public BmpWriter(WriteableBitmap bitmap, GifPalette palette)
{
_bitmap = bitmap;
_palette = palette;
#if !SILVERLIGHT
_buffer = new byte[(int)_bitmap.Height * (int)_bitmap.Width * 4];
#endif
}
private GifFrame ReadImageData(BinaryReader reader)
{
var imageDescriptor = ImageDescriptor.Read(reader);
var localPalette = imageDescriptor.HasLocalPalette ? GifPalette.Read(reader, imageDescriptor.LocalPaletteColorCount) : null;
var lzwInitialCodeSize = reader.ReadByte() + 1;
var lzwBitReader = new GifLzwBitReader(new GifLzwByteReader(reader));
var lzwCodeSize = lzwInitialCodeSize;
var nextIncValue = (2 << (lzwCodeSize - 1)) - 1;
var decodeTable = new GifDecodeTable(_sreenDescriptor.GlobalPaletteColorCount);
int value;
#if SILVERLIGHT
var writeableBmp = new WriteableBitmap(_sreenDescriptor.Width, _sreenDescriptor.Height);
#else
var writeableBmp = new WriteableBitmap(_sreenDescriptor.Width, _sreenDescriptor.Height, 96.0, 96.0, PixelFormats.Bgra32, null);
#endif
var bmpWriter = new BmpWriter(writeableBmp, _globalPalette);
while (lzwBitReader.Read(lzwCodeSize, out value))
{
if (decodeTable.Count == nextIncValue)
{
lzwCodeSize++;
nextIncValue = (2 << (lzwCodeSize - 1)) - 1;
}
bool reset;
if (decodeTable.ProcessNextCode(value, bmpWriter, out reset) == false)
{
break;
}
if (reset)
{
lzwCodeSize = lzwInitialCodeSize;
nextIncValue = (2 << (lzwCodeSize - 1)) - 1;
}
if (lzwCodeSize > 12)
{
lzwCodeSize = 12;
}
}
bmpWriter.Flush();
return(new GifFrame(imageDescriptor, localPalette, writeableBmp));
}
public GifImageSource(Stream stream)
{
try
{
_gifStream = new MemoryStream();
stream.CopyTo(_gifStream);
_gifStream.Seek(0, SeekOrigin.Begin);
using (var reader = new BinaryReader(_gifStream))
{
var gifSign = new string(reader.ReadChars(6));
var gif89a = string.Equals(gifSign, "gif89a", StringComparison.OrdinalIgnoreCase);
var gif87a = string.Equals(gifSign, "gif87a", StringComparison.OrdinalIgnoreCase);
if ((gif87a || gif89a) == false)
{
return;
}
_sreenDescriptor = LogicalScreenDescriptor.Read(reader);
_globalPalette = _sreenDescriptor.HasGlobalPalette ? GifPalette.Read(reader, _sreenDescriptor.GlobalPaletteColorCount) : null;
while (true)
{
var ch = reader.ReadChar();
if (ch == ';' && reader.BaseStream.Position == reader.BaseStream.Length)
{
break;
}
switch (ch)
{
case '!':
SkipExtension(reader);
break;
case ',':
_frames.Add(ReadImage(reader));
break;
}
}
}
_isValid = true;
}
catch (Exception)
{
_isValid = false;
}
}
public static GifPalette Read(BinaryReader reader, int colorsCount)
{
var palette = new GifPalette();
for (var i = 0; i < colorsCount; i++)
{
var r = reader.ReadByte();
var g = reader.ReadByte();
var b = reader.ReadByte();
palette._colors.Add((0xFF << 24) | (r << 16) | (g << 8) | b);
}
return(palette);
}
private static Dictionary <int, GifPalette> CreatePalettes(GifDataStream metadata)
{
var palettes = new Dictionary <int, GifPalette>();
Color[] globalColorTable = null;
if (metadata.Header.LogicalScreenDescriptor.HasGlobalColorTable)
{
globalColorTable =
metadata.GlobalColorTable
.Select(gc => Color.FromArgb(0xFF, gc.R, gc.G, gc.B))
.ToArray();
}
for (int i = 0; i < metadata.Frames.Count; i++)
{
var frame = metadata.Frames[i];
var colorTable = globalColorTable;
if (frame.Descriptor.HasLocalColorTable)
{
colorTable =
frame.LocalColorTable
.Select(gc => Color.FromArgb(0xFF, gc.R, gc.G, gc.B))
.ToArray();
}
int?transparencyIndex = null;
var gce = frame.GraphicControl;
if (gce != null && gce.HasTransparency)
{
transparencyIndex = gce.TransparencyIndex;
}
palettes[i] = new GifPalette(transparencyIndex, colorTable);
}
return(palettes);
}
private static Dictionary<int, GifPalette> CreatePalettes(GifDataStream metadata)
{
var palettes = new Dictionary<int, GifPalette>();
Color[] globalColorTable = null;
if (metadata.Header.LogicalScreenDescriptor.HasGlobalColorTable)
{
globalColorTable =
metadata.GlobalColorTable
.Select(gc => Color.FromArgb(0xFF, gc.R, gc.G, gc.B))
.ToArray();
}
for (int i = 0; i < metadata.Frames.Count; i++)
{
var frame = metadata.Frames[i];
var colorTable = globalColorTable;
if (frame.Descriptor.HasLocalColorTable)
{
colorTable =
frame.LocalColorTable
.Select(gc => Color.FromArgb(0xFF, gc.R, gc.G, gc.B))
.ToArray();
}
int? transparencyIndex = null;
var gce = frame.GraphicControl;
if (gce != null && gce.HasTransparency)
{
transparencyIndex = gce.TransparencyIndex;
}
palettes[i] = new GifPalette(transparencyIndex, colorTable);
}
return palettes;
}
public GifFrame(ImageDescriptor imageDescriptor, GifPalette localPalette, WriteableBitmap writeableBmp)
{
_imageDescriptor = imageDescriptor;
_localPalette = localPalette;
_writeableBmp = writeableBmp;
}
