public static Bitmap DecompressBC1(ReadOnlySpan <byte> data, int width, int height, bool IsSRGB)
{
int W = (width + 3) / 4;
int H = (height + 3) / 4;
byte[] Output = new byte[W * H * 64];
for (int Y = 0; Y < H; Y++)
{
for (int X = 0; X < W; X++)
{
int IOffs = (Y * W + X) * 8;
byte[] Tile = BCnDecodeTile(data, IOffs, true);
int TOffset = 0;
for (int TY = 0; TY < 4; TY++)
{
for (int TX = 0; TX < 4; TX++)
{
int OOffset = (X * 4 + TX + (Y * 4 + TY) * W * 4) * 4;
Output[OOffset + 0] = Tile[TOffset + 0];
Output[OOffset + 1] = Tile[TOffset + 1];
Output[OOffset + 2] = Tile[TOffset + 2];
Output[OOffset + 3] = Tile[TOffset + 3];
TOffset += 4;
}
}
}
}
return(BitmapExporter.GetBitmapFromBytes(Output, W * 4, H * 4));
}
public static Bitmap DecompressBC3(ReadOnlySpan <byte> data, int width, int height, bool IsSRGB)
{
int W = (width + 3) / 4;
int H = (height + 3) / 4;
byte[] Output = new byte[W * H * 64];
for (int Y = 0; Y < H; Y++)
{
for (int X = 0; X < W; X++)
{
int IOffs = (Y * W + X) * 16;
byte[] Tile = BCnDecodeTile(data, IOffs + 8, false);
byte[] Alpha = new byte[8];
Alpha[0] = data[IOffs + 0];
Alpha[1] = data[IOffs + 1];
CalculateBC3Alpha(Alpha);
int AlphaLow = data.GetInt32(IOffs + 2);
int AlphaHigh = data.GetUInt16(IOffs + 6);
ulong AlphaCh = (uint)AlphaLow | (ulong)AlphaHigh << 32;
int TOffset = 0;
for (int TY = 0; TY < 4; TY++)
{
for (int TX = 0; TX < 4; TX++)
{
int OOffset = (X * 4 + TX + (Y * 4 + TY) * W * 4) * 4;
byte AlphaPx = Alpha[(AlphaCh >> (TY * 12 + TX * 3)) & 7];
Output[OOffset + 0] = Tile[TOffset + 0];
Output[OOffset + 1] = Tile[TOffset + 1];
Output[OOffset + 2] = Tile[TOffset + 2];
Output[OOffset + 3] = AlphaPx;
TOffset += 4;
}
}
}
}
return(BitmapExporter.GetBitmapFromBytes(Output, W * 4, H * 4));
}
