102 lines
3.1 KiB
C#
102 lines
3.1 KiB
C#
/////////////////////////////////////////////////////////////////////////////////
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//
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// Photoshop PSD FileType Plugin for Paint.NET
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// http://psdplugin.codeplex.com/
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//
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// This software is provided under the MIT License:
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// Copyright (c) 2006-2007 Frank Blumenberg
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// Copyright (c) 2010-2016 Tao Yue
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//
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// See LICENSE.txt for complete licensing and attribution information.
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//
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/////////////////////////////////////////////////////////////////////////////////
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using System;
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using PDNWrapper;
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using System.IO;
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using System.IO.Compression;
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namespace PhotoshopFile.Compression
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{
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internal class ZipImage : ImageData
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{
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private MemoryStream zipDataStream;
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private DeflateStream zipStream;
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protected override bool AltersWrittenData
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{
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get { return false; }
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}
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public ZipImage(byte[] data, Size size, int bitDepth)
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: base(size, bitDepth)
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{
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if (data == null)
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{
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InitCompress();
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}
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else
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{
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InitDecompress(data);
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}
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}
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private void InitCompress()
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{
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zipDataStream = new MemoryStream();
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// Write 2-byte zlib (RFC 1950) header
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//
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// CMF Compression Method and flags:
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// CM 0:3 = 8 = deflate
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// CINFO 4:7 = 4 = undefined, RFC 1950 only defines CINFO = 8
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//
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// FLG Flags:
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// FCHECK 0:4 = 9 = check bits for CMF and FLG
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// FDICT 5 = 0 = no preset dictionary
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// FLEVEL 6:7 = 2 = default compression level
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zipDataStream.WriteByte(0x48);
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zipDataStream.WriteByte(0x89);
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zipStream = new DeflateStream(zipDataStream, CompressionMode.Compress,
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true);
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}
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private void InitDecompress(byte[] data)
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{
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zipDataStream = new MemoryStream(data);
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// .NET implements Deflate (RFC 1951) but not zlib (RFC 1950),
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// so we have to skip the first two bytes.
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zipDataStream.ReadByte();
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zipDataStream.ReadByte();
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zipStream = new DeflateStream(zipDataStream, CompressionMode.Decompress,
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true);
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}
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internal override void Read(byte[] buffer)
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{
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var bytesToRead = (long)Size.Height * BytesPerRow;
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Util.CheckByteArrayLength(bytesToRead);
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var bytesRead = zipStream.Read(buffer, 0, (int)bytesToRead);
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if (bytesRead != bytesToRead)
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{
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throw new Exception("ZIP stream was not fully decompressed.");
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}
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}
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public override byte[] ReadCompressed()
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{
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// Write out the last block. (Flush leaves the last block open.)
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zipStream.Close();
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// Do not write the zlib header when the image data is empty
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var result = (zipDataStream.Length == 2)
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? new byte[0]
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: zipDataStream.ToArray();
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return result;
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}
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}
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}
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