About calling the super() function

[illunara]

Hi everybody
I'm using QtDesign to create my own UI and convert it to python version. So after subclass the UI python file, i had written some function to implement mouseEvent for QGraphicsView. Just one small question. How can i call the super() function for the QGraphicsView?

class RigModuleUi(QtGui.QMainWindow,Ui_RiggingModuleUI):
def __init__(self,parent = None):
super(RigModuleUi,self).__init__(parent = parent)
self.GraphicsView.mousePressEvent = self.qView_mousePressEvent

def qView_mousePressEvent(self,event):
if event.button() == QtCore.Qt.LeftButton:
super(RigModuleUi,self).mousePressEvent(event)

Look like the super(RigModuleUi,self).mousePressEvent(event)will return the mouseEvent for QMainWindow, not QGraphicsView. So all other option for mouse like rubberBand will lost.

I try this too, but no go at all.

super(QtGui.QGraphicsView,self.GraphicsView).mouseMoveEvent(event)

Thanks

[Justin Israel]

I first started out by doing the same thing, and replacing the bound method with another one. Nowadays I find it a bit messy and prefer the event filter approach if I am not subclassing the target object.

Here are two example of the way you are trying to do it, followed by the event filter approach...

(http://pastebin.com/EUAEJ0TH)

###

## Example 1 - just call the class directly

class RigModuleUi(QtGui.QMainWindow,Ui_RiggingModuleUI):

    def __init__(self,parent = None):

        super(RigModuleUi,self).__init__(parent = parent)

        self.setupUi(self)

        self.GraphicsView.mousePressEvent = self.qView_mousePressEvent

    def qView_mousePressEvent(self,event):

        if event.button() == QtCore.Qt.LeftButton:

            view = self.GraphicsView

            # directly call the class and pass the instance

            QtGui.QGraphicsView.mousePressEvent(view, event)

## Example 2 - save the original bound method

    def __init__(self,parent = None):

        ...

        view = self.GraphicsView

        view._mousePressEvent = view.mousePressEvent

        view.mousePressEvent = self.qView_mousePressEvent

    def qView_mousePressEvent(self,event):

        if event.button() == QtCore.Qt.LeftButton:

            view = self.GraphicsView

            view._mousePressEvent(event)

## Example 3 - Use an event filter to manage composed objects and route their actions

class RigModuleUi(QtGui.QMainWindow,Ui_RiggingModuleUI):

    def __init__(self,parent = None):

        super(RigModuleUi,self).__init__(parent = parent)

        self.setupUi(self)

        self.GraphicsView.mousePressEvent = self.qView_mousePressEvent

    def eventFilter(self, obj, event):

        if obj is self.GraphicsView:

            # If its not a left button then we wanted to do

            # some custom handling, so we call our own handler

            # and return True which means that the event is filtered

            # and the original object will not ever see this event.

            if event.button() != QtCore.Qt.LeftButton:

                self.qView_mousePressEvent(event)

                return True

        return super(RigModuleUi, self).eventFilter(obj, event)

    def qView_mousePressEvent(self, event):

        event.accept()

        view = self.GraphicsView

        # do something custom with the view and event

####

I like the event filter approach because I don't have to replace the bound methods at all. I simply catch the events before the objects ever see them. You can route multiple objects in that event filter and send them to other methods.

-- justin

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[Tuan Nguyen]

Maybe i had done something funny when reimplement mouseEvent, so the result after calling class out still wrong. I will check the script again, also thank for show me how to use eventFilter. I try to go with it at first place, but since time is short, i chose replace the bounding method instead :D

Thank for your reply, Justin

[Tuan Nguyen]

Sorry to dig this up, at that time, i were using the first way you told me, it works fine so i think i will left it like that for a while and come back after had finished other part. But somehow, i think the eventFilter is not working at all,

self.GraphicsView.mousePressEvent = self.qView_mousePressEvent

def eventFilter(self, obj, event):

        if obj is self.GraphicsView:

            if event.button() != QtCore.Qt.LeftButton:

                self.qView_mousePressEvent(event)

                return True

in the mousePressEvent i had a case when event.button() == QtCore.Qt.LeftButton, it will return the QGraphicsView,mousePressEvent. And if i remove it, the leftMousePressEvent is gone too

I also try install the eventFilter on GraphicsView but no luck :(

http://pastebin.com/SbJfsHTG

[Justin Israel]

Did you confirm that the eventFilter() is being called? Put a print statement right after:

    if obj is self.GraphicsView

Also remember to do   event.accept()  if you are handling the event yourself so that it doesn't bubble up.

[Tuan Nguyen]

yes, i try it too, the print statement. But nothing is print out, so i guess its not working?

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[Tuan Nguyen]

oh and i'm sorry. The script in pastebin  missing the event.accept() line, but still, the eventFilter is not working :(

[Justin Israel]

If you are installing the event filter on an object and you have defined the eventFilter() method, then I am not sure why it would not get called. Please post a small, concise, fully working example of the problem, so we can test it for you.

[Tuan Nguyen]

Ah, about that. I just got it work, i really really sorry, that was my mistake :(

However can i ask another question? Can i use the eventFilter on QGraphicsItem? they are not widget .... and i have to make an except on it when call the QGraphicsView's keyPressEvent :(

[Justin Israel]

Glad you got the problem resolved.

For the other question, don't forget to check the docs!
http://qt-project.org/doc/qt-4.8/qgraphicsitem.html#events

[Tuan Nguyen]

Thanks
But those events drive my crazy :( i don't know why it keep jump up to Maya's keyEvent, even i put an eventFilter on.  When i reimplement QGraphicsView's keyPressEvent, i have to skip calling events super class, else Maya's hotkey still working as well.

[Justin Israel]

If you call the super class method then of course it will pass the event up.
The way to prevent it from bubbling up is to do event.accept() and return True from the eventFilter.

[Tuan Nguyen]

Ah, everything work as expect :D thank a ton, David XD

[Tuan Nguyen]

Ah, everything work as expect, thank a ton Justin :3

[Justin Israel]

No problem, David :-)

[Tuan Nguyen]

eh, sorry about that. I though i delete the last one, and send a new one :D

[Justin Israel]

Haha I am just teasing. You can't really delete messages off the message group ;-)

[Tuan Nguyen]

I feel bad about it, just type in on a whim :( .

And, there are 2 last thing about eventFilter i'm confusing about, can you confirm it for me? :D

def eventFilter(self,obj,event):
.....if obj is item:

This is quite a pain since eventFilter can only chose one specify item to filter on. I try change the method, like in, isinstance but no luck :(

The second thing is, sceneEventFilterEvent not working on itself, and its child either?

:3

[Justin Israel]

The eventFilter does not just operate on a single object. You can set something to be an event filter to 100 objects if you want. But you will usually want to check what the object is to ensure you handle it in the appropriate way:

# check for a specific instance

if obj is foo:

# check for a number of instance types:

if isinstance(obj, (str, int, float, list, tuple, dict)):

# duck typing

if hasattr(obj, "someAttribute"):

You can set any QObject subclass to be an event filter of any other QObject