mirror of https://github.com/SixLabors/ImageSharp
Anton Firszov
8 years ago
7 changed files with 225 additions and 194 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.Runtime.CompilerServices; |
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using SixLabors.ImageSharp.Memory; |
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using SixLabors.Memory; |
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namespace SixLabors.ImageSharp.Processing.Processors.Transforms |
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{ |
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/// <summary>
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/// Holds the <see cref="ResizeKernel"/> values in an optimized contigous memory region.
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/// </summary>
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internal class KernelMap : IDisposable |
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{ |
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private readonly Buffer2D<float> data; |
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/// <summary>
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/// Initializes a new instance of the <see cref="KernelMap"/> class.
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/// </summary>
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/// <param name="memoryAllocator">The <see cref="MemoryAllocator"/> to use for allocations.</param>
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/// <param name="destinationSize">The size of the destination window</param>
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/// <param name="kernelRadius">The radius of the kernel</param>
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public KernelMap(MemoryAllocator memoryAllocator, int destinationSize, float kernelRadius) |
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{ |
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int width = (int)Math.Ceiling(kernelRadius * 2); |
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this.data = memoryAllocator.Allocate2D<float>(width, destinationSize, AllocationOptions.Clean); |
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this.Kernels = new ResizeKernel[destinationSize]; |
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} |
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/// <summary>
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/// Gets the calculated <see cref="Kernels"/> values.
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/// </summary>
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public ResizeKernel[] Kernels { get; } |
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/// <summary>
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/// Disposes <see cref="KernelMap"/> instance releasing it's backing buffer.
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/// </summary>
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public void Dispose() |
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{ |
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this.data.Dispose(); |
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} |
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/// <summary>
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/// Computes the weights to apply at each pixel when resizing.
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/// </summary>
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/// <param name="sampler">The <see cref="IResampler"/></param>
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/// <param name="destinationSize">The destination size</param>
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/// <param name="sourceSize">The source size</param>
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/// <param name="memoryAllocator">The <see cref="MemoryAllocator"/> to use for buffer allocations</param>
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/// <returns>The <see cref="KernelMap"/></returns>
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public static KernelMap Calculate( |
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IResampler sampler, |
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int destinationSize, |
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int sourceSize, |
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MemoryAllocator memoryAllocator) |
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{ |
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float ratio = (float)sourceSize / destinationSize; |
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float scale = ratio; |
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if (scale < 1F) |
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{ |
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scale = 1F; |
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} |
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float radius = MathF.Ceiling(scale * sampler.Radius); |
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var result = new KernelMap(memoryAllocator, destinationSize, radius); |
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for (int i = 0; i < destinationSize; i++) |
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{ |
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float center = ((i + .5F) * ratio) - .5F; |
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// Keep inside bounds.
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int left = (int)MathF.Ceiling(center - radius); |
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if (left < 0) |
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{ |
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left = 0; |
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} |
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int right = (int)MathF.Floor(center + radius); |
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if (right > sourceSize - 1) |
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{ |
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right = sourceSize - 1; |
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} |
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float sum = 0; |
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ResizeKernel ws = result.CreateKernel(i, left, right); |
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result.Kernels[i] = ws; |
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ref float weightsBaseRef = ref ws.GetStartReference(); |
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for (int j = left; j <= right; j++) |
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{ |
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float weight = sampler.GetValue((j - center) / scale); |
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sum += weight; |
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// weights[j - left] = weight:
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Unsafe.Add(ref weightsBaseRef, j - left) = weight; |
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} |
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// Normalize, best to do it here rather than in the pixel loop later on.
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if (sum > 0) |
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{ |
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for (int w = 0; w < ws.Length; w++) |
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{ |
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// weights[w] = weights[w] / sum:
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ref float wRef = ref Unsafe.Add(ref weightsBaseRef, w); |
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wRef /= sum; |
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} |
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} |
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} |
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return result; |
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} |
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/// <summary>
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/// Slices a weights value at the given positions.
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/// </summary>
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/// <param name="destIdx">The index in destination buffer</param>
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/// <param name="leftIdx">The local left index value</param>
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/// <param name="rightIdx">The local right index value</param>
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/// <returns>The weights</returns>
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private ResizeKernel CreateKernel(int destIdx, int leftIdx, int rightIdx) |
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{ |
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return new ResizeKernel(destIdx, leftIdx, this.data, rightIdx - leftIdx + 1); |
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} |
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} |
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} |
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@ -1,56 +0,0 @@ |
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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.Memory; |
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using SixLabors.Memory; |
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namespace SixLabors.ImageSharp.Processing.Processors.Transforms |
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{ |
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/// <summary>
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/// Holds the <see cref="WeightsWindow"/> values in an optimized contigous memory region.
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/// </summary>
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internal class WeightsBuffer : IDisposable |
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{ |
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private readonly Buffer2D<float> dataBuffer; |
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/// <summary>
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/// Initializes a new instance of the <see cref="WeightsBuffer"/> class.
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/// </summary>
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/// <param name="memoryAllocator">The <see cref="MemoryAllocator"/> to use for allocations.</param>
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/// <param name="destinationSize">The size of the destination window</param>
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/// <param name="kernelRadius">The radius of the kernel</param>
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public WeightsBuffer(MemoryAllocator memoryAllocator, int destinationSize, float kernelRadius) |
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{ |
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int width = (int)Math.Ceiling(kernelRadius * 2); |
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this.dataBuffer = memoryAllocator.Allocate2D<float>(width, destinationSize, AllocationOptions.Clean); |
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this.Weights = new WeightsWindow[destinationSize]; |
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} |
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/// <summary>
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/// Gets the calculated <see cref="Weights"/> values.
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/// </summary>
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public WeightsWindow[] Weights { get; } |
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/// <summary>
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/// Disposes <see cref="WeightsBuffer"/> instance releasing it's backing buffer.
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/// </summary>
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public void Dispose() |
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{ |
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this.dataBuffer.Dispose(); |
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} |
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/// <summary>
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/// Slices a weights value at the given positions.
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/// </summary>
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/// <param name="destIdx">The index in destination buffer</param>
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/// <param name="leftIdx">The local left index value</param>
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/// <param name="rightIdx">The local right index value</param>
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/// <returns>The weights</returns>
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public WeightsWindow GetWeightsWindow(int destIdx, int leftIdx, int rightIdx) |
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{ |
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return new WeightsWindow(destIdx, leftIdx, this.dataBuffer, rightIdx - leftIdx + 1); |
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} |
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} |
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} |
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@ -0,0 +1,61 @@ |
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using System; |
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using System.IO; |
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using System.Text; |
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using SixLabors.ImageSharp.PixelFormats; |
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using SixLabors.ImageSharp.Processing; |
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using SixLabors.ImageSharp.Processing.Processors.Transforms; |
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using SixLabors.Primitives; |
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using Xunit; |
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using Xunit.Abstractions; |
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namespace SixLabors.ImageSharp.Tests.Processing.Processors.Transforms |
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{ |
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public class KernelMapTests |
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{ |
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private ITestOutputHelper Output { get; } |
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public KernelMapTests(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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[InlineData(500, 200, nameof(KnownResamplers.Bicubic))] |
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[InlineData(50, 40, nameof(KnownResamplers.Bicubic))] |
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[InlineData(40, 30, nameof(KnownResamplers.Bicubic))] |
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[InlineData(500, 200, nameof(KnownResamplers.Lanczos8))] |
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[InlineData(100, 80, nameof(KnownResamplers.Lanczos8))] |
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[InlineData(100, 10, nameof(KnownResamplers.Lanczos8))] |
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[InlineData(10, 100, nameof(KnownResamplers.Lanczos8))] |
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public void PrintKernelMap(int srcSize, int destSize, string resamplerName) |
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{ |
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var resampler = (IResampler)typeof(KnownResamplers).GetProperty(resamplerName).GetValue(null); |
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var kernelMap = KernelMap.Calculate(resampler, destSize, srcSize, Configuration.Default.MemoryAllocator); |
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var bld = new StringBuilder(); |
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foreach (ResizeKernel window in kernelMap.Kernels) |
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{ |
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Span<float> span = window.GetSpan(); |
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for (int i = 0; i < window.Length; i++) |
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{ |
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float value = span[i]; |
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bld.Append($"{value,7:F4}"); |
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bld.Append("| "); |
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} |
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bld.AppendLine(); |
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} |
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string outDir = TestEnvironment.CreateOutputDirectory("." + nameof(this.PrintKernelMap)); |
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string fileName = $@"{outDir}\{resamplerName}_{srcSize}_{destSize}.MD"; |
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File.WriteAllText(fileName, bld.ToString()); |
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this.Output.WriteLine(bld.ToString()); |
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} |
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} |
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} |
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