mirror of https://github.com/SixLabors/ImageSharp
Brian Popow
6 years ago
8 changed files with 147 additions and 107 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.IO; |
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using SixLabors.ImageSharp.Memory; |
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using SixLabors.Memory; |
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namespace SixLabors.ImageSharp.Formats.WebP |
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{ |
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/// <summary>
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/// Base class for VP8 and VP8L bitreader.
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/// </summary>
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internal abstract class BitReaderBase |
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{ |
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/// <summary>
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/// Gets raw encoded image data.
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/// </summary>
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protected byte[] Data { get; private set; } |
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/// <summary>
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/// Reads a single bit from the stream.
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/// </summary>
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/// <returns>True if the bit read was 1, false otherwise.</returns>
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public abstract bool ReadBit(); |
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/// <summary>
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/// Reads a unsigned short value from the inputStream. The bits of each byte are read in least-significant-bit-first order.
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/// </summary>
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/// <param name="nBits">The number of bits to read (should not exceed 16).</param>
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/// <returns>A ushort value.</returns>
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public abstract uint ReadValue(int nBits); |
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/// <summary>
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/// Copies the raw encoded image data from the stream into a byte array.
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/// </summary>
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/// <param name="input">The input stream.</param>
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/// <param name="bytesToRead">Number of bytes to read as indicated from the chunk size.</param>
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/// <param name="memoryAllocator">Used for allocating memory during reading data from the stream.</param>
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protected void ReadImageDataFromStream(Stream input, int bytesToRead, MemoryAllocator memoryAllocator) |
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{ |
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using (var ms = new MemoryStream()) |
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using (IManagedByteBuffer buffer = memoryAllocator.AllocateManagedByteBuffer(4096)) |
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{ |
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Span<byte> bufferSpan = buffer.GetSpan(); |
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int read; |
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while (bytesToRead > 0 && (read = input.Read(buffer.Array, 0, Math.Min(bufferSpan.Length, bytesToRead))) > 0) |
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{ |
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ms.Write(buffer.Array, 0, read); |
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bytesToRead -= read; |
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} |
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if (bytesToRead > 0) |
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{ |
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WebPThrowHelper.ThrowImageFormatException("image file has insufficient data"); |
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} |
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this.Data = ms.ToArray(); |
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} |
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} |
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} |
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} |
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