RetroZilla/modules/libpr0n/decoders/icon/nsIconDecoder.h

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#ifndef nsIconDecoder_h__
#define nsIconDecoder_h__

#include "imgIDecoder.h"

#include "nsCOMPtr.h"

#include "imgIContainer.h"
#include "imgIDecoderObserver.h"
#include "gfxIImageFrame.h"

#define NS_ICONDECODER_CID                           \
{ /* FFC08380-256C-11d5-9905-001083010E9B */         \
     0xffc08380,                                     \
     0x256c,                                         \
     0x11d5,                                         \
    { 0x99, 0x5, 0x0, 0x10, 0x83, 0x1, 0xe, 0x9b }   \
}


//////////////////////////////////////////////////////////////////////////////////////////////
// The icon decoder is a decoder specifically tailored for loading icons 
// from the OS. We've defined our own little format to represent these icons
// and this decoder takes that format and converts it into 24-bit RGB with alpha channel
// support. It was modeled a bit off the PPM decoder.
//
// Assumptions about the decoder:
// (1) We receive ALL of the data from the icon channel in one OnDataAvailable call. We don't
//     support multiple ODA calls yet.
// (2) the format of the incoming data is as follows:
//     The first two bytes contain the width and the height of the icon. 
//     The third byte contains the number of bits per pixel in the alpha
//       channel (either 1 or 8).
//     Followed by 3 bytes per pixel for the color bitmap row after row,
//       from top to bottom, with pixels left to right within rows, and
//       RGB order within pixels, in platform endianness.
//     Followed by alpha data (1 or 8 bits per pixel, see above) in the
//       same order as the RGB data, and also in platform endianness.
//
//
//////////////////////////////////////////////////////////////////////////////////////////////

class nsIconDecoder : public imgIDecoder
{
public:
  NS_DECL_ISUPPORTS
  NS_DECL_IMGIDECODER

  nsIconDecoder();
  virtual ~nsIconDecoder();

private:
  nsCOMPtr<imgIContainer> mImage;
  nsCOMPtr<gfxIImageFrame> mFrame;
  nsCOMPtr<imgIDecoderObserver> mObserver; // this is just qi'd from mRequest for speed
};

#endif // nsIconDecoder_h__