Moving GraphicsContext and dependencies from core to platform.

Source/platform/image-decoders/bmp/BMPImageReader.h

+/*
+ * Copyright (c) 2008, 2009, Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. 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 "platform/image-decoders/ImageDecoder.h"
+#include "wtf/CPU.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 PLATFORM_EXPORT BMPImageReader {
+    WTF_MAKE_FAST_ALLOCATED;
+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