PySide：可移動項目在鼠標事件中的位置重置

Question

我有PySide的問題（我在編程方面仍然是菜鳥）。我創建了名爲RBNode的自定義QGraphicsItem。它應該停留在mouseReleaseEvent發生的位置。我不知道爲什麼，但是當我試圖不止一次地移動RBNode類的實例時，這個實例的位置重置。我怎樣才能避免重置職位？ 在此先感謝您的幫助。

#!/usr/bin/python 
# -*- coding: utf-8 -*- 

import sys 
from PySide.QtGui import * 
from PySide.QtCore import * 

class RBNode(QGraphicsItem): 
    def __init__(self, factorView = None): 
     super(RBNode, self).__init__() 
     self.factor = factorView 
     self.pressed = False 
     self.x = self.pos().x() 
     self.y = self.pos().y() 
     self.setFlag(QGraphicsItem.ItemIsMovable) 

    def boundingRect(self): 
     return QRectF(-50,-50,100,100) 

    def paint(self, painter, option, widget): 
     rect = QRectF(-50,-50,100,100) 

     if self.pressed: 
      painter.setBrush(Qt.red) 
     else: 
      painter.setBrush(Qt.darkGray) 

     painter.drawEllipse(rect) 

    def mousePressEvent(self, event): 
     self.pressed = True 
     self.update() 
     QGraphicsItem.mousePressEvent(event) 

    def mouseReleaseEvent(self, event): 
     self.pressed = False 
     self.update() 
     QGraphicsItem.mouseReleaseEvent(event) 


class RBGraphicView(QGraphicsView): 
    def __init__(self): 
     super(RBGraphicView, self).__init__() 
     self.factorView = 1 

     self.initScene() 
     self.initGui() 

    def initGui(self): 
     self.setWindowTitle("A Simple Animation") 
     self.show() 

    def initScene(self): 
     self.rbScene = QGraphicsScene(self) 
     self.rbAddItem(self.rbScene) 
     self.setScene(self.rbScene) 

    def rbAddItem(self, scene): 

     rbNode1 = RBNode(self.factorView) 
     rbNode1.setPos(100,100) 
     scene.addItem(rbNode1) 


if __name__ == '__main__': 
    try: 
     myApp = QApplication(sys.argv) 
     myView = RBGraphicView() 
     myApp.exec_() 
     sys.exit(0) 

    except NameError: 
     print("Name Error:", sys.exc_info()[1]) 

    except SystemExit: 
     print("Closing Window...") 

    except Exception: 
     print(sys.exc_info()[1]) 

Answer 1

您在調用mousePressEvent，超類的mouseReleaseEvent的時候忘了自己作爲參數。

QGraphicsItem.mousePressEvent(self, event) 

    QGraphicsItem.mouseReleaseEvent(self, event)