internal void ReadImageDescriptorFromFile(BinaryReader reader, GifGraphicsControlExtension extensionOrNull)
{
_extensionOrNull = extensionOrNull;
_bounds.X = (int)reader.ReadUInt16();
_bounds.Y = (int)reader.ReadUInt16();
_bounds.Width = (int)reader.ReadUInt16();
_bounds.Height = (int)reader.ReadUInt16();
byte flags = reader.ReadByte();
bool hasLocalColourTable = (flags & 0x80) != 0;
_isInterlaced = (flags & 0x40) != 0;
_isSorted = (flags & 0x20) != 0;
int sizeOfLocalColourTable = 1 << (1 + (flags & 0x07));
if (hasLocalColourTable)
{
_colourTable = new GifColourTable();
_colourTable.ReadFromFile(reader, sizeOfLocalColourTable);
}
else
{
_colourTable = null;
}
ReadImageDataFromFile(reader);
}
public GifFrame()
{
_bounds = new Rectangle();
_colourTable = null;
_subBlocks = null;
_extensionOrNull = null;
}
void ReadBlocksFromFile(BinaryReader reader)
{
GifGraphicsControlExtension capturedExtension = null;
while (true)
{
byte blockType = reader.ReadByte();
byte extensionType;
switch (blockType)
{
case GifConstants.ImageDescriptorLabel:
GifFrame frame = new GifFrame();
frame.ReadImageDescriptorFromFile(reader, capturedExtension);
_frames.Add(frame);
capturedExtension = null;
break;
case GifConstants.FileTerminatorLabel:
return;
case GifConstants.ExtensionLabel:
extensionType = reader.ReadByte();
switch (extensionType)
{
case GifConstants.GraphicsControlExtensionSubLabel:
capturedExtension = new GifGraphicsControlExtension();
capturedExtension.ReadFromFile(reader);
break;
default:
ReadUnknownBlockFromFile(reader, true);
break;
}
ReadBlockTerminatorFromFile(reader);
break;
default:
ReadUnknownBlockFromFile(reader, false);
ReadBlockTerminatorFromFile(reader);
break;
}
}
}
