QT5涂料对儿童小部件的繁殖

Question

我正在尝试在pyqt5中编写基本游戏循环。我里面有一个QWidget和一个QGraphicsView。我使用QTimer和update()在QWidget和QGraphicsView上触发paintEvent()。QWidget paintEvent()更新了，但QGraphicsView paintEvent()没有。

这是我的代码：

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_())

运行脚本时，我将获得以下输出：

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

解决方案是调用基类的paintEvent()(在这种情况下为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_())