QString path = QFileDialog::getOpenFileName(this, tr("选择视频"), ".", tr("Image Files(*.jpg *.png)"));    QImage* img=new QImage;    QImage* scaledimg=new QImage;//分别保存原图和缩放之后的图片            if(! ( img->load(path) ) ) //加载图像            {                QMessageBox::information(this,                                         tr("打开图像失败"),                                         tr("打开图像失败!"));                delete img;                return;            }            int Owidth=img->width(),Oheight=img->height();            int Fwidth,Fheight;       //缩放后的图片大小            ui->label->setGeometry(100,100,400,300);            int Mul;            //记录图片与label大小的比例，用于缩放图片            if(Owidth/400>=Oheight/300)                Mul=Owidth/400;            else                Mul=Oheight/300;                       Fwidth=Owidth/Mul;                       Fheight=Oheight/Mul;                       *scaledimg=img->scaled(Fwidth,Fheight,Qt::KeepAspectRatio);                       //ui->label_text->setText(QString("width: ")+StrWidth.setNum(Fwidth)                       //                        +QString("\nheight: ")+StrHeigth.setNum(Fheight));                       ui->label->setPixmap(QPixmap::fromImage(*scaledimg));