Qt5 paintEvent Propagierung zu Kind Widgets

Question

Ich versuche, eine grundlegende Spielschleife in PyQt5 zu schreiben. Ich habe eine QWidget und eine QGraphicsView drin. Ich verwende QTimer und update(), um die paintEvent() auf QWidget und QGraphicsView auszulösen. Die QWidgetpaintEvent() wird aktualisiert, aber QGraphicsViewpaintEvent() nicht.

Hier ist mein Code:

import sys, random 

from PyQt5.QtWidgets import QWidget, QGridLayout, QApplication, QGraphicsView, QGraphicsScene 
from PyQt5.QtCore import Qt, QTimer 
from PyQt5.QtGui import QPainter, QColor, QPen, QBrush, QColor 



class Window(QWidget): 

    WIDTH = 800 
    HEIGHT = 480 
    SPEED = 500 

    def __init__(self): 

     super().__init__() 
     self.initUi() 
     self.initDisplay() 
     self.show() 

    def initUi(self): 

     layout = QGridLayout() 

     scene = GraphicsScene()   
     self.view = GraphicsView() 
     self.view.setScene(scene) 

     layout.addWidget(self.view) 
     self.setLayout(layout) 


    def initDisplay(self):  

     self.resize(Window.WIDTH, Window.HEIGHT) 

     self.timer = QTimer() 
     self.timer.setInterval(Window.SPEED) 
     self.timer.timeout.connect(self.timerEvent) 
     self.isStarted = False 
     self.isPaused = False 

     self.timer.start() 


    def start(self): 

     if self.isPaused: 
      return 

     self.isStarted = True 
     self.timer.start(Display.SPEED) 


    def pause(self): 

     if not self.isStarted: 
      return 

     self.isPaused = not self.isPaused 

     if self.isPaused: 
      self.timer.stop()    
     else: 
      self.timer.start(Display.SPEED) 

     self.update() 


    def paintEvent(self, event): 
     print('paint event ...') 


    def timerEvent(self): 
     self.update() 
     self.view.update() 
     print('timer event ...') 



class GraphicsView(QGraphicsView): 


    def __init__(self): 
     super(GraphicsView, self).__init__() 


    def paintEvent(self, event): 
     self.scene().add_shapes() 
     print('view paint event') 



class GraphicsScene(QGraphicsScene): 

    def __init__(self): 
     super(GraphicsScene, self).__init__() 


    def add_shapes(self): 

     self.setSceneRect(0.0, 0.0, 800.0, 640.0) 

     self.addRect(100, 100, 150, 150) 

     pen = QPen(Qt.SolidLine) 
     pen.setColor(Qt.red) 
     brush = QBrush(Qt.Dense3Pattern) 
     brush.setColor(Qt.darkGreen) 
     self.addEllipse(300, 300, 100, 100, pen, brush) 
     print('add shapes')   



if __name__ == '__main__': 

    app = QApplication([]) 
    window = Window()  
    sys.exit(app.exec_()) 

Als ich das Skript ich folgende Ausgabe:

paint event ... 
add shapes 
view paint event 
paint event ... 
add shapes 
view paint event 
timer event ... 
paint event ... 
paint event ... 
timer event ... 
paint event ... 
paint event ... 
timer event ... 
paint event ... 
paint event ... 
timer event ... 
paint event ... 
paint event ... 
timer event ... 
paint event ... 
paint event ... 

Answer 1

Die Lösung ist die paintEvent() der Basisklasse zu nennen (in diesem Fall QGraphicsView :

import sys, random 

from PyQt5.QtWidgets import QWidget, QGridLayout, QApplication, QGraphicsView, QGraphicsScene 
from PyQt5.QtCore import Qt, QTimer 
from PyQt5.QtGui import QPainter, QColor, QPen, QBrush, QColor 



class Window(QWidget): 

    WIDTH = 800 
    HEIGHT = 480 
    SPEED = 500 

    def __init__(self): 

     super().__init__() 
     self.initUi() 
     self.initDisplay() 
     self.show() 

    def initUi(self): 

     layout = QGridLayout() 

     self.scene = GraphicsScene() 
     self.view = GraphicsView(self, self.scene) 

     layout.addWidget(self.view) 
     self.setLayout(layout) 


    def initDisplay(self):  

     self.resize(Window.WIDTH, Window.HEIGHT) 

     self.timer = QTimer() 
     self.timer.setInterval(Window.SPEED) 
     self.timer.timeout.connect(self.timerEvent) 
     self.isStarted = False 
     self.isPaused = False 

     self.timer.start() 


    def start(self): 

     if self.isPaused: 
      return 

     self.isStarted = True 
     self.timer.start(Display.SPEED) 


    def pause(self): 

     if not self.isStarted: 
      return 

     self.isPaused = not self.isPaused 

     if self.isPaused: 
      self.timer.stop()    
     else: 
      self.timer.start(Display.SPEED) 

     self.update() 


    def paintEvent(self, event): 
     print('paint event ...') 


    def timerEvent(self): 
     self.update() 
     self.view.update() 
     self.scene.update() 
     print('timer event ...') 



class GraphicsView(QGraphicsView): 


    def __init__(self, parent, scene): 

     super(GraphicsView, self).__init__() 
     self.scene = scene 
     self.parent = parent 
     self.setScene(self.scene) 


    def paintEvent(self, event): 
     QGraphicsView.paintEvent(self, event)######### 
     self.setScene(self.scene) 
     self.scene.add_shapes() 
     print('view paint event') 



class GraphicsScene(QGraphicsScene): 

    def __init__(self): 
     super(GraphicsScene, self).__init__() 


    def add_shapes(self): 

     self.setSceneRect(0.0, 0.0, 700.0, 450.0) 

     self.addRect(100, 100, 150, 150) 

     pen = QPen(Qt.SolidLine) 
     pen.setColor(Qt.red) 
     brush = QBrush(Qt.Dense3Pattern) 
     brush.setColor(Qt.darkGreen) 
     self.addEllipse(300, 300, 100, 100, pen, brush) 
     print('add shapes')   



if __name__ == '__main__': 

    app = QApplication([]) 
    window = Window()  
    sys.exit(app.exec_())