mirror of https://github.com/SixLabors/ImageSharp
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Better organisation, handles all color types + maintains image quality. Former-commit-id: 27d65b60f5e468e9678d0f9dd0314700e658036e Former-commit-id: 1ed0afaccc0218f60cdc749a83725c9f9693ab4a Former-commit-id: d20d7fd77362ad6cbb570b46105f2817df99c85cpull/1/head
James Jackson-South
10 years ago
7 changed files with 265 additions and 491 deletions
@ -1,76 +0,0 @@ |
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// <copyright file="GrayscaleReader.cs" company="James Jackson-South">
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// Copyright (c) James Jackson-South and contributors.
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// Licensed under the Apache License, Version 2.0.
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// </copyright>
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namespace ImageProcessorCore.Formats |
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{ |
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/// <summary>
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/// Color reader for reading grayscale colors from a png file.
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/// </summary>
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internal sealed class GrayscaleReader : IColorReader |
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{ |
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/// <summary>
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/// Whether t also read the alpha channel.
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/// </summary>
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private readonly bool useAlpha; |
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/// <summary>
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/// The current row.
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/// </summary>
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private int row; |
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/// <summary>
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/// Initializes a new instance of the <see cref="GrayscaleReader"/> class.
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/// </summary>
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/// <param name="useAlpha">
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/// If set to <c>true</c> the color reader will also read the
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/// alpha channel from the scanline.
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/// </param>
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public GrayscaleReader(bool useAlpha) |
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{ |
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this.useAlpha = useAlpha; |
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} |
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/// <inheritdoc/>
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public void ReadScanline<T, TP>(byte[] scanline, T[] pixels, PngHeader header) |
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where T : IPackedVector<TP> |
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where TP : struct |
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{ |
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int offset; |
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byte[] newScanline = scanline.ToArrayByBitsLength(header.BitDepth); |
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// Stored in r-> g-> b-> a order.
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if (this.useAlpha) |
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{ |
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for (int x = 0; x < header.Width / 2; x++) |
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{ |
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offset = (this.row * header.Width) + x; |
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byte rgb = newScanline[x * 2]; |
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byte a = newScanline[(x * 2) + 1]; |
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T color = default(T); |
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color.PackFromBytes(rgb, rgb, rgb, a); |
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pixels[offset] = color; |
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} |
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} |
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else |
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{ |
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for (int x = 0; x < header.Width; x++) |
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{ |
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offset = (this.row * header.Width) + x; |
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byte rgb = newScanline[x]; |
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T color = default(T); |
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color.PackFromBytes(rgb, rgb, rgb, 255); |
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pixels[offset] = color; |
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} |
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} |
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this.row++; |
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} |
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} |
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} |
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@ -1,29 +0,0 @@ |
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// <copyright file="IColorReader.cs" company="James Jackson-South">
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// Copyright (c) James Jackson-South and contributors.
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// Licensed under the Apache License, Version 2.0.
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// </copyright>
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namespace ImageProcessorCore.Formats |
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{ |
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/// <summary>
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/// Encapsulates methods for color readers, which are responsible for reading
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/// different color formats from a png file.
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/// </summary>
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public interface IColorReader |
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{ |
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/// <summary>
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/// Reads the specified scanline.
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/// </summary>
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/// <typeparam name="T">The pixel format.</typeparam>
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/// <typeparam name="TP">The packed format. <example>long, float.</example></typeparam>
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/// <param name="scanline">The scanline.</param>
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/// <param name="pixels">The pixels to read the image row to.</param>
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/// <param name="header">
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/// The header, which contains information about the png file, like
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/// the width of the image and the height.
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/// </param>
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void ReadScanline<T, TP>(byte[] scanline, T[] pixels, PngHeader header) |
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where T : IPackedVector<TP> |
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where TP : struct; |
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} |
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} |
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@ -1,95 +0,0 @@ |
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// <copyright file="PaletteIndexReader.cs" company="James Jackson-South">
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// Copyright (c) James Jackson-South and contributors.
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// Licensed under the Apache License, Version 2.0.
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// </copyright>
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namespace ImageProcessorCore.Formats |
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{ |
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/// <summary>
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/// A color reader for reading palette indices from the png file.
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/// </summary>
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internal sealed class PaletteIndexReader : IColorReader |
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{ |
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/// <summary>
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/// The palette.
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/// </summary>
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private readonly byte[] palette; |
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/// <summary>
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/// The alpha palette.
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/// </summary>
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private readonly byte[] paletteAlpha; |
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/// <summary>
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/// The current row.
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/// </summary>
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private int row; |
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/// <summary>
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/// Initializes a new instance of the <see cref="PaletteIndexReader"/> class.
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/// </summary>
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/// <param name="palette">The palette as simple byte array. It will contains 3 values for each
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/// color, which represents the red-, the green- and the blue channel.</param>
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/// <param name="paletteAlpha">The alpha palette. Can be null, if the image does not have an
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/// alpha channel and can contain less entries than the number of colors in the palette.</param>
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public PaletteIndexReader(byte[] palette, byte[] paletteAlpha) |
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{ |
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this.palette = palette; |
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this.paletteAlpha = paletteAlpha; |
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} |
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/// <inheritdoc/>
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public void ReadScanline<T, TP>(byte[] scanline, T[] pixels, PngHeader header) |
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where T : IPackedVector<TP> |
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where TP : struct |
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{ |
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byte[] newScanline = scanline.ToArrayByBitsLength(header.BitDepth); |
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int offset, index; |
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if (this.paletteAlpha != null && this.paletteAlpha.Length > 0) |
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{ |
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// If the alpha palette is not null and does one or
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// more entries, this means, that the image contains and alpha
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// channel and we should try to read it.
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for (int i = 0; i < header.Width; i++) |
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{ |
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index = newScanline[i]; |
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offset = (this.row * header.Width) + i; |
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int pixelOffset = index * 3; |
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byte r = this.palette[pixelOffset]; |
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byte g = this.palette[pixelOffset + 1]; |
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byte b = this.palette[pixelOffset + 2]; |
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byte a = this.paletteAlpha.Length > index |
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? this.paletteAlpha[index] |
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: (byte)255; |
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T color = default(T); |
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color.PackFromBytes(r, g, b, a); |
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pixels[offset] = color; |
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} |
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} |
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else |
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{ |
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for (int i = 0; i < header.Width; i++) |
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{ |
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index = newScanline[i]; |
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offset = (this.row * header.Width) + i; |
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int pixelOffset = index * 3; |
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byte r = this.palette[pixelOffset]; |
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byte g = this.palette[pixelOffset + 1]; |
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byte b = this.palette[pixelOffset + 2]; |
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T color = default(T); |
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color.PackFromBytes(r, g, b, 255); |
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pixels[offset] = color; |
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} |
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} |
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this.row++; |
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} |
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} |
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} |
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@ -1,61 +0,0 @@ |
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// <copyright file="PngColorTypeInformation.cs" company="James Jackson-South">
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// Copyright (c) James Jackson-South and contributors.
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// Licensed under the Apache License, Version 2.0.
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// </copyright>
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namespace ImageProcessorCore.Formats |
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{ |
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using System; |
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/// <summary>
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/// Contains information that are required when loading a png with a specific color type.
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/// </summary>
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internal sealed class PngColorTypeInformation |
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{ |
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/// <summary>
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/// Initializes a new instance of the <see cref="PngColorTypeInformation"/> class with
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/// the scanline factory, the function to create the color reader and the supported bit depths.
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/// </summary>
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/// <param name="scanlineFactor">The scanline factor.</param>
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/// <param name="supportedBitDepths">The supported bit depths.</param>
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/// <param name="scanlineReaderFactory">The factory to create the color reader.</param>
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public PngColorTypeInformation(int scanlineFactor, int[] supportedBitDepths, Func<byte[], byte[], IColorReader> scanlineReaderFactory) |
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{ |
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this.ChannelsPerColor = scanlineFactor; |
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this.ScanlineReaderFactory = scanlineReaderFactory; |
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this.SupportedBitDepths = supportedBitDepths; |
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} |
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/// <summary>
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/// Gets an array with the bit depths that are supported for the color type
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/// where this object is created for.
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/// </summary>
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/// <value>The supported bit depths that can be used in combination with this color type.</value>
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public int[] SupportedBitDepths { get; private set; } |
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/// <summary>
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/// Gets a function that is used the create the color reader for the color type where
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/// this object is created for.
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/// </summary>
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/// <value>The factory function to create the color type.</value>
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public Func<byte[], byte[], IColorReader> ScanlineReaderFactory { get; private set; } |
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/// <summary>
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/// Gets a factor that is used when iterating through the scan lines.
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/// </summary>
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/// <value>The scanline factor.</value>
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public int ChannelsPerColor { get; private set; } |
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/// <summary>
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/// Creates the color reader for the color type where this object is create for.
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/// </summary>
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/// <param name="palette">The palette of the image. Can be null when no palette is used.</param>
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/// <param name="paletteAlpha">The alpha palette of the image. Can be null when
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/// no palette is used for the image or when the image has no alpha.</param>
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/// <returns>The color reader for the image.</returns>
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public IColorReader CreateColorReader(byte[] palette, byte[] paletteAlpha) |
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{ |
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return this.ScanlineReaderFactory(palette, paletteAlpha); |
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} |
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} |
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} |
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@ -1,81 +0,0 @@ |
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// <copyright file="TrueColorReader.cs" company="James Jackson-South">
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// Copyright (c) James Jackson-South and contributors.
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// Licensed under the Apache License, Version 2.0.
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// </copyright>
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namespace ImageProcessorCore.Formats |
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{ |
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/// <summary>
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/// Color reader for reading true colors from a png file. Only colors
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/// with 24 or 32 bit (3 or 4 bytes) per pixel are supported at the moment.
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/// </summary>
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internal sealed class TrueColorReader : IColorReader |
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{ |
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/// <summary>
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/// Whether t also read the alpha channel.
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/// </summary>
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private readonly bool useAlpha; |
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/// <summary>
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/// The current row.
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/// </summary>
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private int row; |
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/// <summary>
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/// Initializes a new instance of the <see cref="TrueColorReader"/> class.
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/// </summary>
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/// <param name="useAlpha">if set to <c>true</c> the color reader will also read the
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/// alpha channel from the scanline.</param>
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public TrueColorReader(bool useAlpha) |
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{ |
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this.useAlpha = useAlpha; |
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} |
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/// <inheritdoc/>
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public void ReadScanline<T, TP>(byte[] scanline, T[] pixels, PngHeader header) |
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where T : IPackedVector<TP> |
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where TP : struct |
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{ |
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int offset; |
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byte[] newScanline = scanline.ToArrayByBitsLength(header.BitDepth); |
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if (this.useAlpha) |
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{ |
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for (int x = 0; x < newScanline.Length; x += 4) |
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{ |
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offset = (this.row * header.Width) + (x >> 2); |
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// We want to convert to premultiplied alpha here.
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byte r = newScanline[x]; |
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byte g = newScanline[x + 1]; |
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byte b = newScanline[x + 2]; |
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byte a = newScanline[x + 3]; |
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T color = default(T); |
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color.PackFromBytes(r, g, b, a); |
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pixels[offset] = color; |
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} |
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} |
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else |
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{ |
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for (int x = 0; x < newScanline.Length / 3; x++) |
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{ |
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offset = (this.row * header.Width) + x; |
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int pixelOffset = x * 3; |
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byte r = newScanline[pixelOffset]; |
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byte g = newScanline[pixelOffset + 1]; |
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byte b = newScanline[pixelOffset + 2]; |
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T color = default(T); |
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color.PackFromBytes(r, g, b, 255); |
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pixels[offset] = color; |
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} |
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} |
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this.row++; |
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} |
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} |
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} |
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