Skip to content

Commit

Permalink
Skia - Only reverse gradient stops if we reach the end
Browse files Browse the repository at this point in the history
  • Loading branch information
@Gillibald
Gillibald committed Jan 9, 2025
1 parent 0dd628f commit 90125e4
Showing 1 changed file with 104 additions and 73 deletions.
177 changes: 104 additions & 73 deletions src/Skia/Avalonia.Skia/DrawingContextImpl.cs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -915,90 +915,121 @@ private static void ConfigureGradientBrush(ref PaintWrapper paintWrapper, Rect t
break;
}
case IRadialGradientBrush radialGradient:
{
var centerPoint = radialGradient.Center.ToPixels(targetRect);
var center = centerPoint.ToSKPoint();

var radiusX = (radialGradient.RadiusX.ToValue(targetRect.Width));
var radiusY = (radialGradient.RadiusY.ToValue(targetRect.Height));

var originPoint = radialGradient.GradientOrigin.ToPixels(targetRect);

Matrix? transform = null;

if (radiusX != radiusY)
transform =
Matrix.CreateTranslation(-centerPoint)
* Matrix.CreateScale(1, radiusY / radiusX)
* Matrix.CreateTranslation(centerPoint);


if (radialGradient.Transform != null)
{
var transformOrigin = radialGradient.TransformOrigin.ToPixels(targetRect);
var offset = Matrix.CreateTranslation(transformOrigin);
var brushTransform = (-offset) * radialGradient.Transform.Value * (offset);
transform = transform.HasValue ? transform * brushTransform : brushTransform;
}

if (originPoint.Equals(centerPoint))
{
// when the origin is the same as the center the Skia RadialGradient acts the same as D2D
using (var shader =
transform.HasValue
? SKShader.CreateRadialGradient(center, (float)radiusX, stopColors, stopOffsets, tileMode,
transform.Value.ToSKMatrix())
: SKShader.CreateRadialGradient(center, (float)radiusX, stopColors, stopOffsets, tileMode)
)
var centerPoint = radialGradient.Center.ToPixels(targetRect);
var center = centerPoint.ToSKPoint();

var radiusX = (radialGradient.RadiusX.ToValue(targetRect.Width));
var radiusY = (radialGradient.RadiusY.ToValue(targetRect.Height));

var originPoint = radialGradient.GradientOrigin.ToPixels(targetRect);

Matrix? transform = null;

if (radiusX != radiusY)
transform =
Matrix.CreateTranslation(-centerPoint)
* Matrix.CreateScale(1, radiusY / radiusX)
* Matrix.CreateTranslation(centerPoint);


if (radialGradient.Transform != null)
{
paintWrapper.Paint.Shader = shader;
var transformOrigin = radialGradient.TransformOrigin.ToPixels(targetRect);
var offset = Matrix.CreateTranslation(transformOrigin);
var brushTransform = (-offset) * radialGradient.Transform.Value * (offset);
transform = transform.HasValue ? transform * brushTransform : brushTransform;
}
}
else
{
// when the origin is different to the center use a two point ConicalGradient to match the behaviour of D2D

if (radiusX != radiusY)
// Adjust the origin point for radiusX/Y transformation by reversing it
originPoint = originPoint.WithY(
(originPoint.Y - centerPoint.Y) * radiusX / radiusY + centerPoint.Y);

var origin = originPoint.ToSKPoint();

// 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++)
if (originPoint.Equals(centerPoint))
{
reversedStops[i] = stopOffsets[i];
if (reversedStops[i] > 0 && reversedStops[i] < 1)
// when the origin is the same as the center the Skia RadialGradient acts the same as D2D
using (var shader =
transform.HasValue
? SKShader.CreateRadialGradient(center, (float)radiusX, stopColors, stopOffsets, tileMode,
transform.Value.ToSKMatrix())
: SKShader.CreateRadialGradient(center, (float)radiusX, stopColors, stopOffsets, tileMode)
)
{
reversedStops[i] = Math.Abs(1 - stopOffsets[i]);
paintWrapper.Paint.Shader = shader;
}
}

// 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]),
transform.HasValue
? SKShader.CreateTwoPointConicalGradient(center, (float)radiusX, origin, 0,
reversedColors, reversedStops, tileMode, transform.Value.ToSKMatrix())
: SKShader.CreateTwoPointConicalGradient(center, (float)radiusX, origin, 0,
reversedColors, reversedStops, tileMode)

)
)
else
{
paintWrapper.Paint.Shader = shader;
// when the origin is different to the center use a two point ConicalGradient to match the behaviour of D2D

if (radiusX != radiusY)
// Adjust the origin point for radiusX/Y transformation by reversing it
originPoint = originPoint.WithY(
(originPoint.Y - centerPoint.Y) * radiusX / radiusY + centerPoint.Y);

var origin = originPoint.ToSKPoint();

//// reverse the order of the stops to match D2D
var reversedColors = new SKColor[stopColors.Length];
Array.Copy(stopColors, reversedColors, stopColors.Length);
Array.Reverse(reversedColors);

var end = 0.0;

//// and then reverse the reference point of the stops
var reversedStops = new float[stopOffsets.Length];
for (var i = 0; i < stopOffsets.Length; i++)
{
var offset = stopOffsets[i];

if (end < offset)
{
end = offset;
}

reversedStops[i] = offset;
if (reversedStops[i] > 0 && reversedStops[i] < 1)
{
reversedStops[i] = Math.Abs(1 - offset);
}
}

var reverse = MathUtilities.AreClose(1, end);

if (reverse)
{
// 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]),
transform.HasValue
? SKShader.CreateTwoPointConicalGradient(center, (float)radiusX, origin, 0,
reversedColors, reversedStops, tileMode, transform.Value.ToSKMatrix())
: SKShader.CreateTwoPointConicalGradient(center, (float)radiusX, origin, 0,
reversedColors, reversedStops, tileMode)

)
)
{
paintWrapper.Paint.Shader = shader;
}
}
else
{
// 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(stopColors[0]),
transform.HasValue
? SKShader.CreateTwoPointConicalGradient(origin, 0, center, (float)radiusX,
stopColors, stopOffsets, tileMode, transform.Value.ToSKMatrix())
: SKShader.CreateTwoPointConicalGradient(origin, 0, center, (float)radiusX,
stopColors, stopOffsets, tileMode)

)
)
{
paintWrapper.Paint.Shader = shader;
}
}
}
}

break;
}
break;
}
case IConicGradientBrush conicGradient:
{
var center = conicGradient.Center.ToPixels(targetRect).ToSKPoint();
Expand Down

0 comments on commit 90125e4

Please sign in to comment.