Make QSpinBox.valueChanged() only respond to Mouse Wheel

Question

I have QSpinBox's Signal valueChanged connected to a QWidget's function like:

class MyWidget(QtGui.QWidget):
    def __init__(self, *args):
        QtGui.QWidget.__init__(self, *args)
        #just an example
        mySpinBox = QtGui.QSpinBox()
        mySpinBox.valueChanged.connect(self.foo)

   def foo(self):
       if value was changed by Mouse Wheel:
            #do this
       else:
            #do nothing

Gombat · Answer 1 · 2015-09-08T12:21:50.233

1

Derive QSpinBox and override the wheelevent

http://pyqt.sourceforge.net/Docs/PyQt4/qwidget.html#wheelEvent

You can define your own signal which will be emitted by the wheelevent to obtain the behavior you want to have.

For an example / tutorial, see: http://pythoncentral.io/pysidepyqt-tutorial-creating-your-own-signals-and-slots/

edited Sep 08 '15 at 12:21

answered Sep 08 '15 at 12:02

Gombat

1,994
16
21

Thanks for the answer. Can you give an example on how to create a Qt Signal? Cause so far i've only used default Signals/Slots. – tobilocker Sep 08 '15 at 12:13
I appended a link to a tutorial in my answer. – Gombat Sep 08 '15 at 12:23
1

Deriving is one way, another way is to install an event filter. Qt's event filtration system has been designed specifically so that altering class behavior is easier without having to subclass. – Kuba hasn't forgotten Monica Sep 08 '15 at 12:39
actually i did both. i will provide an answer to that – tobilocker Sep 08 '15 at 16:04

score 0 · Accepted Answer · edited May 23 '17 at 12:14

Based on Gombat's answer and this question (because how it is explained in provided tutorial it wil raise an error) i did this in the widget

class MyWidget(QtGui.QWidget):
    mySignal1 = QtCore.pyqtSignal() #these have to be here or... 
    mySignal2 = QtCore.pyqtSignal() #...there will be an attribute error

    def __init__(self, *args):
        QtGui.QWidget.__init__(self, *args)
        #just an example
        self.mySpinBox1 = QtGui.QSpinBox()
        self.mySpinBox2 = QtGui.QSpinBox()
        self.mySpinBox1.installEventFilter(self)
        self.mySpinBox2.installEventFilter(self)
        self.mySignal1.connect(self.foo)
        self.mySignal2.connect(self.bar)

   def eventFilter(self, source, event):
       if source is self.spinBox1:
           if event.type() == QtCore.QEvent.Wheel:
                self.spinBox1.wheelEvent(event)
                self.mySignal1.emit()
           return True
       else:
           return False
    elif source is self.spinBox2:
        if event.type() == QtCore.QEvent.Wheel:
            self.spinBox2.wheelEvent(event)
            self.mySignal2.emit()
            return True
        else:
            return False
    else:
        return QtGui.QWidget.eventFilter(self, source, event)

    def foo(self):
        #right here, when a mouse wheel event occured in spinbox1

    def bar(self):
        #right here, when a mouse wheel event occured in spinbox2

hope this helps. thanks (untested, because it is just an example, there might be errors)

Make QSpinBox.valueChanged() only respond to Mouse Wheel

2 Answers2