Merge branch 'master' into logical-extensions

src/Avalonia.Visuals/Rendering/DeferredRenderer.cs

@@ -35,6 +35,7 @@ namespace Avalonia.Rendering
         private IRef<IDrawOperation> _currentDraw;
         private readonly IDeferredRendererLock _lock;
         private readonly object _sceneLock = new object();
+        private readonly Action _updateSceneIfNeededDelegate;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="DeferredRenderer"/> class.
@@ -49,7 +50,7 @@ namespace Avalonia.Rendering
             IRenderLoop renderLoop,
             ISceneBuilder sceneBuilder = null,
             IDispatcher dispatcher = null,
-            IDeferredRendererLock rendererLock = null)
+            IDeferredRendererLock rendererLock = null) : base(true)
         {
             Contract.Requires<ArgumentNullException>(root != null);
 
@@ -59,6 +60,7 @@ namespace Avalonia.Rendering
             Layers = new RenderLayers();
             _renderLoop = renderLoop;
             _lock = rendererLock ?? new ManagedDeferredRendererLock();
+            _updateSceneIfNeededDelegate = UpdateSceneIfNeeded;
         }
 
         /// <summary>
@@ -73,7 +75,7 @@ namespace Avalonia.Rendering
         public DeferredRenderer(
             IVisual root,
             IRenderTarget renderTarget,
-            ISceneBuilder sceneBuilder = null)
+            ISceneBuilder sceneBuilder = null) : base(true)
         {
             Contract.Requires<ArgumentNullException>(root != null);
             Contract.Requires<ArgumentNullException>(renderTarget != null);
@@ -83,6 +85,7 @@ namespace Avalonia.Rendering
             _sceneBuilder = sceneBuilder ?? new SceneBuilder();
             Layers = new RenderLayers();
             _lock = new ManagedDeferredRendererLock();
+            _updateSceneIfNeededDelegate = UpdateSceneIfNeeded;
         }
 
         /// <inheritdoc/>
@@ -261,7 +264,8 @@ namespace Avalonia.Rendering
                     try
                     {
                         var (scene, updated) = UpdateRenderLayersAndConsumeSceneIfNeeded(ref context);
-
+                        if (updated)
+                            FpsTick();
                         using (scene)
                         {
                             if (scene?.Item != null)
@@ -318,17 +322,25 @@ namespace Avalonia.Rendering
                         _lastSceneId = scene.Generation;
 
 
+                    var isUiThread = Dispatcher.UIThread.CheckAccess();
                     // We have consumed the previously available scene, but there might be some dirty 
                     // rects since the last update. *If* we are on UI thread, we can force immediate scene
                     // rebuild before rendering anything on-screen
                     // We are calling the same method recursively here 
-                    if (!recursiveCall && Dispatcher.UIThread.CheckAccess() && NeedsUpdate)
+                    if (!recursiveCall && isUiThread && NeedsUpdate)
                     {
                         UpdateScene();
                         var (rs, _) = UpdateRenderLayersAndConsumeSceneIfNeeded(ref context, true);
                         return (rs, true);
                     }
 
+                    // We are rendering a new scene version, so it's highly likely
+                    // that there is already a pending update for animations
+                    // So we are scheduling an update call so UI thread could prepare a scene before
+                    // the next render timer tick
+                    if (!recursiveCall && !isUiThread)
+                        Dispatcher.UIThread.Post(_updateSceneIfNeededDelegate, DispatcherPriority.Render);
+
                     // Indicate that we have updated the layers
                     return (sceneRef.Clone(), true);
                 }
@@ -534,6 +546,12 @@ namespace Avalonia.Rendering
             context = RenderTarget.CreateDrawingContext(this);
         }
 
+        private void UpdateSceneIfNeeded()
+        {
+            if(NeedsUpdate)
+                UpdateScene();
+        }
+        
         private void UpdateScene()
         {
             Dispatcher.UIThread.VerifyAccess();

src/Avalonia.Visuals/Rendering/RendererBase.cs

@@ -7,6 +7,7 @@ namespace Avalonia.Rendering
 {
     public class RendererBase
     {
+        private readonly bool _useManualFpsCounting;
         private static int s_fontSize = 18;
         private readonly Stopwatch _stopwatch = Stopwatch.StartNew();
         private int _framesThisSecond;
@@ -14,8 +15,9 @@ namespace Avalonia.Rendering
         private FormattedText _fpsText;
         private TimeSpan _lastFpsUpdate;
 
-        public RendererBase()
+        public RendererBase(bool useManualFpsCounting = false)
         {
+            _useManualFpsCounting = useManualFpsCounting;
             _fpsText = new FormattedText
             {
                 Typeface = FontManager.Current?.GetOrAddTypeface(FontFamily.Default),
@@ -23,12 +25,15 @@ namespace Avalonia.Rendering
             };
         }
 
+        protected void FpsTick() => _framesThisSecond++;
+
         protected void RenderFps(IDrawingContextImpl context, Rect clientRect, int? layerCount)
         {
             var now = _stopwatch.Elapsed;
             var elapsed = now - _lastFpsUpdate;
 
-            ++_framesThisSecond;
+            if (!_useManualFpsCounting)
+                ++_framesThisSecond;
 
             if (elapsed.TotalSeconds > 1)
             {

tests/Avalonia.RenderTests/TestBase.cs

@@ -184,7 +184,7 @@ namespace Avalonia.Direct2D1.RenderTests
 
             public void Signal(DispatcherPriority prio)
             {
-                throw new NotImplementedException();
+                // No-op
             }
 
             public IDisposable StartTimer(DispatcherPriority priority, TimeSpan interval, Action tick)