In my GUI there is a embeded QLabel with “fixed” Size. At least Size is fixed, if user would like to zoom in/out.
So there are many very usefull attempts with QLabels resizing due to the Pixmap. But I would like to keep my QLabel-Size fixed all the time! First view of the pic should be scaled to the Labelsize:

myPixmap = QtGui.QPixmap(filepath)
myScaledPixmap = myPixmap.scaled(self.ui.LBL_bild.size(), Qt.KeepAspectRatio)

On “Mouse over Label” – Event AND “Mouse-Wheel-turned” – Event the Picture should resize, without stretching the Label. Here is my attempt:

        if self.mouse_over_pic:
        self.ui.LBL_bild.setSizePolicy(QSizePolicy.Fixed, QSizePolicy.Fixed)
        px = self.ui.LBL_bild.pixmap()
        lbl_size = self.ui.LBL_bild.size()
        if px:
            if event.angleDelta().y() > 0:
                faktor = 1.1
            else:
                faktor = 0.9
            new_width = int(px.width() * faktor)
            old_ratio = px.width()/px.height()
            new_height = int(new_width/old_ratio)

            scaledPix = px.scaled(new_width, new_height, transformMode=Qt.SmoothTransformation)
            self.ui.LBL_bild.setPixmap(scaledPix)

I’m facing two issues:

1. the Picture is getting really clumpsy during zooming… I guessed the SmoothTransformationMode should prevent it? So how can I keep the quality (solution/density) of the picture?

2. The Label is resizing with the pixmap. I have no clue how to prevent that. Even though I fixed the horizontal and vertical SizePolicy to Fixed, the Size is changed. I also tried painting instead of seting again:

    painter = QtGui.QPainter(self.ui.LBL_bild)
    point = QtCore.QPoint(0, 0)
    point.setX(int((lbl_size.width() - scaledPix.width())/2))
    point.setY(int((lbl_size.height() - scaledPix.height()) / 2))
    print(point.x(), " ", point.y())
    painter.drawPixmap(point, scaledPix)
   

But with that I didn’t get any change to the picture.
I am really looking forward to your ideas.