mirror of https://github.com/SixLabors/ImageSharp
Anton Firszov
7 years ago
6 changed files with 547 additions and 14 deletions
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// Copyright (c) Six Labors and contributors.
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// Licensed under the Apache License, Version 2.0.
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using System; |
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using System.Collections.Generic; |
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using System.Linq; |
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using System.Numerics; |
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using SixLabors.ImageSharp.PixelFormats; |
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using SixLabors.Primitives; |
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using SixLabors.Shapes; |
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namespace SixLabors.ImageSharp.Processing |
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{ |
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/// <summary>
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/// Provides an implementation of a brush for painting gradients between multiple color positions in 2D coordinates.
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/// It works similarly with the class in System.Drawing.Drawing2D of the same name.
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/// </summary>
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public sealed class PathGradientBrush : IBrush |
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{ |
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private readonly Polygon path; |
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private readonly IList<Edge> edges; |
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private readonly Color centerColor; |
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/// <summary>
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/// Initializes a new instance of the <see cref="PathGradientBrush"/> class.
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/// </summary>
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/// <param name="lines">Line segments of a polygon that represents the gradient area.</param>
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/// <param name="colors">Array of colors that correspond to each point in the polygon.</param>
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/// <param name="centerColor">Color at the center of the gradient area to which the other colors converge.</param>
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public PathGradientBrush(ILineSegment[] lines, Color[] colors, Color centerColor) |
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{ |
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if (lines == null) |
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{ |
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throw new ArgumentNullException(nameof(lines)); |
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} |
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if (lines.Length < 3) |
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{ |
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throw new ArgumentOutOfRangeException( |
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nameof(lines), |
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"There must be at least 3 lines to construct a path gradient brush."); |
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} |
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if (colors == null) |
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{ |
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throw new ArgumentNullException(nameof(colors)); |
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} |
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if (!colors.Any()) |
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{ |
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throw new ArgumentOutOfRangeException( |
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nameof(colors), |
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"One or more color is needed to construct a path gradient brush."); |
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} |
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this.path = new Polygon(lines); |
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this.centerColor = centerColor; |
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Color ColorAt(int index) => colors[index % colors.Length]; |
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this.edges = this.path.LineSegments.Select(s => new Path(s)) |
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.Select((path, i) => new Edge(path, ColorAt(i), ColorAt(i + 1))).ToList(); |
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} |
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/// <summary>
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/// Initializes a new instance of the <see cref="PathGradientBrush"/> class.
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/// </summary>
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/// <param name="lines">Line segments of a polygon that represents the gradient area.</param>
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/// <param name="colors">Array of colors that correspond to each point in the polygon.</param>
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public PathGradientBrush(ILineSegment[] lines, Color[] colors) |
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: this(lines, colors, CalculateCenterColor(colors)) |
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{ |
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} |
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/// <inheritdoc />
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public BrushApplicator<TPixel> CreateApplicator<TPixel>( |
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ImageFrame<TPixel> source, |
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RectangleF region, |
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GraphicsOptions options) |
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where TPixel : struct, IPixel<TPixel> |
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{ |
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return new PathGradientBrushApplicator<TPixel>(source, this.path, this.edges, this.centerColor, options); |
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} |
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private static Color CalculateCenterColor(Color[] colors) |
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{ |
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if (colors == null) |
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{ |
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throw new ArgumentNullException(nameof(colors)); |
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} |
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if (!colors.Any()) |
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{ |
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throw new ArgumentOutOfRangeException( |
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nameof(colors), |
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"One or more color is needed to construct a path gradient brush."); |
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} |
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return new Color(colors.Select(c => c.ToVector4()).Aggregate((p1, p2) => p1 + p2) / colors.Length); |
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} |
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private static float DistanceBetween(PointF p1, PointF p2) => ((Vector2)(p2 - p1)).Length(); |
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private struct Intersection |
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{ |
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public Intersection(PointF point, float distance) |
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{ |
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this.Point = point; |
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this.Distance = distance; |
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} |
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public PointF Point { get; } |
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public float Distance { get; } |
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} |
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/// <summary>
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/// An edge of the polygon that represents the gradient area.
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/// </summary>
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private class Edge |
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{ |
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private readonly Path path; |
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private readonly float length; |
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private readonly PointF[] buffer; |
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public Edge(Path path, Color startColor, Color endColor) |
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{ |
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this.path = path; |
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Vector2[] points = path.LineSegments.SelectMany(s => s.Flatten()).Select(p => (Vector2)p).ToArray(); |
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this.Start = points.First(); |
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this.StartColor = startColor.ToVector4(); |
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this.End = points.Last(); |
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this.EndColor = endColor.ToVector4(); |
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this.length = DistanceBetween(this.End, this.Start); |
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this.buffer = new PointF[this.path.MaxIntersections]; |
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} |
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public PointF Start { get; } |
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public Vector4 StartColor { get; } |
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public PointF End { get; } |
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public Vector4 EndColor { get; } |
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public Intersection? FindIntersection(PointF start, PointF end) |
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{ |
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int intersections = this.path.FindIntersections(start, end, this.buffer); |
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if (intersections == 0) |
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{ |
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return null; |
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} |
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return this.buffer.Take(intersections) |
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.Select(p => new Intersection(point: p, distance: ((Vector2)(p - start)).LengthSquared())) |
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.Aggregate((min, current) => min.Distance > current.Distance ? current : min); |
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} |
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public Vector4 ColorAt(float distance) |
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{ |
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float ratio = this.length > 0 ? distance / this.length : 0; |
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return Vector4.Lerp(this.StartColor, this.EndColor, ratio); |
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} |
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public Vector4 ColorAt(PointF point) => this.ColorAt(DistanceBetween(point, this.Start)); |
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} |
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/// <summary>
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/// The path gradient brush applicator.
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/// </summary>
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private class PathGradientBrushApplicator<TPixel> : BrushApplicator<TPixel> |
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where TPixel : struct, IPixel<TPixel> |
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{ |
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private readonly Path path; |
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private readonly PointF center; |
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private readonly Vector4 centerColor; |
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private readonly float maxDistance; |
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private readonly IList<Edge> edges; |
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/// <summary>
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/// Initializes a new instance of the <see cref="PathGradientBrushApplicator{TPixel}"/> class.
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/// </summary>
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/// <param name="source">The source image.</param>
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/// <param name="path">A polygon that represents the gradient area.</param>
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/// <param name="edges">Edges of the polygon.</param>
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/// <param name="centerColor">Color at the center of the gradient area to which the other colors converge.</param>
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/// <param name="options">The options.</param>
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public PathGradientBrushApplicator( |
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ImageFrame<TPixel> source, |
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Path path, |
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IList<Edge> edges, |
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Color centerColor, |
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GraphicsOptions options) |
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: base(source, options) |
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{ |
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this.path = path; |
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this.edges = edges; |
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PointF[] points = path.LineSegments.Select(s => s.EndPoint).ToArray(); |
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this.center = points.Aggregate((p1, p2) => p1 + p2) / points.Length; |
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this.centerColor = centerColor.ToVector4(); |
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this.maxDistance = points.Select(p => (Vector2)(p - this.center)).Select(d => d.Length()).Max(); |
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} |
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/// <inheritdoc />
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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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var point = new PointF(x, y); |
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if (point == this.center) |
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{ |
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return new Color(this.centerColor).ToPixel<TPixel>(); |
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} |
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if (!this.path.Contains(point)) |
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{ |
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return Color.Transparent.ToPixel<TPixel>(); |
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} |
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Vector2 direction = Vector2.Normalize(point - this.center); |
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PointF end = point + (PointF)(direction * this.maxDistance); |
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(Edge edge, Intersection? info) = this.FindIntersection(point, end); |
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PointF intersection = info.Value.Point; |
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Vector4 edgeColor = edge.ColorAt(intersection); |
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float length = DistanceBetween(intersection, this.center); |
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float ratio = length > 0 ? DistanceBetween(intersection, point) / length : 0; |
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Vector4 color = Vector4.Lerp(edgeColor, this.centerColor, ratio); |
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return new Color(color).ToPixel<TPixel>(); |
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} |
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} |
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private (Edge edge, Intersection? info) FindIntersection(PointF start, PointF end) |
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{ |
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(Edge edge, Intersection? info) closest = default; |
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foreach (Edge edge in this.edges) |
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{ |
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Intersection? intersection = edge.FindIntersection(start, end); |
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if (!intersection.HasValue) |
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{ |
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continue; |
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} |
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if (closest.info == null || closest.info.Value.Distance > intersection.Value.Distance) |
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{ |
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closest = (edge, intersection); |
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} |
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} |
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return closest; |
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} |
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/// <inheritdoc />
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public override void Dispose() |
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{ |
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} |
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} |
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} |
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} |
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@ -0,0 +1,209 @@ |
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// Copyright (c) Six Labors and contributors.
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// Licensed under the Apache License, Version 2.0.
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using System; |
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using SixLabors.ImageSharp.PixelFormats; |
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using SixLabors.ImageSharp.Processing; |
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using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison; |
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using SixLabors.Primitives; |
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using SixLabors.Shapes; |
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using Xunit; |
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namespace SixLabors.ImageSharp.Tests.Drawing |
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{ |
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[GroupOutput("Drawing/GradientBrushes")] |
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public class FillPathGradientBrushTests |
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{ |
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public static ImageComparer TolerantComparer = ImageComparer.TolerantPercentage(0.01f); |
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[Theory] |
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[WithBlankImages(10, 10, PixelTypes.Rgba32)] |
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public void FillRectangleWithDifferentColors<TPixel>(TestImageProvider<TPixel> provider) |
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where TPixel : struct, IPixel<TPixel> |
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{ |
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provider.VerifyOperation( |
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TolerantComparer, |
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image => |
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{ |
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ILineSegment[] path = |
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{ |
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new LinearLineSegment(new PointF(0, 0), new PointF(10, 0)), |
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new LinearLineSegment(new PointF(10, 0), new PointF(10, 10)), |
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new LinearLineSegment(new PointF(10, 10), new PointF(0, 10)), |
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new LinearLineSegment(new PointF(0, 10), new PointF(0, 0)) |
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}; |
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Color[] colors = { Color.Black, Color.Red, Color.Yellow, Color.Green }; |
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var brush = new PathGradientBrush(path, colors); |
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image.Mutate(x => x.Fill(brush)); |
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image.DebugSave(provider, appendPixelTypeToFileName: false, appendSourceFileOrDescription: false); |
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}); |
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} |
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[Theory] |
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[WithBlankImages(10, 10, PixelTypes.Rgba32)] |
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public void FillTriangleWithDifferentColors<TPixel>(TestImageProvider<TPixel> provider) |
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where TPixel : struct, IPixel<TPixel> |
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{ |
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provider.VerifyOperation( |
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TolerantComparer, |
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image => |
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{ |
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ILineSegment[] path = |
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{ |
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new LinearLineSegment(new PointF(5, 0), new PointF(10, 10)), |
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new LinearLineSegment(new PointF(10, 10), new PointF(0, 10)), |
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new LinearLineSegment(new PointF(0, 10), new PointF(5, 0)) |
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}; |
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Color[] colors = { Color.Red, Color.Green, Color.Blue }; |
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var brush = new PathGradientBrush(path, colors); |
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image.Mutate(x => x.Fill(brush)); |
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image.DebugSave(provider, appendPixelTypeToFileName: false, appendSourceFileOrDescription: false); |
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}); |
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} |
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[Theory] |
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[WithBlankImages(10, 10, PixelTypes.Rgba32)] |
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public void FillRectangleWithSingleColor<TPixel>(TestImageProvider<TPixel> provider) |
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where TPixel : struct, IPixel<TPixel> |
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{ |
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using (Image<TPixel> image = provider.GetImage()) |
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{ |
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ILineSegment[] path = |
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{ |
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new LinearLineSegment(new PointF(0, 0), new PointF(10, 0)), |
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new LinearLineSegment(new PointF(10, 0), new PointF(10, 10)), |
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new LinearLineSegment(new PointF(10, 10), new PointF(0, 10)), |
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new LinearLineSegment(new PointF(0, 10), new PointF(0, 0)) |
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}; |
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Color[] colors = { Color.Red }; |
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var brush = new PathGradientBrush(path, colors); |
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image.Mutate(x => x.Fill(brush)); |
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image.ComparePixelBufferTo(Color.Red); |
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} |
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} |
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[Theory] |
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[WithBlankImages(10, 10, PixelTypes.Rgba32)] |
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public void ShouldRotateTheColorsWhenThereAreMorePoints<TPixel>(TestImageProvider<TPixel> provider) |
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where TPixel : struct, IPixel<TPixel> |
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{ |
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provider.VerifyOperation( |
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TolerantComparer, |
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image => |
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{ |
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ILineSegment[] path = |
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{ |
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new LinearLineSegment(new PointF(0, 0), new PointF(10, 0)), |
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new LinearLineSegment(new PointF(10, 0), new PointF(10, 10)), |
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new LinearLineSegment(new PointF(10, 10), new PointF(0, 10)), |
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new LinearLineSegment(new PointF(0, 10), new PointF(0, 0)) |
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}; |
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Color[] colors = { Color.Red, Color.Yellow }; |
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var brush = new PathGradientBrush(path, colors); |
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image.Mutate(x => x.Fill(brush)); |
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image.DebugSave(provider, appendPixelTypeToFileName: false, appendSourceFileOrDescription: false); |
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}); |
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} |
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[Theory] |
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[WithBlankImages(10, 10, PixelTypes.Rgba32)] |
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public void FillWithCustomCenterColor<TPixel>(TestImageProvider<TPixel> provider) |
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where TPixel : struct, IPixel<TPixel> |
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{ |
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provider.VerifyOperation( |
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TolerantComparer, |
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image => |
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{ |
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ILineSegment[] path = |
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{ |
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new LinearLineSegment(new PointF(0, 0), new PointF(10, 0)), |
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new LinearLineSegment(new PointF(10, 0), new PointF(10, 10)), |
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new LinearLineSegment(new PointF(10, 10), new PointF(0, 10)), |
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new LinearLineSegment(new PointF(0, 10), new PointF(0, 0)) |
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}; |
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Color[] colors = { Color.Black, Color.Red, Color.Yellow, Color.Green }; |
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var brush = new PathGradientBrush(path, colors, Color.White); |
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image.Mutate(x => x.Fill(brush)); |
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image.DebugSave(provider, appendPixelTypeToFileName: false, appendSourceFileOrDescription: false); |
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}); |
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} |
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[Fact] |
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public void ShouldThrowArgumentNullExceptionWhenLinesAreNull() |
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{ |
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Color[] colors = { Color.Black, Color.Red, Color.Yellow, Color.Green }; |
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PathGradientBrush Create() => new PathGradientBrush(null, colors, Color.White); |
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Assert.Throws<ArgumentNullException>(Create); |
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} |
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[Fact] |
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public void ShouldThrowArgumentOutOfRangeExceptionWhenLessThan3LinesAreGiven() |
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{ |
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ILineSegment[] path = |
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{ |
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new LinearLineSegment(new PointF(0, 0), new PointF(10, 0)), |
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new LinearLineSegment(new PointF(10, 0), new PointF(10, 10)) |
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}; |
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Color[] colors = { Color.Black, Color.Red, Color.Yellow, Color.Green }; |
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PathGradientBrush Create() => new PathGradientBrush(path, colors, Color.White); |
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Assert.Throws<ArgumentOutOfRangeException>(Create); |
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} |
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[Fact] |
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public void ShouldThrowArgumentNullExceptionWhenColorsAreNull() |
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{ |
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ILineSegment[] path = |
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{ |
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new LinearLineSegment(new PointF(0, 0), new PointF(10, 0)), |
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new LinearLineSegment(new PointF(10, 0), new PointF(10, 10)), |
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new LinearLineSegment(new PointF(10, 10), new PointF(0, 10)), |
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new LinearLineSegment(new PointF(0, 10), new PointF(0, 0)) |
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}; |
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PathGradientBrush Create() => new PathGradientBrush(path, null, Color.White); |
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Assert.Throws<ArgumentNullException>(Create); |
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} |
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[Fact] |
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public void ShouldThrowArgumentOutOfRangeExceptionWhenEmptyColorArrayIsGiven() |
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{ |
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ILineSegment[] path = |
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{ |
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new LinearLineSegment(new PointF(0, 0), new PointF(10, 0)), |
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new LinearLineSegment(new PointF(10, 0), new PointF(10, 10)), |
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new LinearLineSegment(new PointF(10, 10), new PointF(0, 10)), |
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new LinearLineSegment(new PointF(0, 10), new PointF(0, 0)) |
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}; |
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var colors = new Color[0]; |
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PathGradientBrush Create() => new PathGradientBrush(path, colors, Color.White); |
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Assert.Throws<ArgumentOutOfRangeException>(Create); |
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} |
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} |
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} |
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@ -1 +1 @@ |
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Subproject commit 36f39bc624f8a49caf512077bf70cab30c2e5fb4 |
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Subproject commit 99a2bc523cd4eb00e37af20d1b2088fa11564c57 |
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