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78 lines
2.9 KiB
78 lines
2.9 KiB
// --------------------------------------------------------------------------------------------------------------------
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// <copyright file="GifDecoder.cs" company="James South">
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// Copyright © James South and contributors.
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// Licensed under the Apache License, Version 2.0.
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// </copyright>
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// <summary>
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// Encoder for generating an image out of a gif encoded stream.
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// </summary>
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// --------------------------------------------------------------------------------------------------------------------
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namespace ImageProcessor.Formats
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{
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using System;
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using System.IO;
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/// <summary>
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/// Encoder for generating an image out of a gif encoded stream.
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/// </summary>
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public class GifDecoder : IImageDecoder
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{
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/// <summary>
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/// Gets the size of the header for this image type.
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/// </summary>
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/// <value>The size of the header.</value>
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public int HeaderSize
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{
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get
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{
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return 6;
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}
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}
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/// <summary>
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/// Returns a value indicating whether the <see cref="IImageDecoder"/> supports the specified
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/// file header.
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/// </summary>
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/// <param name="extension">The <see cref="string"/> containing the file extension.</param>
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/// <returns>
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/// True if the decoder supports the file extension; otherwise, false.
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/// </returns>
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public bool IsSupportedFileExtension(string extension)
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{
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Guard.NotNullOrEmpty(extension, "extension");
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extension = extension.StartsWith(".") ? extension.Substring(1) : extension;
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return extension.Equals("GIF", StringComparison.OrdinalIgnoreCase);
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}
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/// <summary>
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/// Returns a value indicating whether the <see cref="IImageDecoder"/> supports the specified
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/// file header.
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/// </summary>
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/// <param name="header">The <see cref="T:byte[]"/> containing the file header.</param>
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/// <returns>
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/// True if the decoder supports the file header; otherwise, false.
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/// </returns>
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public bool IsSupportedFileFormat(byte[] header)
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{
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return header.Length >= 6 &&
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header[0] == 0x47 && // G
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header[1] == 0x49 && // I
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header[2] == 0x46 && // F
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header[3] == 0x38 && // 8
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(header[4] == 0x39 || header[4] == 0x37) && // 9 or 7
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header[5] == 0x61; // a
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}
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/// <summary>
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/// Decodes the image from the specified stream to the <see cref="ImageBase"/>.
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/// </summary>
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/// <param name="image">The <see cref="ImageBase"/> to decode to.</param>
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/// <param name="stream">The <see cref="Stream"/> containing image data.</param>
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public void Decode(Image image, Stream stream)
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{
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new GifDecoderCore().Decode(image, stream);
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}
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}
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}
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