jsonValue) => Trim.FromPercent(ReadFloat(jsonValue));
-
-        // Indicates that the given field will not be read because we don't yet support it.
-        void IgnoreFieldThatIsNotYetSupported(JCObject obj, string fieldName)
+        static Vector2[] ReadArrayOfVector2(in LottieJsonArrayElement array)
         {
-            obj.ReadFields.Add(fieldName);
-        }
-
-        // Indicates that the given field is not read because we don't need to read it.
-        void IgnoreFieldIntentionally(JCObject obj, string fieldName)
-        {
-            obj.ReadFields.Add(fieldName);
-        }
-
-        // Reports an issue if the given JsonObject has fields that were not read.
-        void AssertAllFieldsRead(JCObject obj, [CallerMemberName]string memberName = "")
-        {
-            var read = obj.ReadFields;
-            var unread = new List<string>();
-            foreach (var pair in obj)
+            var len = array.Count;
+            var result = new Vector2[len];
+            for (var i = 0; i < len; i++)
             {
-                if (!read.Contains(pair.Key))
-                {
-                    unread.Add(pair.Key);
-                }
+                result[i] = array[i].AsArray()?.AsVector2() ?? default(Vector2);
             }
 
-            unread.Sort();
-            foreach (var unreadField in unread)
+            return result;
+        }
+
+        static Opacity ParseOpacity(in LottieJsonElement jsonValue) => Opacity.FromPercent(jsonValue.AsDouble() ?? 0);
+
+        static Rotation ParseRotation(in LottieJsonElement jsonValue) => Rotation.FromDegrees(jsonValue.AsDouble() ?? 0);
+
+        static Trim ParseTrim(in LottieJsonElement jsonValue) => Trim.FromPercent(jsonValue.AsDouble() ?? 0);
+
+        static Vector3 ParseVector3(in LottieJsonElement jsonValue)
+        {
+            switch (jsonValue.Kind)
             {
-                _issues.IgnoredField($"{memberName}.{unreadField}");
+                case JsonValueKind.Object:
+                    return jsonValue.AsObject()?.AsVector3() ?? Vector3.Zero;
+                case JsonValueKind.Array:
+                    return jsonValue.AsArray()?.AsVector3() ?? Vector3.Zero;
+                default: return default(Vector3);
             }
         }
 
-        static void ExpectToken(ref Reader reader, JsonToken token)
+        static void ExpectToken(ref Reader reader, JsonTokenType token)
         {
             if (reader.TokenType != token)
             {
@@ -475,7 +445,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
 
         T[] ParseArray<T>(ref Reader reader, Parser<T> parser)
         {
-            ExpectToken(ref reader, JsonToken.StartArray);
+            ExpectToken(ref reader, JsonTokenType.StartArray);
 
             IList<T> list = EmptyList<T>.Singleton;
 
@@ -483,7 +453,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             {
                 switch (reader.TokenType)
                 {
-                    case JsonToken.StartObject:
+                    case JsonTokenType.StartObject:
                         var result = parser(ref reader);
                         if (result != null)
                         {
@@ -497,7 +467,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
 
                         break;
 
-                    case JsonToken.EndArray:
+                    case JsonTokenType.EndArray:
                         return list.ToArray();
 
                     default:
@@ -523,7 +493,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
         // The JSON is malformed - we found an unexpected token. Fatal.
         static LottieCompositionReaderException UnexpectedTokenException(ref Reader reader) => Exception($"Unexpected token: {reader.TokenType}", ref reader);
 
-        static LottieCompositionReaderException UnexpectedTokenException(JTokenType tokenType) => Exception($"Unexpected token: {tokenType}");
+        static LottieCompositionReaderException UnexpectedTokenException(JsonValueKind kind) => Exception($"Unexpected token: {kind}");
 
         static LottieCompositionReaderException Exception(string message, ref Reader reader) => Exception($"{message} @ {reader.NewtonsoftReader.Path}");
 

source/LottieReader/Serialization/LottieJsonArrayElement.cs

@@ -0,0 +1,113 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Diagnostics;
+using Newtonsoft.Json.Linq;
+
+namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
+{
+#pragma warning disable SA1205 // Partial elements should declare access
+#pragma warning disable SA1601 // Partial elements should be documented
+    sealed partial class LottieCompositionReader
+    {
+        internal readonly struct LottieJsonArrayElement
+        {
+            readonly LottieCompositionReader _owner;
+            readonly JArray _wrapped;
+
+            internal LottieJsonArrayElement(LottieCompositionReader owner, JToken wrapped)
+            {
+                Debug.Assert(wrapped.Type == JTokenType.Array, "Precondition");
+                _owner = owner;
+                _wrapped = (JArray)wrapped;
+            }
+
+            internal int Count => _wrapped.Count;
+
+            public LottieJsonElement this[int index] => new LottieJsonElement(_owner, _wrapped[index]);
+
+            public Vector2? AsVector2()
+            {
+                double? x = null;
+                double? y = null;
+                for (var i = 0; i < Count; i++)
+                {
+                    switch (i)
+                    {
+                        case 0:
+                            x = this[0].AsDouble();
+                            break;
+                        case 1:
+                            y = this[1].AsDouble();
+                            break;
+                    }
+                }
+
+                return x is null
+                    ? (Vector2?)null
+                    : new Vector2(x.Value, y ?? 0);
+            }
+
+            public Vector3? AsVector3()
+            {
+                double? x = null;
+                double? y = null;
+                double? z = null;
+                for (var i = 0; i < Count; i++)
+                {
+                    switch (i)
+                    {
+                        case 0:
+                            x = this[0].AsDouble();
+                            break;
+                        case 1:
+                            y = this[1].AsDouble();
+                            break;
+                        case 2:
+                            z = this[2].AsDouble();
+                            break;
+                    }
+                }
+
+                return x is null
+                    ? (Vector3?)null
+                    : new Vector3(x.Value, y ?? 0, z ?? 0);
+            }
+
+            public Enumerator GetEnumerator() => new Enumerator(this);
+
+            internal T[] Select<T>(LottieJsonElementReader<T> reader)
+            {
+                var count = Count;
+                var result = new T[count];
+                for (var i = 0; i < Count; i++)
+                {
+                    result[i] = reader(this[i]);
+                }
+
+                return result;
+            }
+
+            internal struct Enumerator
+            {
+                readonly LottieJsonArrayElement _owner;
+                int _currentIndex;
+
+                internal Enumerator(LottieJsonArrayElement owner)
+                {
+                    _owner = owner;
+                    _currentIndex = -1;
+                }
+
+                public LottieJsonElement Current => new LottieJsonElement(_owner._owner, _owner._wrapped[_currentIndex]);
+
+                public bool MoveNext() => _owner._wrapped.Count > ++_currentIndex;
+
+                public void Dispose()
+                {
+                }
+            }
+        }
+    }
+}

source/LottieReader/Serialization/LottieJsonElement.cs

@@ -0,0 +1,154 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Text.Json;
+using Newtonsoft.Json.Linq;
+
+namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
+{
+#pragma warning disable SA1205 // Partial elements should declare access
+#pragma warning disable SA1601 // Partial elements should be documented
+    sealed partial class LottieCompositionReader
+    {
+        internal delegate T LottieJsonElementReader<T>(in LottieJsonElement element);
+
+        internal readonly struct LottieJsonElement
+        {
+            readonly LottieCompositionReader _owner;
+            readonly JToken _wrapped;
+
+            internal LottieJsonElement(LottieCompositionReader owner, JToken wrapped)
+            {
+                if (wrapped is null)
+                {
+                    throw new ArgumentException();
+                }
+
+                _owner = owner;
+                _wrapped = wrapped;
+            }
+
+            internal JsonValueKind Kind
+            {
+                get
+                {
+                    switch (_wrapped.Type)
+                    {
+                        case JTokenType.Array:
+                            return JsonValueKind.Array;
+                        case JTokenType.Boolean:
+                            return JsonValueKind.False;
+                        case JTokenType.Integer:
+                        case JTokenType.Float:
+                            return JsonValueKind.Number;
+                        case JTokenType.Null:
+                            return JsonValueKind.Null;
+                        case JTokenType.Object:
+                            return JsonValueKind.Object;
+                        case JTokenType.String:
+                            return JsonValueKind.String;
+
+                        case JTokenType.None:
+                        case JTokenType.Constructor:
+                        case JTokenType.Property:
+                        case JTokenType.Comment:
+                        case JTokenType.Undefined:
+                        case JTokenType.Date:
+                        case JTokenType.Raw:
+                        case JTokenType.Bytes:
+                        case JTokenType.Guid:
+                        case JTokenType.Uri:
+                        case JTokenType.TimeSpan:
+                        default:
+                            return JsonValueKind.Undefined;
+                    }
+                }
+            }
+
+            internal LottieJsonArrayElement? AsArray()
+                => _wrapped.Type == JTokenType.Array
+                    ? new LottieJsonArrayElement(_owner, _wrapped)
+                    : (LottieJsonArrayElement?)null;
+
+            internal LottieJsonObjectElement? AsObject()
+                => _wrapped.Type == JTokenType.Object
+                    ? new LottieJsonObjectElement(_owner, _wrapped)
+                    : (LottieJsonObjectElement?)null;
+
+            internal bool? AsBoolean()
+            {
+                switch (_wrapped.Type)
+                {
+                    case JTokenType.Boolean:
+                        return (bool)_wrapped;
+                    default:
+                        var number = AsDouble();
+                        return number.HasValue
+                            ? number != 0
+                            : (bool?)null;
+                }
+            }
+
+            internal double? AsDouble()
+            {
+                switch (_wrapped.Type)
+                {
+                    case JTokenType.Float:
+                    case JTokenType.Integer:
+                        return (double)_wrapped;
+                    case JTokenType.String:
+                        return double.TryParse((string)_wrapped, out var result)
+                            ? result
+                            : (double?)null;
+
+                    case JTokenType.Array:
+                        {
+                            var array = AsArray().Value;
+                            switch (array.Count)
+                            {
+                                case 0:
+                                    return null;
+                                case 1:
+                                    return array[0].AsDouble();
+                                default:
+                                    // Some Lottie files have multiple values in arrays that should only have one. Just
+                                    // take the first value.
+                                    return array[0].AsDouble();
+                            }
+                        }
+
+                    default:
+                        return null;
+                }
+            }
+
+            internal int? AsInt32()
+            {
+                var value = AsDouble();
+                if (value.HasValue)
+                {
+                    var intValue = unchecked((int)Math.Round(value.Value));
+                    if (intValue == value.Value)
+                    {
+                        return intValue;
+                    }
+                }
+
+                return null;
+            }
+
+            internal string AsString()
+            {
+                switch (_wrapped.Type)
+                {
+                    case JTokenType.String:
+                        return (string)_wrapped;
+                    default:
+                        return null;
+                }
+            }
+        }
+    }
+}

source/LottieReader/Serialization/LottieJsonObjectElement.cs

@@ -0,0 +1,211 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using Newtonsoft.Json.Linq;
+
+namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
+{
+#pragma warning disable SA1205 // Partial elements should declare access
+#pragma warning disable SA1601 // Partial elements should be documented
+    sealed partial class LottieCompositionReader
+    {
+        internal readonly struct LottieJsonObjectElement
+        {
+            readonly LottieCompositionReader _owner;
+            readonly JObject _wrapped;
+            readonly (bool unread, string propertyName)[] _propertyNames;
+
+            internal LottieJsonObjectElement(LottieCompositionReader owner, JToken wrapped)
+            {
+                Debug.Assert(wrapped.Type == JTokenType.Object, "Precondition");
+                _owner = owner;
+                _wrapped = (JObject)wrapped;
+
+                // Get the list of property names.
+                _propertyNames = ((IEnumerable<KeyValuePair<string, JToken>>)wrapped).Select(s => (true, s.Key)).ToArray();
+
+                // Sort the names so they can be binary searched.
+                Array.Sort(_propertyNames, Comparer.Instance);
+            }
+
+            public Vector3? AsVector3()
+            {
+                var x = DoubleOrNullProperty("x");
+                var y = DoubleOrNullProperty("y");
+                var z = DoubleOrNullProperty("z");
+                return x is null
+                    ? (Vector3?)null
+                    : new Vector3(x.Value, y ?? 0, z ?? 0);
+            }
+
+            internal LottieJsonArrayElement? AsArrayProperty(string propertyName)
+                => TryGetProperty(propertyName, out var value) ? value.AsArray() : null;
+
+            internal bool? BoolOrNullProperty(string propertyName)
+                => TryGetProperty(propertyName, out var value) ? value.AsBoolean() : null;
+
+            internal double? DoubleOrNullProperty(string propertyName)
+                => TryGetProperty(propertyName, out var value) ? value.AsDouble() : null;
+
+            internal int? Int32OrNullProperty(string propertyName)
+                => TryGetProperty(propertyName, out var value) ? value.AsInt32() : null;
+
+            internal LottieJsonObjectElement? ObjectOrNullProperty(string propertyName)
+                => TryGetProperty(propertyName, out var value) ? value.AsObject() : null;
+
+            internal string StringOrNullProperty(string propertyName)
+                => TryGetProperty(propertyName, out var value) ? value.AsString() : null;
+
+            // Indicates that the given property will not be read because we don't yet support it.
+            internal void IgnorePropertyThatIsNotYetSupported(string propertyName)
+                => MarkPropertyAsRead(propertyName);
+
+            internal void IgnorePropertyThatIsNotYetSupported(
+                string propertyName1,
+                string propertyName2)
+            {
+                MarkPropertyAsRead(propertyName1);
+                MarkPropertyAsRead(propertyName2);
+            }
+
+            internal void IgnorePropertyThatIsNotYetSupported(
+                string propertyName1,
+                string propertyName2,
+                string propertyName3)
+            {
+                MarkPropertyAsRead(propertyName1);
+                MarkPropertyAsRead(propertyName2);
+                MarkPropertyAsRead(propertyName3);
+            }
+
+            internal void IgnorePropertyThatIsNotYetSupported(
+                string propertyName1,
+                string propertyName2,
+                string propertyName3,
+                string propertyName4)
+            {
+                MarkPropertyAsRead(propertyName1);
+                MarkPropertyAsRead(propertyName2);
+                MarkPropertyAsRead(propertyName3);
+                MarkPropertyAsRead(propertyName4);
+            }
+
+            internal void IgnorePropertyThatIsNotYetSupported(
+                string propertyName1,
+                string propertyName2,
+                string propertyName3,
+                string propertyName4,
+                string propertyName5)
+            {
+                MarkPropertyAsRead(propertyName1);
+                MarkPropertyAsRead(propertyName2);
+                MarkPropertyAsRead(propertyName3);
+                MarkPropertyAsRead(propertyName4);
+                MarkPropertyAsRead(propertyName5);
+            }
+
+            // Indicates that the given property is not read because we don't need to read it.
+            internal void IgnorePropertyIntentionally(string propertyName)
+                => MarkPropertyAsRead(propertyName);
+
+            internal bool ContainsProperty(string propertyName)
+                => TryGetProperty(propertyName, out _);
+
+            internal bool TryGetProperty(string propertyName, out LottieJsonElement value)
+            {
+                if (_wrapped.TryGetValue(propertyName, out var jtokenValue))
+                {
+                    MarkPropertyAsRead(propertyName);
+                    value = new LottieJsonElement(_owner, jtokenValue);
+                    return true;
+                }
+
+                value = default(LottieJsonElement);
+
+                return false;
+            }
+
+            internal static LottieJsonObjectElement Load(LottieCompositionReader owner, ref Reader reader, JsonLoadSettings settings)
+            {
+                return new LottieJsonObjectElement(owner, JObject.Load(reader.NewtonsoftReader, settings));
+            }
+
+            internal void AssertAllPropertiesRead([CallerMemberName]string memberName = "")
+            {
+                foreach (var pair in _propertyNames)
+                {
+                    if (pair.unread)
+                    {
+                        _owner._issues.IgnoredField($"{memberName}.{pair.propertyName}");
+                    }
+                }
+            }
+
+            public Enumerator GetEnumerator() => new Enumerator(this, _wrapped);
+
+            // Marks the given property name as being read.
+            void MarkPropertyAsRead(string propertyName)
+            {
+                int min = 0;
+                int max = _propertyNames.Length - 1;
+                while (min <= max)
+                {
+                    int mid = (min + max) / 2;
+                    var current = _propertyNames[mid].propertyName;
+                    if (propertyName == current)
+                    {
+                        _propertyNames[mid].unread = false;
+                        return;
+                    }
+                    else if (string.CompareOrdinal(propertyName, current) < 0)
+                    {
+                        // Look left.
+                        max = mid - 1;
+                    }
+                    else
+                    {
+                        // Look right.
+                        min = mid + 1;
+                    }
+                }
+
+                // Not found.
+            }
+
+            sealed class Comparer : IComparer<(bool, string)>
+            {
+                internal static readonly Comparer Instance = new Comparer();
+
+                int IComparer<(bool, string)>.Compare((bool, string) x, (bool, string) y)
+                    => string.CompareOrdinal(x.Item2, y.Item2);
+            }
+
+            public struct Enumerator
+            {
+                readonly LottieJsonObjectElement _owner;
+                readonly IEnumerator<KeyValuePair<string, JToken>> _wrapped;
+
+                internal Enumerator(LottieJsonObjectElement owner, JObject wrapped)
+                {
+                    _owner = owner;
+                    _wrapped = wrapped.GetEnumerator();
+                }
+
+                public KeyValuePair<string, LottieJsonElement> Current
+                    => new KeyValuePair<string, LottieJsonElement>(
+                            _wrapped.Current.Key,
+                            new LottieJsonElement(_owner._owner, _wrapped.Current.Value));
+
+                public void Dispose() => _wrapped.Dispose();
+
+                public bool MoveNext() => _wrapped.MoveNext();
+            }
+        }
+    }
+}

source/LottieReader/Serialization/Markers.cs

@@ -2,7 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using Newtonsoft.Json;
+using System.Text.Json;
 
 namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
 {
@@ -12,7 +12,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
     {
         Marker ParseMarker(ref Reader reader)
         {
-            ExpectToken(ref reader, JsonToken.StartObject);
+            ExpectToken(ref reader, JsonTokenType.StartObject);
 
             string name = null;
             double durationMilliseconds = 0;
@@ -22,7 +22,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             {
                 switch (reader.TokenType)
                 {
-                    case JsonToken.PropertyName:
+                    case JsonTokenType.PropertyName:
                         var currentProperty = reader.GetString();
 
                         ConsumeToken(ref reader);
@@ -33,10 +33,10 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                                 name = reader.GetString();
                                 break;
                             case "dr":
-                                durationMilliseconds = ParseDouble(ref reader);
+                                durationMilliseconds = reader.ParseDouble();
                                 break;
                             case "tm":
-                                frame = ParseDouble(ref reader);
+                                frame = reader.ParseDouble();
                                 break;
                             default:
                                 _issues.IgnoredField(currentProperty);
@@ -45,7 +45,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                         }
 
                         break;
-                    case JsonToken.EndObject:
+                    case JsonTokenType.EndObject:
                         return new Marker(name: name, frame: frame, durationMilliseconds: durationMilliseconds);
                     default:
                         throw UnexpectedTokenException(ref reader);

source/LottieReader/Serialization/Primitives.cs

@@ -1,223 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using Newtonsoft.Json;
-using Newtonsoft.Json.Linq;
-
-namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
-{
-#pragma warning disable SA1205 // Partial elements should declare access
-#pragma warning disable SA1601 // Partial elements should be documented
-    sealed partial class LottieCompositionReader
-    {
-        static bool ParseBool(ref Reader reader)
-        {
-            switch (reader.TokenType)
-            {
-                case JsonToken.Integer:
-                    return reader.GetInt64() != 0;
-                case JsonToken.Float:
-                    return reader.GetDouble() != 0;
-                case JsonToken.Boolean:
-                    return reader.GetBoolean();
-                default:
-                    throw Exception($"Expected a bool, but got {reader.TokenType}", ref reader);
-            }
-        }
-
-        static double ParseDouble(ref Reader reader)
-        {
-            switch (reader.TokenType)
-            {
-                case JsonToken.Integer:
-                    return reader.GetInt64();
-                case JsonToken.Float:
-                    return reader.GetDouble();
-                case JsonToken.String:
-                    if (double.TryParse(reader.GetString(), out var result))
-                    {
-                        return result;
-                    }
-
-                    break;
-            }
-
-            throw Exception($"Expected a number, but got {reader.TokenType}", ref reader);
-        }
-
-        static int ParseInt(ref Reader reader)
-        {
-            switch (reader.TokenType)
-            {
-                case JsonToken.Integer:
-                    return checked((int)reader.GetInt64());
-                case JsonToken.Float:
-                    return checked((int)(long)Math.Round(reader.GetDouble()));
-                case JsonToken.String:
-                    if (double.TryParse(reader.GetString(), out var result))
-                    {
-                        return checked((int)(long)Math.Round(result));
-                    }
-
-                    break;
-            }
-
-            throw Exception($"Expected a number, but got {reader.TokenType}", ref reader);
-        }
-
-        static bool? ReadBool(JCObject obj, string name)
-        {
-            if (!obj.ContainsKey(name))
-            {
-                return null;
-            }
-
-            var value = obj.GetNamedValue(name);
-
-            switch (value.Type)
-            {
-                case JTokenType.Boolean:
-                    return obj.GetNamedBoolean(name);
-                case JTokenType.Integer:
-                case JTokenType.Float:
-                    return ReadInt(obj, name)?.Equals(1);
-                case JTokenType.Null:
-                    // Treat a missing value as false.
-                    return false;
-                case JTokenType.String:
-                case JTokenType.Array:
-                case JTokenType.Object:
-                default:
-                    throw UnexpectedTokenException(value.Type);
-            }
-        }
-
-        static double ReadFloat(JToken jsonValue)
-        {
-            switch (jsonValue.Type)
-            {
-                case JTokenType.Float:
-                case JTokenType.Integer:
-                    return (double)jsonValue;
-                case JTokenType.Array:
-                    {
-                        var array = jsonValue.AsArray();
-                        switch (array.Count)
-                        {
-                            case 0:
-                                throw UnexpectedTokenException(jsonValue.Type);
-                            case 1:
-                                return (double)array[0];
-                            default:
-                                // Some Lottie files have multiple values in arrays that should only have one. Just
-                                // take the first value.
-                                return (double)array[0];
-                        }
-                    }
-
-                case JTokenType.Null:
-                    // Treat a missing value as 0.
-                    return 0.0;
-
-                case JTokenType.Boolean:
-                case JTokenType.String:
-                case JTokenType.Object:
-                default:
-                    throw UnexpectedTokenException(jsonValue.Type);
-            }
-        }
-
-        static int? ReadInt(JCObject obj, string name)
-        {
-            var value = obj.GetNamedNumber(name, double.NaN);
-            if (double.IsNaN(value))
-            {
-                return null;
-            }
-
-            // Newtonsoft has its own casting logic so to bypass this, we first cast to a double and then round
-            // because the desired behavior is to round doubles to the nearest value.
-            var intValue = unchecked((int)Math.Round((double)value));
-            if (value != intValue)
-            {
-                return null;
-            }
-
-            return intValue;
-        }
-
-        static Vector2[] ReadVector2Array(JCArray array)
-        {
-            IEnumerable<Vector2> ToVector2Enumerable()
-            {
-                var count = array.Count;
-                for (int i = 0; i < count; i++)
-                {
-                    yield return ReadVector2FromJsonArray(array[i].AsArray());
-                }
-            }
-
-            return ToVector2Enumerable().ToArray();
-        }
-
-        static Vector2 ReadVector2FromJsonArray(JCArray array)
-        {
-            double x = 0;
-            double y = 0;
-            int i = 0;
-            var count = array.Count;
-            for (; i < count; i++)
-            {
-                // NOTE: indexing JsonArray is faster than enumerating it.
-                var number = (double)array[i];
-                switch (i)
-                {
-                    case 0:
-                        x = number;
-                        break;
-                    case 1:
-                        y = number;
-                        break;
-                }
-            }
-
-            // Allow any number of values to be specified. Assume 0 for any missing values.
-            return new Vector2(x, y);
-        }
-
-        static Vector3 ReadVector3(JToken jsonValue) => ReadVector3FromJsonArray(jsonValue.AsArray());
-
-        static Vector3 ReadVector3FromJsonArray(JCArray array)
-        {
-            double x = 0;
-            double y = 0;
-            double z = 0;
-            int i = 0;
-            var count = array.Count;
-            for (; i < count; i++)
-            {
-                // NOTE: indexing JsonArray is faster than enumerating it.
-                var number = (double)array[i];
-                switch (i)
-                {
-                    case 0:
-                        x = number;
-                        break;
-                    case 1:
-                        y = number;
-                        break;
-                    case 2:
-                        z = number;
-                        break;
-                }
-            }
-
-            // Allow any number of values to be specified. Assume 0 for any missing values.
-            return new Vector3(x, y, z);
-        }
-    }
-}

source/LottieReader/Serialization/Reader.cs

@@ -3,7 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
-using System.Linq;
+using System.Text.Json;
 using Newtonsoft.Json;
 
 namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
@@ -19,7 +19,46 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             _reader = reader;
         }
 
-        internal JsonToken TokenType => _reader.TokenType;
+        internal JsonTokenType TokenType
+        {
+            get
+            {
+                switch (_reader.TokenType)
+                {
+                    case JsonToken.None:
+                        return JsonTokenType.None;
+                    case JsonToken.StartObject:
+                        return JsonTokenType.StartObject;
+                    case JsonToken.StartArray:
+                        return JsonTokenType.StartArray;
+                    case JsonToken.PropertyName:
+                        return JsonTokenType.PropertyName;
+                    case JsonToken.Comment:
+                        return JsonTokenType.Comment;
+                    case JsonToken.Integer:
+                    case JsonToken.Float:
+                        return JsonTokenType.Number;
+                    case JsonToken.String:
+                        return JsonTokenType.String;
+                    case JsonToken.Boolean:
+                        return JsonTokenType.False;
+                    case JsonToken.Null:
+                        return JsonTokenType.Null;
+                    case JsonToken.EndObject:
+                        return JsonTokenType.EndObject;
+                    case JsonToken.EndArray:
+                        return JsonTokenType.EndArray;
+                    case JsonToken.Bytes:
+                    case JsonToken.Date:
+                    case JsonToken.EndConstructor:
+                    case JsonToken.Raw:
+                    case JsonToken.StartConstructor:
+                    case JsonToken.Undefined:
+                    default:
+                        throw Exceptions.Unreachable;
+                }
+            }
+        }
 
         internal bool Read() => _reader.Read();
 
@@ -33,6 +72,61 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
 
         internal string GetString() => (string)_reader.Value;
 
+        internal bool ParseBool()
+        {
+            switch (_reader.TokenType)
+            {
+                case JsonToken.Integer:
+                    return GetInt64() != 0;
+                case JsonToken.Float:
+                    return GetDouble() != 0;
+                case JsonToken.Boolean:
+                    return GetBoolean();
+                default:
+                    throw new LottieCompositionReaderException($"Expected a bool, but got {_reader.TokenType}");
+            }
+        }
+
+        internal double ParseDouble()
+        {
+            switch (_reader.TokenType)
+            {
+                case JsonToken.Integer:
+                    return GetInt64();
+                case JsonToken.Float:
+                    return GetDouble();
+                case JsonToken.String:
+                    if (double.TryParse(GetString(), out var result))
+                    {
+                        return result;
+                    }
+
+                    break;
+            }
+
+            throw new LottieCompositionReaderException($"Expected a number, but got {_reader.TokenType}");
+        }
+
+        internal int ParseInt()
+        {
+            switch (_reader.TokenType)
+            {
+                case JsonToken.Integer:
+                    return checked((int)GetInt64());
+                case JsonToken.Float:
+                    return checked((int)(long)Math.Round(GetDouble()));
+                case JsonToken.String:
+                    if (double.TryParse(GetString(), out var result))
+                    {
+                        return checked((int)(long)Math.Round(result));
+                    }
+
+                    break;
+            }
+
+            throw new LottieCompositionReaderException($"Expected a number, but got {_reader.TokenType}");
+        }
+
         // Not part of System.Text.Json. This is a backdoor to get access to the
         // underlying Newtonsoft reader while we transition the code more to
         // System.Text.Json patterns.

source/LottieReader/Serialization/ShapeLayerContents.cs

@@ -11,12 +11,12 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
 #pragma warning disable SA1601 // Partial elements should be documented
     sealed partial class LottieCompositionReader
     {
-        ShapeLayerContent ReadShapeContent(JCObject obj)
+        ShapeLayerContent ReadShapeContent(in LottieJsonObjectElement obj)
         {
             var args = default(ShapeLayerContent.ShapeLayerContentArgs);
             ReadShapeLayerContentArgs(obj, ref args);
 
-            var type = obj.GetNamedString("ty");
+            var type = obj.StringOrNullProperty("ty") ?? string.Empty;
 
             switch (type)
             {
@@ -54,68 +54,72 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             }
         }
 
-        ShapeGroup ReadShapeGroup(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        ShapeGroup ReadShapeGroup(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            // Not clear whether we need to read these fields.
-            IgnoreFieldThatIsNotYetSupported(obj, "cix");
-            IgnoreFieldThatIsNotYetSupported(obj, "cl");
-            IgnoreFieldThatIsNotYetSupported(obj, "ix");
-            IgnoreFieldThatIsNotYetSupported(obj, "hd");
+            // Not clear whether we need to read these properties.
+            obj.IgnorePropertyThatIsNotYetSupported("cix", "cl", "ix", "hd");
 
-            var numberOfProperties = ReadInt(obj, "np");
-            var items = ReadShapesList(obj.GetNamedArray("it", null));
-            AssertAllFieldsRead(obj);
+            var numberOfProperties = obj.Int32OrNullProperty("np");
+            var items = ReadShapesList(obj.AsArrayProperty("it"));
+            obj.AssertAllPropertiesRead();
             return new ShapeGroup(in shapeLayerContentArgs, items);
         }
 
-        void ReadShapeLayerContentArgs(JCObject obj, ref ShapeLayerContent.ShapeLayerContentArgs args)
+        void ReadShapeLayerContentArgs(
+            in LottieJsonObjectElement obj,
+            ref ShapeLayerContent.ShapeLayerContentArgs args)
         {
             args.Name = ReadName(obj);
             args.MatchName = ReadMatchName(obj);
-            args.BlendMode = BmToBlendMode(obj.GetNamedNumber("bm", 0));
+            args.BlendMode = BmToBlendMode(obj.DoubleOrNullProperty("bm"));
         }
 
         // "st"
-        SolidColorStroke ReadSolidColorStroke(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        SolidColorStroke ReadSolidColorStroke(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            // Not clear whether we need to read these fields.
-            IgnoreFieldThatIsNotYetSupported(obj, "fillEnabled");
-            IgnoreFieldThatIsNotYetSupported(obj, "hd");
+            // Not clear whether we need to read these properties.
+            obj.IgnorePropertyThatIsNotYetSupported("fillEnabled", "hd");
 
             var color = ReadColorFromC(obj);
             var opacity = ReadOpacityFromO(obj);
-            var strokeWidth = ReadAnimatableFloat(obj.GetNamedObject("w"));
-            var capType = LcToLineCapType(obj.GetNamedNumber("lc"));
-            var joinType = LjToLineJoinType(obj.GetNamedNumber("lj"));
-            var miterLimit = obj.GetNamedNumber("ml", 4); // Default miter limit in After Effects is 4
+            var strokeWidth = ReadAnimatableFloat(obj.ObjectOrNullProperty("w"));
+            var capType = LcToLineCapType(obj.DoubleOrNullProperty("lc"));
+            var joinType = LjToLineJoinType(obj.DoubleOrNullProperty("lj"));
+            var miterLimit = obj.DoubleOrNullProperty("ml") ?? 4; // Default miter limit in After Effects is 4
 
             // Get dash pattern to be set as StrokeDashArray
             Animatable<double> offset = null;
             var dashPattern = new List<double>();
-            var dashesJson = obj.GetNamedArray("d", null);
-            if (dashesJson != null)
+            var dashes = obj.AsArrayProperty("d");
+            if (dashes != null)
             {
-                for (int i = 0; i < dashesJson.Count; i++)
-                {
-                    var dashObj = dashesJson[i].AsObject();
+                var dashesArray = dashes.Value;
 
-                    switch (dashObj.GetNamedString("n"))
+                for (int i = 0; i < dashesArray.Count; i++)
+                {
+                    var dashObj = dashesArray[i].AsObject();
+
+                    switch (dashObj?.StringOrNullProperty("n"))
                     {
                         case "o":
-                            offset = ReadAnimatableFloat(dashObj.GetNamedObject("v"));
+                            offset = ReadAnimatableFloat(dashObj?.ObjectOrNullProperty("v"));
                             break;
                         case "d":
                         case "g":
-                            dashPattern.Add(ReadAnimatableFloat(dashObj.GetNamedObject("v")).InitialValue);
+                            dashPattern.Add(ReadAnimatableFloat(dashObj?.ObjectOrNullProperty("v")).InitialValue);
                             break;
                     }
                 }
             }
 
-            AssertAllFieldsRead(obj);
+            obj.AssertAllPropertiesRead();
             return new SolidColorStroke(
                 in shapeLayerContentArgs,
-                offset ?? s_animatable_0,
+                offset ?? s_animatableDoubleZero,
                 dashPattern,
                 color,
                 opacity,
@@ -126,9 +130,11 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
         }
 
         // gs
-        ShapeLayerContent ReadGradientStroke(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        ShapeLayerContent ReadGradientStroke(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            switch (TToGradientType(obj.GetNamedNumber("t")))
+            switch (TToGradientType(obj.DoubleOrNullProperty("t")))
             {
                 case GradientType.Linear:
                     return ReadLinearGradientStroke(obj, in shapeLayerContentArgs);
@@ -139,23 +145,23 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             }
         }
 
-        LinearGradientStroke ReadLinearGradientStroke(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        LinearGradientStroke ReadLinearGradientStroke(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            // Not clear whether we need to read these fields.
-            IgnoreFieldThatIsNotYetSupported(obj, "hd");
-            IgnoreFieldThatIsNotYetSupported(obj, "t");
-            IgnoreFieldThatIsNotYetSupported(obj, "1");
+            // Not clear whether we need to read these properties.
+            obj.IgnorePropertyThatIsNotYetSupported("hd", "t", "1");
 
             var opacity = ReadOpacityFromO(obj);
-            var strokeWidth = ReadAnimatableFloat(obj.GetNamedObject("w"));
-            var capType = LcToLineCapType(obj.GetNamedNumber("lc"));
-            var joinType = LjToLineJoinType(obj.GetNamedNumber("lj"));
-            var miterLimit = obj.GetNamedNumber("ml", 4); // Default miter limit in After Effects is 4
-            var startPoint = ReadAnimatableVector3(obj.GetNamedObject("s"));
-            var endPoint = ReadAnimatableVector3(obj.GetNamedObject("e"));
-            ReadAnimatableGradientStops(obj.GetNamedObject("g"), out var gradientStops);
+            var strokeWidth = ReadAnimatableFloat(obj.ObjectOrNullProperty("w"));
+            var capType = LcToLineCapType(obj.DoubleOrNullProperty("lc"));
+            var joinType = LjToLineJoinType(obj.DoubleOrNullProperty("lj"));
+            var miterLimit = obj.DoubleOrNullProperty("ml") ?? 4; // Default miter limit in After Effects is 4
+            var startPoint = ReadAnimatableVector3(obj.ObjectOrNullProperty("s"));
+            var endPoint = ReadAnimatableVector3(obj.ObjectOrNullProperty("e"));
+            var gradientStops = ReadAnimatableGradientStops(obj.ObjectOrNullProperty("g"));
 
-            AssertAllFieldsRead(obj);
+            obj.AssertAllPropertiesRead();
             return new LinearGradientStroke(
                 in shapeLayerContentArgs,
                 opacity,
@@ -168,39 +174,29 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                 gradientStops);
         }
 
-        RadialGradientStroke ReadRadialGradientStroke(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        RadialGradientStroke ReadRadialGradientStroke(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            // Not clear whether we need to read these fields.
-            IgnoreFieldThatIsNotYetSupported(obj, "t");
+            // Not clear whether we need to read these properties.
+            obj.IgnorePropertyThatIsNotYetSupported("t", "h", "1");
 
-            IgnoreFieldThatIsNotYetSupported(obj, "h");
+            var highlightLengthObject = obj.ObjectOrNullProperty("h");
+            var highlightLength = ReadAnimatableFloat(highlightLengthObject);
 
-            IgnoreFieldThatIsNotYetSupported(obj, "1");
-
-            Animatable<double> highlightLength = null;
-            var highlightLengthObject = obj.GetNamedObject("h");
-            if (highlightLengthObject != null)
-            {
-                highlightLength = ReadAnimatableFloat(highlightLengthObject);
-            }
-
-            Animatable<double> highlightDegrees = null;
-            var highlightAngleObject = obj.GetNamedObject("a");
-            if (highlightAngleObject != null)
-            {
-                highlightDegrees = ReadAnimatableFloat(highlightAngleObject);
-            }
+            var highlightAngleObject = obj.ObjectOrNullProperty("a");
+            var highlightDegrees = ReadAnimatableFloat(highlightAngleObject);
 
             var opacity = ReadOpacityFromO(obj);
-            var strokeWidth = ReadAnimatableFloat(obj.GetNamedObject("w"));
-            var capType = LcToLineCapType(obj.GetNamedNumber("lc"));
-            var joinType = LjToLineJoinType(obj.GetNamedNumber("lj"));
-            var miterLimit = obj.GetNamedNumber("ml", 4); // Default miter limit in After Effects is 4
-            var startPoint = ReadAnimatableVector3(obj.GetNamedObject("s"));
-            var endPoint = ReadAnimatableVector3(obj.GetNamedObject("e"));
-            ReadAnimatableGradientStops(obj.GetNamedObject("g"), out var gradientStops);
+            var strokeWidth = ReadAnimatableFloat(obj.ObjectOrNullProperty("w"));
+            var capType = LcToLineCapType(obj.DoubleOrNullProperty("lc"));
+            var joinType = LjToLineJoinType(obj.DoubleOrNullProperty("lj"));
+            var miterLimit = obj.DoubleOrNullProperty("ml") ?? 4; // Default miter limit in After Effects is 4
+            var startPoint = ReadAnimatableVector3(obj.ObjectOrNullProperty("s"));
+            var endPoint = ReadAnimatableVector3(obj.ObjectOrNullProperty("e"));
+            var gradientStops = ReadAnimatableGradientStops(obj.ObjectOrNullProperty("g"));
 
-            AssertAllFieldsRead(obj);
+            obj.AssertAllPropertiesRead();
             return new RadialGradientStroke(
                 in shapeLayerContentArgs,
                 opacity: opacity,
@@ -216,25 +212,27 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
         }
 
         // "fl"
-        SolidColorFill ReadSolidColorFill(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        SolidColorFill ReadSolidColorFill(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            // Not clear whether we need to read these fields.
-            IgnoreFieldThatIsNotYetSupported(obj, "fillEnabled");
-            IgnoreFieldThatIsNotYetSupported(obj, "cl");
-            IgnoreFieldThatIsNotYetSupported(obj, "hd");
+            // Not clear whether we need to read these properties.
+            obj.IgnorePropertyThatIsNotYetSupported("fillEnabled", "cl", "hd");
 
             var fillType = ReadFillType(obj);
             var opacity = ReadOpacityFromO(obj);
             var color = ReadColorFromC(obj);
 
-            AssertAllFieldsRead(obj);
+            obj.AssertAllPropertiesRead();
             return new SolidColorFill(in shapeLayerContentArgs, fillType, opacity, color);
         }
 
         // gf
-        ShapeLayerContent ReadGradientFill(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        ShapeLayerContent ReadGradientFill(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            switch (TToGradientType(obj.GetNamedNumber("t")))
+            switch (TToGradientType(obj.DoubleOrNullProperty("t")))
             {
                 case GradientType.Linear:
                     return ReadLinearGradientFill(obj, in shapeLayerContentArgs);
@@ -245,33 +243,26 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             }
         }
 
-        RadialGradientFill ReadRadialGradientFill(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        RadialGradientFill ReadRadialGradientFill(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            // Not clear whether we need to read these fields.
-            IgnoreFieldThatIsNotYetSupported(obj, "hd");
-            IgnoreFieldThatIsNotYetSupported(obj, "1");
+            // Not clear whether we need to read these properties.
+            obj.IgnorePropertyThatIsNotYetSupported("hd", "1");
 
             var fillType = ReadFillType(obj);
             var opacity = ReadOpacityFromO(obj);
-            var startPoint = ReadAnimatableVector3(obj.GetNamedObject("s"));
-            var endPoint = ReadAnimatableVector3(obj.GetNamedObject("e"));
-            ReadAnimatableGradientStops(obj.GetNamedObject("g"), out var gradientStops);
+            var startPoint = ReadAnimatableVector3(obj.ObjectOrNullProperty("s"));
+            var endPoint = ReadAnimatableVector3(obj.ObjectOrNullProperty("e"));
+            var gradientStops = ReadAnimatableGradientStops(obj.ObjectOrNullProperty("g"));
 
-            Animatable<double> highlightLength = null;
-            var highlightLengthObject = obj.GetNamedObject("h");
-            if (highlightLengthObject != null)
-            {
-                highlightLength = ReadAnimatableFloat(highlightLengthObject);
-            }
+            var highlightLengthObject = obj.ObjectOrNullProperty("h");
+            var highlightLength = ReadAnimatableFloat(highlightLengthObject);
 
-            Animatable<double> highlightDegrees = null;
-            var highlightAngleObject = obj.GetNamedObject("a");
-            if (highlightAngleObject != null)
-            {
-                highlightDegrees = ReadAnimatableFloat(highlightAngleObject);
-            }
+            var highlightAngleObject = obj.ObjectOrNullProperty("a");
+            var highlightDegrees = ReadAnimatableFloat(highlightAngleObject);
 
-            AssertAllFieldsRead(obj);
+            obj.AssertAllPropertiesRead();
             return new RadialGradientFill(
                 in shapeLayerContentArgs,
                 fillType: fillType,
@@ -279,22 +270,24 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                 startPoint: startPoint,
                 endPoint: endPoint,
                 gradientStops: gradientStops,
-                highlightLength: null,
-                highlightDegrees: null);
+                highlightLength: highlightLength,
+                highlightDegrees: highlightDegrees);
         }
 
-        LinearGradientFill ReadLinearGradientFill(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        LinearGradientFill ReadLinearGradientFill(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            // Not clear whether we need to read these fields.
-            IgnoreFieldThatIsNotYetSupported(obj, "hd");
+            // Not clear whether we need to read these properties.
+            obj.IgnorePropertyThatIsNotYetSupported("hd");
 
             var fillType = ReadFillType(obj);
             var opacity = ReadOpacityFromO(obj);
-            var startPoint = ReadAnimatableVector3(obj.GetNamedObject("s"));
-            var endPoint = ReadAnimatableVector3(obj.GetNamedObject("e"));
-            ReadAnimatableGradientStops(obj.GetNamedObject("g"), out var gradientStops);
+            var startPoint = ReadAnimatableVector3(obj.ObjectOrNullProperty("s"));
+            var endPoint = ReadAnimatableVector3(obj.ObjectOrNullProperty("e"));
+            var gradientStops = ReadAnimatableGradientStops(obj.ObjectOrNullProperty("g"));
 
-            AssertAllFieldsRead(obj);
+            obj.AssertAllPropertiesRead();
             return new LinearGradientFill(
                 in shapeLayerContentArgs,
                 fillType: fillType,
@@ -304,58 +297,54 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                 gradientStops: gradientStops);
         }
 
-        Ellipse ReadEllipse(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        Ellipse ReadEllipse(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            // Not clear whether we need to read these fields.
-            IgnoreFieldThatIsNotYetSupported(obj, "closed");
-            IgnoreFieldThatIsNotYetSupported(obj, "hd");
+            // Not clear whether we need to read these properties.
+            obj.IgnorePropertyThatIsNotYetSupported("closed", "hd");
 
-            var position = ReadAnimatableVector3(obj.GetNamedObject("p"));
-            var diameter = ReadAnimatableVector3(obj.GetNamedObject("s"));
-            var direction = ReadBool(obj, "d") == true;
-            AssertAllFieldsRead(obj);
+            var position = ReadAnimatableVector3(obj.ObjectOrNullProperty("p"));
+            var diameter = ReadAnimatableVector3(obj.ObjectOrNullProperty("s"));
+            var direction = obj.BoolOrNullProperty("d") == true;
+            obj.AssertAllPropertiesRead();
             return new Ellipse(in shapeLayerContentArgs, direction, position, diameter);
         }
 
-        Polystar ReadPolystar(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        Polystar ReadPolystar(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            // Not clear whether we need to read these fields.
-            IgnoreFieldThatIsNotYetSupported(obj, "ix");
+            // Not clear whether we need to read these properties.
+            obj.IgnorePropertyThatIsNotYetSupported("ix");
 
-            var direction = ReadBool(obj, "d") == true;
+            var direction = obj.BoolOrNullProperty("d") == true;
 
-            var type = SyToPolystarType(obj.GetNamedNumber("sy", double.NaN));
-
-            if (!type.HasValue)
-            {
-                return null;
-            }
-
-            var points = ReadAnimatableFloat(obj.GetNamedObject("pt"));
+            var points = ReadAnimatableFloat(obj.ObjectOrNullProperty("pt"));
             if (points.IsAnimated)
             {
                 _issues.PolystarAnimation("points");
             }
 
-            var position = ReadAnimatableVector3(obj.GetNamedObject("p"));
+            var position = ReadAnimatableVector3(obj.ObjectOrNullProperty("p"));
             if (position.IsAnimated)
             {
                 _issues.PolystarAnimation("position");
             }
 
-            var rotation = ReadAnimatableFloat(obj.GetNamedObject("r"));
+            var rotation = ReadAnimatableFloat(obj.ObjectOrNullProperty("r"));
             if (rotation.IsAnimated)
             {
                 _issues.PolystarAnimation("rotation");
             }
 
-            var outerRadius = ReadAnimatableFloat(obj.GetNamedObject("or"));
+            var outerRadius = ReadAnimatableFloat(obj.ObjectOrNullProperty("or"));
             if (outerRadius.IsAnimated)
             {
                 _issues.PolystarAnimation("outer radius");
             }
 
-            var outerRoundedness = ReadAnimatableFloat(obj.GetNamedObject("os"));
+            var outerRoundedness = ReadAnimatableFloat(obj.ObjectOrNullProperty("os"));
             if (outerRoundedness.IsAnimated)
             {
                 _issues.PolystarAnimation("outer roundedness");
@@ -364,31 +353,36 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
             Animatable<double> innerRadius;
             Animatable<double> innerRoundedness;
 
-            if (type == Polystar.PolyStarType.Star)
-            {
-                innerRadius = ReadAnimatableFloat(obj.GetNamedObject("ir"));
-                if (innerRadius.IsAnimated)
-                {
-                    _issues.PolystarAnimation("inner radius");
-                }
+            var polystarType = SyToPolystarType(obj.DoubleOrNullProperty("sy")) ?? Polystar.PolyStarType.Polygon;
 
-                innerRoundedness = ReadAnimatableFloat(obj.GetNamedObject("is"));
-                if (innerRoundedness.IsAnimated)
-                {
-                    _issues.PolystarAnimation("inner roundedness");
-                }
-            }
-            else
+            switch (polystarType)
             {
-                innerRadius = null;
-                innerRoundedness = null;
+                case Polystar.PolyStarType.Star:
+                    innerRadius = ReadAnimatableFloat(obj.ObjectOrNullProperty("ir"));
+                    if (innerRadius.IsAnimated)
+                    {
+                        _issues.PolystarAnimation("inner radius");
+                    }
+
+                    innerRoundedness = ReadAnimatableFloat(obj.ObjectOrNullProperty("is"));
+                    if (innerRoundedness.IsAnimated)
+                    {
+                        _issues.PolystarAnimation("inner roundedness");
+                    }
+
+                    break;
+
+                default:
+                    innerRadius = null;
+                    innerRoundedness = null;
+                    break;
             }
 
-            AssertAllFieldsRead(obj);
+            obj.AssertAllPropertiesRead();
             return new Polystar(
                 in shapeLayerContentArgs,
                 direction,
-                type.Value,
+                polystarType,
                 points,
                 position,
                 rotation,
@@ -398,46 +392,47 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                 outerRoundedness);
         }
 
-        Rectangle ReadRectangle(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        Rectangle ReadRectangle(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            // Not clear whether we need to read these fields.
-            IgnoreFieldThatIsNotYetSupported(obj, "hd");
+            // Not clear whether we need to read these properties.
+            obj.IgnorePropertyThatIsNotYetSupported("hd");
 
-            var direction = ReadBool(obj, "d") == true;
-            var position = ReadAnimatableVector3(obj.GetNamedObject("p"));
-            var size = ReadAnimatableVector3(obj.GetNamedObject("s"));
-            var cornerRadius = ReadAnimatableFloat(obj.GetNamedObject("r"));
+            var direction = obj.BoolOrNullProperty("d") == true;
+            var position = ReadAnimatableVector3(obj.ObjectOrNullProperty("p"));
+            var size = ReadAnimatableVector3(obj.ObjectOrNullProperty("s"));
+            var cornerRadius = ReadAnimatableFloat(obj.ObjectOrNullProperty("r"));
 
-            AssertAllFieldsRead(obj);
+            obj.AssertAllPropertiesRead();
             return new Rectangle(in shapeLayerContentArgs, direction, position, size, cornerRadius);
         }
 
-        Path ReadPath(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        Path ReadPath(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            // Not clear whether we need to read these fields.
-            IgnoreFieldThatIsNotYetSupported(obj, "ind");
-            IgnoreFieldThatIsNotYetSupported(obj, "ix");
-            IgnoreFieldThatIsNotYetSupported(obj, "hd");
-            IgnoreFieldThatIsNotYetSupported(obj, "cl");
-            IgnoreFieldThatIsNotYetSupported(obj, "closed");
+            // Not clear whether we need to read these properties.
+            obj.IgnorePropertyThatIsNotYetSupported("ind", "ix", "hd", "cl", "closed");
 
-            var geometry = ReadAnimatableGeometry(obj.GetNamedObject("ks"));
-            var direction = ReadBool(obj, "d") == true;
-            AssertAllFieldsRead(obj);
+            var geometry = ReadAnimatableGeometry(obj.ObjectOrNullProperty("ks"));
+            var direction = obj.BoolOrNullProperty("d") == true;
+            obj.AssertAllPropertiesRead();
             return new Path(in shapeLayerContentArgs, direction, geometry);
         }
 
-        TrimPath ReadTrimPath(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        TrimPath ReadTrimPath(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            // Not clear whether we need to read these fields.
-            IgnoreFieldThatIsNotYetSupported(obj, "ix");
-            IgnoreFieldThatIsNotYetSupported(obj, "hd");
+            // Not clear whether we need to read these properties.
+            obj.IgnorePropertyThatIsNotYetSupported("ix", "hd");
 
-            var startTrim = ReadAnimatableTrim(obj.GetNamedObject("s"));
-            var endTrim = ReadAnimatableTrim(obj.GetNamedObject("e"));
-            var offset = ReadAnimatableRotation(obj.GetNamedObject("o"));
-            var trimType = MToTrimType(obj.GetNamedNumber("m", 1));
-            AssertAllFieldsRead(obj);
+            var startTrim = ReadAnimatableTrim(obj.ObjectOrNullProperty("s"));
+            var endTrim = ReadAnimatableTrim(obj.ObjectOrNullProperty("e"));
+            var offset = ReadAnimatableRotation(obj.ObjectOrNullProperty("o"));
+            var trimType = MToTrimType(obj.DoubleOrNullProperty("m"));
+            obj.AssertAllPropertiesRead();
             return new TrimPath(
                 in shapeLayerContentArgs,
                 trimType,
@@ -446,52 +441,94 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                 offset);
         }
 
-        Repeater ReadRepeater(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        Repeater ReadRepeater(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            var count = ReadAnimatableFloat(obj.GetNamedObject("c"));
-            var offset = ReadAnimatableFloat(obj.GetNamedObject("o"));
-            var transform = ReadRepeaterTransform(obj.GetNamedObject("tr"), in shapeLayerContentArgs);
+            var count = ReadAnimatableFloat(obj.ObjectOrNullProperty("c"));
+            var offset = ReadAnimatableFloat(obj.ObjectOrNullProperty("o"));
+            var transform = ReadRepeaterTransform(obj.ObjectOrNullProperty("tr"), in shapeLayerContentArgs);
             return new Repeater(in shapeLayerContentArgs, count, offset, transform);
         }
 
-        MergePaths ReadMergePaths(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        MergePaths ReadMergePaths(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            // Not clear whether we need to read these fields.
-            IgnoreFieldThatIsNotYetSupported(obj, "hd");
+            // Not clear whether we need to read these properties.
+            obj.IgnorePropertyThatIsNotYetSupported("hd");
 
-            var mergeMode = MmToMergeMode(obj.GetNamedNumber("mm"));
-            AssertAllFieldsRead(obj);
+            var mergeMode = MmToMergeMode(obj.DoubleOrNullProperty("mm"));
+            obj.AssertAllPropertiesRead();
             return new MergePaths(
                 in shapeLayerContentArgs,
                 mergeMode);
         }
 
-        RoundedCorner ReadRoundedCorner(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        RoundedCorner ReadRoundedCorner(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            // Not clear whether we need to read these fields.
-            IgnoreFieldThatIsNotYetSupported(obj, "hd");
-            IgnoreFieldThatIsNotYetSupported(obj, "ix");
+            // Not clear whether we need to read these properties.
+            obj.IgnorePropertyThatIsNotYetSupported("hd", "ix");
 
-            var radius = ReadAnimatableFloat(obj.GetNamedObject("r"));
-            AssertAllFieldsRead(obj);
+            var radius = ReadAnimatableFloat(obj.ObjectOrNullProperty("r"));
+            obj.AssertAllPropertiesRead();
             return new RoundedCorner(
                 in shapeLayerContentArgs,
                 radius);
         }
 
-        ShapeFill.PathFillType ReadFillType(JCObject obj)
+        ShapeFill.PathFillType ReadFillType(in LottieJsonObjectElement obj)
         {
-            var isWindingFill = ReadBool(obj, "r") == true;
-            return isWindingFill ? ShapeFill.PathFillType.Winding : ShapeFill.PathFillType.EvenOdd;
+            // If not specified, the fill type is EvenOdd.
+            var windingValue = obj.Int32OrNullProperty("r");
+            switch (windingValue)
+            {
+                case 0: return ShapeFill.PathFillType.EvenOdd;
+                case 1: return ShapeFill.PathFillType.Winding;
+
+                // TODO - some files have a "2" value. There
+                // may be another fill type.
+                default: return ShapeFill.PathFillType.EvenOdd;
+            }
         }
 
         // Reads the transform for a repeater. Repeater transforms are the same as regular transforms
         // except they have an extra couple properties.
-        RepeaterTransform ReadRepeaterTransform(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        RepeaterTransform ReadRepeaterTransform(
+            in LottieJsonObjectElement? obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            var startOpacity = ReadOpacityFromObject(obj.GetNamedObject("so", null));
-            var endOpacity = ReadOpacityFromObject(obj.GetNamedObject("eo", null));
+            if (obj is null)
+            {
+                return new RepeaterTransform(
+                    shapeLayerContentArgs,
+                    s_animatableVector3Zero,
+                    s_animatableVector3Zero,
+                    s_animatableVector3Zero,
+                    s_animatableRotationNone,
+                    s_animatableOpacityOpaque,
+                    s_animatableOpacityOpaque,
+                    s_animatableOpacityOpaque);
+            }
+            else
+            {
+                return ReadRepeaterTransform(obj.Value, shapeLayerContentArgs);
+            }
+        }
+
+        RepeaterTransform ReadRepeaterTransform(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        {
+            obj.IgnorePropertyThatIsNotYetSupported("nm", "ty");
+
+            var startOpacity = ReadOpacityFromObject(obj.ObjectOrNullProperty("so"));
+            var endOpacity = ReadOpacityFromObject(obj.ObjectOrNullProperty("eo"));
             var transform = ReadTransform(obj, in shapeLayerContentArgs);
+
+            obj.AssertAllPropertiesRead();
             return new RepeaterTransform(
                 in shapeLayerContentArgs,
                 transform.Anchor,
@@ -503,38 +540,54 @@ namespace Microsoft.Toolkit.Uwp.UI.Lottie.LottieData.Serialization
                 endOpacity);
         }
 
-        Transform ReadTransform(JCObject obj, in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        Transform ReadTransform(
+            in LottieJsonObjectElement? obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
         {
-            var anchorJson = obj.GetNamedObject("a", null);
+            if (obj is null)
+            {
+                return new Transform(
+                    shapeLayerContentArgs,
+                    s_animatableVector3Zero,
+                    s_animatableVector3Zero,
+                    s_animatableVector3Zero,
+                    s_animatableRotationNone,
+                    s_animatableOpacityOpaque);
+            }
+            else
+            {
+                return ReadTransform(obj.Value, shapeLayerContentArgs);
+            }
+        }
 
-            var anchor =
-                anchorJson != null
-                ? ReadAnimatableVector3(anchorJson)
-                : new AnimatableVector3(Vector3.Zero, null);
+        Transform ReadTransform(
+            in LottieJsonObjectElement obj,
+            in ShapeLayerContent.ShapeLayerContentArgs shapeLayerContentArgs)
+        {
+            // Not clear whether we need to read these properties.
+            obj.IgnorePropertyThatIsNotYetSupported("sa", "sk");
+            obj.IgnorePropertyThatIsNotYetSupported("or", "rx", "ry");
+            obj.IgnorePropertyThatIsNotYetSupported("nm", "ty");
 
-            var positionJson = obj.GetNamedObject("p", null);
+            var anchorJson = obj.ObjectOrNullProperty("a");
 
-            var position =
-                positionJson != null
-                    ? ReadAnimatableVector3(positionJson)
-                    : new AnimatableVector3(Vector3.Zero, null);
-
-            var scaleJson = obj.GetNamedObject("s", null);
+            var anchor = ReadAnimatableVector3(anchorJson);
+            var positionJson = obj.ObjectOrNullProperty("p");
+            var position = ReadAnimatableVector3(positionJson);
+            var scaleJson = obj.ObjectOrNullProperty("s");
 
             var scalePercent =
                 scaleJson != null
                     ? ReadAnimatableVector3(scaleJson)
                     : new AnimatableVector3(new Vector3(100, 100, 100), null);
 
-            var rotationJson = obj.GetNamedObject("r", null) ?? obj.GetNamedObject("rz", null);
+            var rotationJson = obj.ObjectOrNullProperty("r") ?? obj.ObjectOrNullProperty("rz");
 
-            var rotation =
-                    rotationJson != null
-                        ? ReadAnimatableRotation(rotationJson)
-                        : new Animatable<Rotation>(Rotation.None, null);
+            var rotation = ReadAnimatableRotation(rotationJson);
 
             var opacity = ReadOpacityFromO(obj);
 
+            obj.AssertAllPropertiesRead();
             return new Transform(in shapeLayerContentArgs, anchor, position, scalePercent, rotation, opacity);
         }
     }