diff --git a/src/Skia/Avalonia.Skia/DrawingContextImpl.cs b/src/Skia/Avalonia.Skia/DrawingContextImpl.cs index b794c5e00a..65989610b8 100644 --- a/src/Skia/Avalonia.Skia/DrawingContextImpl.cs +++ b/src/Skia/Avalonia.Skia/DrawingContextImpl.cs @@ -585,12 +585,43 @@ namespace Avalonia.Skia var origin = radialGradient.GradientOrigin.ToPixels(targetSize).ToSKPoint(); - // would be nice to cache these shaders possibly? - using (var shader = SKShader.CreateCompose( - SKShader.CreateColor(stopColors.Last()), - SKShader.CreateTwoPointConicalGradient(center, radius, origin, 0, stopColors.Reverse().ToArray(), stopOffsets, tileMode)) - ) { - paintWrapper.Paint.Shader = shader; + if (origin.Equals(center)) + { + // when the origin is the same as the center the Skia RadialGradient acts the same as D2D + using (var shader = + SKShader.CreateRadialGradient(center, radius, stopColors, stopOffsets, tileMode)) + { + paintWrapper.Paint.Shader = shader; + } + } + else + { + // when the origin is different to the center use a two point ConicalGradient to match the behaviour of D2D + + // reverse the order of the stops to match D2D + var reversedColors = new SKColor[stopColors.Length]; + Array.Copy(stopColors, reversedColors, stopColors.Length); + Array.Reverse(reversedColors); + + // and then reverse the reference point of the stops + var reversedStops = new float[stopOffsets.Length]; + for (var i = 0; i < stopOffsets.Length; i++) + { + reversedStops[i] = stopOffsets[i]; + if (reversedStops[i] > 0 && reversedStops[i] < 1) + { + reversedStops[i] = Math.Abs(1 - stopOffsets[i]); + } + } + + // compose with a background colour of the final stop to match D2D's behaviour of filling with the final color + using (var shader = SKShader.CreateCompose( + SKShader.CreateColor(reversedColors[0]), + SKShader.CreateTwoPointConicalGradient(center, radius, origin, 0, reversedColors, reversedStops, tileMode) + )) + { + paintWrapper.Paint.Shader = shader; + } } break; diff --git a/tests/Avalonia.RenderTests/Media/RadialGradientBrushTests.cs b/tests/Avalonia.RenderTests/Media/RadialGradientBrushTests.cs index 63d4d9992d..2941b8dc34 100644 --- a/tests/Avalonia.RenderTests/Media/RadialGradientBrushTests.cs +++ b/tests/Avalonia.RenderTests/Media/RadialGradientBrushTests.cs @@ -44,6 +44,9 @@ namespace Avalonia.Direct2D1.RenderTests.Media CompareImages(); } + /// + /// Tests using a GradientOrigin that falls inside of the circle described by Center/Radius. + /// [Fact] public async Task RadialGradientBrush_RedBlue_Offset_Inside() { @@ -70,6 +73,9 @@ namespace Avalonia.Direct2D1.RenderTests.Media CompareImages(); } + /// + /// Tests using a GradientOrigin that falls outside of the circle described by Center/Radius. + /// [Fact] public async Task RadialGradientBrush_RedBlue_Offset_Outside() { @@ -96,6 +102,9 @@ namespace Avalonia.Direct2D1.RenderTests.Media CompareImages(); } + /// + /// Tests using a GradientOrigin that falls inside of the circle described by Center/Radius. + /// [Fact] public async Task RadialGradientBrush_RedGreenBlue_Offset_Inside() { @@ -114,7 +123,9 @@ namespace Avalonia.Direct2D1.RenderTests.Media new GradientStop { Color = Colors.Green, Offset = 0.5 }, new GradientStop { Color = Colors.Blue, Offset = 1 } }, - GradientOrigin = new RelativePoint(0.25, 0.25, RelativeUnit.Relative) + GradientOrigin = new RelativePoint(0.25, 0.25, RelativeUnit.Relative), + Center = new RelativePoint(0.5, 0.5, RelativeUnit.Relative), + Radius = 0.5 } } }; @@ -123,6 +134,9 @@ namespace Avalonia.Direct2D1.RenderTests.Media CompareImages(); } + /// + /// Tests using a GradientOrigin that falls outside of the circle described by Center/Radius. + /// [Fact] public async Task RadialGradientBrush_RedGreenBlue_Offset_Outside() { @@ -138,10 +152,12 @@ namespace Avalonia.Direct2D1.RenderTests.Media GradientStops = { new GradientStop { Color = Colors.Red, Offset = 0 }, - new GradientStop { Color = Colors.Green, Offset = 0.5 }, + new GradientStop { Color = Colors.Green, Offset = 0.25 }, new GradientStop { Color = Colors.Blue, Offset = 1 } }, - GradientOrigin = new RelativePoint(0.1, 0.1, RelativeUnit.Relative) + GradientOrigin = new RelativePoint(0.1, 0.1, RelativeUnit.Relative), + Center = new RelativePoint(0.5, 0.5, RelativeUnit.Relative), + Radius = 0.5 } } }; diff --git a/tests/TestFiles/Direct2D1/Media/RadialGradientBrush/RadialGradientBrush_RedGreenBlue_Offset_Outside.expected.png b/tests/TestFiles/Direct2D1/Media/RadialGradientBrush/RadialGradientBrush_RedGreenBlue_Offset_Outside.expected.png index 91068ca1cf..ea1009b54a 100644 Binary files a/tests/TestFiles/Direct2D1/Media/RadialGradientBrush/RadialGradientBrush_RedGreenBlue_Offset_Outside.expected.png and b/tests/TestFiles/Direct2D1/Media/RadialGradientBrush/RadialGradientBrush_RedGreenBlue_Offset_Outside.expected.png differ diff --git a/tests/TestFiles/Skia/Media/RadialGradientBrush/RadialGradientBrush_RedGreenBlue_Offset_Outside.expected.png b/tests/TestFiles/Skia/Media/RadialGradientBrush/RadialGradientBrush_RedGreenBlue_Offset_Outside.expected.png index 91068ca1cf..ea1009b54a 100644 Binary files a/tests/TestFiles/Skia/Media/RadialGradientBrush/RadialGradientBrush_RedGreenBlue_Offset_Outside.expected.png and b/tests/TestFiles/Skia/Media/RadialGradientBrush/RadialGradientBrush_RedGreenBlue_Offset_Outside.expected.png differ