private void WriteGraphicsControlExtension(GraphicsControlExtension extension)
{
var data = new byte[4];
data[0] = (byte)(extension.DisposalMethod << 2 |
(extension.UserInputFlag ? 1 : 0) << 1 |
(extension.TransparencyFlag ? 1 : 0));
data[1] = (byte)(extension.DelayTime & 0xFF);
data[2] = (byte)((extension.DelayTime & 0xFF00) >> 8);
data[3] = (byte)extension.TransparencyIndex;
this.WriteExtension(0xF9, data);
}
private void createImage(uint[] colorIndexes, ImageDescriptor imageDescriptor, ColorTable localColorTable)
{
uint localX = imageDescriptor.X;
uint localY = imageDescriptor.Y;
uint localW = imageDescriptor.Width;
uint localH = imageDescriptor.Height;
//Every pixel consists of 4 bytes: R, G, B, A values
byte[] data = new byte[localW * localH * 4];
int transparentColorIndex = -1;
int delay = 0;
FrameDisposalMethod disposalMethod = FrameDisposalMethod.Clear;
if (_extensions.Count > 0 && _extensions.Last() is GraphicsControlExtension)
{
GraphicsControlExtension gce = _extensions.Last() as GraphicsControlExtension;
delay = gce.Delay;
if (gce.HasTransparency)
{
transparentColorIndex = gce.TransparentColorIndex;
}
disposalMethod = gce.DisposalMethod;
}
for (int i = 0; i < data.Length; i += 4)
{
Color color = localColorTable[(int)colorIndexes[i / 4]];
data[i + 0] = color.R;
data[i + 1] = color.G;
data[i + 2] = color.B;
if (colorIndexes[i / 4] == transparentColorIndex)
{
data[i + 3] = 0;
}
else
{
data[i + 3] = byte.MaxValue;
}
}
if (imageDescriptor.Interlaced)
{
data = interlace(data, localW, localH);
}
_images.Add(new GifImage(data, localX, localY, localW, localH, delay, disposalMethod));
}
