public void read(Reader reader, bool skipHeader = false, int clrCnt = 0x80)
{
#region Header
if (!skipHeader)
{
reader.seek(6, System.IO.SeekOrigin.Begin); // GIF89a
width = reader.ReadByte();
width |= (ushort)(reader.ReadByte() << 8);
height = reader.ReadByte();
height |= (ushort)(reader.ReadByte() << 8);
byte info = reader.ReadByte(); // Palette Size
clrCnt = (info & 0x7) + 1;
if (clrCnt > 0)
{
clrCnt = 1 << clrCnt;
}
reader.ReadByte(); // background colour index
reader.ReadByte(); // unused
if (clrCnt != 0x100)
{
throw new Exception("RSDK-Formatted Gif files must use 256 colours!");
}
}
for (int c = 0; c < clrCnt; ++c)
{
palette[c].R = reader.ReadByte();
palette[c].G = reader.ReadByte();
palette[c].B = reader.ReadByte();
}
#endregion
#region Blocks
byte blockType = reader.ReadByte();
while (blockType != 0 && blockType != ';')
{
switch (blockType)
{
default: // Unknown
Console.WriteLine($"Unknown Block Type ({blockType})");
break;
case (byte)'!': // Extension
{
byte extensionType = reader.ReadByte();
switch (extensionType)
{
case 0xF9: // Graphics Control Extension
{
int blockSize = reader.ReadByte();
byte disposalFlag = reader.ReadByte();
ushort frameDelay = reader.ReadUInt16();
byte transparentIndex = reader.ReadByte();
reader.ReadByte(); // terminator
}
break;
case 0x01: // Plain Text Extension
case 0xFE: // Comment Extension
case 0xFF: // Application Extension
{
int blockSize = reader.ReadByte();
while (blockSize != 0)
{
// Read block
reader.BaseStream.Position += blockSize;
blockSize = reader.ReadByte(); // next block Size, if its 0 we know its the end of block
}
}
break;
default: // Unknown
Console.WriteLine($"Unknown Extension Type ({extensionType})");
return;
}
}
break;
case (byte)',': // Image descriptor
{
int left = reader.ReadUInt16();
int top = reader.ReadUInt16();
int right = reader.ReadUInt16();
int bottom = reader.ReadUInt16();
byte info2 = reader.ReadByte();
bool interlaced = (info2 & 0x40) != 0;
if (info2 >> 7 == 1)
{
for (int c = 0x80; c < 0x100; ++c)
{
palette[c].R = reader.ReadByte();
palette[c].G = reader.ReadByte();
palette[c].B = reader.ReadByte();
}
}
readPictureData(width, height, interlaced, reader);
}
break;
}
blockType = reader.ReadByte();
}
#endregion
if (!skipHeader)
{
reader.Close();
}
}
