[Win32] Fix GL-rendering jitter on resize

samples/ControlCatalog.NetCore/ControlCatalog.NetCore.csproj

@@ -10,6 +10,7 @@
     <ProjectReference Include="..\ControlCatalog\ControlCatalog.csproj" />
     <ProjectReference Include="..\..\src\Avalonia.Desktop\Avalonia.Desktop.csproj" />
     <ProjectReference Include="..\..\src\Avalonia.X11\Avalonia.X11.csproj" />
+    <PackageReference Include="Avalonia.Angle.Windows.Natives" Version="2.1.0.2019013001"/>
   </ItemGroup>
 
 

src/Avalonia.OpenGL/EglDisplay.cs

@@ -97,6 +97,7 @@ namespace Avalonia.OpenGL
         
         public GlDisplayType Type { get; }
         public GlInterface GlInterface { get; }
+        public EglInterface EglInterface => _egl;
         public IGlContext CreateContext(IGlContext share)
         {
             var shareCtx = (EglContext)share;

src/Avalonia.OpenGL/EglGlPlatformSurface.cs

@@ -26,31 +26,44 @@ namespace Avalonia.OpenGL
         public IGlPlatformSurfaceRenderTarget CreateGlRenderTarget()
         {
             var glSurface = _display.CreateWindowSurface(_info.Handle);
-            return new RenderTarget(_context, glSurface, _info);
+            return new RenderTarget(_display, _context, glSurface, _info);
         }
 
-        class RenderTarget : IGlPlatformSurfaceRenderTarget
+        class RenderTarget : IGlPlatformSurfaceRenderTargetWithCorruptionInfo
         {
+            private readonly EglDisplay _display;
             private readonly EglContext _context;
             private readonly EglSurface _glSurface;
             private readonly IEglWindowGlPlatformSurfaceInfo _info;
+            private PixelSize _initialSize;
 
-            public RenderTarget(EglContext context, EglSurface glSurface, IEglWindowGlPlatformSurfaceInfo info)
+            public RenderTarget(EglDisplay display, EglContext context,
+                EglSurface glSurface, IEglWindowGlPlatformSurfaceInfo info)
             {
+                _display = display;
                 _context = context;
                 _glSurface = glSurface;
                 _info = info;
+                _initialSize = info.Size;
             }
 
             public void Dispose() => _glSurface.Dispose();
 
+            public bool IsCorrupted => _initialSize != _info.Size;
+            
             public IGlPlatformSurfaceRenderingSession BeginDraw()
             {
                 var l = _context.Lock();
                 try
                 {
+                    if (IsCorrupted)
+                        throw new RenderTargetCorruptedException();
                     _context.MakeCurrent(_glSurface);
-                    return new Session(_context, _glSurface, _info, l);
+                    _display.EglInterface.WaitClient();
+                    _display.EglInterface.WaitGL();
+                    _display.EglInterface.WaitNative();
+                    
+                    return new Session(_display, _context, _glSurface, _info, l);
                 }
                 catch
                 {
@@ -61,15 +74,19 @@ namespace Avalonia.OpenGL
             
             class Session : IGlPlatformSurfaceRenderingSession
             {
-                private readonly IGlContext _context;
+                private readonly EglContext _context;
                 private readonly EglSurface _glSurface;
                 private readonly IEglWindowGlPlatformSurfaceInfo _info;
+                private readonly EglDisplay _display;
                 private IDisposable _lock;
+                
 
-                public Session(IGlContext context, EglSurface glSurface, IEglWindowGlPlatformSurfaceInfo info,
+                public Session(EglDisplay display, EglContext context,
+                    EglSurface glSurface, IEglWindowGlPlatformSurfaceInfo info,
                     IDisposable @lock)
                 {
                     _context = context;
+                    _display = display;
                     _glSurface = glSurface;
                     _info = info;
                     _lock = @lock;
@@ -78,7 +95,11 @@ namespace Avalonia.OpenGL
                 public void Dispose()
                 {
                     _context.Display.GlInterface.Flush();
+                    _display.EglInterface.WaitGL();
                     _glSurface.SwapBuffers();
+                    _display.EglInterface.WaitClient();
+                    _display.EglInterface.WaitGL();
+                    _display.EglInterface.WaitNative();
                     _context.Display.ClearContext();
                     _lock.Dispose();
                 }

src/Avalonia.OpenGL/EglInterface.cs

@@ -107,6 +107,18 @@ namespace Avalonia.OpenGL
         [GlEntryPoint("eglGetConfigAttrib")]
         public EglGetConfigAttrib GetConfigAttrib { get; }
 
+        public delegate bool EglWaitGL();
+        [GlEntryPoint("eglWaitGL")]
+        public EglWaitGL WaitGL { get; }
+        
+        public delegate bool EglWaitClient();
+        [GlEntryPoint("eglWaitClient")]
+        public EglWaitGL WaitClient { get; }
+        
+        public delegate bool EglWaitNative();
+        [GlEntryPoint("eglWaitNative")]
+        public EglWaitGL WaitNative { get; }
+
         // ReSharper restore UnassignedGetOnlyAutoProperty
     }
 }

src/Avalonia.OpenGL/IGlPlatformSurfaceRenderTarget.cs

@@ -6,4 +6,9 @@ namespace Avalonia.OpenGL
     {
         IGlPlatformSurfaceRenderingSession BeginDraw();
     }
-}
+
+    public interface IGlPlatformSurfaceRenderTargetWithCorruptionInfo : IGlPlatformSurfaceRenderTarget
+    {
+        bool IsCorrupted { get; }
+    }
+}

src/Avalonia.Visuals/Platform/IRenderTarget.cs

@@ -23,4 +23,9 @@ namespace Avalonia.Platform
         /// </param>
         IDrawingContextImpl CreateDrawingContext(IVisualBrushRenderer visualBrushRenderer);
     }
+
+    public interface IRenderTargetWithCorruptionInfo : IRenderTarget
+    {
+        bool IsCorrupted { get; }
+    }
 }

src/Avalonia.Visuals/Rendering/DeferredRenderer.cs

@@ -248,6 +248,11 @@ namespace Avalonia.Rendering
                         {
                             if (context != null)
                                 return context;
+                            if ((RenderTarget as IRenderTargetWithCorruptionInfo)?.IsCorrupted == true)
+                            {
+                                RenderTarget.Dispose();
+                                RenderTarget = null;
+                            }
                             if (RenderTarget == null)
                                 RenderTarget = ((IRenderRoot)_root).CreateRenderTarget();
                             return context = RenderTarget.CreateDrawingContext(this);

src/Avalonia.Visuals/Rendering/ManagedDeferredRendererLock.cs

@@ -7,11 +7,25 @@ namespace Avalonia.Rendering
     public class ManagedDeferredRendererLock : IDeferredRendererLock
     {
         private readonly object _lock = new object();
+        
+        /// <summary>
+        /// Tries to lock the target surface or window
+        /// </summary>
+        /// <returns>IDisposable if succeeded to obtain the lock</returns>
         public IDisposable TryLock()
         {
             if (Monitor.TryEnter(_lock))
                 return Disposable.Create(() => Monitor.Exit(_lock));
             return null;
         }
+
+        /// <summary>
+        /// Enters a waiting lock, only use from platform code, not from the renderer
+        /// </summary>
+        public IDisposable Lock()
+        {
+            Monitor.Enter(_lock);
+            return Disposable.Create(() => Monitor.Exit(_lock));
+        }
     }
 }

src/Avalonia.Visuals/Rendering/UiThreadRenderTimer.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Diagnostics;
+using System.Reactive.Disposables;
+using Avalonia.Threading;
+
+namespace Avalonia.Rendering
+{
+    /// <summary>
+    /// Render timer that ticks on UI thread. Useful for debugging or bootstrapping on new platforms 
+    /// </summary>
+    
+    public class UiThreadRenderTimer : DefaultRenderTimer
+    {
+        public UiThreadRenderTimer(int framesPerSecond) : base(framesPerSecond)
+        {
+        }
+
+        protected override IDisposable StartCore(Action<TimeSpan> tick)
+        {
+            bool cancelled = false;
+            var st = Stopwatch.StartNew();
+            DispatcherTimer.Run(() =>
+            {
+                if (cancelled)
+                    return false;
+                tick(st.Elapsed);
+                return !cancelled;
+            }, TimeSpan.FromSeconds(1.0 / FramesPerSecond), DispatcherPriority.Render);
+            return Disposable.Create(() => cancelled = true);
+        }
+    }
+}

src/Skia/Avalonia.Skia/GlRenderTarget.cs

@@ -8,7 +8,7 @@ using static Avalonia.OpenGL.GlConsts;
 
 namespace Avalonia.Skia
 {
-    public class GlRenderTarget : IRenderTarget
+    public class GlRenderTarget : IRenderTargetWithCorruptionInfo
     {
         private readonly GRContext _grContext;
         private IGlPlatformSurfaceRenderTarget _surface;
@@ -21,6 +21,8 @@ namespace Avalonia.Skia
 
         public void Dispose() => _surface.Dispose();
 
+        public bool IsCorrupted => (_surface as IGlPlatformSurfaceRenderTargetWithCorruptionInfo)?.IsCorrupted == true;
+        
         public IDrawingContextImpl CreateDrawingContext(IVisualBrushRenderer visualBrushRenderer)
         {
             var session = _surface.BeginDraw();

src/Windows/Avalonia.Win32/WindowImpl.cs

@@ -31,6 +31,7 @@ namespace Avalonia.Win32
         private string _className;
         private IntPtr _hwnd;
         private IInputRoot _owner;
+        private ManagedDeferredRendererLock _rendererLock = new ManagedDeferredRendererLock();
         private bool _trackingMouse;
         private bool _decorated = true;
         private bool _resizable = true;
@@ -148,7 +149,9 @@ namespace Avalonia.Win32
             if (customRendererFactory != null)
                 return customRendererFactory.Create(root, loop);
 
-            return Win32Platform.UseDeferredRendering ? (IRenderer)new DeferredRenderer(root, loop) : new ImmediateRenderer(root);
+            return Win32Platform.UseDeferredRendering ?
+                (IRenderer)new DeferredRenderer(root, loop, rendererLock: _rendererLock) :
+                new ImmediateRenderer(root);
         }
 
         public void Resize(Size value)
@@ -627,18 +630,26 @@ namespace Avalonia.Win32
                     break;
 
                 case UnmanagedMethods.WindowsMessage.WM_PAINT:
-                    UnmanagedMethods.PAINTSTRUCT ps;
-                    if (UnmanagedMethods.BeginPaint(_hwnd, out ps) != IntPtr.Zero)
+                    using (_rendererLock.Lock())
                     {
-                        var f = Scaling;
-                        var r = ps.rcPaint;
-                        Paint?.Invoke(new Rect(r.left / f, r.top / f, (r.right - r.left) / f, (r.bottom - r.top) / f));
-                        UnmanagedMethods.EndPaint(_hwnd, ref ps);
+                        UnmanagedMethods.PAINTSTRUCT ps;
+                        if (UnmanagedMethods.BeginPaint(_hwnd, out ps) != IntPtr.Zero)
+                        {
+                            var f = Scaling;
+                            var r = ps.rcPaint;
+                            Paint?.Invoke(new Rect(r.left / f, r.top / f, (r.right - r.left) / f,
+                                (r.bottom - r.top) / f));
+                            UnmanagedMethods.EndPaint(_hwnd, ref ps);
+                        }
                     }
 
                     return IntPtr.Zero;
 
                 case UnmanagedMethods.WindowsMessage.WM_SIZE:
+                    using (_rendererLock.Lock())
+                    {
+                        // Do nothing here, just block until the pending frame render is completed on the render thread
+                    }
                     var size = (UnmanagedMethods.SizeCommand)wParam;
 
                     if (Resized != null &&
@@ -704,7 +715,8 @@ namespace Avalonia.Win32
                 }
             }
 
-            return UnmanagedMethods.DefWindowProc(hWnd, msg, wParam, lParam);
+            using (_rendererLock.Lock())
+                return UnmanagedMethods.DefWindowProc(hWnd, msg, wParam, lParam);
         }
 
         static InputModifiers GetMouseModifiers(IntPtr wParam)