1094 lines
34 KiB
C#
1094 lines
34 KiB
C#
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//#define mgGIF_UNSAFE
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using UnityEngine;
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using System;
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using System.Runtime.CompilerServices;
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using System.Text;
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using System.Runtime.InteropServices; // unsafe
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namespace MG.GIF
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{
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////////////////////////////////////////////////////////////////////////////////
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public class Image : ICloneable
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{
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public int Width;
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public int Height;
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public int Delay; // milliseconds
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public Color32[] RawImage;
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public Image()
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{
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}
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public Image( Image img )
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{
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Width = img.Width;
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Height = img.Height;
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Delay = img.Delay;
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RawImage = img.RawImage != null ? (Color32[]) img.RawImage.Clone() : null;
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}
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public object Clone()
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{
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return new Image( this );
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}
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public Texture2D CreateTexture()
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{
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var tex = new Texture2D( Width, Height, TextureFormat.ARGB32, false )
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{
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filterMode = FilterMode.Point,
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wrapMode = TextureWrapMode.Clamp
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};
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tex.SetPixels32( RawImage );
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tex.Apply();
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return tex;
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}
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}
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////////////////////////////////////////////////////////////////////////////////
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#if mgGIF_UNSAFE
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unsafe
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#endif
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public class Decoder : IDisposable
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{
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public string Version;
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public ushort Width;
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public ushort Height;
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public Color32 BackgroundColour;
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//------------------------------------------------------------------------------
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// GIF format enums
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[Flags]
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enum ImageFlag
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{
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Interlaced = 0x40,
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ColourTable = 0x80,
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TableSizeMask = 0x07,
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BitDepthMask = 0x70,
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}
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enum Block
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{
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Image = 0x2C,
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Extension = 0x21,
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End = 0x3B
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}
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enum Extension
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{
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GraphicControl = 0xF9,
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Comments = 0xFE,
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PlainText = 0x01,
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ApplicationData = 0xFF
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}
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enum Disposal
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{
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None = 0x00,
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DoNotDispose = 0x04,
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RestoreBackground = 0x08,
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ReturnToPrevious = 0x0C
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}
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[Flags]
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enum ControlFlags
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{
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HasTransparency = 0x01,
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DisposalMask = 0x0C
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}
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//------------------------------------------------------------------------------
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const uint NoCode = 0xFFFF;
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const ushort NoTransparency = 0xFFFF;
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// input stream to decode
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byte[] Input;
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int D;
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// colour table
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Color32[] GlobalColourTable;
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Color32[] LocalColourTable;
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Color32[] ActiveColourTable;
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ushort TransparentIndex;
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// current image
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Image Image = new Image();
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ushort ImageLeft;
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ushort ImageTop;
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ushort ImageWidth;
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ushort ImageHeight;
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Color32[] Output;
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Color32[] PreviousImage;
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readonly int[] Pow2 = { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096 };
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//------------------------------------------------------------------------------
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// ctor
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public Decoder( byte[] data )
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: this()
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{
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Load( data );
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}
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public Decoder Load( byte[] data )
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{
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Input = data;
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D = 0;
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GlobalColourTable = new Color32[ 256 ];
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LocalColourTable = new Color32[ 256 ];
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TransparentIndex = NoTransparency;
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Output = null;
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PreviousImage = null;
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Image.Delay = 0;
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return this;
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}
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//------------------------------------------------------------------------------
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// reading data utility functions
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[MethodImpl( MethodImplOptions.AggressiveInlining )]
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byte ReadByte()
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{
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return Input[ D++ ];
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}
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[MethodImpl( MethodImplOptions.AggressiveInlining )]
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ushort ReadUInt16()
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{
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return (ushort) ( Input[ D++ ] | Input[ D++ ] << 8 );
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}
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//------------------------------------------------------------------------------
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void ReadHeader()
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{
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if( Input == null || Input.Length <= 12 )
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{
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throw new Exception( "Invalid data" );
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}
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// signature
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Version = Encoding.ASCII.GetString( Input, 0, 6 );
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D = 6;
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if( Version != "GIF87a" && Version != "GIF89a" )
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{
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throw new Exception( "Unsupported GIF version" );
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}
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// read header
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Width = ReadUInt16();
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Height = ReadUInt16();
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Image.Width = Width;
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Image.Height = Height;
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var flags = (ImageFlag) ReadByte();
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var bgIndex = ReadByte(); // background colour
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ReadByte(); // aspect ratio
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if( flags.HasFlag( ImageFlag.ColourTable ) )
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{
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ReadColourTable( GlobalColourTable, flags );
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}
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BackgroundColour = GlobalColourTable[ bgIndex ];
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}
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//------------------------------------------------------------------------------
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public Image NextImage()
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{
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// if at start of data, read header
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if( D == 0 )
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{
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ReadHeader();
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}
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// read blocks until we find an image block
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while( true )
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{
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var block = (Block) ReadByte();
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switch( block )
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{
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case Block.Image:
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{
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// return the image if we got one
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var img = ReadImageBlock();
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if( img != null )
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{
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return img;
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}
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}
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break;
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case Block.Extension:
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{
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var ext = (Extension) ReadByte();
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if( ext == Extension.GraphicControl )
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{
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ReadControlBlock();
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}
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else
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{
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SkipBlocks();
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}
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}
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break;
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case Block.End:
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{
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// end block - stop!
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return null;
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}
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default:
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{
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throw new Exception( "Unexpected block type" );
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}
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}
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}
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}
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//------------------------------------------------------------------------------
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Color32[] ReadColourTable( Color32[] colourTable, ImageFlag flags )
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{
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var tableSize = Pow2[ (int)( flags & ImageFlag.TableSizeMask ) + 1 ];
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for( var i = 0; i < tableSize; i++ )
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{
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colourTable[ i ] = new Color32(
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Input[ D++ ],
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Input[ D++ ],
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Input[ D++ ],
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0xFF
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);
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}
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return colourTable;
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}
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//------------------------------------------------------------------------------
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void SkipBlocks()
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{
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var blockSize = Input[ D++ ];
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while( blockSize != 0x00 )
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{
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D += blockSize;
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blockSize = Input[ D++ ];
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}
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}
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//------------------------------------------------------------------------------
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void ReadControlBlock()
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{
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// read block
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ReadByte(); // block size (0x04)
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var flags = (ControlFlags) ReadByte(); // flags
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Image.Delay = ReadUInt16() * 10; // delay (1/100th -> milliseconds)
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var transparentColour = ReadByte(); // transparent colour
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ReadByte(); // terminator (0x00)
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// has transparent colour?
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if( flags.HasFlag( ControlFlags.HasTransparency ) )
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{
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TransparentIndex = transparentColour;
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}
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else
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{
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TransparentIndex = NoTransparency;
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}
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// dispose of current image
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switch( (Disposal)( flags & ControlFlags.DisposalMask ) )
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{
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default:
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case Disposal.None:
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case Disposal.DoNotDispose:
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// remember current image in case we need to "return to previous"
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PreviousImage = Output;
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break;
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case Disposal.RestoreBackground:
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// empty image - don't track
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Output = new Color32[ Width * Height ];
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break;
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case Disposal.ReturnToPrevious:
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// return to previous image
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Output = new Color32[ Width * Height ];
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if( PreviousImage != null )
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{
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Array.Copy( PreviousImage, Output, Output.Length );
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}
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break;
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}
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}
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//------------------------------------------------------------------------------
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Image ReadImageBlock()
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{
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// read image block header
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ImageLeft = ReadUInt16();
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ImageTop = ReadUInt16();
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ImageWidth = ReadUInt16();
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ImageHeight = ReadUInt16();
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var flags = (ImageFlag) ReadByte();
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// bad image if we don't have any dimensions
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if( ImageWidth == 0 || ImageHeight == 0 )
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{
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return null;
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}
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// read colour table
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if( flags.HasFlag( ImageFlag.ColourTable ) )
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{
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ActiveColourTable = ReadColourTable( LocalColourTable, flags );
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}
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else
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{
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ActiveColourTable = GlobalColourTable;
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}
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if( Output == null )
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{
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Output = new Color32[ Width * Height ];
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PreviousImage = Output;
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}
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// read image data
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DecompressLZW();
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// deinterlace
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if( flags.HasFlag( ImageFlag.Interlaced ) )
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{
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Deinterlace();
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}
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// return image
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Image.RawImage = Output;
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return Image;
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}
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//------------------------------------------------------------------------------
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// decode interlaced images
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void Deinterlace()
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{
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var numRows = Output.Length / Width;
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var writePos = Output.Length - Width; // NB: work backwards due to Y-coord flip
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var input = Output;
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Output = new Color32[ Output.Length ];
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for( var row = 0; row < numRows; row++ )
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{
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int copyRow;
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// every 8th row starting at 0
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if( row % 8 == 0 )
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{
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copyRow = row / 8;
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}
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// every 8th row starting at 4
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else if( ( row + 4 ) % 8 == 0 )
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{
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var o = numRows / 8;
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copyRow = o + ( row - 4 ) / 8;
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}
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// every 4th row starting at 2
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else if( ( row + 2 ) % 4 == 0 )
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{
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var o = numRows / 4;
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copyRow = o + ( row - 2 ) / 4;
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}
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// every 2nd row starting at 1
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||
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else // if( ( r + 1 ) % 2 == 0 )
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||
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{
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var o = numRows / 2;
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copyRow = o + ( row - 1 ) / 2;
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||
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}
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||
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Array.Copy( input, ( numRows - copyRow - 1 ) * Width, Output, writePos, Width );
|
||
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writePos -= Width;
|
||
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}
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||
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}
|
||
|
|
|
||
|
|
//------------------------------------------------------------------------------
|
||
|
|
// DecompressLZW()
|
||
|
|
|
||
|
|
#if mgGIF_UNSAFE
|
||
|
|
|
||
|
|
bool Disposed = false;
|
||
|
|
|
||
|
|
int CodesLength;
|
||
|
|
IntPtr CodesHandle;
|
||
|
|
ushort* pCodes;
|
||
|
|
|
||
|
|
IntPtr CurBlock;
|
||
|
|
uint* pCurBlock;
|
||
|
|
|
||
|
|
const int MaxCodes = 4096;
|
||
|
|
IntPtr Indices;
|
||
|
|
ushort** pIndicies;
|
||
|
|
|
||
|
|
public Decoder()
|
||
|
|
{
|
||
|
|
// unmanaged allocations
|
||
|
|
|
||
|
|
CodesLength = 128 * 1024;
|
||
|
|
CodesHandle = Marshal.AllocHGlobal( CodesLength * sizeof( ushort ) );
|
||
|
|
pCodes = (ushort*) CodesHandle.ToPointer();
|
||
|
|
|
||
|
|
CurBlock = Marshal.AllocHGlobal( 64 * sizeof( uint ) );
|
||
|
|
pCurBlock = (uint*) CurBlock.ToPointer();
|
||
|
|
|
||
|
|
Indices = Marshal.AllocHGlobal( MaxCodes * sizeof( ushort* ) );
|
||
|
|
pIndicies = (ushort**) Indices.ToPointer();
|
||
|
|
}
|
||
|
|
|
||
|
|
protected virtual void Dispose( bool disposing )
|
||
|
|
{
|
||
|
|
if( Disposed )
|
||
|
|
{
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
// release unmanaged resources
|
||
|
|
|
||
|
|
Marshal.FreeHGlobal( CodesHandle );
|
||
|
|
Marshal.FreeHGlobal( CurBlock );
|
||
|
|
Marshal.FreeHGlobal( Indices );
|
||
|
|
|
||
|
|
Disposed = true;
|
||
|
|
}
|
||
|
|
|
||
|
|
~Decoder()
|
||
|
|
{
|
||
|
|
Dispose( false );
|
||
|
|
}
|
||
|
|
|
||
|
|
public void Dispose()
|
||
|
|
{
|
||
|
|
Dispose( true );
|
||
|
|
GC.SuppressFinalize( this );
|
||
|
|
}
|
||
|
|
|
||
|
|
void DecompressLZW()
|
||
|
|
{
|
||
|
|
var pCodeBufferEnd = pCodes + CodesLength;
|
||
|
|
|
||
|
|
fixed( byte* pData = Input )
|
||
|
|
{
|
||
|
|
fixed( Color32* pOutput = Output, pColourTable = ActiveColourTable )
|
||
|
|
{
|
||
|
|
var row = ( Height - ImageTop - 1 ) * Width; // start at end of array as we are reversing the row order
|
||
|
|
var safeWidth = ImageLeft + ImageWidth > Width ? Width - ImageLeft : ImageWidth;
|
||
|
|
|
||
|
|
var pWrite = &pOutput[ row + ImageLeft ];
|
||
|
|
var pRow = pWrite;
|
||
|
|
var pRowEnd = pWrite + ImageWidth;
|
||
|
|
var pImageEnd = pWrite + safeWidth;
|
||
|
|
|
||
|
|
// setup codes
|
||
|
|
|
||
|
|
int minimumCodeSize = Input[ D++ ];
|
||
|
|
|
||
|
|
if( minimumCodeSize > 11 )
|
||
|
|
{
|
||
|
|
minimumCodeSize = 11;
|
||
|
|
}
|
||
|
|
|
||
|
|
var codeSize = minimumCodeSize + 1;
|
||
|
|
var nextSize = Pow2[ codeSize ];
|
||
|
|
var maximumCodeSize = Pow2[ minimumCodeSize ];
|
||
|
|
var clearCode = maximumCodeSize;
|
||
|
|
var endCode = maximumCodeSize + 1;
|
||
|
|
|
||
|
|
// initialise buffers
|
||
|
|
|
||
|
|
var numCodes = maximumCodeSize + 2;
|
||
|
|
var pCodesEnd = pCodes;
|
||
|
|
|
||
|
|
for( ushort i = 0; i < numCodes; i++ )
|
||
|
|
{
|
||
|
|
pIndicies[ i ] = pCodesEnd;
|
||
|
|
*pCodesEnd++ = 1;
|
||
|
|
*pCodesEnd++ = i;
|
||
|
|
}
|
||
|
|
|
||
|
|
// LZW decode loop
|
||
|
|
|
||
|
|
uint previousCode = NoCode; // last code processed
|
||
|
|
uint mask = (uint) ( nextSize - 1 ); // mask out code bits
|
||
|
|
uint shiftRegister = 0; // shift register holds the bytes coming in from the input stream, we shift down by the number of bits
|
||
|
|
|
||
|
|
int bitsAvailable = 0; // number of bits available to read in the shift register
|
||
|
|
int bytesAvailable = 0; // number of bytes left in current block
|
||
|
|
|
||
|
|
uint* pD = pCurBlock; // pointer to next bits in current block
|
||
|
|
|
||
|
|
while( true )
|
||
|
|
{
|
||
|
|
// get next code
|
||
|
|
|
||
|
|
uint curCode = shiftRegister & mask;
|
||
|
|
|
||
|
|
// did we read enough bits?
|
||
|
|
|
||
|
|
if( bitsAvailable >= codeSize )
|
||
|
|
{
|
||
|
|
// we had enough bits in the shift register so shunt it down
|
||
|
|
bitsAvailable -= codeSize;
|
||
|
|
shiftRegister >>= codeSize;
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
// not enough bits in register, so get more
|
||
|
|
|
||
|
|
// if start of new block
|
||
|
|
|
||
|
|
if( bytesAvailable <= 0 )
|
||
|
|
{
|
||
|
|
// read blocksize
|
||
|
|
|
||
|
|
var pBlock = &pData[ D++ ];
|
||
|
|
bytesAvailable = *pBlock++;
|
||
|
|
D += bytesAvailable;
|
||
|
|
|
||
|
|
// exit if end of stream
|
||
|
|
|
||
|
|
if( bytesAvailable == 0 )
|
||
|
|
{
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
// copy block into buffer
|
||
|
|
|
||
|
|
pCurBlock[ ( bytesAvailable - 1 ) / 4 ] = 0; // zero last entry
|
||
|
|
Buffer.MemoryCopy( pBlock, pCurBlock, 256, bytesAvailable );
|
||
|
|
|
||
|
|
// reset data pointer
|
||
|
|
pD = pCurBlock;
|
||
|
|
}
|
||
|
|
|
||
|
|
// load shift register from data pointer
|
||
|
|
|
||
|
|
shiftRegister = *pD++;
|
||
|
|
int newBits = bytesAvailable >= 4 ? 32 : bytesAvailable * 8;
|
||
|
|
bytesAvailable -= 4;
|
||
|
|
|
||
|
|
// read remaining bits
|
||
|
|
|
||
|
|
if( bitsAvailable > 0 )
|
||
|
|
{
|
||
|
|
var bitsRemaining = codeSize - bitsAvailable;
|
||
|
|
curCode |= ( shiftRegister << bitsAvailable ) & mask;
|
||
|
|
shiftRegister >>= bitsRemaining;
|
||
|
|
bitsAvailable = newBits - bitsRemaining;
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
curCode = shiftRegister & mask;
|
||
|
|
shiftRegister >>= codeSize;
|
||
|
|
bitsAvailable = newBits - codeSize;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// process code
|
||
|
|
|
||
|
|
if( curCode == clearCode )
|
||
|
|
{
|
||
|
|
// reset codes
|
||
|
|
codeSize = minimumCodeSize + 1;
|
||
|
|
nextSize = Pow2[ codeSize ];
|
||
|
|
numCodes = maximumCodeSize + 2;
|
||
|
|
|
||
|
|
// reset buffer write pos
|
||
|
|
pCodesEnd = &pCodes[ numCodes * 2 ];
|
||
|
|
|
||
|
|
// clear previous code
|
||
|
|
previousCode = NoCode;
|
||
|
|
mask = (uint)( nextSize - 1 );
|
||
|
|
|
||
|
|
continue;
|
||
|
|
}
|
||
|
|
else if( curCode == endCode )
|
||
|
|
{
|
||
|
|
// stop
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
|
||
|
|
bool plusOne = false;
|
||
|
|
ushort* pCodePos = null;
|
||
|
|
|
||
|
|
if( curCode < numCodes )
|
||
|
|
{
|
||
|
|
// write existing code
|
||
|
|
pCodePos = pIndicies[ curCode ];
|
||
|
|
}
|
||
|
|
else if( previousCode != NoCode )
|
||
|
|
{
|
||
|
|
// write previous code
|
||
|
|
pCodePos = pIndicies[ previousCode ];
|
||
|
|
plusOne = true;
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
continue;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
// output colours
|
||
|
|
|
||
|
|
var codeLength = *pCodePos++;
|
||
|
|
var newCode = *pCodePos;
|
||
|
|
var pEnd = pCodePos + codeLength;
|
||
|
|
|
||
|
|
do
|
||
|
|
{
|
||
|
|
var code = *pCodePos++;
|
||
|
|
|
||
|
|
if( code != TransparentIndex && pWrite < pImageEnd )
|
||
|
|
{
|
||
|
|
*pWrite = pColourTable[ code ];
|
||
|
|
}
|
||
|
|
|
||
|
|
if( ++pWrite == pRowEnd )
|
||
|
|
{
|
||
|
|
pRow -= Width;
|
||
|
|
pWrite = pRow;
|
||
|
|
pRowEnd = pRow + ImageWidth;
|
||
|
|
pImageEnd = pRow + safeWidth;
|
||
|
|
|
||
|
|
if( pWrite < pOutput )
|
||
|
|
{
|
||
|
|
SkipBlocks();
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
while( pCodePos < pEnd );
|
||
|
|
|
||
|
|
if( plusOne )
|
||
|
|
{
|
||
|
|
if( newCode != TransparentIndex && pWrite < pImageEnd )
|
||
|
|
{
|
||
|
|
*pWrite = pColourTable[ newCode ];
|
||
|
|
}
|
||
|
|
|
||
|
|
if( ++pWrite == pRowEnd )
|
||
|
|
{
|
||
|
|
pRow -= Width;
|
||
|
|
pWrite = pRow;
|
||
|
|
pRowEnd = pRow + ImageWidth;
|
||
|
|
pImageEnd = pRow + safeWidth;
|
||
|
|
|
||
|
|
if( pWrite < pOutput )
|
||
|
|
{
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// create new code
|
||
|
|
|
||
|
|
if( previousCode != NoCode && numCodes != MaxCodes )
|
||
|
|
{
|
||
|
|
// get previous code from buffer
|
||
|
|
|
||
|
|
pCodePos = pIndicies[ previousCode ];
|
||
|
|
codeLength = *pCodePos++;
|
||
|
|
|
||
|
|
// resize buffer if required (should be rare)
|
||
|
|
|
||
|
|
if( pCodesEnd + codeLength + 1 >= pCodeBufferEnd )
|
||
|
|
{
|
||
|
|
var pBase = pCodes;
|
||
|
|
|
||
|
|
// realloc buffer
|
||
|
|
CodesLength *= 2;
|
||
|
|
CodesHandle = Marshal.ReAllocHGlobal( CodesHandle, (IntPtr)( CodesLength * sizeof( ushort ) ) );
|
||
|
|
|
||
|
|
pCodes = (ushort*) CodesHandle.ToPointer();
|
||
|
|
pCodeBufferEnd = pCodes + CodesLength;
|
||
|
|
|
||
|
|
// rebase pointers
|
||
|
|
|
||
|
|
pCodesEnd = pCodes + ( pCodesEnd - pBase );
|
||
|
|
|
||
|
|
for( int i=0; i < numCodes; i++ )
|
||
|
|
{
|
||
|
|
pIndicies[ i ] = pCodes + ( pIndicies[ i ] - pBase );
|
||
|
|
}
|
||
|
|
|
||
|
|
pCodePos = pIndicies[ previousCode ];
|
||
|
|
pCodePos++;
|
||
|
|
}
|
||
|
|
|
||
|
|
// add new code
|
||
|
|
|
||
|
|
pIndicies[ numCodes++ ] = pCodesEnd;
|
||
|
|
*pCodesEnd++ = (ushort)( codeLength + 1 );
|
||
|
|
|
||
|
|
// copy previous code sequence
|
||
|
|
|
||
|
|
Buffer.MemoryCopy( pCodePos, pCodesEnd, codeLength * sizeof( ushort ), codeLength * sizeof( ushort ) );
|
||
|
|
pCodesEnd += codeLength;
|
||
|
|
|
||
|
|
// append new code
|
||
|
|
|
||
|
|
*pCodesEnd++ = newCode;
|
||
|
|
}
|
||
|
|
|
||
|
|
// increase code size?
|
||
|
|
|
||
|
|
if( numCodes >= nextSize && codeSize < 12 )
|
||
|
|
{
|
||
|
|
nextSize = Pow2[ ++codeSize ];
|
||
|
|
mask = (uint)( nextSize - 1 );
|
||
|
|
}
|
||
|
|
|
||
|
|
// remember last code processed
|
||
|
|
previousCode = curCode;
|
||
|
|
}
|
||
|
|
|
||
|
|
// consume any remaining blocks
|
||
|
|
SkipBlocks();
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
#else
|
||
|
|
|
||
|
|
// dispose isn't needed for the safe implementation but keep here for interface parity
|
||
|
|
|
||
|
|
public Decoder() { }
|
||
|
|
public void Dispose() { Dispose( true ); }
|
||
|
|
protected virtual void Dispose( bool disposing ) { }
|
||
|
|
|
||
|
|
|
||
|
|
int[] Indices = new int[ 4096 ];
|
||
|
|
ushort[] Codes = new ushort[ 128 * 1024 ];
|
||
|
|
uint[] CurBlock = new uint[ 64 ];
|
||
|
|
|
||
|
|
void DecompressLZW()
|
||
|
|
{
|
||
|
|
// output write position
|
||
|
|
|
||
|
|
int row = ( Height - ImageTop - 1 ) * Width; // reverse rows for unity texture coords
|
||
|
|
int col = ImageLeft;
|
||
|
|
int rightEdge = ImageLeft + ImageWidth;
|
||
|
|
|
||
|
|
// setup codes
|
||
|
|
|
||
|
|
int minimumCodeSize = Input[ D++ ];
|
||
|
|
|
||
|
|
if( minimumCodeSize > 11 )
|
||
|
|
{
|
||
|
|
minimumCodeSize = 11;
|
||
|
|
}
|
||
|
|
|
||
|
|
var codeSize = minimumCodeSize + 1;
|
||
|
|
var nextSize = Pow2[ codeSize ];
|
||
|
|
var maximumCodeSize = Pow2[ minimumCodeSize ];
|
||
|
|
var clearCode = maximumCodeSize;
|
||
|
|
var endCode = maximumCodeSize + 1;
|
||
|
|
|
||
|
|
// initialise buffers
|
||
|
|
|
||
|
|
var codesEnd = 0;
|
||
|
|
var numCodes = maximumCodeSize + 2;
|
||
|
|
|
||
|
|
for( ushort i = 0; i < numCodes; i++ )
|
||
|
|
{
|
||
|
|
Indices[ i ] = codesEnd;
|
||
|
|
Codes[ codesEnd++ ] = 1; // length
|
||
|
|
Codes[ codesEnd++ ] = i; // code
|
||
|
|
}
|
||
|
|
|
||
|
|
// LZW decode loop
|
||
|
|
|
||
|
|
uint previousCode = NoCode; // last code processed
|
||
|
|
uint mask = (uint) ( nextSize - 1 ); // mask out code bits
|
||
|
|
uint shiftRegister = 0; // shift register holds the bytes coming in from the input stream, we shift down by the number of bits
|
||
|
|
|
||
|
|
int bitsAvailable = 0; // number of bits available to read in the shift register
|
||
|
|
int bytesAvailable = 0; // number of bytes left in current block
|
||
|
|
|
||
|
|
int blockPos = 0;
|
||
|
|
|
||
|
|
while( true )
|
||
|
|
{
|
||
|
|
// get next code
|
||
|
|
|
||
|
|
uint curCode = shiftRegister & mask;
|
||
|
|
|
||
|
|
if( bitsAvailable >= codeSize )
|
||
|
|
{
|
||
|
|
bitsAvailable -= codeSize;
|
||
|
|
shiftRegister >>= codeSize;
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
// reload shift register
|
||
|
|
|
||
|
|
|
||
|
|
// if start of new block
|
||
|
|
|
||
|
|
if( bytesAvailable <= 0 )
|
||
|
|
{
|
||
|
|
// read blocksize
|
||
|
|
bytesAvailable = Input[ D++ ];
|
||
|
|
|
||
|
|
// exit if end of stream
|
||
|
|
if( bytesAvailable == 0 )
|
||
|
|
{
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
// read block
|
||
|
|
CurBlock[ ( bytesAvailable - 1 ) / 4 ] = 0; // zero last entry
|
||
|
|
Buffer.BlockCopy( Input, D, CurBlock, 0, bytesAvailable );
|
||
|
|
blockPos = 0;
|
||
|
|
D += bytesAvailable;
|
||
|
|
}
|
||
|
|
|
||
|
|
// load shift register
|
||
|
|
|
||
|
|
shiftRegister = CurBlock[ blockPos++ ];
|
||
|
|
int newBits = bytesAvailable >= 4 ? 32 : bytesAvailable * 8;
|
||
|
|
bytesAvailable -= 4;
|
||
|
|
|
||
|
|
// read remaining bits
|
||
|
|
|
||
|
|
if( bitsAvailable > 0 )
|
||
|
|
{
|
||
|
|
var bitsRemaining = codeSize - bitsAvailable;
|
||
|
|
curCode |= ( shiftRegister << bitsAvailable ) & mask;
|
||
|
|
shiftRegister >>= bitsRemaining;
|
||
|
|
bitsAvailable = newBits - bitsRemaining;
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
curCode = shiftRegister & mask;
|
||
|
|
shiftRegister >>= codeSize;
|
||
|
|
bitsAvailable = newBits - codeSize;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// process code
|
||
|
|
|
||
|
|
if( curCode == clearCode )
|
||
|
|
{
|
||
|
|
// reset codes
|
||
|
|
codeSize = minimumCodeSize + 1;
|
||
|
|
nextSize = Pow2[ codeSize ];
|
||
|
|
numCodes = maximumCodeSize + 2;
|
||
|
|
|
||
|
|
// reset buffer write pos
|
||
|
|
codesEnd = numCodes * 2;
|
||
|
|
|
||
|
|
// clear previous code
|
||
|
|
previousCode = NoCode;
|
||
|
|
mask = (uint) ( nextSize - 1 );
|
||
|
|
|
||
|
|
continue;
|
||
|
|
}
|
||
|
|
else if( curCode == endCode )
|
||
|
|
{
|
||
|
|
// stop
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
|
||
|
|
bool plusOne = false;
|
||
|
|
int codePos = 0;
|
||
|
|
|
||
|
|
if( curCode < numCodes )
|
||
|
|
{
|
||
|
|
// write existing code
|
||
|
|
codePos = Indices[ curCode ];
|
||
|
|
}
|
||
|
|
else if( previousCode != NoCode )
|
||
|
|
{
|
||
|
|
// write previous code
|
||
|
|
codePos = Indices[ previousCode ];
|
||
|
|
plusOne = true;
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
continue;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
// output colours
|
||
|
|
|
||
|
|
var codeLength = Codes[ codePos++ ];
|
||
|
|
var newCode = Codes[ codePos ];
|
||
|
|
|
||
|
|
for( int i = 0; i < codeLength; i++ )
|
||
|
|
{
|
||
|
|
var code = Codes[ codePos++ ];
|
||
|
|
|
||
|
|
if( code != TransparentIndex && col < Width )
|
||
|
|
{
|
||
|
|
Output[ row + col ] = ActiveColourTable[ code ];
|
||
|
|
}
|
||
|
|
|
||
|
|
if( ++col == rightEdge )
|
||
|
|
{
|
||
|
|
col = ImageLeft;
|
||
|
|
row -= Width;
|
||
|
|
|
||
|
|
if( row < 0 )
|
||
|
|
{
|
||
|
|
SkipBlocks();
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
if( plusOne )
|
||
|
|
{
|
||
|
|
if( newCode != TransparentIndex && col < Width )
|
||
|
|
{
|
||
|
|
Output[ row + col ] = ActiveColourTable[ newCode ];
|
||
|
|
}
|
||
|
|
|
||
|
|
if( ++col == rightEdge )
|
||
|
|
{
|
||
|
|
col = ImageLeft;
|
||
|
|
row -= Width;
|
||
|
|
|
||
|
|
if( row < 0 )
|
||
|
|
{
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// create new code
|
||
|
|
|
||
|
|
if( previousCode != NoCode && numCodes != Indices.Length )
|
||
|
|
{
|
||
|
|
// get previous code from buffer
|
||
|
|
|
||
|
|
codePos = Indices[ previousCode ];
|
||
|
|
codeLength = Codes[ codePos++ ];
|
||
|
|
|
||
|
|
// resize buffer if required (should be rare)
|
||
|
|
|
||
|
|
if( codesEnd + codeLength + 1 >= Codes.Length )
|
||
|
|
{
|
||
|
|
Array.Resize( ref Codes, Codes.Length * 2 );
|
||
|
|
}
|
||
|
|
|
||
|
|
// add new code
|
||
|
|
|
||
|
|
Indices[ numCodes++ ] = codesEnd;
|
||
|
|
Codes[ codesEnd++ ] = (ushort) ( codeLength + 1 );
|
||
|
|
|
||
|
|
// copy previous code sequence
|
||
|
|
|
||
|
|
var stop = codesEnd + codeLength;
|
||
|
|
|
||
|
|
while( codesEnd < stop )
|
||
|
|
{
|
||
|
|
Codes[ codesEnd++ ] = Codes[ codePos++ ];
|
||
|
|
}
|
||
|
|
|
||
|
|
// append new code
|
||
|
|
|
||
|
|
Codes[ codesEnd++ ] = newCode;
|
||
|
|
}
|
||
|
|
|
||
|
|
// increase code size?
|
||
|
|
|
||
|
|
if( numCodes >= nextSize && codeSize < 12 )
|
||
|
|
{
|
||
|
|
nextSize = Pow2[ ++codeSize ];
|
||
|
|
mask = (uint) ( nextSize - 1 );
|
||
|
|
}
|
||
|
|
|
||
|
|
// remember last code processed
|
||
|
|
previousCode = curCode;
|
||
|
|
}
|
||
|
|
|
||
|
|
// skip any remaining blocks
|
||
|
|
SkipBlocks();
|
||
|
|
}
|
||
|
|
#endif // mgGIF_UNSAFE
|
||
|
|
|
||
|
|
public static string Ident()
|
||
|
|
{
|
||
|
|
var v = "1.1";
|
||
|
|
var e = BitConverter.IsLittleEndian ? "L" : "B";
|
||
|
|
|
||
|
|
#if ENABLE_IL2CPP
|
||
|
|
var b = "N";
|
||
|
|
#else
|
||
|
|
var b = "M";
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#if mgGIF_UNSAFE
|
||
|
|
var s = "U";
|
||
|
|
#else
|
||
|
|
var s = "S";
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#if NET_4_6
|
||
|
|
var n = "4.x";
|
||
|
|
#else
|
||
|
|
var n = "2.0";
|
||
|
|
#endif
|
||
|
|
|
||
|
|
return String.Format("{0} {1}{2}{3} {4}", v, e, s, b, n);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|