Implement SkCanvas::SaveLayerRec (#2962)

* feat(SaveLayerRec): implement SkCanvas::SaveLayerRec

* Update the API to handle the future

* Use a struct as a class is not necessary

* Update externals

---------

Co-authored-by: Matthew Leibowitz <[email protected]>

Author: ahmed605

binding/SkiaSharp/SKCanvas.cs

@@ -51,25 +51,29 @@ public bool QuickReject (SKPath path)
 
 		// Save*
 
+#nullable enable
 		public int Save ()
 		{
 			if (Handle == IntPtr.Zero)
 				throw new ObjectDisposedException ("SKCanvas");
 			return SkiaApi.sk_canvas_save (Handle);
 		}
 
-		public int SaveLayer (SKRect limit, SKPaint paint)
-		{
-			return SkiaApi.sk_canvas_save_layer (Handle, &limit, paint == null ? IntPtr.Zero : paint.Handle);
-		}
+		public int SaveLayer (SKRect limit, SKPaint? paint) =>
+			SkiaApi.sk_canvas_save_layer (Handle, &limit, paint?.Handle ?? IntPtr.Zero);
+	
+		public int SaveLayer (SKPaint? paint) =>
+			SkiaApi.sk_canvas_save_layer (Handle, null, paint?.Handle ?? IntPtr.Zero);
 
-		public int SaveLayer (SKPaint paint)
+		public int SaveLayer (in SKCanvasSaveLayerRec rec)
 		{
-			return SkiaApi.sk_canvas_save_layer (Handle, null, paint == null ? IntPtr.Zero : paint.Handle);
+			var native = rec.ToNative ();
+			return SkiaApi.sk_canvas_save_layer_rec (Handle, &native);
 		}
 
 		public int SaveLayer () =>
-			SaveLayer (null);
+			SkiaApi.sk_canvas_save_layer (Handle, null, IntPtr.Zero);
+#nullable disable
 
 		// DrawColor
 
@@ -1080,4 +1084,25 @@ public void Restore ()
 			}
 		}
 	}
+
+#nullable enable
+	public unsafe struct SKCanvasSaveLayerRec
+	{
+		public SKRect? Bounds { readonly get; set; }
+
+		public SKPaint? Paint { readonly get; set; }
+
+		public SKImageFilter? Backdrop { readonly get; set; }
+
+		public SKCanvasSaveLayerRecFlags Flags { readonly get; set; }
+
+		internal readonly SKCanvasSaveLayerRecNative ToNative () =>
+			new SKCanvasSaveLayerRecNative {
+				fBounds = Bounds is { } bounds ? &bounds : (SKRect*)null,
+				fPaint = Paint?.Handle ?? IntPtr.Zero,
+				fBackdrop = Backdrop?.Handle ?? IntPtr.Zero,
+				fFlags = Flags
+			};
+	}
+#nullable disable
 }

binding/SkiaSharp/SkiaApi.generated.cs

@@ -3088,6 +3088,25 @@ internal static Int32 sk_canvas_save_layer (sk_canvas_t ccanvas, SKRect* crect,
 			(sk_canvas_save_layer_delegate ??= GetSymbol<Delegates.sk_canvas_save_layer> ("sk_canvas_save_layer")).Invoke (ccanvas, crect, cpaint);
 		#endif
 
+		// int sk_canvas_save_layer_rec(sk_canvas_t* ccanvas, const sk_canvas_savelayerrec_t* crec)
+		#if !USE_DELEGATES
+		#if USE_LIBRARY_IMPORT
+		[LibraryImport (SKIA)]
+		internal static partial Int32 sk_canvas_save_layer_rec (sk_canvas_t ccanvas, SKCanvasSaveLayerRecNative* crec);
+		#else // !USE_LIBRARY_IMPORT
+		[DllImport (SKIA, CallingConvention = CallingConvention.Cdecl)]
+		internal static extern Int32 sk_canvas_save_layer_rec (sk_canvas_t ccanvas, SKCanvasSaveLayerRecNative* crec);
+		#endif
+		#else
+		private partial class Delegates {
+			[UnmanagedFunctionPointer (CallingConvention.Cdecl)]
+			internal delegate Int32 sk_canvas_save_layer_rec (sk_canvas_t ccanvas, SKCanvasSaveLayerRecNative* crec);
+		}
+		private static Delegates.sk_canvas_save_layer_rec sk_canvas_save_layer_rec_delegate;
+		internal static Int32 sk_canvas_save_layer_rec (sk_canvas_t ccanvas, SKCanvasSaveLayerRecNative* crec) =>
+			(sk_canvas_save_layer_rec_delegate ??= GetSymbol<Delegates.sk_canvas_save_layer_rec> ("sk_canvas_save_layer_rec")).Invoke (ccanvas, crec);
+		#endif
+
 		// void sk_canvas_scale(sk_canvas_t* ccanvas, float sx, float sy)
 		#if !USE_DELEGATES
 		#if USE_LIBRARY_IMPORT
@@ -18008,6 +18027,47 @@ public readonly override int GetHashCode ()
 
 	}
 
+	// sk_canvas_savelayerrec_t
+	[StructLayout (LayoutKind.Sequential)]
+	internal unsafe partial struct SKCanvasSaveLayerRecNative : IEquatable<SKCanvasSaveLayerRecNative> {
+		// public sk_rect_t* fBounds
+		public SKRect* fBounds;
+
+		// public sk_paint_t* fPaint
+		public sk_paint_t fPaint;
+
+		// public sk_imagefilter_t* fBackdrop
+		public sk_imagefilter_t fBackdrop;
+
+		// public sk_canvas_savelayerrec_flags_t fFlags
+		public SKCanvasSaveLayerRecFlags fFlags;
+
+		public readonly bool Equals (SKCanvasSaveLayerRecNative obj) =>
+#pragma warning disable CS8909
+			fBounds == obj.fBounds && fPaint == obj.fPaint && fBackdrop == obj.fBackdrop && fFlags == obj.fFlags;
+#pragma warning restore CS8909
+
+		public readonly override bool Equals (object obj) =>
+			obj is SKCanvasSaveLayerRecNative f && Equals (f);
+
+		public static bool operator == (SKCanvasSaveLayerRecNative left, SKCanvasSaveLayerRecNative right) =>
+			left.Equals (right);
+
+		public static bool operator != (SKCanvasSaveLayerRecNative left, SKCanvasSaveLayerRecNative right) =>
+			!left.Equals (right);
+
+		public readonly override int GetHashCode ()
+		{
+			var hash = new HashCode ();
+			hash.Add (fBounds);
+			hash.Add (fPaint);
+			hash.Add (fBackdrop);
+			hash.Add (fFlags);
+			return hash.ToHashCode ();
+		}
+
+	}
+
 	// sk_codec_frameinfo_t
 	[StructLayout (LayoutKind.Sequential)]
 	public unsafe partial struct SKCodecFrameInfo : IEquatable<SKCodecFrameInfo> {
@@ -20177,6 +20237,18 @@ public enum SKBlurStyle {
 		Inner = 3,
 	}
 
+	// sk_canvas_savelayerrec_flags_t
+	public enum SKCanvasSaveLayerRecFlags {
+		// NONE_SK_CANVAS_SAVELAYERREC_FLAGS = 0
+		None = 0,
+		// PRESERVE_LCD_TEXT_SK_CANVAS_SAVELAYERREC_FLAGS = 1 << 1
+		PreserveLcdText = 2,
+		// INITIALIZE_WITH_PREVIOUS_SK_CANVAS_SAVELAYERREC_FLAGS = 1 << 2
+		InitializeWithPrevious = 4,
+		// F16_COLOR_TYPE_SK_CANVAS_SAVELAYERREC_FLAGS = 1 << 4
+		F16ColorType = 16,
+	}
+
 	// sk_clipop_t
 	public enum SKClipOperation {
 		// DIFFERENCE_SK_CLIPOP = 0

binding/libSkiaSharp.json

@@ -98,6 +98,13 @@
         "cs": "GRContextOptionsNative",
         "internal": true
       },
+      "sk_canvas_savelayerrec_t": {
+        "cs": "SKCanvasSaveLayerRecNative",
+        "internal": true
+      },
+      "sk_canvas_savelayerrec_flags_t": {
+        "cs": "SKCanvasSaveLayerRecFlags"
+      },
       "sk_color4f_t": {
         "cs": "SKColorF",
         "readonly": true,

externals/skia

@@ -689,5 +689,59 @@ public void DrawPointReplacesColor(uint initial, uint color)
 			canvas.DrawPoint(0, 0, color);
 			Assert.Equal(color, bmp.GetPixel(0, 0));
 		}
+
+		[SkippableFact]
+		public void SaveLayerRecWithPaintIsCorrect()
+		{
+			using var bmp = new SKBitmap(100, 100);
+			using var canvas = new SKCanvas(bmp);
+			canvas.Clear(SKColors.Green);
+
+			var rec = new SKCanvasSaveLayerRec
+			{
+				Paint = new SKPaint
+				{
+					BlendMode = SKBlendMode.Plus
+				},
+				Flags = SKCanvasSaveLayerRecFlags.InitializeWithPrevious
+			};
+			canvas.SaveLayer(rec);
+
+			using var paint = new SKPaint
+			{
+				BlendMode = SKBlendMode.Clear
+			};
+			canvas.DrawCircle(50, 50, 40, paint);
+
+			canvas.Restore();
+
+			Assert.Equal(SKColors.Green, bmp.GetPixel(50, 50));
+			Assert.Equal(SKColors.Green, bmp.GetPixel(15, 50));
+			Assert.Equal((SKColor)0xFF00FF00, bmp.GetPixel(15, 15));
+		}
+
+		[SkippableFact]
+		public void SaveLayerRecWithImageFilterIsCorrect()
+		{
+			using var bmp = new SKBitmap(80, 80);
+			using var canvas = new SKCanvas(bmp);
+			canvas.Clear(SKColors.White);
+
+			canvas.DrawCircle(10, 10, 10, new SKPaint { Color = SKColors.Red });
+
+			var rec = new SKCanvasSaveLayerRec
+			{
+				Backdrop = SKImageFilter.CreateMatrix(SKMatrix.CreateScale(4, 4), SKSamplingOptions.Default),
+			};
+			canvas.SaveLayer(rec);
+
+			canvas.DrawCircle(40, 40, 10, new SKPaint { Color = SKColors.Green });
+
+			canvas.Restore();
+
+			Assert.Equal(SKColors.Red, bmp.GetPixel(25, 40));
+			Assert.Equal(SKColors.Red, bmp.GetPixel(40, 25));
+			Assert.Equal(SKColors.Green, bmp.GetPixel(40, 40));
+		}
 	}
 }