public void WriteToStream(Stream stream)
{
Header.WriteToStream(stream);
LogicalScreenDescriptor.WriteToStream(stream);
if (LogicalScreenDescriptor.HasGlobalColorTable)
{
GlobalColorTable.WriteToStream(stream);
}
foreach (var frame in Frames)
{
frame.WriteToStream(stream);
}
stream.WriteByte(trailer);
}
/// <summary>
/// Populates the global color table byte[] from the source image, and performs lexical parsing on the array.
/// </summary>
/// <param name="bytes"></param>
public static GlobalColorTable ParseGlobalColorTable(byte[] bytes)
{
GlobalColorTable gct = new GlobalColorTable()
{
TotalBlockLength = bytes.Length,
Bytes = (byte[])bytes.Clone(),
DistinctColorCount = bytes.Length / 3
};
for (int i = 0; i <= bytes.Length - 3; i += 3)
{
gct.Colors.Add(new byte[3] {
bytes[i], bytes[i + 1], bytes[i + 2]
});
}
return(gct);
}
private void WriteLogicalScreenDescriptor()
{
if (Debug)
{
Console.Error.WriteLine("Writing logical screen descriptor");
}
WriteShort(ScreenWidth);
WriteShort(ScreenHeight);
int packedFields = 0;
if (GlobalColorTable != null)
{
packedFields |= 128 | (GlobalColorTable.BitSize() - 1);
if (GlobalColorTable.Ordered)
{
packedFields |= 8;
}
}
packedFields |= (ColorResolution - 1) << 4;
WriteByte(packedFields);
if (GlobalColorTable != null)
{
WriteByte(GlobalColorTable.BackgroundColorIndex);
}
else
{
WriteByte(0);
}
if (PixelAspectRatio != 0)
{
WriteByte((int)(64 * PixelAspectRatio - 15));
}
else
{
WriteByte(0);
}
}
private void Read(BinaryReader br)
{
ReadSignature(br);
ReadVersion(br);
ReadScreenConfig(br);
ReadGlobalColorTable(br);
ReadBackgroundColorIndex(br);
ReadAspectRatio(br);
GlobalColorTable?.ReadTable(br);
GraphicsControlExtensionBlock gcb = null;
do
{
var b = br.ReadByte();
if (b == 0x2C)
{
var frame = new GifFrame {
ControlExtension = gcb
};
frame.Read(br);
gcb = null;
Frames.Add(frame);
}
else if (b == 0x21)
{
var label = br.ReadByte();
if (label == 0xF9)
{
gcb = new GraphicsControlExtensionBlock(br);
}
else if (label == 0x01)
{
var frame = new GifFrame {
PlainTextExtension = new PlainTextExtensionBlock(br),
ControlExtension = gcb
};
gcb = null;
Frames.Add(frame);
}
else if (label == 0xFF)
{
ApplicationExtensionBlocks.Add(new ApplicationExtensionBlock(br));
}
else if (label == 0xFE)
{
CommentExtensionBlocks.Add(new CommentExtensionBlock(br));
}
else
{
throw new GifDecodingException($"Unknown extension label {label:X2}");
}
}
else if (b == 0x3B)
{
break;
}
else
{
throw new GifDecodingException($"Unknown separator {b:X2}");
}
} while (true);
}
public GlobalColorTableMangler(ref VcvjImage vcvjImage)
{
VcvjImage = vcvjImage;
GlobalColorTable = VcvjImage.DataStream.LogicalScreen.GlobalColorTable;
}