public static GifRenderBlock Read(Stream s)
{
GifRenderBlock ret = new GifRenderBlock();
ret.Shift = s.Position;
s.ReadByte();
ret.LeftPosition = s.ReadUshort();
ret.TopPosition = s.ReadUshort();
ret.Width = s.ReadUshort();
ret.Height = s.ReadUshort();
ret.PackedByte = (byte)s.ReadByte();
if (ret.LocalColorTableFlag)
{
ret.ColorTable = new GifColorTable();
ret.ColorTable.ColorsAmount = (int)Math.Pow(2, ret.SizeOfColorTable + 1);
ret.ColorTable.Read(s);
}
ret.LZWMinCodeSize = (byte)s.ReadByte();
var b = s.ReadByte();
List <byte[]> dl = new List <byte[]>();
while (b != 0)
{
ret.Data.Add((byte)b);
var dd = new byte[b];
s.Read(dd, 0, b);
ret.Data.AddRange(dd);
dl.Add(dd);
b = s.ReadByte();
}
ret.DataList = dl.ToArray();
return(ret);
}
public static byte[] GetDecodedData(GifRenderBlock imgBlock)
{
// Combine LZW compressed data
List <byte> lzwData = new List <byte>();
for (int i = 0; i < imgBlock.DataList.Length; i++)
{
for (int k = 0; k < imgBlock.DataList[i].Length; k++)
{
lzwData.Add(imgBlock.DataList[i][k]);
}
}
// LZW decode
int needDataSize = imgBlock.Height * imgBlock.Width;
byte[] decodedData = DecodeGifLZW(lzwData, imgBlock.LZWMinCodeSize, needDataSize);
// Sort interlace GIF
if (imgBlock.InterlaceFlag)
{
decodedData = SortInterlaceGifData(decodedData, imgBlock.Width);
}
return(decodedData);
}
public static GifContainer Parse(Stream fs)
{
GifContainer ret = new GifContainer();
{
ret.Header.Read(fs);
ret.LogicalScreen.Read(fs);
int findex = 0;
//lookahead
while (true)
{
var b = fs.ReadByte();
fs.Position--;
if (b == 0x3b)
{
break;
}
if (b == 0x21)
{
b = fs.ReadByte();
var b2 = fs.ReadByte();
fs.Position -= 2;;
if (b2 == 0xf9)
{
ret.Data.Add(GraphicControlExtension.Read(fs));
}
else
if (b2 == 0xff)
{
ret.Data.Add(GifApplicationExtension.Read(fs));
}
else
if (b2 == 0xfe)
{
ret.Data.Add(GifCommentBlock.Read(fs));
}
else
{
throw new GifParsingException("unknown header: " + b.ToString("X2") + b2.ToString("X2") + ", shift: " + fs.Position);
}
}
else
if (b == 0x2c)
{
var r = GifRenderBlock.Read(fs);
ret.Data.Add(r);
r.FrameIndex = findex++;
}
else
{
throw new GifParsingException("unknown header: " + b.ToString("X2") + ", shift: " + fs.Position);
}
}
}
ret.UpdateInfo();
return(ret);
}
public MemoryStream GetRawFrameStream(int index)
{
MemoryStream ms = new MemoryStream();
Header.Write(ms);
//LogicalScreen.GlobalColorTable.Colors[LogicalScreen.Desc.BackgroundColorIndex] = Color.Black;
LogicalScreen.Write(ms);
int frame = 0;
for (int i = 0; i < Data.Count; i++)
{
var t = Data[i];
if (frame == index && t is GifRenderBlock)
{
int j = 0;
for (j = i - 1; j > 0; j--)
{
if (Data[j] is GifRenderBlock)
{
j++;
break;
}
}
LastGceBlock = null;
for (int y = j; y <= i; y++)
{
if (Data[y] is GraphicControlExtension)
{
LastGceBlock = Data[y] as GraphicControlExtension;
// LogicalScreen.GlobalColorTable.Colors[LastGceBlock.TransparentColorIndex] = Color.Black;
}
if (Data[y] is GifRenderBlock)
{
LastRenderBlock = Data[y] as GifRenderBlock;
}
Data[y].Write(ms);
}
break;
}
if (t is GifRenderBlock)
{
frame++;
}
}
ms.WriteByte(0x3b);
return(ms);
}
public GraphicControlExtension GetGceBlock(GifRenderBlock gr)
{
GraphicControlExtension gce = null;
foreach (var item in Data)
{
if (item is GraphicControlExtension)
{
gce = item as GraphicControlExtension;
}
if (gr == item)
{
break;
}
}
return(gce);
}
public Bitmap GetDecodedBmp(int _index)
{
var fr = GetRenderBlock(_index);
var gce = GetGceBlock(fr);
LastRenderBlock = fr;
LastGceBlock = gce;
Bitmap decbmp = new Bitmap(fr.Width, fr.Height);
LockBitmap l = new LockBitmap(decbmp);
l.LockBits();
var dec = GifParser.GetDecodedData(fr);
GifColorTable clrt = LogicalScreen.GlobalColorTable;
if (fr.LocalColorTableFlag)
{
clrt = fr.ColorTable;
}
for (int i = 0; i < fr.Width; i++)
{
for (int j = 0; j < fr.Height; j++)
{
int index = j * fr.Width + i;
var clr = clrt.Colors[dec[index]];
if (gce.TransparencyFlag && gce.TransparentColorIndex == dec[index])
{
l.SetPixel(i, j, Color.Transparent);
}
else
{
l.SetPixel(i, j, clr);
}
}
}
l.UnlockBits();
return(decbmp);
}
