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Fix #787

pull/788/head
James Jackson-South 7 years ago
parent
4544512771
commit
3917e397f5
4 changed files with 83 additions and 38 deletions
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  1. 13
      src/ImageSharp/Processing/Processors/Transforms/ProjectiveTransformProcessor.cs
  2. 79
      src/ImageSharp/Processing/Processors/Transforms/TransformUtils.cs
  3. 27
      tests/ImageSharp.Tests/Processing/Transforms/ProjectiveTransformTests.cs
  4. 2
      tests/Images/External

13
src/ImageSharp/Processing/Processors/Transforms/ProjectiveTransformProcessor.cs
View File

@ -75,7 +75,6 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
// Convert from screen to world space.
Matrix4x4.Invert(this.TransformMatrix, out Matrix4x4 matrix);
const float Epsilon = 0.0000001F;
if (this.Sampler is NearestNeighborResampler)
{
@ -90,11 +89,9 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
for (int x = 0; x < width; x++)
{
var v3 = Vector3.Transform(new Vector3(x, y, 1), matrix);
float z = MathF.Max(v3.Z, Epsilon);
int px = (int)MathF.Round(v3.X / z);
int py = (int)MathF.Round(v3.Y / z);
Vector2 point = TransformUtils.ProjectiveTransform2D(x, y, matrix);
int px = (int)MathF.Round(point.X);
int py = (int)MathF.Round(point.Y);
if (sourceRectangle.Contains(px, py))
{
@ -127,9 +124,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
{
// Use the single precision position to calculate correct bounding pixels
// otherwise we get rogue pixels outside of the bounds.
var v3 = Vector3.Transform(new Vector3(x, y, 1F), matrix);
Vector2 point = new Vector2(v3.X, v3.Y) / MathF.Max(v3.Z, Epsilon);
Vector2 point = TransformUtils.ProjectiveTransform2D(x, y, matrix);
kernel.Convolve(point, x, ref ySpanRef, ref xSpanRef, source.PixelBuffer, vectorSpan);
}

79
src/ImageSharp/Processing/Processors/Transforms/TransformUtils.cs
View File

@ -3,6 +3,7 @@
using System;
using System.Numerics;
using System.Runtime.CompilerServices;
using SixLabors.Primitives;
namespace SixLabors.ImageSharp.Processing.Processors.Transforms
@ -12,6 +13,21 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
/// </summary>
internal static class TransformUtils
{
/// <summary>
/// Applies the projective transform against the given coordinates flattened into the 2D space.
/// </summary>
/// <param name="x">The "x" vector coordinate.</param>
/// <param name="y">The "y" vector coordinate.</param>
/// <param name="matrix">The transform matrix.</param>
/// <returns>The <see cref="Vector2"/>.</returns>
[MethodImpl(InliningOptions.ShortMethod)]
public static Vector2 ProjectiveTransform2D(float x, float y, Matrix4x4 matrix)
{
const float Epsilon = 0.0000001F;
var v4 = Vector4.Transform(new Vector4(x, y, 0, 1F), matrix);
return new Vector2(v4.X, v4.Y) / MathF.Max(v4.W, Epsilon);
}
/// <summary>
/// Creates a centered rotation matrix using the given rotation in degrees and the source size.
/// </summary>
@ -94,12 +110,28 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
{
Matrix4x4 matrix = Matrix4x4.Identity;
/*
* SkMatrix is layed out in the following manner:
*
* [ ScaleX SkewY Persp0 ]
* [ SkewX ScaleY Persp1 ]
* [ TransX TransY Persp2 ]
*
* When converting from Matrix4x4 to SkMatrix, the third row and
* column is dropped. When converting from SkMatrix to Matrix4x4
* the third row and column remain as identity:
*
* [ a b c ] [ a b 0 c ]
* [ d e f ] -> [ d e 0 f ]
* [ g h i ] [ 0 0 1 0 ]
* [ g h 0 i ]
*/
switch (side)
{
case TaperSide.Left:
matrix.M11 = fraction;
matrix.M22 = fraction;
matrix.M13 = (fraction - 1) / size.Width;
matrix.M14 = (fraction - 1) / size.Width;
switch (corner)
{
@ -107,13 +139,13 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
break;
case TaperCorner.LeftOrTop:
matrix.M12 = size.Height * matrix.M13;
matrix.M32 = size.Height * (1 - fraction);
matrix.M12 = size.Height * matrix.M14;
matrix.M42 = size.Height * (1 - fraction);
break;
case TaperCorner.Both:
matrix.M12 = size.Height * .5F * matrix.M13;
matrix.M32 = size.Height * (1 - fraction) / 2;
matrix.M12 = size.Height * .5F * matrix.M14;
matrix.M42 = size.Height * (1 - fraction) / 2;
break;
}
@ -122,7 +154,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
case TaperSide.Top:
matrix.M11 = fraction;
matrix.M22 = fraction;
matrix.M23 = (fraction - 1) / size.Height;
matrix.M24 = (fraction - 1) / size.Height;
switch (corner)
{
@ -130,13 +162,13 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
break;
case TaperCorner.LeftOrTop:
matrix.M21 = size.Width * matrix.M23;
matrix.M31 = size.Width * (1 - fraction);
matrix.M21 = size.Width * matrix.M24;
matrix.M41 = size.Width * (1 - fraction);
break;
case TaperCorner.Both:
matrix.M21 = size.Width * .5F * matrix.M23;
matrix.M31 = size.Width * (1 - fraction) / 2;
matrix.M21 = size.Width * .5F * matrix.M24;
matrix.M41 = size.Width * (1 - fraction) * .5F;
break;
}
@ -144,7 +176,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
case TaperSide.Right:
matrix.M11 = 1 / fraction;
matrix.M13 = (1 - fraction) / (size.Width * fraction);
matrix.M14 = (1 - fraction) / (size.Width * fraction);
switch (corner)
{
@ -152,11 +184,11 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
break;
case TaperCorner.LeftOrTop:
matrix.M12 = size.Height * matrix.M13;
matrix.M12 = size.Height * matrix.M14;
break;
case TaperCorner.Both:
matrix.M12 = size.Height * .5F * matrix.M13;
matrix.M12 = size.Height * .5F * matrix.M14;
break;
}
@ -164,7 +196,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
case TaperSide.Bottom:
matrix.M22 = 1 / fraction;
matrix.M23 = (1 - fraction) / (size.Height * fraction);
matrix.M24 = (1 - fraction) / (size.Height * fraction);
switch (corner)
{
@ -172,11 +204,11 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
break;
case TaperCorner.LeftOrTop:
matrix.M21 = size.Width * matrix.M23;
matrix.M21 = size.Width * matrix.M24;
break;
case TaperCorner.Both:
matrix.M21 = size.Width * .5F * matrix.M23;
matrix.M21 = size.Width * .5F * matrix.M24;
break;
}
@ -260,17 +292,10 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
return rectangle;
}
Vector2 GetVector(float x, float y)
{
const float Epsilon = 0.0000001F;
var v3 = Vector3.Transform(new Vector3(x, y, 1F), matrix);
return new Vector2(v3.X, v3.Y) / MathF.Max(v3.Z, Epsilon);
}
Vector2 tl = GetVector(rectangle.Left, rectangle.Top);
Vector2 tr = GetVector(rectangle.Right, rectangle.Top);
Vector2 bl = GetVector(rectangle.Left, rectangle.Bottom);
Vector2 br = GetVector(rectangle.Right, rectangle.Bottom);
Vector2 tl = ProjectiveTransform2D(rectangle.Left, rectangle.Top, matrix);
Vector2 tr = ProjectiveTransform2D(rectangle.Right, rectangle.Top, matrix);
Vector2 bl = ProjectiveTransform2D(rectangle.Left, rectangle.Bottom, matrix);
Vector2 br = ProjectiveTransform2D(rectangle.Right, rectangle.Bottom, matrix);
return GetBoundingRectangle(tl, tr, bl, br);
}

27
tests/ImageSharp.Tests/Processing/Transforms/ProjectiveTransformTests.cs
View File

@ -111,7 +111,32 @@ namespace SixLabors.ImageSharp.Tests.Processing.Transforms
using (Image<TPixel> image = provider.GetImage())
{
Matrix4x4 matrix = Matrix4x4.Identity;
matrix.M13 = 0.01F;
matrix.M14 = 0.01F;
ProjectiveTransformBuilder builder = new ProjectiveTransformBuilder()
.AppendMatrix(matrix);
image.Mutate(i => i.Transform(builder));
image.DebugSave(provider);
image.CompareToReferenceOutput(TolerantComparer, provider);
}
}
[Theory]
[WithSolidFilledImages(290, 154, 0, 0, 255, PixelTypes.Rgba32)]
public void PerspectiveTransformMatchesCSS<TPixel>(TestImageProvider<TPixel> provider)
where TPixel : struct, IPixel<TPixel>
{
// https://jsfiddle.net/dFrHS/545/
// https://github.com/SixLabors/ImageSharp/issues/787
using (Image<TPixel> image = provider.GetImage())
{
var matrix = new Matrix4x4(
0.260987f, -0.434909f, 0, -0.0022184f,
0.373196f, 0.949882f, 0, -0.000312129f,
0, 0, 1, 0,
52, 165, 0, 1);
ProjectiveTransformBuilder builder = new ProjectiveTransformBuilder()
.AppendMatrix(matrix);

2
tests/Images/External

@ -1 +1 @@
Subproject commit 1edb0f3e04c18974821a3012a87f7c2e073c8019
Subproject commit 69603ee5b6f7dd64114fc44d321e50d9b2d439be
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