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