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- move to GradientBrushes namespace - add abstract base class for Gradient Brushes, that implements the GetGradientSegment implementtion and the color picking.af/merge-core
Unknown
8 years ago
4 changed files with 204 additions and 131 deletions
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using System.Numerics; |
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using SixLabors.ImageSharp.PixelFormats; |
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using SixLabors.ImageSharp.PixelFormats.PixelBlenders; |
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using SixLabors.Primitives; |
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namespace SixLabors.ImageSharp.Processing.Drawing.Brushes.GradientBrushes |
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{ |
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/// <summary>
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/// Base class for Gradient brushes
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/// </summary>
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/// <typeparam name="TPixel">The pixel format</typeparam>
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public abstract class AbstractGradientBrush<TPixel> : IBrush<TPixel> |
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where TPixel : struct, IPixel<TPixel> |
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{ |
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/// <inheritdoc cref="IBrush{TPixel}"/>
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/// <param name="colorStops">The gradient colors.</param>
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protected AbstractGradientBrush(params ColorStop<TPixel>[] colorStops) |
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{ |
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this.ColorStops = colorStops; |
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} |
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/// <summary>
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/// Gets the list of color stops for this gradient.
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/// </summary>
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protected ColorStop<TPixel>[] ColorStops { get; } |
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/// <inheritdoc cref="IBrush{TPixel}" />
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public abstract BrushApplicator<TPixel> CreateApplicator( |
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ImageFrame<TPixel> source, |
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RectangleF region, |
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GraphicsOptions options); |
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/// <summary>
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/// Base class for gradient brush applicators
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/// </summary>
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protected abstract class AbstractGradientBrushApplicator : BrushApplicator<TPixel> |
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{ |
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private readonly ColorStop<TPixel>[] colorStops; |
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/// <summary>
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/// Initializes a new instance of the <see cref="AbstractGradientBrushApplicator"/> class.
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/// </summary>
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/// <param name="target">The target.</param>
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/// <param name="options">The options.</param>
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/// <param name="colorStops">an array of color stops sorted by their position.</param>
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/// <param name="region">TODO: use region, compare with other Brushes for reference</param>
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protected AbstractGradientBrushApplicator( |
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ImageFrame<TPixel> target, |
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GraphicsOptions options, |
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ColorStop<TPixel>[] colorStops, |
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RectangleF region) |
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: base(target, options) |
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{ |
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this.colorStops = colorStops; // TODO: requires colorStops to be sorted by position - should that be checked?
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} |
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/// <summary>
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/// Base implementation of the indexer for gradients
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/// (follows the facade pattern, using abstract methods)
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/// </summary>
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/// <param name="x">X coordinate of the Pixel.</param>
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/// <param name="y">Y coordinate of the Pixel.</param>
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internal override TPixel this[int x, int y] |
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{ |
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get |
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{ |
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float positionOnCompleteGradient = this.PositionOnGradient(x, y); |
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var (from, to) = this.GetGradientSegment(positionOnCompleteGradient); |
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if (from.Color.Equals(to.Color)) |
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{ |
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return from.Color; |
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} |
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else |
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{ |
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var fromAsVector = from.Color.ToVector4(); |
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var toAsVector = to.Color.ToVector4(); |
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float onLocalGradient = (positionOnCompleteGradient - from.Ratio) / to.Ratio; |
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// TODO: this should be changeble for different gradienting functions
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Vector4 result = PorterDuffFunctions.Normal( |
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fromAsVector, |
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toAsVector, |
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onLocalGradient); |
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TPixel resultColor = default; |
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resultColor.PackFromVector4(result); |
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return resultColor; |
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} |
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} |
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} |
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/// <summary>
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/// calculates the position on the gradient for a given pixel.
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/// This method is abstract as it's content depends on the shape of the gradient.
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/// </summary>
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/// <param name="x">The x coordinate of the pixel</param>
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/// <param name="y">The y coordinate of the pixel</param>
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/// <returns>
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/// The position the given pixel has on the gradient.
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/// The position is not bound to the [0..1] interval.
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/// Values outside of that interval may be treated differently,
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/// e.g. for the <see cref="GradientRepetitionMode" /> enum.
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/// </returns>
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protected abstract float PositionOnGradient(int x, int y); |
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private (ColorStop<TPixel> from, ColorStop<TPixel> to) GetGradientSegment( |
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float positionOnCompleteGradient) |
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{ |
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var localGradientFrom = this.colorStops[0]; |
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ColorStop<TPixel> localGradientTo = default; |
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// TODO: ensure colorStops has at least 2 items (technically 1 would be okay, but that's no gradient)
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foreach (var colorStop in this.colorStops) |
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{ |
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localGradientTo = colorStop; |
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if (colorStop.Ratio > positionOnCompleteGradient) |
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{ |
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// we're done here, so break it!
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break; |
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} |
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localGradientFrom = localGradientTo; |
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} |
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return (localGradientFrom, localGradientTo); |
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} |
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} |
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} |
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} |
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@ -0,0 +1,36 @@ |
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using System.Diagnostics; |
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using SixLabors.ImageSharp.PixelFormats; |
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namespace SixLabors.ImageSharp.Processing.Drawing.Brushes.GradientBrushes |
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{ |
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/// <summary>
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/// A struct that defines a single color stop.
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/// </summary>
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/// <typeparam name="TPixel">The pixel format.</typeparam>
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[DebuggerDisplay("ColorStop({Ratio} -> {Color}")] |
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public struct ColorStop<TPixel> |
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where TPixel : struct, IPixel<TPixel> |
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{ |
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/// <summary>
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/// Initializes a new instance of the <see cref="ColorStop{TPixel}" /> struct.
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/// </summary>
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/// <param name="ratio">Where should it be? 0 is at the start, 1 at the end of the Gradient.</param>
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/// <param name="color">What color should be used at that point?</param>
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public ColorStop(float ratio, TPixel color) |
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{ |
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this.Ratio = ratio; |
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this.Color = color; |
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} |
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/// <summary>
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/// Gets the point along the defined gradient axis.
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/// </summary>
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public float Ratio { get; } |
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/// <summary>
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/// Gets the color to be used.
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/// </summary>
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public TPixel Color { get; } |
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} |
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} |
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