From ead6ac81b13c4e6e81749094c83705c6e1580f38 Mon Sep 17 00:00:00 2001
From: Nikita Tsukanov <keks9n@gmail.com>
Date: Tue, 11 Feb 2025 04:03:50 +0500
Subject: [PATCH] [SKIA] Don't re-create SKImage on every WriteableBitmap draw
 call (#18164)

---
 src/Skia/Avalonia.Skia/WriteableBitmapImpl.cs | 27 ++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/src/Skia/Avalonia.Skia/WriteableBitmapImpl.cs b/src/Skia/Avalonia.Skia/WriteableBitmapImpl.cs
index 865bcae99c..313c7e06de 100644
--- a/src/Skia/Avalonia.Skia/WriteableBitmapImpl.cs
+++ b/src/Skia/Avalonia.Skia/WriteableBitmapImpl.cs
@@ -15,7 +15,9 @@ namespace Avalonia.Skia
     internal class WriteableBitmapImpl : IWriteableBitmapImpl, IDrawableBitmapImpl
     {
         private static readonly SKBitmapReleaseDelegate s_releaseDelegate = ReleaseProc;
-        private readonly SKBitmap _bitmap;
+        private SKBitmap _bitmap;
+        private SKImage? _image;
+        private bool _imageValid;
         private readonly object _lock = new();
         
         /// <summary>
@@ -119,13 +121,31 @@ namespace Avalonia.Skia
         public void Draw(DrawingContextImpl context, SKRect sourceRect, SKRect destRect, SKPaint paint)
         {
             lock (_lock)
-                context.Canvas.DrawBitmap(_bitmap, sourceRect, destRect, paint);
+            {
+                if (_image == null || !_imageValid)
+                {
+                    _image?.Dispose();
+                    _image = null;
+                    // NOTE: this does a snapshot of the bitmap. If SKCanvas is not GPU-backed we might want to avoid
+                    // that by force-sharing the pixel data with SKBitmap, but that would require manual pixel
+                    // buffer management
+                    _image = GetSnapshot();
+                    _imageValid = true;
+                }
+                context.Canvas.DrawImage(_image, sourceRect, destRect, paint);
+            }
         }
 
         /// <inheritdoc />
         public virtual void Dispose()
         {
-            _bitmap.Dispose();
+            lock (_lock)
+            {
+                _image?.Dispose();
+                _image = null;
+                _bitmap.Dispose();
+                _bitmap = null!;
+            }
         }
 
         /// <inheritdoc />
@@ -198,6 +218,7 @@ namespace Avalonia.Skia
             {
                 _bitmap.NotifyPixelsChanged();
                 _parent.Version++;
+                _parent._imageValid = false;
                 Monitor.Exit(_parent._lock);
                 _bitmap = null!;
                 _parent = null!;