Question

我正在尝试在Ubuntu 14.04上使用Intel icpc编译Qt，并且在此文件中出现编译错误 - qpnghandler.cpp

从qpnghandler.cpp文件中我得到的是相关代码 -

static
void setup_qt(QImage& image, png_structp png_ptr, png_infop info_ptr, float screen_gamma=0.0)
{
  if (screen_gamma != 0.0 && png_get_valid(png_ptr, info_ptr, PNG_INFO_gAMA)) {
    double file_gamma;
    png_get_gAMA(png_ptr, info_ptr, &file_gamma);
    png_set_gamma(png_ptr, screen_gamma, file_gamma);
}

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);

if (color_type == PNG_COLOR_TYPE_GRAY) {
    // Black & White or 8-bit grayscale
    if (bit_depth == 1 && info_ptr->channels == 1) {
        png_set_invert_mono(png_ptr);
        png_read_update_info(png_ptr, info_ptr);
        if (image.size() != QSize(width, height) || image.format() != QImage::Format_Mono) {
            image = QImage(width, height, QImage::Format_Mono);
            if (image.isNull())
                return;
        }
        image.setColorCount(2);
        image.setColor(1, qRgb(0,0,0));
        image.setColor(0, qRgb(255,255,255));
    } else if (bit_depth == 16 && png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
        png_set_expand(png_ptr);
        png_set_strip_16(png_ptr);
        png_set_gray_to_rgb(png_ptr);
        if (image.size() != QSize(width, height) || image.format() != QImage::Format_ARGB32) {
            image = QImage(width, height, QImage::Format_ARGB32);
            if (image.isNull())
                return;
        }
        if (QSysInfo::ByteOrder == QSysInfo::BigEndian)
            png_set_swap_alpha(png_ptr);

        png_read_update_info(png_ptr, info_ptr);
    } else {
        if (bit_depth == 16)
            png_set_strip_16(png_ptr);
        else if (bit_depth < 8)
            png_set_packing(png_ptr);
        int ncols = bit_depth < 8 ? 1 << bit_depth : 256;
        png_read_update_info(png_ptr, info_ptr);
        if (image.size() != QSize(width, height) || image.format() != QImage::Format_Indexed8) {
            image = QImage(width, height, QImage::Format_Indexed8);
            if (image.isNull())
                return;
        }
        image.setColorCount(ncols);
        for (int i=0; i<ncols; i++) {
            int c = i*255/(ncols-1);
            image.setColor(i, qRgba(c,c,c,0xff));
        }
        if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
#if PNG_LIBPNG_VER_MAJOR < 1 || (PNG_LIBPNG_VER_MAJOR == 1 && PNG_LIBPNG_VER_MINOR < 4)
            const int g = info_ptr->trans_values.gray;
#else
            const int g = info_ptr->trans_color.gray;
#endif
            if (g < ncols) {
                image.setColor(g, 0);
            }
        }
    }
} else if (color_type == PNG_COLOR_TYPE_PALETTE
           && png_get_valid(png_ptr, info_ptr, PNG_INFO_PLTE)
           && info_ptr->num_palette <= 256)
{
    // 1-bit and 8-bit color
    if (bit_depth != 1)
        png_set_packing(png_ptr);
    png_read_update_info(png_ptr, info_ptr);
    png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, 0, 0, 0);
    QImage::Format format = bit_depth == 1 ? QImage::Format_Mono : QImage::Format_Indexed8;
    if (image.size() != QSize(width, height) || image.format() != format) {
        image = QImage(width, height, format);
        if (image.isNull())
            return;
    }
    image.setColorCount(info_ptr->num_palette);
    int i = 0;
    if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
        while (i < info_ptr->num_trans) {
            image.setColor(i, qRgba(
                info_ptr->palette[i].red,
                info_ptr->palette[i].green,
                info_ptr->palette[i].blue,
 #if PNG_LIBPNG_VER_MAJOR < 1 || (PNG_LIBPNG_VER_MAJOR == 1 && PNG_LIBPNG_VER_MINOR < 4)
                info_ptr->trans[i]
 #else
                info_ptr->trans_alpha[i]
#endif
               )
           );
            i++;
        }
    }
    while (i < info_ptr->num_palette) {
        image.setColor(i, qRgba(
            info_ptr->palette[i].red,
            info_ptr->palette[i].green,
            info_ptr->palette[i].blue,
            0xff
           )
       );
        i++;
    }
} else {
    // 32-bit
    if (bit_depth == 16)
        png_set_strip_16(png_ptr);

    png_set_expand(png_ptr);

    if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
        png_set_gray_to_rgb(png_ptr);

    QImage::Format format = QImage::Format_ARGB32;
    // Only add filler if no alpha, or we can get 5 channel data.
    if (!(color_type & PNG_COLOR_MASK_ALPHA)
        && !png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
        png_set_filler(png_ptr, 0xff, QSysInfo::ByteOrder == QSysInfo::BigEndian ?
                       PNG_FILLER_BEFORE : PNG_FILLER_AFTER);
        // We want 4 bytes, but it isn't an alpha channel
        format = QImage::Format_RGB32;
    }
    if (image.size() != QSize(width, height) || image.format() != format) {
        image = QImage(width, height, format);
        if (image.isNull())
            return;
    }

    if (QSysInfo::ByteOrder == QSysInfo::BigEndian)
        png_set_swap_alpha(png_ptr);

    png_read_update_info(png_ptr, info_ptr);
}

// Qt==ARGB==Big(ARGB)==Little(BGRA)
if (QSysInfo::ByteOrder == QSysInfo::LittleEndian) {
    png_set_bgr(png_ptr);
}

}

有人可以指导我对该文件进行哪些修改，以便我可以编译qpnghandler.cpp吗？

icpc -c -wd654,1572 -g -pthread -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -O2 -fvisibility=hidden -fvisibility-inlines-hidden -D_REENTRANT -I/usr/include/freetype2 -fPIC -DQT_SHARED -DQT_BUILD_GUI_LIB -DQT_NO_USING_NAMESPACE -DQT_NO_CAST_TO_ASCII -DQT_ASCII_CAST_WARNINGS -DQT3_SUPPORT -DQT_MOC_COMPAT -DQT_HAVE_MMX -DQT_HAVE_SSE -DQT_HAVE_MMXEXT -DQT_HAVE_SSE2 -DQT_NO_OPENTYPE -DQT_NO_STYLE_MAC -DQT_NO_STYLE_WINDOWSVISTA -DQT_NO_STYLE_WINDOWSXP -DQT_NO_STYLE_WINDOWSCE -DQT_NO_STYLE_WINDOWSMOBILE -DQT_NO_STYLE_S60 -DQ_INTERNAL_QAPP_SRC -DQT_NO_DEBUG -DQT_CORE_LIB -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -I../../mkspecs/linux-icc -I. -I../../include/QtCore -I../../include -I../../include/QtGui -I.rcc/release-shared -I../3rdparty/xorg -I/usr/include/freetype2 -I../3rdparty/harfbuzz/src -Idialogs -I.moc/release-shared -I/usr/X11R6/include -I.uic/release-shared -o .obj/release-shared/qpnghandler.o image/qpnghandler.cpp

image/qpnghandler.cpp(169): error: pointer to incomplete class type is not allowed
      if (bit_depth == 1 && info_ptr->channels == 1) {
                            ^

image/qpnghandler.cpp(214): error: pointer to incomplete class type is not allowed
              const int g = info_ptr->trans_color.gray;
                            ^

image/qpnghandler.cpp(223): error: pointer to incomplete class type is not allowed
             && info_ptr->num_palette <= 256)
                ^

image/qpnghandler.cpp(236): error: pointer to incomplete class type is not allowed
      image.setColorCount(info_ptr->num_palette);
                          ^

image/qpnghandler.cpp(239): error: pointer to incomplete class type is not allowed
          while (i < info_ptr->num_trans) {
                     ^

 image/qpnghandler.cpp(241): error: pointer to incomplete class type is not allowed
                  info_ptr->palette[i].red,
                  ^

image/qpnghandler.cpp(242): error: pointer to incomplete class type is not allowed
                  info_ptr->palette[i].green,
                  ^

Answer 1

TL; DR：你正在为一个新的libpng编译一个古老的Qt。这个新的libpng以不兼容的方式更改了它的API。较新的Qt支持这个较新的libpng。

Qt 4.6于2009年发布。如果你出于某种原因坚持使用Qt 4.x，你肯定应该使用4.8分支 - 因为它包含安全性和可移植性修复，如解决问题的那个'重击。但是，对Qt的4.x分支的上游支持已经结束，所以如果你正在积极地处理这个项目，你应该考虑将你的代码移植到Qt 5.x（如果你希望将来继续使用它））。

如果你出于某种原因拼命想要创建一个Qt 4.6的Frankenstein版本（也许你在Qt 4中将一个棘手的错误分成两半并且想要追溯到历史七年，看看那个版本是否也有错误），你应该考虑使用libpng的1.4分支。如果由于某种原因您无法做到这一点，那么您可以将Qt的PNG代码小心地移植到libpng-1.5或libpng-1.6的API。有关如何执行此操作的详细信息，请访问libpng 1.5.10 error: dereferencing pointer to incomplete type。

编译错误在Ubuntu 14.04上用icpc编译Qt

1 个答案: