Python PyQt4 how to detect control press + mouse Scroll

Question

I am developing an app.I would like there to be an option to zoom in and out. to do this I would like to have the program get when the control key is clicked and the mouse is being scrolled at the same time, and zoom accordingly(scroll up for zoom in, and scroll down for zoom out) I've been doing a lot of searching and reading,but only found ways to get a control press and a mouse click-event, not a mouse scroll-event. I also found a way to get a mouse scroll but couldn't get it to work with just control press. - and to ignore all other presses.

Could anyone suggest something to help me???

Answer 1

It depends a bit on the structure of your application. One way to get scroll-events is to add a wheelEvent handler to your Widget

def wheelEvent(self, QWheelEvent):
    modifiers = QtGui.QApplication.keyboardModifiers()
    if modifiers == QtCore.Qt.ControlModifier:
        # do your processing

Another approach could be to install an eventFilter in the component where you want to intercept the scroll-events by

component.viewport().installEventFilter(self)  

(maybe you have to install the event filter on the component itself iso on the viewport).

and self has an eventFilter function like

 def eventFilter(self, qobject, event):
        if (event.type() == QtCore.QEvent.Wheel) :
            modifiers = QtGui.QApplication.keyboardModifiers()
            if modifiers == QtCore.Qt.ControlModifier:
                #do some scaling stuff
                return True
            return False
        else:
            # standard event processing
            return False

Hope this helps.