michael@0: /* vim:set tw=80 expandtab softtabstop=4 ts=4 sw=4: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: 
michael@0: #ifndef _nsBMPDecoder_h
michael@0: #define _nsBMPDecoder_h
michael@0: 
michael@0: #include "nsAutoPtr.h"
michael@0: #include "gfxColor.h"
michael@0: #include "Decoder.h"
michael@0: #include "BMPFileHeaders.h"
michael@0: 
michael@0: namespace mozilla {
michael@0: namespace image {
michael@0: 
michael@0: class RasterImage;
michael@0: 
michael@0: /**
michael@0:  * Decoder for BMP-Files, as used by Windows and OS/2
michael@0:  */
michael@0: class nsBMPDecoder : public Decoder
michael@0: {
michael@0: public:
michael@0: 
michael@0:     nsBMPDecoder(RasterImage &aImage);
michael@0:     ~nsBMPDecoder();
michael@0: 
michael@0:     // Specifies whether or not the BMP file will contain alpha data
michael@0:     // If set to true and the BMP is 32BPP, the alpha data will be
michael@0:     // retrieved from the 4th byte of image data per pixel 
michael@0:     void SetUseAlphaData(bool useAlphaData);
michael@0:     // Obtains the bits per pixel from the internal BIH header
michael@0:     int32_t GetBitsPerPixel() const;
michael@0:     // Obtains the width from the internal BIH header
michael@0:     int32_t GetWidth() const;
michael@0:     // Obtains the abs-value of the height from the internal BIH header
michael@0:     int32_t GetHeight() const;
michael@0:     // Obtains the internal output image buffer
michael@0:     uint32_t* GetImageData();
michael@0:     // Obtains the size of the compressed image resource
michael@0:     int32_t GetCompressedImageSize() const;
michael@0:     // Obtains whether or not a BMP file had alpha data in its 4th byte
michael@0:     // for 32BPP bitmaps.  Only use after the bitmap has been processed.
michael@0:     bool HasAlphaData() const;
michael@0: 
michael@0:     virtual void WriteInternal(const char* aBuffer, uint32_t aCount, DecodeStrategy aStrategy);
michael@0:     virtual void FinishInternal();
michael@0: 
michael@0: private:
michael@0: 
michael@0:     /** Calculates the red-, green- and blueshift in mBitFields using
michael@0:      * the bitmasks from mBitFields */
michael@0:     NS_METHOD CalcBitShift();
michael@0: 
michael@0:     uint32_t mPos;
michael@0: 
michael@0:     BMPFILEHEADER mBFH;
michael@0:     BITMAPV5HEADER mBIH;
michael@0:     char mRawBuf[WIN_V3_INTERNAL_BIH_LENGTH];
michael@0: 
michael@0:     uint32_t mLOH; ///< Length of the header
michael@0: 
michael@0:     uint32_t mNumColors; ///< The number of used colors, i.e. the number of entries in mColors
michael@0:     colorTable *mColors;
michael@0: 
michael@0:     bitFields mBitFields;
michael@0: 
michael@0:     uint8_t *mRow;      ///< Holds one raw line of the image
michael@0:     uint32_t mRowBytes; ///< How many bytes of the row were already received
michael@0:     int32_t mCurLine;   ///< Index of the line of the image that's currently being decoded: [height,1]
michael@0:     int32_t mOldLine;   ///< Previous index of the line 
michael@0:     int32_t mCurPos;    ///< Index in the current line of the image
michael@0: 
michael@0:     ERLEState mState;   ///< Maintains the current state of the RLE decoding
michael@0:     uint32_t mStateData;///< Decoding information that is needed depending on mState
michael@0: 
michael@0:     /** Set mBFH from the raw data in mRawBuf, converting from little-endian
michael@0:      * data to native data as necessary */
michael@0:     void ProcessFileHeader();
michael@0:     /** Set mBIH from the raw data in mRawBuf, converting from little-endian
michael@0:      * data to native data as necessary */
michael@0:     void ProcessInfoHeader();
michael@0: 
michael@0:     // Stores whether the image data may store alpha data, or if
michael@0:     // the alpha data is unspecified and filled with a padding byte of 0. 
michael@0:     // When a 32BPP bitmap is stored in an ICO or CUR file, its 4th byte
michael@0:     // is used for alpha transparency.  When it is stored in a BMP, its
michael@0:     // 4th byte is reserved and is always 0.
michael@0:     // Reference: 
michael@0:     // http://en.wikipedia.org/wiki/ICO_(file_format)#cite_note-9
michael@0:     // Bitmaps where the alpha bytes are all 0 should be fully visible.
michael@0:     bool mUseAlphaData;
michael@0:     // Whether the 4th byte alpha data was found to be non zero and hence used.
michael@0:     bool mHaveAlphaData;
michael@0: };
michael@0: 
michael@0: /** Sets the pixel data in aDecoded to the given values.
michael@0:  * @param aDecoded pointer to pixel to be set, will be incremented to point to the next pixel.
michael@0:  */
michael@0: static inline void SetPixel(uint32_t*& aDecoded, uint8_t aRed, uint8_t aGreen, uint8_t aBlue, uint8_t aAlpha = 0xFF)
michael@0: {
michael@0:     *aDecoded++ = gfxPackedPixel(aAlpha, aRed, aGreen, aBlue);
michael@0: }
michael@0: 
michael@0: static inline void SetPixel(uint32_t*& aDecoded, uint8_t idx, colorTable* aColors)
michael@0: {
michael@0:     SetPixel(aDecoded, aColors[idx].red, aColors[idx].green, aColors[idx].blue);
michael@0: }
michael@0: 
michael@0: /** Sets two (or one if aCount = 1) pixels
michael@0:  * @param aDecoded where the data is stored. Will be moved 4 resp 8 bytes
michael@0:  * depending on whether one or two pixels are written.
michael@0:  * @param aData The values for the two pixels
michael@0:  * @param aCount Current count. Is decremented by one or two.
michael@0:  */
michael@0: inline void Set4BitPixel(uint32_t*& aDecoded, uint8_t aData,
michael@0:                          uint32_t& aCount, colorTable* aColors)
michael@0: {
michael@0:     uint8_t idx = aData >> 4;
michael@0:     SetPixel(aDecoded, idx, aColors);
michael@0:     if (--aCount > 0) {
michael@0:         idx = aData & 0xF;
michael@0:         SetPixel(aDecoded, idx, aColors);
michael@0:         --aCount;
michael@0:     }
michael@0: }
michael@0: 
michael@0: } // namespace image
michael@0: } // namespace mozilla
michael@0: 
michael@0: 
michael@0: #endif
michael@0: