C++ (Cpp) readPngHeader Examples

Example #1

File: qpnghandler.cpp Project: AlekSi/phantomjs

/*!
    \internal
*/
bool Q_INTERNAL_WIN_NO_THROW QPngHandlerPrivate::readPngImage(QImage *outImage)
{
    if (state == Error)
        return false;

    if (state == Ready && !readPngHeader()) {
        state = Error;
        return false;
    }

    row_pointers = 0;
    if (setjmp(png_jmpbuf(png_ptr))) {
        png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
        delete [] row_pointers;
        png_ptr = 0;
        state = Error;
        return false;
    }

    setup_qt(*outImage, png_ptr, info_ptr, gamma);

    if (outImage->isNull()) {
        png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
        delete [] row_pointers;
        png_ptr = 0;
        state = Error;
        return false;
    }

    png_uint_32 width;
    png_uint_32 height;
    int bit_depth;
    int color_type;
    png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
                 0, 0, 0);

    uchar *data = outImage->bits();
    int bpl = outImage->bytesPerLine();
    row_pointers = new png_bytep[height];

    for (uint y = 0; y < height; y++)
        row_pointers[y] = data + y * bpl;

    png_read_image(png_ptr, row_pointers);

#if 0 // libpng takes care of this.
    png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)
        if (outImage->depth()==32 && png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
            QRgb trans = 0xFF000000 | qRgb(
                (info_ptr->trans_values.red << 8 >> bit_depth)&0xff,
                (info_ptr->trans_values.green << 8 >> bit_depth)&0xff,
                (info_ptr->trans_values.blue << 8 >> bit_depth)&0xff);
            for (uint y=0; y<height; y++) {
                for (uint x=0; x<info_ptr->width; x++) {
                    if (((uint**)jt)[y][x] == trans) {
                        ((uint**)jt)[y][x] &= 0x00FFFFFF;
                    } else {
                    }
                }
            }
        }

Example #2

File: qpnghandler.cpp Project: 2gis/2gisqt5android

bool Q_INTERNAL_WIN_NO_THROW QPngHandlerPrivate::readPngImage(QImage *outImage)
{
    if (state == Error)
        return false;

    if (state == Ready && !readPngHeader()) {
        state = Error;
        return false;
    }

    if (setjmp(png_jmpbuf(png_ptr))) {
        png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
        png_ptr = 0;
        amp.deallocate();
        state = Error;
        return false;
    }

    bool doScaledRead = false;
    setup_qt(*outImage, png_ptr, info_ptr, scaledSize, &doScaledRead, gamma, fileGamma);

    if (outImage->isNull()) {
        png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
        png_ptr = 0;
        amp.deallocate();
        state = Error;
        return false;
    }

    if (doScaledRead) {
        read_image_scaled(outImage, png_ptr, info_ptr, amp, scaledSize);
    } else {
        png_uint_32 width = 0;
        png_uint_32 height = 0;
        png_int_32 offset_x = 0;
        png_int_32 offset_y = 0;

        int bit_depth = 0;
        int color_type = 0;
        int unit_type = PNG_OFFSET_PIXEL;
        png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, 0, 0, 0);
        png_get_oFFs(png_ptr, info_ptr, &offset_x, &offset_y, &unit_type);
        uchar *data = outImage->bits();
        int bpl = outImage->bytesPerLine();
        amp.row_pointers = new png_bytep[height];

        for (uint y = 0; y < height; y++)
            amp.row_pointers[y] = data + y * bpl;

        png_read_image(png_ptr, amp.row_pointers);
        amp.deallocate();

        outImage->setDotsPerMeterX(png_get_x_pixels_per_meter(png_ptr,info_ptr));
        outImage->setDotsPerMeterY(png_get_y_pixels_per_meter(png_ptr,info_ptr));

        if (unit_type == PNG_OFFSET_PIXEL)
            outImage->setOffset(QPoint(offset_x, offset_y));

        // sanity check palette entries
        if (color_type == PNG_COLOR_TYPE_PALETTE && outImage->format() == QImage::Format_Indexed8) {
            int color_table_size = outImage->colorCount();
            for (int y=0; y<(int)height; ++y) {
                uchar *p = FAST_SCAN_LINE(data, bpl, y);
                uchar *end = p + width;
                while (p < end) {
                    if (*p >= color_table_size)
                        *p = 0;
                    ++p;
                }
            }
        }
    }

    state = ReadingEnd;
    png_read_end(png_ptr, end_info);

    readPngTexts(end_info);
    for (int i = 0; i < readTexts.size()-1; i+=2)
        outImage->setText(readTexts.at(i), readTexts.at(i+1));

    png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
    png_ptr = 0;
    amp.deallocate();
    state = Ready;

    if (scaledSize.isValid() && outImage->size() != scaledSize)
        *outImage = outImage->scaled(scaledSize, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);

    return true;
}