[Android, iOS] Allow transparent background color in SwipeView Content (#9726) fixes #9305

* Allow transparent background color in SwipeView

* Update Xamarin.Forms.Controls.Issues.Shared.projitems

Co-authored-by: Rui Marinho <me@ruimarinho.net>

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue9305.xaml

@@ -0,0 +1,59 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<controls:TestContentPage xmlns="http://xamarin.com/schemas/2014/forms"
+             xmlns:controls="clr-namespace:Xamarin.Forms.Controls"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:d="http://xamarin.com/schemas/2014/forms/design"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             mc:Ignorable="d"
+             x:Class="Xamarin.Forms.Controls.Issues.Issue9305">
+    <ContentPage.Content>
+        <Grid>
+           <Image
+               Aspect="AspectFill"
+               Source="Fruits.jpg"/>
+            <StackLayout>
+                 <SwipeView>
+                    <SwipeView.LeftItems>
+                        <SwipeItems>
+                            <SwipeItem
+                                Text="Favorite"
+                                BackgroundColor="LightGreen" />
+                            <SwipeItem
+                                Text="Delete"
+                                BackgroundColor="LightPink" />
+                        </SwipeItems>
+                    </SwipeView.LeftItems>
+                    <Grid
+                        HeightRequest="60"
+                        WidthRequest="300">
+                        <Label
+                            Text="Swipe right"
+                            HorizontalOptions="Center"
+                            VerticalOptions="Center" />
+                    </Grid>
+                </SwipeView>
+                <SwipeView
+                    BackgroundColor="Transparent">
+                    <SwipeView.LeftItems>
+                        <SwipeItems>
+                            <SwipeItem
+                                Text="Favorite"
+                                BackgroundColor="LightGreen" />
+                            <SwipeItem
+                                Text="Delete"
+                                BackgroundColor="LightPink" />
+                        </SwipeItems>
+                    </SwipeView.LeftItems>
+                    <Grid
+                        HeightRequest="60"
+                        WidthRequest="300">
+                        <Label
+                            Text="Swipe right"
+                            HorizontalOptions="Center"
+                            VerticalOptions="Center" />
+                    </Grid>
+                </SwipeView>
+            </StackLayout>
+        </Grid>
+    </ContentPage.Content>
+</controls:TestContentPage>

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue9305.xaml.cs

@@ -0,0 +1,29 @@
+using Xamarin.Forms.CustomAttributes;
+using System.Collections.Generic;
+
+#if UITEST
+using Xamarin.Forms.Core.UITests;
+using Xamarin.UITest;
+using NUnit.Framework;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Issue(IssueTracker.Github, 9305, "Swipe View BackgroundColor Issues", PlatformAffected.Android | PlatformAffected.iOS)]
+	public partial class Issue9305 : TestContentPage
+	{
+		public Issue9305()
+		{
+#if APP
+			Device.SetFlags(new List<string> { ExperimentalFlags.SwipeViewExperimental });
+			Title = "Issue 9305";
+			InitializeComponent();
+#endif
+		}
+
+		protected override void Init()
+		{
+
+		}
+	}
+}

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems

@@ -1268,6 +1268,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue8777.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue9588.xaml.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue9329.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Issue9305.xaml.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue9767.cs" />
   </ItemGroup>
   <ItemGroup>
@@ -1418,6 +1419,10 @@
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue8326.xaml" />
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue8449.xaml" />
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue7924.xaml" />
+    <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue9305.xaml">
+       <SubType>Designer</SubType>
+       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue9588.xaml">
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
     </EmbeddedResource>
@@ -1834,4 +1839,4 @@
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
     </EmbeddedResource>
   </ItemGroup>
-</Project>
+</Project>

Xamarin.Forms.Platform.Android/Renderers/SwipeViewRenderer.cs

@@ -28,7 +28,6 @@ namespace Xamarin.Forms.Platform.Android
 	public class SwipeViewRenderer : ViewRenderer<SwipeView, AView>, GestureDetector.IOnGestureListener
 	{
 		const int SwipeThreshold = 250;
-		const int SwipeThresholdMargin = 0;
 		const int SwipeItemWidth = 100;
 		const long SwipeAnimationDuration = 200;
 		const float SwipeMinimumDelta = 10f;
@@ -141,7 +140,7 @@ namespace Xamarin.Forms.Platform.Android
 
 				SetBackgroundColor(backgroundColor);
 
-				if (Element.Content == null)
+				if (Element.Content == null || (Element.Content != null && Element.Content.BackgroundColor == Color.Default))
 					_contentView?.SetBackgroundColor(backgroundColor);
 			}
 			else
@@ -578,7 +577,7 @@ namespace Xamarin.Forms.Platform.Android
 
 		void UpdateSwipeItems()
 		{
-			if (_contentView == null)
+			if (_contentView == null || _actionView != null)
 				return;
 
 			var items = GetSwipeItemsByDirection();
@@ -730,7 +729,7 @@ namespace Xamarin.Forms.Platform.Android
 		{
 			if (_actionView != null)
 			{
-				RemoveView(_actionView);
+				_actionView.RemoveFromParent();
 				_actionView.Dispose();
 				_actionView = null;
 			}
@@ -1019,13 +1018,13 @@ namespace Xamarin.Forms.Platform.Android
 				if (swipeThreshold > contentWidth)
 					swipeThreshold = contentWidth;
 
-				return swipeThreshold - SwipeThresholdMargin;
+				return swipeThreshold;
 			}
 
 			if (swipeThreshold > contentHeight)
 				swipeThreshold = contentHeight;
 
-			return swipeThreshold - SwipeThresholdMargin / 2;
+			return swipeThreshold;
 		}
 
 		Size GetSwipeItemSize(ISwipeItem swipeItem)

Xamarin.Forms.Platform.iOS/Renderers/SwipeViewRenderer.cs

@@ -14,7 +14,6 @@ namespace Xamarin.Forms.Platform.iOS
 	public class SwipeViewRenderer : ViewRenderer<SwipeView, UIView>
 	{
 		const double SwipeThreshold = 250;
-		const int SwipeThresholdMargin = 0;
 		const double SwipeItemWidth = 100;
 		const double SwipeAnimationDuration = 0.2;
 		const double SwipeMinimumDelta = 10;
@@ -148,7 +147,7 @@ namespace Xamarin.Forms.Platform.iOS
 			{
 				BackgroundColor = Element.BackgroundColor.ToUIColor();
 
-				if (_contentView != null && Element.Content == null)
+				if (_contentView != null && (Element.Content == null || (Element.Content != null && Element.Content.BackgroundColor == Color.Default)))
 					_contentView.BackgroundColor = Element.BackgroundColor.ToUIColor();
 			}
 			else
@@ -916,13 +915,13 @@ namespace Xamarin.Forms.Platform.iOS
 				if (swipeThreshold > _contentView.Frame.Width)
 					swipeThreshold = _contentView.Frame.Width;
 
-				return swipeThreshold - SwipeThresholdMargin;
+				return swipeThreshold;
 			}
 
 			if (swipeThreshold > _contentView.Frame.Height)
 				swipeThreshold = _contentView.Frame.Height;
 
-			return swipeThreshold - SwipeThresholdMargin / 2;
+			return swipeThreshold;
 		}
 
 		Size GetSwipeItemSize(ISwipeItem swipeItem)