root/Source/platform/image-decoders/png/PNGImageDecoder.cpp

DEFINITIONS

1. decodingFailed
2. decodingWarning
3. headerAvailable
4. rowAvailable
5. pngComplete
6. m_rowBuffer
7. close
8. decode
9. pngPtr
10. infoPtr
11. setReadOffset
12. currentBufferSize
13. decodingSizeOnly
14. setHasAlpha
15. hasAlpha
16. interlaceBuffer
17. createInterlaceBuffer
18. rowBuffer
19. createRowBuffer
20. colorTransform
21. createColorTransform
22. m_doNothingOnFailure
23. isSizeAvailable
24. frameBufferAtIndex
25. setFailed
26. readColorProfile
27. headerAvailable
28. rowAvailable
29. pngComplete
30. decode

/*
 * Copyright (C) 2006 Apple Computer, Inc.
 * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
 *
 * Portions are Copyright (C) 2001 mozilla.org
 *
 * Other contributors:
 *   Stuart Parmenter <stuart@mozilla.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Alternatively, the contents of this file may be used under the terms
 * of either the Mozilla Public License Version 1.1, found at
 * http://www.mozilla.org/MPL/ (the "MPL") or the GNU General Public
 * License Version 2.0, found at http://www.fsf.org/copyleft/gpl.html
 * (the "GPL"), in which case the provisions of the MPL or the GPL are
 * applicable instead of those above.  If you wish to allow use of your
 * version of this file only under the terms of one of those two
 * licenses (the MPL or the GPL) and not to allow others to use your
 * version of this file under the LGPL, indicate your decision by
 * deletingthe provisions above and replace them with the notice and
 * other provisions required by the MPL or the GPL, as the case may be.
 * If you do not delete the provisions above, a recipient may use your
 * version of this file under any of the LGPL, the MPL or the GPL.
 */

#include "config.h"
#include "platform/image-decoders/png/PNGImageDecoder.h"

#include "platform/PlatformInstrumentation.h"
#include "wtf/PassOwnPtr.h"

#include "png.h"
#if USE(QCMSLIB)
#include "qcms.h"
#endif

#if defined(PNG_LIBPNG_VER_MAJOR) && defined(PNG_LIBPNG_VER_MINOR) && (PNG_LIBPNG_VER_MAJOR > 1 || (PNG_LIBPNG_VER_MAJOR == 1 && PNG_LIBPNG_VER_MINOR >= 4))
#define JMPBUF(png_ptr) png_jmpbuf(png_ptr)
#else
#define JMPBUF(png_ptr) png_ptr->jmpbuf
#endif

namespace WebCore {

// Gamma constants.
const double cMaxGamma = 21474.83;
const double cDefaultGamma = 2.2;
const double cInverseGamma = 0.45455;

// Protect against large PNGs. See Mozilla's bug #251381 for more info.
const unsigned long cMaxPNGSize = 1000000UL;

// Called if the decoding of the image fails.
static void PNGAPI decodingFailed(png_structp png, png_const_charp)
{
    longjmp(JMPBUF(png), 1);
}

// Callbacks given to the read struct.  The first is for warnings (we want to
// treat a particular warning as an error, which is why we have to register this
// callback).
static void PNGAPI decodingWarning(png_structp png, png_const_charp warningMsg)
{
    // Mozilla did this, so we will too.
    // Convert a tRNS warning to be an error (see
    // http://bugzilla.mozilla.org/show_bug.cgi?id=251381 )
    if (!strncmp(warningMsg, "Missing PLTE before tRNS", 24))
        png_error(png, warningMsg);
}

// Called when we have obtained the header information (including the size).
static void PNGAPI headerAvailable(png_structp png, png_infop)
{
    static_cast<PNGImageDecoder*>(png_get_progressive_ptr(png))->headerAvailable();
}

// Called when a row is ready.
static void PNGAPI rowAvailable(png_structp png, png_bytep rowBuffer, png_uint_32 rowIndex, int interlacePass)
{
    static_cast<PNGImageDecoder*>(png_get_progressive_ptr(png))->rowAvailable(rowBuffer, rowIndex, interlacePass);
}

// Called when we have completely finished decoding the image.
static void PNGAPI pngComplete(png_structp png, png_infop)
{
    static_cast<PNGImageDecoder*>(png_get_progressive_ptr(png))->pngComplete();
}

class PNGImageReader {
    WTF_MAKE_FAST_ALLOCATED;
public:
    PNGImageReader(PNGImageDecoder* decoder)
        : m_readOffset(0)
        , m_currentBufferSize(0)
        , m_decodingSizeOnly(false)
        , m_hasAlpha(false)
        , m_interlaceBuffer(0)
#if USE(QCMSLIB)
        , m_transform(0)
        , m_rowBuffer()
#endif
    {
        m_png = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, decodingFailed, decodingWarning);
        m_info = png_create_info_struct(m_png);
        png_set_progressive_read_fn(m_png, decoder, headerAvailable, rowAvailable, pngComplete);
    }

    ~PNGImageReader()
    {
        close();
    }

    void close()
    {
        if (m_png && m_info)
            // This will zero the pointers.
            png_destroy_read_struct(&m_png, &m_info, 0);
#if USE(QCMSLIB)
        if (m_transform)
            qcms_transform_release(m_transform);
        m_transform = 0;
#endif
        delete[] m_interlaceBuffer;
        m_interlaceBuffer = 0;
        m_readOffset = 0;
    }

    bool decode(const SharedBuffer& data, bool sizeOnly)
    {
        m_decodingSizeOnly = sizeOnly;
        PNGImageDecoder* decoder = static_cast<PNGImageDecoder*>(png_get_progressive_ptr(m_png));

        // We need to do the setjmp here. Otherwise bad things will happen.
        if (setjmp(JMPBUF(m_png)))
            return decoder->setFailed();

        const char* segment;
        while (unsigned segmentLength = data.getSomeData(segment, m_readOffset)) {
            m_readOffset += segmentLength;
            m_currentBufferSize = m_readOffset;
            png_process_data(m_png, m_info, reinterpret_cast<png_bytep>(const_cast<char*>(segment)), segmentLength);
            // We explicitly specify the superclass isSizeAvailable() because we
            // merely want to check if we've managed to set the size, not
            // (recursively) trigger additional decoding if we haven't.
            if (sizeOnly ? decoder->ImageDecoder::isSizeAvailable() : decoder->isComplete())
                return true;
        }
        return false;
    }

    png_structp pngPtr() const { return m_png; }
    png_infop infoPtr() const { return m_info; }

    void setReadOffset(unsigned offset) { m_readOffset = offset; }
    unsigned currentBufferSize() const { return m_currentBufferSize; }
    bool decodingSizeOnly() const { return m_decodingSizeOnly; }
    void setHasAlpha(bool hasAlpha) { m_hasAlpha = hasAlpha; }
    bool hasAlpha() const { return m_hasAlpha; }

    png_bytep interlaceBuffer() const { return m_interlaceBuffer; }
    void createInterlaceBuffer(int size) { m_interlaceBuffer = new png_byte[size]; }
#if USE(QCMSLIB)
    png_bytep rowBuffer() const { return m_rowBuffer.get(); }
    void createRowBuffer(int size) { m_rowBuffer = adoptArrayPtr(new png_byte[size]); }
    qcms_transform* colorTransform() const { return m_transform; }

    void createColorTransform(const ColorProfile& colorProfile, bool hasAlpha)
    {
        if (m_transform)
            qcms_transform_release(m_transform);
        m_transform = 0;

        if (colorProfile.isEmpty())
            return;
        qcms_profile* deviceProfile = ImageDecoder::qcmsOutputDeviceProfile();
        if (!deviceProfile)
            return;
        qcms_profile* inputProfile = qcms_profile_from_memory(colorProfile.data(), colorProfile.size());
        if (!inputProfile)
            return;
        // We currently only support color profiles for RGB and RGBA images.
        ASSERT(icSigRgbData == qcms_profile_get_color_space(inputProfile));
        qcms_data_type dataFormat = hasAlpha ? QCMS_DATA_RGBA_8 : QCMS_DATA_RGB_8;
        // FIXME: Don't force perceptual intent if the image profile contains an intent.
        m_transform = qcms_transform_create(inputProfile, dataFormat, deviceProfile, dataFormat, QCMS_INTENT_PERCEPTUAL);
        qcms_profile_release(inputProfile);
    }
#endif

private:
    png_structp m_png;
    png_infop m_info;
    unsigned m_readOffset;
    unsigned m_currentBufferSize;
    bool m_decodingSizeOnly;
    bool m_hasAlpha;
    png_bytep m_interlaceBuffer;
#if USE(QCMSLIB)
    qcms_transform* m_transform;
    OwnPtr<png_byte[]> m_rowBuffer;
#endif
};

PNGImageDecoder::PNGImageDecoder(ImageSource::AlphaOption alphaOption,
    ImageSource::GammaAndColorProfileOption gammaAndColorProfileOption,
    size_t maxDecodedBytes)
    : ImageDecoder(alphaOption, gammaAndColorProfileOption, maxDecodedBytes)
    , m_doNothingOnFailure(false)
{
}

PNGImageDecoder::~PNGImageDecoder()
{
}

bool PNGImageDecoder::isSizeAvailable()
{
    if (!ImageDecoder::isSizeAvailable())
         decode(true);

    return ImageDecoder::isSizeAvailable();
}

ImageFrame* PNGImageDecoder::frameBufferAtIndex(size_t index)
{
    if (index)
        return 0;

    if (m_frameBufferCache.isEmpty()) {
        m_frameBufferCache.resize(1);
        m_frameBufferCache[0].setPremultiplyAlpha(m_premultiplyAlpha);
    }

    ImageFrame& frame = m_frameBufferCache[0];
    if (frame.status() != ImageFrame::FrameComplete) {
        PlatformInstrumentation::willDecodeImage("PNG");
        decode(false);
        PlatformInstrumentation::didDecodeImage();
    }

    frame.notifyBitmapIfPixelsChanged();
    return &frame;
}

bool PNGImageDecoder::setFailed()
{
    if (m_doNothingOnFailure)
        return false;
    m_reader.clear();
    return ImageDecoder::setFailed();
}

#if USE(QCMSLIB)
static void readColorProfile(png_structp png, png_infop info, ColorProfile& colorProfile)
{
#ifdef PNG_iCCP_SUPPORTED
    char* profileName;
    int compressionType;
#if (PNG_LIBPNG_VER < 10500)
    png_charp profile;
#else
    png_bytep profile;
#endif
    png_uint_32 profileLength;
    if (!png_get_iCCP(png, info, &profileName, &compressionType, &profile, &profileLength))
        return;

    // Only accept RGB color profiles from input class devices.
    bool ignoreProfile = false;
    char* profileData = reinterpret_cast<char*>(profile);
    if (profileLength < ImageDecoder::iccColorProfileHeaderLength)
        ignoreProfile = true;
    else if (!ImageDecoder::rgbColorProfile(profileData, profileLength))
        ignoreProfile = true;
    else if (!ImageDecoder::inputDeviceColorProfile(profileData, profileLength))
        ignoreProfile = true;

    ASSERT(colorProfile.isEmpty());
    if (!ignoreProfile)
        colorProfile.append(profileData, profileLength);
#endif
}
#endif

void PNGImageDecoder::headerAvailable()
{
    png_structp png = m_reader->pngPtr();
    png_infop info = m_reader->infoPtr();
    png_uint_32 width = png_get_image_width(png, info);
    png_uint_32 height = png_get_image_height(png, info);

    // Protect against large images.
    if (width > cMaxPNGSize || height > cMaxPNGSize) {
        longjmp(JMPBUF(png), 1);
        return;
    }

    // We can fill in the size now that the header is available.  Avoid memory
    // corruption issues by neutering setFailed() during this call; if we don't
    // do this, failures will cause |m_reader| to be deleted, and our jmpbuf
    // will cease to exist.  Note that we'll still properly set the failure flag
    // in this case as soon as we longjmp().
    m_doNothingOnFailure = true;
    bool result = setSize(width, height);
    m_doNothingOnFailure = false;
    if (!result) {
        longjmp(JMPBUF(png), 1);
        return;
    }

    int bitDepth, colorType, interlaceType, compressionType, filterType, channels;
    png_get_IHDR(png, info, &width, &height, &bitDepth, &colorType, &interlaceType, &compressionType, &filterType);

    // The options we set here match what Mozilla does.

    // Expand to ensure we use 24-bit for RGB and 32-bit for RGBA.
    if (colorType == PNG_COLOR_TYPE_PALETTE || (colorType == PNG_COLOR_TYPE_GRAY && bitDepth < 8))
        png_set_expand(png);

    png_bytep trns = 0;
    int trnsCount = 0;
    if (png_get_valid(png, info, PNG_INFO_tRNS)) {
        png_get_tRNS(png, info, &trns, &trnsCount, 0);
        png_set_expand(png);
    }

    if (bitDepth == 16)
        png_set_strip_16(png);

    if (colorType == PNG_COLOR_TYPE_GRAY || colorType == PNG_COLOR_TYPE_GRAY_ALPHA)
        png_set_gray_to_rgb(png);

#if USE(QCMSLIB)
    if ((colorType & PNG_COLOR_MASK_COLOR) && !m_ignoreGammaAndColorProfile) {
        // We only support color profiles for color PALETTE and RGB[A] PNG. Supporting
        // color profiles for gray-scale images is slightly tricky, at least using the
        // CoreGraphics ICC library, because we expand gray-scale images to RGB but we
        // do not similarly transform the color profile. We'd either need to transform
        // the color profile or we'd need to decode into a gray-scale image buffer and
        // hand that to CoreGraphics.
        ColorProfile colorProfile;
        readColorProfile(png, info, colorProfile);
        bool decodedImageHasAlpha = (colorType & PNG_COLOR_MASK_ALPHA) || trnsCount;
        m_reader->createColorTransform(colorProfile, decodedImageHasAlpha);
    }
#endif

    // Deal with gamma and keep it under our control.
    double gamma;
    if (!m_ignoreGammaAndColorProfile && png_get_gAMA(png, info, &gamma)) {
        if ((gamma <= 0.0) || (gamma > cMaxGamma)) {
            gamma = cInverseGamma;
            png_set_gAMA(png, info, gamma);
        }
        png_set_gamma(png, cDefaultGamma, gamma);
    } else
        png_set_gamma(png, cDefaultGamma, cInverseGamma);

    // Tell libpng to send us rows for interlaced pngs.
    if (interlaceType == PNG_INTERLACE_ADAM7)
        png_set_interlace_handling(png);

    // Update our info now.
    png_read_update_info(png, info);
    channels = png_get_channels(png, info);
    ASSERT(channels == 3 || channels == 4);

    m_reader->setHasAlpha(channels == 4);

    if (m_reader->decodingSizeOnly()) {
        // If we only needed the size, halt the reader.
#if defined(PNG_LIBPNG_VER_MAJOR) && defined(PNG_LIBPNG_VER_MINOR) && (PNG_LIBPNG_VER_MAJOR > 1 || (PNG_LIBPNG_VER_MAJOR == 1 && PNG_LIBPNG_VER_MINOR >= 5))
        // '0' argument to png_process_data_pause means: Do not cache unprocessed data.
        m_reader->setReadOffset(m_reader->currentBufferSize() - png_process_data_pause(png, 0));
#else
        m_reader->setReadOffset(m_reader->currentBufferSize() - png->buffer_size);
        png->buffer_size = 0;
#endif
    }
}

void PNGImageDecoder::rowAvailable(unsigned char* rowBuffer, unsigned rowIndex, int)
{
    if (m_frameBufferCache.isEmpty())
        return;

    // Initialize the framebuffer if needed.
    ImageFrame& buffer = m_frameBufferCache[0];
    if (buffer.status() == ImageFrame::FrameEmpty) {
        png_structp png = m_reader->pngPtr();
        if (!buffer.setSize(size().width(), size().height())) {
            longjmp(JMPBUF(png), 1);
            return;
        }

        unsigned colorChannels = m_reader->hasAlpha() ? 4 : 3;
        if (PNG_INTERLACE_ADAM7 == png_get_interlace_type(png, m_reader->infoPtr())) {
            m_reader->createInterlaceBuffer(colorChannels * size().width() * size().height());
            if (!m_reader->interlaceBuffer()) {
                longjmp(JMPBUF(png), 1);
                return;
            }
        }

#if USE(QCMSLIB)
        if (m_reader->colorTransform()) {
            m_reader->createRowBuffer(colorChannels * size().width());
            if (!m_reader->rowBuffer()) {
                longjmp(JMPBUF(png), 1);
                return;
            }
        }
#endif
        buffer.setStatus(ImageFrame::FramePartial);
        buffer.setHasAlpha(false);

        // For PNGs, the frame always fills the entire image.
        buffer.setOriginalFrameRect(IntRect(IntPoint(), size()));
    }

    /* libpng comments (here to explain what follows).
     *
     * this function is called for every row in the image.  If the
     * image is interlacing, and you turned on the interlace handler,
     * this function will be called for every row in every pass.
     * Some of these rows will not be changed from the previous pass.
     * When the row is not changed, the new_row variable will be NULL.
     * The rows and passes are called in order, so you don't really
     * need the row_num and pass, but I'm supplying them because it
     * may make your life easier.
     */

    // Nothing to do if the row is unchanged, or the row is outside
    // the image bounds: libpng may send extra rows, ignore them to
    // make our lives easier.
    if (!rowBuffer)
        return;
    int y = rowIndex;
    if (y < 0 || y >= size().height())
        return;

    /* libpng comments (continued).
     *
     * For the non-NULL rows of interlaced images, you must call
     * png_progressive_combine_row() passing in the row and the
     * old row.  You can call this function for NULL rows (it will
     * just return) and for non-interlaced images (it just does the
     * memcpy for you) if it will make the code easier.  Thus, you
     * can just do this for all cases:
     *
     *    png_progressive_combine_row(png_ptr, old_row, new_row);
     *
     * where old_row is what was displayed for previous rows.  Note
     * that the first pass (pass == 0 really) will completely cover
     * the old row, so the rows do not have to be initialized.  After
     * the first pass (and only for interlaced images), you will have
     * to pass the current row, and the function will combine the
     * old row and the new row.
     */

    bool hasAlpha = m_reader->hasAlpha();
    unsigned colorChannels = hasAlpha ? 4 : 3;
    png_bytep row = rowBuffer;

    if (png_bytep interlaceBuffer = m_reader->interlaceBuffer()) {
        row = interlaceBuffer + (rowIndex * colorChannels * size().width());
        png_progressive_combine_row(m_reader->pngPtr(), row, rowBuffer);
    }

#if USE(QCMSLIB)
    if (qcms_transform* transform = m_reader->colorTransform()) {
        qcms_transform_data(transform, row, m_reader->rowBuffer(), size().width());
        row = m_reader->rowBuffer();
    }
#endif

    // Write the decoded row pixels to the frame buffer.
    ImageFrame::PixelData* address = buffer.getAddr(0, y);
    bool nonTrivialAlpha = false;
    int width = size().width();

    png_bytep pixel = row;
    for (int x = 0; x < width; ++x, pixel += colorChannels) {
        unsigned alpha = hasAlpha ? pixel[3] : 255;
        buffer.setRGBA(address++, pixel[0], pixel[1], pixel[2], alpha);
        nonTrivialAlpha |= alpha < 255;
    }

    if (nonTrivialAlpha && !buffer.hasAlpha())
        buffer.setHasAlpha(nonTrivialAlpha);

    buffer.setPixelsChanged(true);
}

void PNGImageDecoder::pngComplete()
{
    if (!m_frameBufferCache.isEmpty())
        m_frameBufferCache.first().setStatus(ImageFrame::FrameComplete);
}

void PNGImageDecoder::decode(bool onlySize)
{
    if (failed())
        return;

    if (!m_reader)
        m_reader = adoptPtr(new PNGImageReader(this));

    // If we couldn't decode the image but we've received all the data, decoding
    // has failed.
    if (!m_reader->decode(*m_data, onlySize) && isAllDataReceived())
        setFailed();
    // If we're done decoding the image, we don't need the PNGImageReader
    // anymore.  (If we failed, |m_reader| has already been cleared.)
    else if (isComplete())
        m_reader.clear();
}

} // namespace WebCore