217 lines
7.8 KiB
C#
217 lines
7.8 KiB
C#
using MediaBrowser.Common.Logging;
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using System;
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using System.Collections.Generic;
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using System.Drawing;
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using System.IO;
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using System.Linq;
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namespace MediaBrowser.Controller.Drawing
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{
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/// <summary>
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/// Taken from http://stackoverflow.com/questions/111345/getting-image-dimensions-without-reading-the-entire-file/111349
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/// http://www.codeproject.com/Articles/35978/Reading-Image-Headers-to-Get-Width-and-Height
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/// Minor improvements including supporting unsigned 16-bit integers when decoding Jfif and added logic
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/// to load the image using new Bitmap if reading the headers fails
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/// </summary>
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public static class ImageHeader
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{
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/// <summary>
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/// The error message
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/// </summary>
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const string errorMessage = "Could not recognize image format.";
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/// <summary>
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/// The image format decoders
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/// </summary>
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private static readonly Dictionary<byte[], Func<BinaryReader, Size>> imageFormatDecoders = new Dictionary<byte[], Func<BinaryReader, Size>>
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{
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{ new byte[] { 0x42, 0x4D }, DecodeBitmap },
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{ new byte[] { 0x47, 0x49, 0x46, 0x38, 0x37, 0x61 }, DecodeGif },
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{ new byte[] { 0x47, 0x49, 0x46, 0x38, 0x39, 0x61 }, DecodeGif },
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{ new byte[] { 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A }, DecodePng },
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{ new byte[] { 0xff, 0xd8 }, DecodeJfif },
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};
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/// <summary>
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/// Gets the dimensions of an image.
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/// </summary>
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/// <param name="path">The path of the image to get the dimensions of.</param>
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/// <returns>The dimensions of the specified image.</returns>
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/// <exception cref="ArgumentException">The image was of an unrecognised format.</exception>
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public static Size GetDimensions(string path)
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{
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try
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{
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using (var fs = File.OpenRead(path))
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{
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using (var binaryReader = new BinaryReader(fs))
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{
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return GetDimensions(binaryReader);
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}
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}
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}
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catch
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{
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Logger.LogInfo("Failed to read image header for {0}. Doing it the slow way.", path);
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using (var fs = File.OpenRead(path))
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{
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// Co it the old fashioned way
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using (var b = Image.FromStream(fs, true, false))
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{
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return b.Size;
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}
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}
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}
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}
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/// <summary>
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/// Gets the dimensions of an image.
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/// </summary>
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/// <param name="binaryReader">The binary reader.</param>
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/// <returns>Size.</returns>
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/// <exception cref="System.ArgumentException">binaryReader</exception>
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/// <exception cref="ArgumentException">The image was of an unrecognized format.</exception>
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private static Size GetDimensions(BinaryReader binaryReader)
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{
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int maxMagicBytesLength = imageFormatDecoders.Keys.OrderByDescending(x => x.Length).First().Length;
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var magicBytes = new byte[maxMagicBytesLength];
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for (int i = 0; i < maxMagicBytesLength; i += 1)
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{
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magicBytes[i] = binaryReader.ReadByte();
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foreach (var kvPair in imageFormatDecoders)
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{
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if (StartsWith(magicBytes, kvPair.Key))
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{
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return kvPair.Value(binaryReader);
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}
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}
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}
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throw new ArgumentException(errorMessage, "binaryReader");
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}
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/// <summary>
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/// Startses the with.
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/// </summary>
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/// <param name="thisBytes">The this bytes.</param>
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/// <param name="thatBytes">The that bytes.</param>
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/// <returns><c>true</c> if XXXX, <c>false</c> otherwise</returns>
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private static bool StartsWith(byte[] thisBytes, byte[] thatBytes)
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{
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for (int i = 0; i < thatBytes.Length; i += 1)
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{
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if (thisBytes[i] != thatBytes[i])
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{
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return false;
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}
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}
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return true;
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}
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/// <summary>
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/// Reads the little endian int16.
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/// </summary>
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/// <param name="binaryReader">The binary reader.</param>
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/// <returns>System.Int16.</returns>
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private static short ReadLittleEndianInt16(BinaryReader binaryReader)
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{
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var bytes = new byte[sizeof(short)];
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for (int i = 0; i < sizeof(short); i += 1)
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{
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bytes[sizeof(short) - 1 - i] = binaryReader.ReadByte();
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}
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return BitConverter.ToInt16(bytes, 0);
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}
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/// <summary>
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/// Reads the little endian int32.
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/// </summary>
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/// <param name="binaryReader">The binary reader.</param>
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/// <returns>System.Int32.</returns>
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private static int ReadLittleEndianInt32(BinaryReader binaryReader)
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{
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var bytes = new byte[sizeof(int)];
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for (int i = 0; i < sizeof(int); i += 1)
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{
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bytes[sizeof(int) - 1 - i] = binaryReader.ReadByte();
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}
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return BitConverter.ToInt32(bytes, 0);
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}
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/// <summary>
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/// Decodes the bitmap.
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/// </summary>
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/// <param name="binaryReader">The binary reader.</param>
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/// <returns>Size.</returns>
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private static Size DecodeBitmap(BinaryReader binaryReader)
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{
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binaryReader.ReadBytes(16);
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int width = binaryReader.ReadInt32();
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int height = binaryReader.ReadInt32();
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return new Size(width, height);
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}
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/// <summary>
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/// Decodes the GIF.
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/// </summary>
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/// <param name="binaryReader">The binary reader.</param>
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/// <returns>Size.</returns>
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private static Size DecodeGif(BinaryReader binaryReader)
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{
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int width = binaryReader.ReadInt16();
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int height = binaryReader.ReadInt16();
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return new Size(width, height);
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}
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/// <summary>
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/// Decodes the PNG.
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/// </summary>
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/// <param name="binaryReader">The binary reader.</param>
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/// <returns>Size.</returns>
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private static Size DecodePng(BinaryReader binaryReader)
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{
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binaryReader.ReadBytes(8);
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int width = ReadLittleEndianInt32(binaryReader);
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int height = ReadLittleEndianInt32(binaryReader);
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return new Size(width, height);
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}
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/// <summary>
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/// Decodes the jfif.
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/// </summary>
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/// <param name="binaryReader">The binary reader.</param>
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/// <returns>Size.</returns>
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/// <exception cref="System.ArgumentException"></exception>
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private static Size DecodeJfif(BinaryReader binaryReader)
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{
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while (binaryReader.ReadByte() == 0xff)
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{
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byte marker = binaryReader.ReadByte();
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short chunkLength = ReadLittleEndianInt16(binaryReader);
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if (marker == 0xc0)
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{
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binaryReader.ReadByte();
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int height = ReadLittleEndianInt16(binaryReader);
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int width = ReadLittleEndianInt16(binaryReader);
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return new Size(width, height);
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}
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if (chunkLength < 0)
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{
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var uchunkLength = (ushort)chunkLength;
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binaryReader.ReadBytes(uchunkLength - 2);
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}
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else
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{
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binaryReader.ReadBytes(chunkLength - 2);
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}
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}
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throw new ArgumentException(errorMessage);
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}
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}
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}
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