从QLabel获取QPixmap

Question

I have a QLabel called Picture which Pixmap has been set to a QImage .
I now want to modify the image in another function.
Is it possible to get the Pixmap from the Picture ?

I tried the following, which results in an unhandled exception:

QPixmap const *pm = ui.Picture->pixmap();  
QImage image(pm->toImage());

Is there any other way?

Answer 1

I think you shall check the return value of the pixmap() function.

const QPixmap* pixmap = ui.Picture->pixmap();
if ( pixmap )
{
    QImage image( pixmap->toImage() );
}

Maybe you just called the function when the image was not set and that caused the exception.