Interacting with qt while other qt functions are running

[di_zou]

I have a QGraphicsScene and QGraphicsView. When I click a button, QGraphicsItems will movearound in the scene. When this happens, I can't do anything else in my Qt app. How do I make it so that I can do other things while my QGraphicsItems are being updated?

Also, I have a stop button. I want to be able to click the stop button to stop the QGraphicsItems from moving. How do I do that?

[wysota]

Please show us your code. You are probably blocking the event loop. You should be using the animation framework.

[di_zou]

class MainWidget(QWidget):
    def __init__(self):
        QWidget.__init__(self)
 
        self.display = DisplayScene(self)
        self.view = DisplayView(self.display)
        self.view.show()
 
        self.playButton = QPushButton("Play")
        self.stepLineEdit = QLineEdit()
    def Update(self):
        if self.display.nodeExist():
            if int(self.stepLineEdit.text()) < self.display.getMovementSteps():
                #if self.display.nodeExist():
                value = self.stepSizeLineEdit.text()
                self.stepSizeSlider.setValue(int(value))
                self.stepSize = value
                self.display.updateScene(int(self.stepLineEdit.text()))
    def Play(self):
        if self.display.nodeExist():
            i = int(self.stepLineEdit.text())
            self.display.ViewNodeMovement()
            totalMovementSteps = self.display.getMovementSteps()
            i = i + int(self.stepSize)
            #print totalMovementSteps
            while i < totalMovementSteps:
                self.stepLineEdit.setText(str(i))
 
                i = i + int(math.ceil(totalMovementSteps / 1000.0))
                self.Update()
                graphViews = self.display.views()
                graphViews [ 0 ].repaint()
                self.stepLineEdit.repaint()
 
class DisplayScene(QGraphicsScene):
    def updateScene(self, index):
        self.currentTimeStep += index - self.currentStep
 
        self.currentStep = index
 
        graphViews = self.views()
        sceneItems = self.items()
        for item in sceneItems:
            self.removeItem(item)
        self.drawScene(sceneItems, graphViews)
    def drawScene(self, sceneItems, graphViews):
        nodePlatformList = [ ]
        for item in sceneItems:
 
                item.setGraphView(graphViews[0])
                #stuff#
                self.addItem(item)

class MainWidget(QWidget):
    def __init__(self):
        QWidget.__init__(self)

        self.display = DisplayScene(self)
        self.view = DisplayView(self.display)
        self.view.show()
        
        self.playButton = QPushButton("Play")
        self.stepLineEdit = QLineEdit()
    def Update(self):
        if self.display.nodeExist():
            if int(self.stepLineEdit.text()) < self.display.getMovementSteps():
                #if self.display.nodeExist():
                value = self.stepSizeLineEdit.text()
                self.stepSizeSlider.setValue(int(value))
                self.stepSize = value
                self.display.updateScene(int(self.stepLineEdit.text()))
    def Play(self):
        if self.display.nodeExist():
            i = int(self.stepLineEdit.text())
            self.display.ViewNodeMovement()
            totalMovementSteps = self.display.getMovementSteps()
            i = i + int(self.stepSize)
            #print totalMovementSteps
            while i < totalMovementSteps:
                self.stepLineEdit.setText(str(i))
                
                i = i + int(math.ceil(totalMovementSteps / 1000.0))
                self.Update()
                graphViews = self.display.views()
                graphViews [ 0 ].repaint()
                self.stepLineEdit.repaint()

class DisplayScene(QGraphicsScene):
    def updateScene(self, index):
        self.currentTimeStep += index - self.currentStep
        
        self.currentStep = index

        graphViews = self.views()
        sceneItems = self.items()
        for item in sceneItems:
            self.removeItem(item)
        self.drawScene(sceneItems, graphViews)
    def drawScene(self, sceneItems, graphViews):
        nodePlatformList = [ ]
        for item in sceneItems:

                item.setGraphView(graphViews[0])
                #stuff#
                self.addItem(item)

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I have a good bit of code, so i cut out a lot of it. If something is not clear, just ask. Basically what happens is I have a play button, and when I click it it cycles through a while loop to update the display scene. So I guess what I want to do is to have some way to stop the while loop.

[wysota]

The while loop has to go. Or at least run QApplication::processEvents() in each iteration.

[Tanuki-no Torigava]

May be you should stop using while loops and use asynchronous signal/slot approach?

[di_zou]

May be you should stop using while loops and use asynchronous signal/slot approach?

Where can I get info to implement an asynchronous signal?

I got it working now with a QApplication.proccessEvents(). I can click the stop button and it will stop the while loop.