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 /* vim:set tw=80 expandtab softtabstop=4 ts=4 sw=4: */

 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this

  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

 #ifndef _nsBMPDecoder_h

 #define _nsBMPDecoder_h

 #include "nsAutoPtr.h"

 #include "gfxColor.h"

 #include "Decoder.h"

 #include "BMPFileHeaders.h"

 namespace mozilla {

 namespace image {

 class RasterImage;

 /**

  * Decoder for BMP-Files, as used by Windows and OS/2

  */

 class nsBMPDecoder : public Decoder

 {

 public:

     nsBMPDecoder(RasterImage &aImage);

     ~nsBMPDecoder();

     // Specifies whether or not the BMP file will contain alpha data

     // If set to true and the BMP is 32BPP, the alpha data will be

     // retrieved from the 4th byte of image data per pixel 

     void SetUseAlphaData(bool useAlphaData);

     // Obtains the bits per pixel from the internal BIH header

     int32_t GetBitsPerPixel() const;

     // Obtains the width from the internal BIH header

     int32_t GetWidth() const;

     // Obtains the abs-value of the height from the internal BIH header

     int32_t GetHeight() const;

     // Obtains the internal output image buffer

     uint32_t* GetImageData();

     // Obtains the size of the compressed image resource

     int32_t GetCompressedImageSize() const;

     // Obtains whether or not a BMP file had alpha data in its 4th byte

     // for 32BPP bitmaps.  Only use after the bitmap has been processed.

     bool HasAlphaData() const;

     virtual void WriteInternal(const char* aBuffer, uint32_t aCount, DecodeStrategy aStrategy);

     virtual void FinishInternal();

 private:

     /** Calculates the red-, green- and blueshift in mBitFields using

      * the bitmasks from mBitFields */

     NS_METHOD CalcBitShift();

     uint32_t mPos;

     BMPFILEHEADER mBFH;

     BITMAPV5HEADER mBIH;

     char mRawBuf[WIN_V3_INTERNAL_BIH_LENGTH];

     uint32_t mLOH; ///< Length of the header

     uint32_t mNumColors; ///< The number of used colors, i.e. the number of entries in mColors

     colorTable *mColors;

     bitFields mBitFields;

     uint8_t *mRow;      ///< Holds one raw line of the image

     uint32_t mRowBytes; ///< How many bytes of the row were already received

     int32_t mCurLine;   ///< Index of the line of the image that's currently being decoded: [height,1]

     int32_t mOldLine;   ///< Previous index of the line 

     int32_t mCurPos;    ///< Index in the current line of the image

     ERLEState mState;   ///< Maintains the current state of the RLE decoding

     uint32_t mStateData;///< Decoding information that is needed depending on mState

     /** Set mBFH from the raw data in mRawBuf, converting from little-endian

      * data to native data as necessary */

     void ProcessFileHeader();

     /** Set mBIH from the raw data in mRawBuf, converting from little-endian

      * data to native data as necessary */

     void ProcessInfoHeader();

     // Stores whether the image data may store alpha data, or if

     // the alpha data is unspecified and filled with a padding byte of 0. 

     // When a 32BPP bitmap is stored in an ICO or CUR file, its 4th byte

     // is used for alpha transparency.  When it is stored in a BMP, its

     // 4th byte is reserved and is always 0.

     // Reference: 

     // http://en.wikipedia.org/wiki/ICO_(file_format)#cite_note-9

     // Bitmaps where the alpha bytes are all 0 should be fully visible.

     bool mUseAlphaData;

     // Whether the 4th byte alpha data was found to be non zero and hence used.

     bool mHaveAlphaData;

 };

 /** Sets the pixel data in aDecoded to the given values.

  * @param aDecoded pointer to pixel to be set, will be incremented to point to the next pixel.

  */

 static inline void SetPixel(uint32_t*& aDecoded, uint8_t aRed, uint8_t aGreen, uint8_t aBlue, uint8_t aAlpha = 0xFF)

 {

     *aDecoded++ = gfxPackedPixel(aAlpha, aRed, aGreen, aBlue);

 }

 static inline void SetPixel(uint32_t*& aDecoded, uint8_t idx, colorTable* aColors)

 {

     SetPixel(aDecoded, aColors[idx].red, aColors[idx].green, aColors[idx].blue);

 }

 /** Sets two (or one if aCount = 1) pixels

  * @param aDecoded where the data is stored. Will be moved 4 resp 8 bytes

  * depending on whether one or two pixels are written.

  * @param aData The values for the two pixels

  * @param aCount Current count. Is decremented by one or two.

  */

 inline void Set4BitPixel(uint32_t*& aDecoded, uint8_t aData,

                          uint32_t& aCount, colorTable* aColors)

 {

     uint8_t idx = aData >> 4;

     SetPixel(aDecoded, idx, aColors);

     if (--aCount > 0) {

         idx = aData & 0xF;

         SetPixel(aDecoded, idx, aColors);

         --aCount;

     }

 }

 } // namespace image

 } // namespace mozilla

 #endif