Merge pull request #2746 from DGenix/unblock-setup

MvxSetupSingleton optimizations / Fix SplashScreen initialization on Android

MvvmCross.Android.Support/V7.AppCompat/MvxAppCompatActivity.cs

@@ -13,7 +13,6 @@ using MvvmCross.Core;
 using MvvmCross.Droid.Support.V7.AppCompat.EventSource;
 using MvvmCross.Platforms.Android.Binding.BindingContext;
 using MvvmCross.Platforms.Android.Binding.Views;
-using MvvmCross.Platforms.Android.Core;
 using MvvmCross.Platforms.Android.Views;
 using MvvmCross.ViewModels;
 
@@ -85,15 +84,16 @@ namespace MvvmCross.Droid.Support.V7.AppCompat
         }
 
         protected override void OnCreate(Bundle bundle)
-        {  
-            var setup = MvxAndroidSetupSingleton.EnsureSingletonAvailable(ApplicationContext);
-            setup.EnsureInitialized();
-
+        {
             base.OnCreate(bundle);
             ViewModel?.ViewCreated();
-            RunAppStart(bundle);
-        }
 
+            if(!(this is IMvxSetupMonitor))
+            {
+                RunAppStart(bundle);
+            }
+        }
+        
         protected virtual void RunAppStart(Bundle bundle)
         {
             var startup = Mvx.Resolve<IMvxAppStart>();

MvvmCross.Android.Support/V7.AppCompat/MvxSplashScreenAppCompatActivity.cs

@@ -7,7 +7,6 @@ using Android.Runtime;
 using Android.Views;
 using MvvmCross.Core;
 using MvvmCross.Platforms.Android.Core;
-using MvvmCross.Platforms.Android.Views;
 using MvvmCross.ViewModels;
 
 namespace MvvmCross.Droid.Support.V7.AppCompat
@@ -20,6 +19,8 @@ namespace MvvmCross.Droid.Support.V7.AppCompat
 
         private readonly int _resourceId;
 
+        private Bundle _bundle;
+
         public new MvxNullViewModel ViewModel
         {
             get { return base.ViewModel as MvxNullViewModel; }
@@ -40,6 +41,8 @@ namespace MvvmCross.Droid.Support.V7.AppCompat
         {
             RequestWindowFeatures();
 
+            _bundle = bundle;
+
             var setup = MvxAndroidSetupSingleton.EnsureSingletonAvailable(ApplicationContext);
             setup.InitializeAndMonitor(this);
 
@@ -77,14 +80,7 @@ namespace MvvmCross.Droid.Support.V7.AppCompat
             if (!_isResumed)
                 return;
 
-            TriggerFirstNavigate();
-        }
-
-        protected virtual void TriggerFirstNavigate()
-        {
-            var startup = Mvx.Resolve<IMvxAppStart>();
-            if (!startup.IsStarted)
-                startup.Start();
+            RunAppStart(_bundle);
         }
     }
 }

MvvmCross.Forms/Platforms/Android/Views/MvxFormsAppCompatActivity.cs

@@ -97,6 +97,8 @@ namespace MvvmCross.Forms.Platforms.Android.Views
 
         protected override void OnCreate(Bundle bundle)
         {
+            // ensuring mvvmcross is running here is required
+            // otherwise app will crash when inflating the view because of the Forms base class
             var setup = MvxAndroidSetupSingleton.EnsureSingletonAvailable(ApplicationContext);
             setup.EnsureInitialized();
 

MvvmCross.Forms/Platforms/Android/Views/MvxFormsApplicationActivity.cs

@@ -95,7 +95,8 @@ namespace MvvmCross.Forms.Platforms.Android.Views
 
         protected override void OnCreate(Bundle bundle)
         {
-            // Required for proper Push notifications handling      
+            // ensuring mvvmcross is running here is required
+            // otherwise app will crash when inflating the view because of the Forms base class
             var setup = MvxAndroidSetupSingleton.EnsureSingletonAvailable(ApplicationContext);
             setup.EnsureInitialized();
 

MvvmCross/Core/MvxSetupSingleton.cs

@@ -10,24 +10,48 @@ using MvvmCross.Logging;
 
 namespace MvvmCross.Core
 {
+    /// <summary>
+    /// The setup singleton is designed to ensure only a single instance
+    /// of MvxSetup is created and invoked. There are three important methods
+    /// to the MvxSetupSingleton class:
+    /// EnsureSingletonAvailable - this is a static method that will return 
+    /// the one and only instance of MvxSetupSingleton. This method is protected
+    /// as it's assumed that each platform will provide a platform specific
+    /// public overload for this method which will include any platform parameters
+    /// required
+    /// EnsureInitialized - this is an instance method that should be called 
+    /// to guarrantee that setup has been created and initialized. This method 
+    /// is blocking so make sure it's only called at a point where there
+    /// are no other UI methods are being invoked. This method is typically called
+    /// in applications where there is no splash screen.
+    /// InitializeAndMonitor - this is an instance method that can be called 
+    /// to make sure that the initialization of setup has begun. It registers
+    /// an object to be notified when setup initialization has completed. The callback
+    /// will be raised on the UI thread. This method is not blocking, and doesn't
+    /// guarrantee setup initialize has finished when it returns. This method is 
+    /// typically called by the splash screen view of an application, passing
+    /// itself in as the object to be notified. On notification the splash screen 
+    /// view will trigger navigation to the first view
+    /// </summary>
     public abstract class MvxSetupSingleton
        : MvxSingleton<MvxSetupSingleton>
     {
         private static readonly object LockObject = new object();
         private static TaskCompletionSource<bool> IsInitialisedTaskCompletionSource;
         private IMvxSetup _setup;
-        private bool _initialized;
         private IMvxSetupMonitor _currentMonitor;
 
-        protected virtual IMvxSetup Setup
-        {
-            get
-            {
-                return _setup;
-            }
-        }
+        protected virtual IMvxSetup Setup => _setup;
 
-        public virtual TMvxSetup PlatformSetup<TMvxSetup>() where TMvxSetup : IMvxSetup
+        /// <summary>
+        /// Returns a platform specific instance of Setup
+        /// A useful overload to allow for platform specific
+        /// setup logic to be invoked.
+        /// </summary>
+        /// <typeparam name="TMvxSetup">The platform specific setup type</typeparam>
+        /// <returns>A platform specific instance of Setup</returns>
+        public virtual TMvxSetup PlatformSetup<TMvxSetup>()
+            where TMvxSetup : IMvxSetup
         {
             try
             {
@@ -40,17 +64,27 @@ namespace MvvmCross.Core
             }
         }
 
+        /// <summary>
+        /// Returns a singleton object that is used to manage the creation and
+        /// execution of setup
+        /// </summary>
+        /// <typeparam name="TMvxSetupSingleton">The platform specific setup singleton type</typeparam>
+        /// <returns>A platform specific setup singleton</returns>
         protected static TMvxSetupSingleton EnsureSingletonAvailable<TMvxSetupSingleton>()
            where TMvxSetupSingleton : MvxSetupSingleton, new()
         {
+            // Double null - check before creating the setup singleton object
             if (Instance != null)
                 return Instance as TMvxSetupSingleton;
-
             lock (LockObject)
             {
                 if (Instance != null)
                     return Instance as TMvxSetupSingleton;
 
+                // Go ahead and create the setup singleton, and then
+                // create the setup instance. 
+                // Note that the Instance property is set within the 
+                // singleton constructor
                 var instance = new TMvxSetupSingleton();
                 instance.CreateSetup();
                 return Instance as TMvxSetupSingleton;
@@ -61,19 +95,18 @@ namespace MvvmCross.Core
         {
             lock (LockObject)
             {
-                if (_initialized)
-                    return;
-
                 if (IsInitialisedTaskCompletionSource == null)
                 {
-                    IsInitialisedTaskCompletionSource = StartSetupInitialization();
+                    StartSetupInitialization();
                 }
                 else
                 {
+                    if (IsInitialisedTaskCompletionSource.Task.IsCompleted)
+                        return;
+
                     MvxLog.Instance.Trace("EnsureInitialized has already been called so now waiting for completion");
                 }
             }
-
             IsInitialisedTaskCompletionSource.Task.GetAwaiter().GetResult();
         }
 
@@ -82,18 +115,21 @@ namespace MvvmCross.Core
             lock (LockObject)
             {
                 _currentMonitor = setupMonitor;
-                if (_initialized)
-                {
-                    _currentMonitor?.InitializationComplete();
-                    return;
-                }
-
+                
+                // if the tcs is not null, it means the initialization is running
                 if (IsInitialisedTaskCompletionSource != null)
                 {
+                    // If the task is already completed at this point, let the monitor know it has finished. 
+                    // but don't do it otherwise because it's done elsewhere
+                    if(IsInitialisedTaskCompletionSource.Task.IsCompleted)
+                    {
+                        _currentMonitor?.InitializationComplete();
+                    }
+
                     return;
                 }
-
-                IsInitialisedTaskCompletionSource = StartSetupInitialization();
+                
+                StartSetupInitialization();
             }
         }
 
@@ -101,17 +137,14 @@ namespace MvvmCross.Core
         {
             lock (LockObject)
             {
-                if (setupMonitor == _currentMonitor)
+                if (setupMonitor != _currentMonitor)
                 {
-                    _currentMonitor = null;
+                    throw new MvxException("The specified IMvxSetupMonitor is not the one registered in MvxSetupSingleton");
                 }
+                _currentMonitor = null;
             }
         }
 
-        protected MvxSetupSingleton()
-        {
-        }
-
         protected virtual void CreateSetup()
         {
             try
@@ -136,17 +169,16 @@ namespace MvvmCross.Core
             base.Dispose(isDisposing);
         }
 
-        private TaskCompletionSource<bool> StartSetupInitialization()
+        private void StartSetupInitialization()
         {
-            var completionSource = new TaskCompletionSource<bool>();
+            IsInitialisedTaskCompletionSource = new TaskCompletionSource<bool>();
             _setup.InitializePrimary();
             Task.Run(() =>
             {
                 _setup.InitializeSecondary();
                 lock (LockObject)
                 {
-                    completionSource.SetResult(true);
-                    _initialized = true;
+                    IsInitialisedTaskCompletionSource.SetResult(true);
                     var dispatcher = Mvx.GetSingleton<IMvxMainThreadDispatcher>();
                     dispatcher.RequestMainThreadAction(() =>
                     {
@@ -157,8 +189,6 @@ namespace MvvmCross.Core
                     });
                 }
             });
-
-            return completionSource;
         }
     }
 }

MvvmCross/Platforms/Android/Views/MvxActivity.cs

@@ -15,7 +15,6 @@ using MvvmCross.Platforms.Android.Binding.BindingContext;
 using MvvmCross.Platforms.Android.Binding.Views;
 using MvvmCross.ViewModels;
 using MvvmCross.Core;
-using MvvmCross.Platforms.Android.Core;
 
 namespace MvvmCross.Platforms.Android.Views
 {
@@ -113,14 +112,15 @@ namespace MvvmCross.Platforms.Android.Views
 
         protected override void OnCreate(Bundle bundle)
         {
-            var setup = MvxAndroidSetupSingleton.EnsureSingletonAvailable(ApplicationContext);
-            setup.EnsureInitialized();
-
             base.OnCreate(bundle);
             ViewModel?.ViewCreated();
-            RunAppStart(bundle);
-        }
 
+            if (!(this is IMvxSetupMonitor))
+            {
+                RunAppStart(bundle);
+            }
+        }
+        
         protected virtual void RunAppStart(Bundle bundle)
         {
             var startup = Mvx.Resolve<IMvxAppStart>();

MvvmCross/Platforms/Android/Views/MvxActivityViewExtensions.cs

@@ -139,7 +139,7 @@ namespace MvvmCross.Platforms.Android.Views
         {
             if (androidView is IMvxSetupMonitor)
             {
-                // splash screen views manage their own setup initialization
+                // setup monitor views manage their own setup initialization
                 return;
             }
 

MvvmCross/Platforms/Android/Views/MvxSplashScreenActivity.cs

@@ -19,6 +19,8 @@ namespace MvvmCross.Platforms.Android.Views
 
         private readonly int _resourceId;
 
+        private Bundle _bundle;
+
         public new MvxNullViewModel ViewModel
         {
             get { return base.ViewModel as MvxNullViewModel; }
@@ -39,6 +41,8 @@ namespace MvvmCross.Platforms.Android.Views
         {
             RequestWindowFeatures();
 
+            _bundle = bundle;
+
             var setup = MvxAndroidSetupSingleton.EnsureSingletonAvailable(ApplicationContext);
             setup.InitializeAndMonitor(this);
 
@@ -76,14 +80,7 @@ namespace MvvmCross.Platforms.Android.Views
             if (!_isResumed)
                 return;
 
-            TriggerFirstNavigate();
-        }
-
-        protected virtual void TriggerFirstNavigate()
-        {
-            var startup = Mvx.Resolve<IMvxAppStart>();
-            if (!startup.IsStarted)
-                startup.Start();
+            RunAppStart(_bundle);
         }
     }
 }

Projects/Playground/Playground.Droid/MainApplication.cs

@@ -6,7 +6,6 @@ using System;
 using Android.App;
 using Android.Runtime;
 using MvvmCross.Droid.Support.V7.AppCompat;
-using MvvmCross.Platforms.Android.Views;
 using Playground.Core;
 
 namespace Playground.Droid

Projects/Playground/Playground.Droid/Playground.Droid.csproj

@@ -114,11 +114,11 @@
       <SubType>Designer</SubType>
     </AndroidResource>
     <AndroidResource Include="Resources\values\Strings.xml" />
-    <AndroidResource Include="Resources\mipmap-hdpi\Icon.png" />
-    <AndroidResource Include="Resources\mipmap-mdpi\Icon.png" />
-    <AndroidResource Include="Resources\mipmap-xhdpi\Icon.png" />
-    <AndroidResource Include="Resources\mipmap-xxhdpi\Icon.png" />
-    <AndroidResource Include="Resources\mipmap-xxxhdpi\Icon.png" />
+    <AndroidResource Include="Resources\mipmap-hdpi\icon.png" />
+    <AndroidResource Include="Resources\mipmap-mdpi\icon.png" />
+    <AndroidResource Include="Resources\mipmap-xhdpi\icon.png" />
+    <AndroidResource Include="Resources\mipmap-xxhdpi\icon.png" />
+    <AndroidResource Include="Resources\mipmap-xxxhdpi\icon.png" />
     <AndroidResource Include="Resources\layout\SplashScreen.axml" />
     <AndroidResource Include="Resources\values\styles.xml" />
     <AndroidResource Include="Resources\values-v21\styles.xml" />

Projects/Playground/Playground.Droid/Resources/layout/SplashScreen.axml

@@ -2,7 +2,8 @@
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:orientation="vertical"
     android:layout_width="match_parent"
-    android:layout_height="match_parent">
+    android:layout_height="match_parent"
+    android:background="@color/colorAccent">
     <TextView
         android:layout_width="match_parent"
         android:layout_height="match_parent"

Projects/Playground/Playground.Droid/SplashScreen.cs

@@ -4,7 +4,7 @@
 
 using Android.App;
 using Android.Content.PM;
-using MvvmCross.Platforms.Android.Views;
+using MvvmCross.Droid.Support.V7.AppCompat;
 
 namespace Playground.Droid
 {
@@ -15,7 +15,7 @@ namespace Playground.Droid
         , Theme = "@style/AppTheme.Splash"
         , NoHistory = true
         , ScreenOrientation = ScreenOrientation.Portrait)]
-    public class SplashScreen : MvxSplashScreenActivity
+    public class SplashScreen : MvxSplashScreenAppCompatActivity
     {
         public SplashScreen()
             : base(Resource.Layout.SplashScreen)

Projects/Playground/Playground.Forms.Droid/SplashScreen.cs

@@ -4,6 +4,7 @@
 
 using Android.App;
 using Android.Content.PM;
+using Android.OS;
 using MvvmCross.Core;
 using MvvmCross.Platforms.Android.Views;
 
@@ -25,10 +26,10 @@ namespace Playground.Forms.Droid
             this.RegisterSetupType<Setup>();
         }
 
-        protected override void TriggerFirstNavigate()
+        protected override void RunAppStart(Bundle bundle)
         {
             StartActivity(typeof(MainActivity));
-            base.TriggerFirstNavigate();
+            base.RunAppStart(bundle);
         }
     }
 }