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IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #ifndef BMPImageReader_h #define BMPImageReader_h #include <stdint.h> #include "ImageDecoder.h" namespace WebCore { // This class decodes a BMP image. It is used in the BMP and ICO decoders, // which wrap it in the appropriate code to read file headers, etc. class BMPImageReader { public: // Read a value from |data[offset]|, converting from little to native // endianness. static inline uint16_t readUint16(SharedBuffer* data, int offset) { uint16_t result; memcpy(&result, &data->data()[offset], 2); #if CPU(BIG_ENDIAN) result = ((result & 0xff) << 8) | ((result & 0xff00) >> 8); #endif return result; } static inline uint32_t readUint32(SharedBuffer* data, int offset) { uint32_t result; memcpy(&result, &data->data()[offset], 4); #if CPU(BIG_ENDIAN) result = ((result & 0xff) << 24) | ((result & 0xff00) << 8) | ((result & 0xff0000) >> 8) | ((result & 0xff000000) >> 24); #endif return result; } // |parent| is the decoder that owns us. // |startOffset| points to the start of the BMP within the file. // |buffer| points at an empty ImageFrame that we'll initialize and // fill with decoded data. BMPImageReader(ImageDecoder* parent, size_t decodedAndHeaderOffset, size_t imgDataOffset, bool usesAndMask); void setBuffer(ImageFrame* buffer) { m_buffer = buffer; } void setData(SharedBuffer* data) { m_data = data; } // Does the actual decoding. If |onlySize| is true, decoding only // progresses as far as necessary to get the image size. Returns // whether decoding succeeded. bool decodeBMP(bool onlySize); private: // The various BMP compression types. We don't currently decode all // these. enum CompressionType { // Universal types RGB = 0, RLE8 = 1, RLE4 = 2, // Windows V3+ only BITFIELDS = 3, JPEG = 4, PNG = 5, // OS/2 2.x-only HUFFMAN1D, // Stored in file as 3 RLE24, // Stored in file as 4 }; enum AndMaskState { None, NotYetDecoded, Decoding, }; enum ProcessingResult { Success, Failure, InsufficientData, }; // These are based on the Windows BITMAPINFOHEADER and RGBTRIPLE // structs, but with unnecessary entries removed. struct BitmapInfoHeader { uint32_t biSize; int32_t biWidth; int32_t biHeight; uint16_t biBitCount; CompressionType biCompression; uint32_t biClrUsed; }; struct RGBTriple { uint8_t rgbBlue; uint8_t rgbGreen; uint8_t rgbRed; }; inline uint16_t readUint16(int offset) const { return readUint16(m_data.get(), m_decodedOffset + offset); } inline uint32_t readUint32(int offset) const { return readUint32(m_data.get(), m_decodedOffset + offset); } // Determines the size of the BMP info header. Returns true if the size // is valid. bool readInfoHeaderSize(); // Processes the BMP info header. Returns true if the info header could // be decoded. bool processInfoHeader(); // Helper function for processInfoHeader() which does the actual reading // of header values from the byte stream. Returns false on error. bool readInfoHeader(); // Returns true if this is a Windows V4+ BMP. inline bool isWindowsV4Plus() const { // Windows V4 info header is 108 bytes. V5 is 124 bytes. return (m_infoHeader.biSize == 108) || (m_infoHeader.biSize == 124); } // Returns false if consistency errors are found in the info header. bool isInfoHeaderValid() const; // For BI_BITFIELDS images, initializes the m_bitMasks[] and // m_bitOffsets[] arrays. processInfoHeader() will initialize these for // other compression types where needed. bool processBitmasks(); // For paletted images, allocates and initializes the m_colorTable[] // array. bool processColorTable(); // Processes an RLE-encoded image. Returns true if the entire image was // decoded. bool processRLEData(); // Processes a set of non-RLE-compressed pixels. Two cases: // * inRLE = true: the data is inside an RLE-encoded bitmap. Tries to // process |numPixels| pixels on the current row. // * inRLE = false: the data is inside a non-RLE-encoded bitmap. // |numPixels| is ignored. Expects |m_coord| to point at the // beginning of the next row to be decoded. Tries to process as // many complete rows as possible. Returns InsufficientData if // there wasn't enough data to decode the whole image. // // This function returns a ProcessingResult instead of a bool so that it // can avoid calling m_parent->setFailed(), which could lead to memory // corruption since that will delete |this| but some callers still want // to access member variables after this returns. ProcessingResult processNonRLEData(bool inRLE, int numPixels); // Returns true if the current y-coordinate plus |numRows| would be past // the end of the image. Here "plus" means "toward the end of the // image", so downwards for m_isTopDown images and upwards otherwise. inline bool pastEndOfImage(int numRows) { return m_isTopDown ? ((m_coord.y() + numRows) >= m_parent->size().height()) : ((m_coord.y() - numRows) < 0); } // Returns the pixel data for the current X coordinate in a uint32_t. // Assumes m_decodedOffset has been set to the beginning of the current // row. // NOTE: Only as many bytes of the return value as are needed to hold // the pixel data will actually be set. inline uint32_t readCurrentPixel(int bytesPerPixel) const { const int offset = m_coord.x() * bytesPerPixel; switch (bytesPerPixel) { case 2: return readUint16(offset); case 3: { // It doesn't matter that we never set the most significant byte // of the return value here in little-endian mode, the caller // won't read it. uint32_t pixel; memcpy(&pixel, &m_data->data()[m_decodedOffset + offset], 3); #if CPU(BIG_ENDIAN) pixel = ((pixel & 0xff00) << 8) | ((pixel & 0xff0000) >> 8) | ((pixel & 0xff000000) >> 24); #endif return pixel; } case 4: return readUint32(offset); default: ASSERT_NOT_REACHED(); return 0; } } // Returns the value of the desired component (0, 1, 2, 3 == R, G, B, A) // in the given pixel data. inline unsigned getComponent(uint32_t pixel, int component) const { return ((pixel & m_bitMasks[component]) >> m_bitShiftsRight[component]) << m_bitShiftsLeft[component]; } inline unsigned getAlpha(uint32_t pixel) const { // For images without alpha, return alpha of 0xff. return m_bitMasks[3] ? getComponent(pixel, 3) : 0xff; } // Sets the current pixel to the color given by |colorIndex|. This also // increments the relevant local variables to move the current pixel // right by one. inline void setI(size_t colorIndex) { setRGBA(m_colorTable[colorIndex].rgbRed, m_colorTable[colorIndex].rgbGreen, m_colorTable[colorIndex].rgbBlue, 0xff); } // Like setI(), but with the individual component values specified. inline void setRGBA(unsigned red, unsigned green, unsigned blue, unsigned alpha) { m_buffer->setRGBA(m_coord.x(), m_coord.y(), red, green, blue, alpha); m_coord.move(1, 0); } // Fills pixels from the current X-coordinate up to, but not including, // |endCoord| with the color given by the individual components. This // also increments the relevant local variables to move the current // pixel right to |endCoord|. inline void fillRGBA(int endCoord, unsigned red, unsigned green, unsigned blue, unsigned alpha) { while (m_coord.x() < endCoord) setRGBA(red, green, blue, alpha); } // Resets the relevant local variables to start drawing at the left edge // of the "next" row, where "next" is above or below the current row // depending on the value of |m_isTopDown|. void moveBufferToNextRow(); // The decoder that owns us. ImageDecoder* m_parent; // The destination for the pixel data. ImageFrame* m_buffer; // The file to decode. RefPtr<SharedBuffer> m_data; // An index into |m_data| representing how much we've already decoded. size_t m_decodedOffset; // The file offset at which the BMP info header starts. size_t m_headerOffset; // The file offset at which the actual image bits start. When decoding // ICO files, this is set to 0, since it's not stored anywhere in a // header; the reader functions expect the image data to start // immediately after the header and (if necessary) color table. size_t m_imgDataOffset; // The BMP info header. BitmapInfoHeader m_infoHeader; // True if this is an OS/2 1.x (aka Windows 2.x) BMP. The struct // layouts for this type of BMP are slightly different from the later, // more common formats. bool m_isOS21x; // True if this is an OS/2 2.x BMP. The meanings of compression types 3 // and 4 for this type of BMP differ from Windows V3+ BMPs. // // This will be falsely negative in some cases, but only ones where the // way we misinterpret the data is irrelevant. bool m_isOS22x; // True if the BMP is not vertically flipped, that is, the first line of // raster data in the file is the top line of the image. bool m_isTopDown; // These flags get set to false as we finish each processing stage. bool m_needToProcessBitmasks; bool m_needToProcessColorTable; // Masks/offsets for the color values for non-palette formats. These // are bitwise, with array entries 0, 1, 2, 3 corresponding to R, G, B, // A. // // The right/left shift values are meant to be applied after the masks. // We need to right shift to compensate for the bitfields' offsets into // the 32 bits of pixel data, and left shift to scale the color values // up for fields with less than 8 bits of precision. Sadly, we can't // just combine these into one shift value because the net shift amount // could go either direction. (If only "<< -x" were equivalent to // ">> x"...) uint32_t m_bitMasks[4]; int m_bitShiftsRight[4]; int m_bitShiftsLeft[4]; // The color palette, for paletted formats. size_t m_tableSizeInBytes; Vector<RGBTriple> m_colorTable; // The coordinate to which we've decoded the image. IntPoint m_coord; // Variables that track whether we've seen pixels with alpha values != 0 // and == 0, respectively. See comments in processNonRLEData() on how // these are used. bool m_seenNonZeroAlphaPixel; bool m_seenZeroAlphaPixel; // ICOs store a 1bpp "mask" immediately after the main bitmap image data // (and, confusingly, add its height to the biHeight value in the info // header, thus doubling it). This variable tracks whether we have such // a mask and if we've started decoding it yet. AndMaskState m_andMaskState; }; } // namespace WebCore #endif