qjpeghandler.cpp

奇趣公司比较新的qt/emd版本

                    cinfo.scale_denom = 1;
                } else if (cinfo.scale_denom < 4) {
                    cinfo.scale_denom = 2;
                } else if (cinfo.scale_denom < 8) {
                    cinfo.scale_denom = 4;
                } else {
                    cinfo.scale_denom = 8;
                }
            }
            
            jpegSmoothScaler scaler(&cinfo, QString().sprintf("Scale( %d, %d, ScaleFree )",
                                                              scaledSize.width(),
                                                              scaledSize.height()).toLatin1().data());
            *outImage = scaler.scale();
#endif
        } else {
            if (cinfo.output_components == 3 || cinfo.output_components == 4) {
                if (outImage->size() != QSize(cinfo.output_width, cinfo.output_height)
                    || outImage->format() != QImage::Format_RGB32) {
                    *outImage = QImage(cinfo.output_width, cinfo.output_height, QImage::Format_RGB32);
                }
            } else if (cinfo.output_components == 1) {
                if (outImage->size() != QSize(cinfo.output_width, cinfo.output_height)
                    || outImage->format() != QImage::Format_Indexed8) {
                    *outImage = QImage(cinfo.output_width, cinfo.output_height, QImage::Format_Indexed8);
                }
                outImage->setNumColors(256);
                for (int i=0; i<256; i++)
                    outImage->setColor(i, qRgb(i,i,i));
            } else {
                // Unsupported format
            }
            if (outImage->isNull())
                return false;

            if (!outImage->isNull()) {
                uchar* data = outImage->bits();
                int bpl = outImage->bytesPerLine();
                while (cinfo.output_scanline < cinfo.output_height) {
                    uchar *d = data + cinfo.output_scanline * bpl;
                    (void) jpeg_read_scanlines(&cinfo,
                                               &d,
                                               1);
                }
                (void) jpeg_finish_decompress(&cinfo);

                if (cinfo.output_components == 3) {
                    // Expand 24->32 bpp.
                    for (uint j=0; j<cinfo.output_height; j++) {
                        uchar *in = outImage->scanLine(j) + cinfo.output_width * 3;
                        QRgb *out = (QRgb*)outImage->scanLine(j);

                        for (uint i=cinfo.output_width; i--;) {
                            in-=3;
                            out[i] = qRgb(in[0], in[1], in[2]);
                        }
                    }
                } else if (cinfo.out_color_space == JCS_CMYK) {
                    for (uint j = 0; j < cinfo.output_height; ++j) {
                        uchar *in = outImage->scanLine(j) + cinfo.output_width * 4;
                        QRgb *out = (QRgb*)outImage->scanLine(j);

                        for (uint i = cinfo.output_width; i--; ) {
                            in-=4;
                            int k = in[3];
                            out[i] = qRgb(k * in[0] / 255, k * in[1] / 255, k * in[2] / 255);
                        }
                    }
                }
                if (cinfo.density_unit == 1) {
                    outImage->setDotsPerMeterX(int(100. * cinfo.X_density / 2.54));
                    outImage->setDotsPerMeterY(int(100. * cinfo.Y_density / 2.54));
                } else if (cinfo.density_unit == 2) {
                    outImage->setDotsPerMeterX(int(100. * cinfo.X_density));
                    outImage->setDotsPerMeterY(int(100. * cinfo.Y_density));
                }
            }
        }
    }

    jpeg_destroy_decompress(&cinfo);
    delete iod_src;
    return !outImage->isNull();
}


struct my_jpeg_destination_mgr : public jpeg_destination_mgr {
    // Nothing dynamic - cannot rely on destruction over longjump
    QIODevice *device;
    JOCTET buffer[max_buf];

public:
    my_jpeg_destination_mgr(QIODevice *);
};


#if defined(Q_C_CALLBACKS)
extern "C" {
#endif

static void qt_init_destination(j_compress_ptr)
{
}

static boolean qt_empty_output_buffer(j_compress_ptr cinfo)
{
    my_jpeg_destination_mgr* dest = (my_jpeg_destination_mgr*)cinfo->dest;

    int written = dest->device->write((char*)dest->buffer, max_buf);
    if (written == -1)
        (*cinfo->err->error_exit)((j_common_ptr)cinfo);

    dest->next_output_byte = dest->buffer;
    dest->free_in_buffer = max_buf;

#if defined(Q_OS_UNIXWARE)
    return B_TRUE;
#else
    return true;
#endif
}

static void qt_term_destination(j_compress_ptr cinfo)
{
    my_jpeg_destination_mgr* dest = (my_jpeg_destination_mgr*)cinfo->dest;
    qint64 n = max_buf - dest->free_in_buffer;

    qint64 written = dest->device->write((char*)dest->buffer, n);
    if (written == -1)
        (*cinfo->err->error_exit)((j_common_ptr)cinfo);
}

#if defined(Q_C_CALLBACKS)
}
#endif

inline my_jpeg_destination_mgr::my_jpeg_destination_mgr(QIODevice *device)
{
    jpeg_destination_mgr::init_destination = qt_init_destination;
    jpeg_destination_mgr::empty_output_buffer = qt_empty_output_buffer;
    jpeg_destination_mgr::term_destination = qt_term_destination;
    this->device = device;
    next_output_byte = buffer;
    free_in_buffer = max_buf;
}


static bool write_jpeg_image(const QImage &sourceImage, QIODevice *device, int sourceQuality)
{
    bool success = false;
    const QImage image = sourceImage;
    const QVector<QRgb> cmap = image.colorTable();

    struct jpeg_compress_struct cinfo;
    JSAMPROW row_pointer[1];
    row_pointer[0] = 0;

    struct my_jpeg_destination_mgr *iod_dest = new my_jpeg_destination_mgr(device);
    struct my_error_mgr jerr;

    cinfo.err = jpeg_std_error(&jerr);
    jerr.error_exit = my_error_exit;

    if (!setjmp(jerr.setjmp_buffer)) {
        // WARNING:
        // this if loop is inside a setjmp/longjmp branch
        // do not create C++ temporaries here because the destructor may never be called
        // if you allocate memory, make sure that you can free it (row_pointer[0])
        jpeg_create_compress(&cinfo);

        cinfo.dest = iod_dest;

        cinfo.image_width = image.width();
        cinfo.image_height = image.height();

        bool gray=false;
        switch (image.depth()) {
        case 1:
        case 8:
            gray = true;
            for (int i = image.numColors(); gray && i--;) {
                gray = gray & (qRed(cmap[i]) == qGreen(cmap[i]) &&
                               qRed(cmap[i]) == qBlue(cmap[i]));
            }
            cinfo.input_components = gray ? 1 : 3;
            cinfo.in_color_space = gray ? JCS_GRAYSCALE : JCS_RGB;
            break;
        case 32:
            cinfo.input_components = 3;
            cinfo.in_color_space = JCS_RGB;
        }

        jpeg_set_defaults(&cinfo);

        qreal diffInch = qAbs(image.dotsPerMeterX()*2.54/100. - qRound(image.dotsPerMeterX()*2.54/100.))
                         + qAbs(image.dotsPerMeterY()*2.54/100. - qRound(image.dotsPerMeterY()*2.54/100.));
        qreal diffCm = (qAbs(image.dotsPerMeterX()/100. - qRound(image.dotsPerMeterX()/100.))
                        + qAbs(image.dotsPerMeterY()/100. - qRound(image.dotsPerMeterY()/100.)))*2.54;
        if (diffInch < diffCm) {
            cinfo.density_unit = 1; // dots/inch
            cinfo.X_density = qRound(image.dotsPerMeterX()*2.54/100.);
            cinfo.Y_density = qRound(image.dotsPerMeterY()*2.54/100.);
        } else {
            cinfo.density_unit = 2; // dots/cm
            cinfo.X_density = (image.dotsPerMeterX()+50) / 100;
            cinfo.Y_density = (image.dotsPerMeterY()+50) / 100;
        }


        int quality = sourceQuality >= 0 ? qMin(sourceQuality,100) : 75;
#if defined(Q_OS_UNIXWARE)
        jpeg_set_quality(&cinfo, quality, B_TRUE /* limit to baseline-JPEG values */);
        jpeg_start_compress(&cinfo, B_TRUE);
#else
        jpeg_set_quality(&cinfo, quality, true /* limit to baseline-JPEG values */);
        jpeg_start_compress(&cinfo, true);
#endif

        row_pointer[0] = new uchar[cinfo.image_width*cinfo.input_components];
        int w = cinfo.image_width;
        while (cinfo.next_scanline < cinfo.image_height) {
            uchar *row = row_pointer[0];
            switch (image.depth()) {
            case 1:
                if (gray) {
                    const uchar* data = image.scanLine(cinfo.next_scanline);
                    if (image.format() == QImage::Format_MonoLSB) {
                        for (int i=0; i<w; i++) {
                            bool bit = !!(*(data + (i >> 3)) & (1 << (i & 7)));
                            row[i] = qRed(cmap[bit]);
                        }
                    } else {
                        for (int i=0; i<w; i++) {
                            bool bit = !!(*(data + (i >> 3)) & (1 << (7 -(i & 7))));
                            row[i] = qRed(cmap[bit]);
                        }
                    }
                } else {
                    const uchar* data = image.scanLine(cinfo.next_scanline);
                    if (image.format() == QImage::Format_MonoLSB) {
                        for (int i=0; i<w; i++) {
                            bool bit = !!(*(data + (i >> 3)) & (1 << (i & 7)));
                            *row++ = qRed(cmap[bit]);
                            *row++ = qGreen(cmap[bit]);
                            *row++ = qBlue(cmap[bit]);
                        }
                    } else {
                        for (int i=0; i<w; i++) {
                            bool bit = !!(*(data + (i >> 3)) & (1 << (7 -(i & 7))));
                            *row++ = qRed(cmap[bit]);
                            *row++ = qGreen(cmap[bit]);
                            *row++ = qBlue(cmap[bit]);
                        }
                    }
                }
                break;
            case 8:
                if (gray) {
                    const uchar* pix = image.scanLine(cinfo.next_scanline);
                    for (int i=0; i<w; i++) {
                        *row = qRed(cmap[*pix]);
                        ++row; ++pix;
                    }
                } else {
                    const uchar* pix = image.scanLine(cinfo.next_scanline);
                    for (int i=0; i<w; i++) {
                        *row++ = qRed(cmap[*pix]);
                        *row++ = qGreen(cmap[*pix]);
                        *row++ = qBlue(cmap[*pix]);
                        ++pix;
                    }
                }
                break;
            case 32: {
                QRgb* rgb = (QRgb*)image.scanLine(cinfo.next_scanline);
                for (int i=0; i<w; i++) {
                    *row++ = qRed(*rgb);
                    *row++ = qGreen(*rgb);
                    *row++ = qBlue(*rgb);
                    ++rgb;
                }
            }
            }
            jpeg_write_scanlines(&cinfo, row_pointer, 1);
        }

        jpeg_finish_compress(&cinfo);
        jpeg_destroy_compress(&cinfo);
        success = true;
    } else {
        jpeg_destroy_compress(&cinfo);
        success = false;
    }

    delete iod_dest;
    delete [] row_pointer[0];
    return success;
}

QJpegHandler::QJpegHandler()
{
    quality = 75;
}

bool QJpegHandler::canRead() const
{
    if (canRead(device())) {
        setFormat("jpeg");
        return true;
    }
    return false;
}

bool QJpegHandler::canRead(QIODevice *device)
{
    if (!device) {
        qWarning("QJpegHandler::canRead() called with no device");
        return false;
    }

    return device->peek(2) == "\xFF\xD8";
}

bool QJpegHandler::read(QImage *image)
{
    if (!canRead())
        return false;
    return read_jpeg_image(device(), image, parameters, scaledSize, quality);
}

bool QJpegHandler::write(const QImage &image)
{
    return write_jpeg_image(image, device(), quality);
}

bool QJpegHandler::supportsOption(ImageOption option) const
{
    return option == Quality
#ifndef QT_NO_IMAGE_SMOOTHSCALE
        || option == ScaledSize
#endif
        || option == Size;
}

QVariant QJpegHandler::option(ImageOption option) const
{
    if (option == Quality) {
        return quality;
#ifndef QT_NO_IMAGE_SMOOTHSCALE
    } else if  (option == ScaledSize) {
        return scaledSize;
#endif
    } else if (option == Size) {
        if (canRead() && !device()->isSequential()) {
            qint64 pos = device()->pos();
            QImage image;
            read_jpeg_image(device(), &image, "GetHeaderInformation", scaledSize, quality);
            device()->seek(pos);
            return image.size();
        }
    }
    return QVariant();
}

void QJpegHandler::setOption(ImageOption option, const QVariant &value)
{
    if (option == Quality)
        quality = value.toInt();
#ifndef QT_NO_IMAGE_SMOOTHSCALE
    else if ( option == ScaledSize )
        scaledSize = value.toSize();
#endif
}

QByteArray QJpegHandler::name() const
{
    return "jpeg";
}