I do not understand your question.
I have a QPixmap that contains an image. is something like this
image.JPG
and I need to make zoom.
for this reason I put it in a QwtPlot, to use the function:
QwtPlotZoomer* zoomer = new MyZoomer(canvas());
zoomer->setMousePattern(QwtEventPattern::MouseSelect2,
Qt::RightButton, Qt::ControlModifier);
zoomer->setMousePattern(QwtEventPattern::MouseSelect3,
Qt::RightButton);
Bookmarks