/// <summary>
/// Provides a configured LinearGradient that can be used in combination with a GradientImageSource to provide a mask for the LensBlurEffect.
/// It will expect the LensBlur will be blurred with 1 kernel when the double is different from None.
/// </summary>
/// <param name="ellipse">The band that represents the focus area in the image. Pixels within this band won't be blurred.
/// Areas outside of the area will be progressively more blurred as the distance from the focus band increases.</param>
/// <param name="strength">Strength of the blur.</param>
/// <returns>A LinearGradient that can be used in combination with a GradientImageSource to be used by LensBlur.</returns>
public static RadialGradient GenerateGradient(FocusEllipse ellipse, KernelGenerator kernelGenerator)
{
if (kernelGenerator.GetKernelBands().Count == 0)
{
return(null);
}
EllipseRadius maxBlurRadius = null;
if ((ellipse.Radius.X < minDiffBetweenStops) && (ellipse.Radius.Y < minDiffBetweenStops))
{
maxBlurRadius = new EllipseRadius(minDiffBetweenStops, minDiffBetweenStops);
}
else
{
double factor = 0.9;
bool widthGtHight = ellipse.Radius.X > ellipse.Radius.Y;
if (widthGtHight)
{
maxBlurRadius = new EllipseRadius(factor, factor * ellipse.Radius.Y / ellipse.Radius.X);
}
else
{
maxBlurRadius = new EllipseRadius(factor * ellipse.Radius.X / ellipse.Radius.Y, factor);
}
}
var gradient = new RadialGradient(ellipse.Center, maxBlurRadius);
SetGradientStops(gradient, ellipse, maxBlurRadius, kernelGenerator);
return(gradient);
}
/// <summary>
/// Provides a configured LinearGradient that can be used in combination with a GradientImageSource to provide a mask for the LensBlurEffect.
/// It will expect the LensBlur will be blurred with 1 kernel when the double is different from None.
/// </summary>
/// <param name="ellipse">The band that represents the focus area in the image. Pixels within this band won't be blurred.
/// Areas outside of the area will be progressively more blurred as the distance from the focus band increases.</param>
/// <param name="strength">Strength of the blur.</param>
/// <returns>A LinearGradient that can be used in combination with a GradientImageSource to be used by LensBlur.</returns>
public static RadialGradient GenerateGradient(FocusEllipse ellipse, KernelGenerator kernelGenerator)
{
if (kernelGenerator.GetKernelBands().Count == 0)
{
return null;
}
EllipseRadius maxBlurRadius = null;
if ((ellipse.Radius.X < minDiffBetweenStops) && (ellipse.Radius.Y < minDiffBetweenStops))
{
maxBlurRadius = new EllipseRadius(minDiffBetweenStops, minDiffBetweenStops);
}
else
{
double factor = 0.9;
bool widthGtHight = ellipse.Radius.X > ellipse.Radius.Y;
if (widthGtHight)
{
maxBlurRadius = new EllipseRadius(factor, factor * ellipse.Radius.Y / ellipse.Radius.X);
}
else
{
maxBlurRadius = new EllipseRadius(factor * ellipse.Radius.X / ellipse.Radius.Y, factor);
}
}
var gradient = new RadialGradient(ellipse.Center, maxBlurRadius);
SetGradientStops(gradient, ellipse, maxBlurRadius, kernelGenerator);
return gradient;
}
private static void SetGradientStops(RadialGradient gradient, FocusEllipse ellipse, EllipseRadius maxBlurRadius, KernelGenerator kernelGenerator)
{
var stops = new List<GradientStop>();
double firstStopOffset;
if (maxBlurRadius.X > minDiffBetweenStops)
{
firstStopOffset = ellipse.Radius.X / maxBlurRadius.X;
//Add the focus area at the center of the ellipse.
stops.Add(new GradientStop() { Color = Color.FromArgb(255, 0, 0, 0), Offset = 0 });
stops.Add(new GradientStop() { Color = Color.FromArgb(255, 0, 0, 0), Offset = firstStopOffset });
}
else
{
firstStopOffset = minDiffBetweenStops;
}
double sumOfBandWidths = kernelGenerator.GetKernelBands().Select(band => band.Width).Sum();
var currentStopOffset = firstStopOffset + minDiffBetweenStops;
var kernelBands = kernelGenerator.GetKernelBands();
byte kernelIndex = 0;
foreach (var band in kernelBands)
{
kernelIndex++;
stops.Add(new GradientStop() { Color = Color.FromArgb(255, kernelIndex, kernelIndex, kernelIndex), Offset = currentStopOffset });
currentStopOffset = currentStopOffset + (band.Width / sumOfBandWidths) * (1 - firstStopOffset) * FocusToBlurTransitionWidth;
}
stops.Add(new GradientStop() { Color = Color.FromArgb(255, kernelIndex, kernelIndex, kernelIndex), Offset = currentStopOffset });
var validStops = EnsureMinDiffBetweenPoints(stops);
gradient.Stops = validStops.ToArray();
}
private protected override void UpdatePaintCore(SKPaint paint, SKRect bounds)
{
var center = EllipseCenter.ToSKPoint();
var gradientOrigin = EllipseCenter.ToSKPoint() + GradientOriginOffset.ToSKPoint();
var radius = EllipseRadius.ToSKPoint();
var transform = CreateTransformMatrix(bounds);
// Transform the points into absolute coordinates.
if (MappingMode == CompositionMappingMode.Relative)
{
// If the point are provided relative they must be multiplied by bounds.
center.X *= bounds.Width;
center.Y *= bounds.Height;
gradientOrigin.X *= bounds.Width;
gradientOrigin.Y *= bounds.Height;
radius.X *= bounds.Width;
radius.Y *= bounds.Height;
}
// Translate gradient points by bounds offset.
center.X += bounds.Left;
center.Y += bounds.Top;
gradientOrigin.X += bounds.Left;
gradientOrigin.Y += bounds.Top;
//
// SkiaSharp does not allow explicit definition of RadiusX and RadiusY.
// Compute transformation matrix to compensate.
ComputeRadiusAndScale(center, radius.X, radius.Y, out float gradientRadius, out SKMatrix matrix);
// Clean up old shader
if (paint.Shader != null)
{
paint.Shader.Dispose();
paint.Shader = null;
}
if (gradientRadius > 0)
{
// Create radial gradient shader.
SKShader shader =
SKShader.CreateTwoPointConicalGradient(
/* start */ gradientOrigin, /* start radius */ 0,
/* end */ center, /* gradient radius */ gradientRadius,
Colors, ColorPositions,
TileMode, transform.PreConcat(matrix));
paint.Shader = shader;
paint.Color = SKColors.Black.WithAlpha((byte)(Compositor.CurrentOpacity * 255));
}
else
{
// With radius equal to 0, SkiaSharp does not draw anything.
// But we expect last gradient color.
// If there are no gradient stops available, use transparent.
SKColor color = SKColors.Transparent;
if (Colors !.Length > 0)
{
color = Colors[Colors.Length - 1];
}
double alpha = (color.Alpha / 255.0) * Compositor.CurrentOpacity;
paint.Color = color.WithAlpha((byte)(alpha * 255));
}
}
public FocusEllipse(double x, double y, double xRadius, double yRadius)
{
Center = new Point(x, y);
Radius = new EllipseRadius(xRadius, yRadius);
}
/// <summary>
/// Creates and initialized a new FocusEllipse with specified center and radius.
/// </summary>
/// <param name="center">The center of the ellipse. Expressed in the unit coordinate space of the image area,
/// i.e., the top left corner of the image is at (0.0), and the bottom right corner is at (1, 1).</param>
/// <param name="radius">The radius of the ellipse. Expressed in the unit coordinate space of the image area,
/// i.e., the top left corner of the image is at (0.0), and the bottom right corner is at (1, 1).</param>
public FocusEllipse(Point center, EllipseRadius radius)
{
Center = center;
Radius = radius;
}
private static void SetGradientStops(RadialGradient gradient, FocusEllipse ellipse, EllipseRadius maxBlurRadius, KernelGenerator kernelGenerator)
{
var stops = new List <GradientStop>();
double firstStopOffset;
if (maxBlurRadius.X > minDiffBetweenStops)
{
firstStopOffset = ellipse.Radius.X / maxBlurRadius.X;
//Add the focus area at the center of the ellipse.
stops.Add(new GradientStop()
{
Color = Color.FromArgb(255, 0, 0, 0), Offset = 0
});
stops.Add(new GradientStop()
{
Color = Color.FromArgb(255, 0, 0, 0), Offset = firstStopOffset
});
}
else
{
firstStopOffset = minDiffBetweenStops;
}
double sumOfBandWidths = kernelGenerator.GetKernelBands().Select(band => band.Width).Sum();
var currentStopOffset = firstStopOffset + minDiffBetweenStops;
var kernelBands = kernelGenerator.GetKernelBands();
byte kernelIndex = 0;
foreach (var band in kernelBands)
{
kernelIndex++;
stops.Add(new GradientStop()
{
Color = Color.FromArgb(255, kernelIndex, kernelIndex, kernelIndex), Offset = currentStopOffset
});
currentStopOffset = currentStopOffset + (band.Width / sumOfBandWidths) * (1 - firstStopOffset) * FocusToBlurTransitionWidth;
}
stops.Add(new GradientStop()
{
Color = Color.FromArgb(255, kernelIndex, kernelIndex, kernelIndex), Offset = currentStopOffset
});
var validStops = EnsureMinDiffBetweenPoints(stops);
gradient.Stops = validStops.ToArray();
}
public FocusEllipse(double x, double y, double xRadius, double yRadius)
{
Center = new Point(x, y);
Radius = new EllipseRadius(xRadius, yRadius);
}
/// <summary>
/// Creates and initialized a new FocusEllipse with specified center and radius.
/// </summary>
/// <param name="center">The center of the ellipse. Expressed in the unit coordinate space of the image area,
/// i.e., the top left corner of the image is at (0.0), and the bottom right corner is at (1, 1).</param>
/// <param name="radius">The radius of the ellipse. Expressed in the unit coordinate space of the image area,
/// i.e., the top left corner of the image is at (0.0), and the bottom right corner is at (1, 1).</param>
public FocusEllipse(Point center, EllipseRadius radius)
{
Center = center;
Radius = radius;
}
