private void LoadBitmap(Stream stream)
{
if (stream == null)
{
throw new ArgumentNullException();
}
if (!stream.CanSeek)
{
throw new ArgumentException("The stream does not support seeking.");
}
if (!stream.CanRead)
{
throw new ArgumentException("The stream does not support reading.");
}
var reader = new BinaryReader(stream, Encoding.ASCII);
// Read the header.
var header = (DDSHEADER)reader.ReadStruct(typeof(DDSHEADER));
if (!header.IsValid())
{
throw new ArgumentException("Invalid header. Stream does not appear to be a valid DDS-file.", nameof(stream));
}
_fourcc = DXT_FOURCC.Unknown;
if ((header.surfaceDesc.ddpfPixelFormat.dwFlags & DDPF.RGB) == DDPF.RGB)
{
_bitmap = LoadRGB(header.surfaceDesc, stream);
}
else if ((header.surfaceDesc.ddpfPixelFormat.dwFlags & DDPF.FOURCC) == DDPF.FOURCC)
{
_fourcc = header.surfaceDesc.ddpfPixelFormat.dwFourCC;
IDXTDecoder decoder;
switch (header.surfaceDesc.ddpfPixelFormat.dwFourCC)
{
case DXT_FOURCC.DXT1:
decoder = new DXT1Decoder();
break;
case DXT_FOURCC.DXT3:
decoder = new DXT3Decoder();
break;
case DXT_FOURCC.DXT5:
decoder = new DXT5Decoder();
break;
default:
throw new NotSupportedException(string.Format("FOURCC {0} is not supported.", header.surfaceDesc.ddpfPixelFormat.dwFourCC));
}
_bitmap = decoder.Decode(header.surfaceDesc, stream);
}
}
