QT-保存低分辨率QPixmap

我希望降低Qpixmap的分辨率,然后将其保存为png

   QPixmap original(imgPath); // read in the image that was selected from tree
   QPixmap cropped = original.copy(cropRectInt); // make copy of image that is cropped to the size of the rect

//***Convert cropped to lower res here***//

   QFile file("5.png");
   cropped.save(&file, "PNG"); // save for testing

   QByteArray byteArray;
   QBuffer buffer(&byteArray);
   cropped.save(&buffer, "PNG"); 
   QString imgBase64 = QString::fromLatin1(byteArray.toBase64().data());