Qt之生成png/jpg/bmp格式图片_qt生成图片-CSDN博客

(1)使用QPainter 

示例关键代码：

    QImage image(QSize(this->width(),this->height()),QImage::Format_ARGB32);
    image.fill("white");
    QPainter *painter = new QPainter(&image);
    painter->save();
    QPen pen;
    pen.setWidth(2);
    pen.setColor(Qt::red);
    painter->setPen(pen);
    painter->drawEllipse(QPoint(width()/2,height()/2),50,50);
    painter->drawLine(QPointF(0,0),QPointF(width()/2,height()/2));
    painter->drawRect(QRect(40,40,150,160));
    painter->restore();
    painter->end();
    QString path=QApplication::applicationDirPath()+"/1.png";
    qDebug()<<path;
    image.save(path);

再提取：

    QImage image(QSize(this->width(),this->height()),QImage::Format_ARGB32);
    image.fill("white");
    QPainter *painter = new QPainter(&image);
    painter->save();
    //使用QPainter进行绘制
    //...
    painter->end();

    //保存为图片
    QString path=QApplication::applicationDirPath()+"/1.png";
    image.save(path);

就是在QImage上绘制图像，再保存为图片。

(2)直接把QWidget窗体上的内容保存为图片。

示例代码：

    Widget w;
    w.show();
    QPixmap pixmap(w.size());
    w.render(&pixmap);
    QString path=QApplication::applicationDirPath()+"/3.png";
    pixmap.save(path);

参考：

保存Qwiget 图像 并调整大小-QT开发中文网 (0voice.com)