[GLX] Resize the platform render target to compositor-provided size (#17779)

We should be doing that for other platforms later as well, since only compositor knows what scene size it's planning to draw

src/Avalonia.Base/Platform/IRenderTarget.cs

@@ -25,30 +25,39 @@ namespace Avalonia.Platform
         public bool IsCorrupted { get; }
     }
 
-    [PrivateApi]
+    [PrivateApi, Obsolete("Use IRenderTarget2", true)]
+    // TODO12: Remove
     public interface IRenderTargetWithProperties : IRenderTarget
+    {
+        RenderTargetProperties Properties { get; }
+    }
+    
+    [PrivateApi]
+    // TODO12: Merge into IRenderTarget
+    public interface IRenderTarget2 : IRenderTarget
     {
         RenderTargetProperties Properties { get; }
 
         /// <summary>
         /// Creates an <see cref="IDrawingContextImpl"/> for a rendering session.
         /// </summary>
-        /// <param name="useScaledDrawing">Apply DPI reported by the render target as a hidden transform matrix</param>
+        /// <param name="expectedPixelSize">The pixel size of the surface</param>
         /// <param name="properties">Returns various properties about the returned drawing context</param>
-        IDrawingContextImpl CreateDrawingContext(bool useScaledDrawing, out RenderTargetDrawingContextProperties properties);
+        IDrawingContextImpl CreateDrawingContext(PixelSize expectedPixelSize,
+            out RenderTargetDrawingContextProperties properties);
     }
     
     internal static class RenderTargetExtensions
     {
         public static IDrawingContextImpl CreateDrawingContextWithProperties(
             this IRenderTarget renderTarget,
-            bool useScaledDrawing,
+            PixelSize expectedPixelSize,
             out RenderTargetDrawingContextProperties properties)
         {
-            if (renderTarget is IRenderTargetWithProperties target)
-                return target.CreateDrawingContext(useScaledDrawing, out properties);
+            if (renderTarget is IRenderTarget2 target)
+                return target.CreateDrawingContext(expectedPixelSize, out properties);
             properties = default;
-            return renderTarget.CreateDrawingContext(useScaledDrawing);
+            return renderTarget.CreateDrawingContext(false);
         }
     }
 }

src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionTarget.cs

@@ -141,7 +141,7 @@ namespace Avalonia.Rendering.Composition.Server
             if (!_redrawRequested)
                 return;
 
-            var renderTargetWithProperties = _renderTarget as IRenderTargetWithProperties;
+            var renderTargetWithProperties = _renderTarget as IRenderTarget2;
 
             
             var needLayer = _overlays.RequireLayer // Check if we don't need overlays
@@ -149,7 +149,8 @@ namespace Avalonia.Rendering.Composition.Server
                             || !(renderTargetWithProperties?.Properties.RetainsPreviousFrameContents == true
                                 && renderTargetWithProperties?.Properties.IsSuitableForDirectRendering == true);
             
-            using (var renderTargetContext = _renderTarget.CreateDrawingContextWithProperties(false, out var properties))
+            using (var renderTargetContext = _renderTarget.CreateDrawingContextWithProperties(
+                       this.PixelSize, out var properties))
             {
                 if(needLayer && (PixelSize != _layerSize || _layer == null || _layer.IsCorrupted))
                 {

src/Avalonia.OpenGL/Surfaces/IGlPlatformSurfaceRenderTarget.cs

@@ -1,4 +1,5 @@
 using System;
+using Avalonia.Metadata;
 
 namespace Avalonia.OpenGL.Surfaces
 {
@@ -11,4 +12,11 @@ namespace Avalonia.OpenGL.Surfaces
     {
         bool IsCorrupted { get; }
     }
+
+    [PrivateApi]
+    public interface IGlPlatformSurfaceRenderTarget2 : IGlPlatformSurfaceRenderTargetWithCorruptionInfo
+    {
+        IGlPlatformSurfaceRenderingSession BeginDraw(PixelSize expectedPixelSize);
+    }
+
 }

src/Avalonia.X11/Glx/GlxDisplay.cs

@@ -18,6 +18,8 @@ namespace Avalonia.X11.Glx
         public XVisualInfo* VisualInfo => _visual;
         public GlxContext DeferredContext { get; }
         public GlxInterface Glx { get; } = new GlxInterface();
+        public X11Info X11Info => _x11;
+        public IntPtr FbConfig => _fbconfig;
         public GlxDisplay(X11Info x11, IList<GlVersion> probeProfiles) 
         {
             _x11 = x11;

src/Avalonia.X11/Glx/GlxGlPlatformSurface.cs

@@ -21,10 +21,11 @@ namespace Avalonia.X11.Glx
             return new RenderTarget((GlxContext)context, _info);
         }
 
-        private class RenderTarget : IGlPlatformSurfaceRenderTarget
+        private class RenderTarget : IGlPlatformSurfaceRenderTarget2
         {
             private readonly GlxContext _context;
             private readonly EglGlPlatformSurface.IEglWindowGlPlatformSurfaceInfo _info;
+            private PixelSize? _lastSize;
 
             public RenderTarget(GlxContext context,  EglGlPlatformSurface.IEglWindowGlPlatformSurfaceInfo info)
             {
@@ -36,29 +37,51 @@ namespace Avalonia.X11.Glx
             {
                 // No-op
             }
-
-            public IGlPlatformSurfaceRenderingSession BeginDraw()
+            
+            public bool IsCorrupted => false;
+            public IGlPlatformSurfaceRenderingSession BeginDraw(PixelSize size) => BeginDrawCore(size);
+            public IGlPlatformSurfaceRenderingSession BeginDraw() => BeginDrawCore(null);
+            public IGlPlatformSurfaceRenderingSession BeginDrawCore(PixelSize? expectedSize)
             {
+                var size = expectedSize ?? _info.Size;
+                if (expectedSize.HasValue)
+                {
+                    XLib.XConfigureResizeWindow(_context.Display.X11Info.DeferredDisplay,
+                        _info.Handle, size.Width, size.Height);
+                    XLib.XFlush(_context.Display.X11Info.DeferredDisplay);
+
+                    if (_lastSize != size)
+                    {
+                        XLib.XSync(_context.Display.X11Info.DeferredDisplay, true);
+                        _lastSize = size;
+                    }
+                    _context.Glx.WaitX();
+                }
+
+                
                 var oldContext = _context.MakeCurrent(_info.Handle);
                 
                 // Reset to default FBO first
                 _context.GlInterface.BindFramebuffer(GL_FRAMEBUFFER, 0);
                     
-                return new Session(_context, _info, oldContext);
+                return new Session(_context, _info, size, oldContext);
             }
 
             private class Session : IGlPlatformSurfaceRenderingSession
             {
                 private readonly GlxContext _context;
                 private readonly EglGlPlatformSurface.IEglWindowGlPlatformSurfaceInfo _info;
+                private readonly PixelSize? _size;
                 private readonly IDisposable _clearContext;
                 public IGlContext Context => _context;
 
                 public Session(GlxContext context, EglGlPlatformSurface.IEglWindowGlPlatformSurfaceInfo info,
+                    PixelSize? size,
                     IDisposable clearContext)
                 {
                     _context = context;
                     _info = info;
+                    _size = size;
                     _clearContext = clearContext;
                 }
 
@@ -71,7 +94,7 @@ namespace Avalonia.X11.Glx
                     _clearContext.Dispose();
                 }
 
-                public PixelSize Size => _info.Size;
+                public PixelSize Size => _size ?? _info.Size;
                 public double Scaling => _info.Scaling;
                 public bool IsYFlipped { get; }
             }

src/Avalonia.X11/X11Window.cs

@@ -67,6 +67,7 @@ namespace Avalonia.X11
         private TransparencyHelper? _transparencyHelper;
         private RawEventGrouper? _rawEventGrouper;
         private bool _useRenderWindow = false;
+        private bool _useCompositorDrivenRenderWindowResize = false;
         private bool _usePositioningFlags = false;
         private X11FocusProxy? _focusProxy;
 
@@ -111,7 +112,12 @@ namespace Avalonia.X11
             
             var glx = glfeature as GlxPlatformGraphics;
             if (glx != null)
+            {
                 visualInfo = *glx.Display.VisualInfo;
+                // TODO: We should query this from the active render surface, however we don't actually track what
+                // the target sufrace currently is
+                _useCompositorDrivenRenderWindowResize = true;
+            }
             else if (glfeature == null)
                 visualInfo = _x11.TransparentVisualInfo;
 
@@ -569,7 +575,8 @@ namespace Avalonia.X11
                             Resized?.Invoke(ClientSize, WindowResizeReason.Unspecified);
 
                     }, DispatcherPriority.AsyncRenderTargetResize);
-                if (_useRenderWindow)
+                
+                if (_useRenderWindow && !_useCompositorDrivenRenderWindowResize)
                     XConfigureResizeWindow(_x11.Display, _renderHandle, ev.ConfigureEvent.width,
                         ev.ConfigureEvent.height);
                 if (_xSyncState == XSyncState.WaitConfigure)
@@ -1081,7 +1088,7 @@ namespace Avalonia.X11
             var pixelSize = ToPixelSize(clientSize);
             UpdateSizeHints(pixelSize);
             XConfigureResizeWindow(_x11.Display, _handle, pixelSize);
-            if (_useRenderWindow)
+            if (_useRenderWindow && !_useCompositorDrivenRenderWindowResize)
                 XConfigureResizeWindow(_x11.Display, _renderHandle, pixelSize);
             XFlush(_x11.Display);
 

src/Skia/Avalonia.Skia/FramebufferRenderTarget.cs

@@ -10,7 +10,7 @@ namespace Avalonia.Skia
     /// <summary>
     /// Skia render target that renders to a framebuffer surface. No gpu acceleration available.
     /// </summary>
-    internal class FramebufferRenderTarget : IRenderTargetWithProperties
+    internal class FramebufferRenderTarget : IRenderTarget2
     {
         private SKImageInfo _currentImageInfo;
         private IntPtr _currentFramebufferAddress;
@@ -50,10 +50,15 @@ namespace Avalonia.Skia
 
         /// <inheritdoc />
         public IDrawingContextImpl CreateDrawingContext(bool scaleDrawingToDpi) =>
-            CreateDrawingContext(scaleDrawingToDpi, out _);
+            CreateDrawingContextCore(scaleDrawingToDpi,   out _);
 
         /// <inheritdoc />
-        public IDrawingContextImpl CreateDrawingContext(bool useScaledDrawing, out RenderTargetDrawingContextProperties properties)
+        public IDrawingContextImpl CreateDrawingContext(PixelSize expectedPixelSize,
+            out RenderTargetDrawingContextProperties properties)
+            => CreateDrawingContextCore(false, out properties);
+        
+        IDrawingContextImpl CreateDrawingContextCore(bool scaleDrawingToDpi,
+            out RenderTargetDrawingContextProperties properties)
         {
             if (_renderTarget == null)
                 throw new ObjectDisposedException(nameof(FramebufferRenderTarget));
@@ -77,7 +82,7 @@ namespace Avalonia.Skia
             {
                 Surface = _framebufferSurface,
                 Dpi = framebuffer.Dpi,
-                ScaleDrawingToDpi = useScaledDrawing
+                ScaleDrawingToDpi = scaleDrawingToDpi
             };
 
             properties = new()

src/Skia/Avalonia.Skia/Gpu/ISkiaGpuRenderTarget.cs

@@ -1,4 +1,5 @@
 using System;
+using Avalonia.Metadata;
 using SkiaSharp;
 
 namespace Avalonia.Skia
@@ -16,4 +17,11 @@ namespace Avalonia.Skia
         
         bool IsCorrupted { get; }
     }
+
+    [PrivateApi]
+    //TODO12: Merge with ISkiaGpuRenderTarget
+    public interface ISkiaGpuRenderTarget2 : ISkiaGpuRenderTarget
+    {
+        ISkiaGpuRenderSession BeginRenderingSession(PixelSize pixelSize);
+    }
 }

src/Skia/Avalonia.Skia/Gpu/OpenGl/GlRenderTarget.cs

@@ -9,7 +9,7 @@ using static Avalonia.OpenGL.GlConsts;
 
 namespace Avalonia.Skia
 {
-    internal class GlRenderTarget : ISkiaGpuRenderTarget
+    internal class GlRenderTarget : ISkiaGpuRenderTarget2
     {
         private readonly GRContext _grContext;
         private IGlPlatformSurfaceRenderTarget _surface;
@@ -59,9 +59,16 @@ namespace Avalonia.Skia
             public double ScaleFactor => _glSession.Scaling;
         }
 
-        public ISkiaGpuRenderSession BeginRenderingSession()
+        public ISkiaGpuRenderSession BeginRenderingSession(PixelSize size) => BeginRenderingSessionCore(size);
+        public ISkiaGpuRenderSession BeginRenderingSession() => BeginRenderingSessionCore(null);
+        
+        ISkiaGpuRenderSession BeginRenderingSessionCore(PixelSize? expectedSize)
         {
-            var glSession = _surface.BeginDraw();
+            var glSession =
+                expectedSize != null && _surface is IGlPlatformSurfaceRenderTarget2 surface2
+                    ? surface2.BeginDraw(expectedSize.Value)
+                    : _surface.BeginDraw();
+            
             bool success = false;
             try
             {

src/Skia/Avalonia.Skia/Gpu/SkiaGpuRenderTarget.cs

@@ -5,7 +5,7 @@ namespace Avalonia.Skia
     /// <summary>
     /// Adapts <see cref="ISkiaGpuRenderTarget"/> to be used within our rendering pipeline.
     /// </summary>
-    internal class SkiaGpuRenderTarget : IRenderTarget
+    internal class SkiaGpuRenderTarget : IRenderTarget2
     {
         private readonly ISkiaGpu _skiaGpu;
         private readonly ISkiaGpuRenderTarget _renderTarget;
@@ -21,9 +21,23 @@ namespace Avalonia.Skia
             _renderTarget.Dispose();
         }
 
+        public IDrawingContextImpl CreateDrawingContext(PixelSize expectedPixelSize,
+            out RenderTargetDrawingContextProperties properties) =>
+            CreateDrawingContextCore(expectedPixelSize, false, out properties);
+
         public IDrawingContextImpl CreateDrawingContext(bool useScaledDrawing)
+            => CreateDrawingContextCore(null, useScaledDrawing, out _);
+        
+        
+        IDrawingContextImpl CreateDrawingContextCore(PixelSize? expectedPixelSize,
+            bool useScaledDrawing,
+            out RenderTargetDrawingContextProperties properties)
         {
-            var session = _renderTarget.BeginRenderingSession();
+            properties = default;
+            var session =
+                expectedPixelSize.HasValue && _renderTarget is ISkiaGpuRenderTarget2 target2
+                    ? target2.BeginRenderingSession(expectedPixelSize.Value)
+                    : _renderTarget.BeginRenderingSession();
 
             var nfo = new DrawingContextImpl.CreateInfo
             {
@@ -39,5 +53,8 @@ namespace Avalonia.Skia
         }
 
         public bool IsCorrupted => _renderTarget.IsCorrupted;
+        public RenderTargetProperties Properties { get; }
+
+
     }
 }