如何修改 Qimage所获得的图片分辨率 [复制链接]

  图片用QIMAGE获得后，如何修改图片大小。跟图片的格式有关吗。单单修改图片的大小。好像会变成一片黑的图。大小改变了 ，图的内容没了。希望大侠指教。

修改图片尺寸？还是质量？
QImage里有各种方法可用，比如sacled()、save()等，请参考Assistant。

修改尺寸，多谢版主指教

{
    Q_UNUSED(pEvent);

    double wscale = 1.0;
    double hscale = 1.0;
    
    double pixwidth = static_cast<double>(m_image.width());
    double pixheight = static_cast<double>(m_image.height());
    double showwidth = static_cast<double>(width());
    double showheight = static_cast<double>(height());

    double Wscalerate = pixwidth / showwidth;
    double Hscalerate = pixheight / showheight;
    double compare = (Wscalerate > Hscalerate ? Wscalerate : Hscalerate);

    QRect _rect( showwidth/2.0 - pixwidth/compare/2.0,
                showheight/2.0- pixheight/compare/2.0,
                pixwidth/compare,
                pixheight/compare);

    QRect _midrect( (showwidth/2.0-pixwidth/2.0),
                   (showheight/2.0-pixheight/2.0),
                   pixwidth,
                   pixheight );

    QPainter painter(this);  

    painter.save();

    painter.translate(showwidth/2.0, (showheight/2.0));
    painter.scale(wscale, hscale);
    painter.translate(-(showwidth/2), -(showheight/2.0));

    if (compare < 1.0)
        painter.drawImage(_midrect, m_image);
    else
        painter.drawImage(_rect, m_image);
    
    painter.restore();
    //QPainter p(this);
    //p.drawImage((SCREEN_WIDTH-m_image.width())/2, (SCREEN_HEIGHT-m_image.height())/2,m_image);
}

仅供参考