mirror of https://github.com/SixLabors/ImageSharp
James Jackson-South
8 years ago
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GitHub
GitHub
8 changed files with 380 additions and 63 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.Numerics; |
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using SixLabors.Primitives; |
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namespace SixLabors.ImageSharp.Processing.Transforms |
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{ |
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/// <summary>
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/// Enumerates the various options which determine which side to taper
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/// </summary>
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public enum TaperSide |
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{ |
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/// <summary>
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/// Taper the left side
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/// </summary>
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Left, |
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/// <summary>
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/// Taper the top side
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/// </summary>
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Top, |
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/// <summary>
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/// Taper the right side
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/// </summary>
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Right, |
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/// <summary>
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/// Taper the bottom side
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/// </summary>
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Bottom |
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} |
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/// <summary>
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/// Enumerates the various options which determine how to taper corners
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/// </summary>
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public enum TaperCorner |
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{ |
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/// <summary>
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/// Taper the left or top corner
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/// </summary>
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LeftOrTop, |
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/// <summary>
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/// Taper the right or bottom corner
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/// </summary>
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RightOrBottom, |
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/// <summary>
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/// Taper the both sets of corners
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/// </summary>
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Both |
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} |
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/// <summary>
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/// Provides helper methods for working with generalized projective transforms.
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/// </summary>
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public static class ProjectiveTransformHelper |
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{ |
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/// <summary>
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/// Creates a matrix that performs a tapering projective transform.
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/// <see href="https://docs.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/graphics/skiasharp/transforms/non-affine"/>
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/// </summary>
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/// <param name="size">The rectangular size of the image being transformed.</param>
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/// <param name="taperSide">An enumeration that indicates the side of the rectangle that tapers.</param>
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/// <param name="taperCorner">An enumeration that indicates on which corners to taper the rectangle.</param>
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/// <param name="taperFraction">The amount to taper.</param>
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/// <returns>The <see cref="Matrix4x4"/></returns>
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public static Matrix4x4 CreateTaperMatrix(Size size, TaperSide taperSide, TaperCorner taperCorner, float taperFraction) |
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{ |
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Matrix4x4 matrix = Matrix4x4.Identity; |
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switch (taperSide) |
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{ |
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case TaperSide.Left: |
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matrix.M11 = taperFraction; |
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matrix.M22 = taperFraction; |
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matrix.M13 = (taperFraction - 1) / size.Width; |
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switch (taperCorner) |
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{ |
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case TaperCorner.RightOrBottom: |
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break; |
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case TaperCorner.LeftOrTop: |
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matrix.M12 = size.Height * matrix.M13; |
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matrix.M32 = size.Height * (1 - taperFraction); |
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break; |
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case TaperCorner.Both: |
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matrix.M12 = (size.Height * 0.5f) * matrix.M13; |
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matrix.M32 = size.Height * (1 - taperFraction) / 2; |
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break; |
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} |
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break; |
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case TaperSide.Top: |
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matrix.M11 = taperFraction; |
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matrix.M22 = taperFraction; |
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matrix.M23 = (taperFraction - 1) / size.Height; |
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switch (taperCorner) |
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{ |
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case TaperCorner.RightOrBottom: |
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break; |
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case TaperCorner.LeftOrTop: |
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matrix.M21 = size.Width * matrix.M23; |
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matrix.M31 = size.Width * (1 - taperFraction); |
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break; |
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case TaperCorner.Both: |
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matrix.M21 = (size.Width * 0.5f) * matrix.M23; |
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matrix.M31 = size.Width * (1 - taperFraction) / 2; |
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break; |
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} |
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break; |
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case TaperSide.Right: |
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matrix.M11 = 1 / taperFraction; |
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matrix.M13 = (1 - taperFraction) / (size.Width * taperFraction); |
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switch (taperCorner) |
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{ |
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case TaperCorner.RightOrBottom: |
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break; |
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case TaperCorner.LeftOrTop: |
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matrix.M12 = size.Height * matrix.M13; |
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break; |
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case TaperCorner.Both: |
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matrix.M12 = (size.Height * 0.5f) * matrix.M13; |
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break; |
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} |
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break; |
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case TaperSide.Bottom: |
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matrix.M22 = 1 / taperFraction; |
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matrix.M23 = (1 - taperFraction) / (size.Height * taperFraction); |
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switch (taperCorner) |
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{ |
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case TaperCorner.RightOrBottom: |
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break; |
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case TaperCorner.LeftOrTop: |
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matrix.M21 = size.Width * matrix.M23; |
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break; |
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case TaperCorner.Both: |
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matrix.M21 = (size.Width * 0.5f) * matrix.M23; |
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break; |
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} |
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break; |
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} |
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return matrix; |
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} |
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} |
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} |
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@ -0,0 +1,137 @@ |
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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.Numerics; |
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using System.Reflection; |
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using SixLabors.ImageSharp.PixelFormats; |
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using SixLabors.ImageSharp.Processing; |
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using SixLabors.ImageSharp.Processing.Transforms; |
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using SixLabors.ImageSharp.Processing.Transforms.Resamplers; |
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using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison; |
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using Xunit; |
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// ReSharper disable InconsistentNaming
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namespace SixLabors.ImageSharp.Tests.Processing.Transforms |
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{ |
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using Xunit.Abstractions; |
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public class ProjectiveTransformTests |
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{ |
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private static readonly ImageComparer ValidatorComparer = ImageComparer.TolerantPercentage(0.03f, 3); |
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private static readonly ImageComparer TolerantComparer = ImageComparer.TolerantPercentage(0.5f, 3); |
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private ITestOutputHelper Output { get; } |
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public static readonly TheoryData<string> ResamplerNames = new TheoryData<string> |
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{ |
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nameof(KnownResamplers.Bicubic), |
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nameof(KnownResamplers.Box), |
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nameof(KnownResamplers.CatmullRom), |
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nameof(KnownResamplers.Hermite), |
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nameof(KnownResamplers.Lanczos2), |
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nameof(KnownResamplers.Lanczos3), |
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nameof(KnownResamplers.Lanczos5), |
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nameof(KnownResamplers.Lanczos8), |
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nameof(KnownResamplers.MitchellNetravali), |
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nameof(KnownResamplers.NearestNeighbor), |
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nameof(KnownResamplers.Robidoux), |
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nameof(KnownResamplers.RobidouxSharp), |
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nameof(KnownResamplers.Spline), |
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nameof(KnownResamplers.Triangle), |
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nameof(KnownResamplers.Welch), |
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}; |
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public static readonly TheoryData<TaperSide, TaperCorner> TaperMatrixData = new TheoryData<TaperSide, TaperCorner> |
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{ |
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{ TaperSide.Bottom, TaperCorner.Both }, |
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{ TaperSide.Bottom, TaperCorner.LeftOrTop }, |
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{ TaperSide.Bottom, TaperCorner.RightOrBottom }, |
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{ TaperSide.Top, TaperCorner.Both }, |
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{ TaperSide.Top, TaperCorner.LeftOrTop }, |
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{ TaperSide.Top, TaperCorner.RightOrBottom }, |
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{ TaperSide.Left, TaperCorner.Both }, |
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{ TaperSide.Left, TaperCorner.LeftOrTop }, |
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{ TaperSide.Left, TaperCorner.RightOrBottom }, |
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{ TaperSide.Right, TaperCorner.Both }, |
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{ TaperSide.Right, TaperCorner.LeftOrTop }, |
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{ TaperSide.Right, TaperCorner.RightOrBottom }, |
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}; |
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public ProjectiveTransformTests(ITestOutputHelper output) |
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{ |
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this.Output = output; |
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} |
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[Theory] |
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[WithTestPatternImages(nameof(ResamplerNames), 150, 150, PixelTypes.Rgba32)] |
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public void Transform_WithSampler<TPixel>(TestImageProvider<TPixel> provider, string resamplerName) |
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where TPixel : struct, IPixel<TPixel> |
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{ |
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IResampler sampler = GetResampler(resamplerName); |
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using (Image<TPixel> image = provider.GetImage()) |
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{ |
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Matrix4x4 m = ProjectiveTransformHelper.CreateTaperMatrix(image.Size(), TaperSide.Right, TaperCorner.Both, .5F); |
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image.Mutate(i => { i.Transform(m, sampler); }); |
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image.DebugSave(provider, resamplerName); |
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image.CompareToReferenceOutput(ValidatorComparer, provider, resamplerName); |
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} |
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} |
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[Theory] |
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[WithSolidFilledImages(nameof(TaperMatrixData), 30, 30, nameof(Rgba32.Red), PixelTypes.Rgba32)] |
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public void Transform_WithTaperMatrix<TPixel>(TestImageProvider<TPixel> provider, TaperSide taperSide, TaperCorner taperCorner) |
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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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Matrix4x4 m = ProjectiveTransformHelper.CreateTaperMatrix(image.Size(), taperSide, taperCorner, .5F); |
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image.Mutate(i => { i.Transform(m); }); |
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string testOutputDetails = $"{taperSide}-{taperCorner}"; |
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image.DebugSave(provider, testOutputDetails); |
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image.CompareFirstFrameToReferenceOutput(TolerantComparer, provider, testOutputDetails); |
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} |
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} |
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[Theory] |
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[WithSolidFilledImages(100, 100, 0, 0, 255, PixelTypes.Rgba32)] |
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public void RawTransformMatchesDocumentedExample<TPixel>(TestImageProvider<TPixel> provider) |
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where TPixel : struct, IPixel<TPixel> |
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{ |
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// Printing some extra output to help investigating roundoff errors:
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this.Output.WriteLine($"Vector.IsHardwareAccelerated: {Vector.IsHardwareAccelerated}"); |
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// This test matches the output described in the example at
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// https://docs.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/graphics/skiasharp/transforms/non-affine
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using (Image<TPixel> image = provider.GetImage()) |
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{ |
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Matrix4x4 m = Matrix4x4.Identity; |
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m.M13 = 0.01F; |
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image.Mutate(i => { i.Transform(m); }); |
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image.DebugSave(provider); |
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image.CompareToReferenceOutput(TolerantComparer, provider); |
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} |
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} |
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private static IResampler GetResampler(string name) |
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{ |
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PropertyInfo property = typeof(KnownResamplers).GetTypeInfo().GetProperty(name); |
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if (property == null) |
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{ |
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throw new Exception("Invalid property name!"); |
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} |
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return (IResampler)property.GetValue(null); |
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} |
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} |
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} |
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@ -1 +1 @@ |
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Subproject commit 5a9a88380166a87521d10048f53cda7f5f761d66 |
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Subproject commit f641620eb5378db49d6153bbf1443ad13bda2379 |
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