How can I let users use control + + for zoom in and control + - for zoom out?

Question

The problem with my code below is that on US/UK keyboard layouts + is generated with shift + =, but when the user uses both the control and shift modif

Answer 1

You have to use Qt.ShiftModifier for reacting on shift key:

Item {
    focus: true
    Keys.onPressed: {
        if ((event.key == Qt.Key_Plus) && (event.modifiers & Qt.ShiftModifier))
            console.log("PRessed");
    }
}

Answer 2

Instead of Key.onPressed use Shortcut and its sequence property :

Shortcut {
    sequence: StandardKey.ZoomIn
    onActivated: zoom(true)
}

Your issue is mentionned in this section of the QKeySequence documentation.