如何在QtGui中創建動畫？

Question

我對Python和Qt相當陌生，但我試圖用一些動畫圖形元素來創建GUI。我可以做一個簡單的動畫工作;在下面的代碼class MyView將在調用時工作，但class GraphicsView不是動畫！

任何人都可以幫我看看問題嗎？

的問題是在類GraphicsScene，我想：

import sys 
from PyQt4 import QtGui, QtCore 

class MyView(QtGui.QGraphicsView): 
    def __init__(self): 
     QtGui.QGraphicsView.__init__(self) 

     self.scene = QtGui.QGraphicsScene(self) 
     self.item = QtGui.QGraphicsEllipseItem(-20, -10, 40, 20) 
     self.scene.addItem(self.item) 
     self.setScene(self.scene) 

     # Remember to hold the references to QTimeLine and QGraphicsItemAnimation instances. 
     # They are not kept anywhere, even if you invoke QTimeLine.start(). 
     self.tl = QtCore.QTimeLine(1000) 
     self.tl.setFrameRange(0, 100) 
     self.a = QtGui.QGraphicsItemAnimation() 
     self.a.setItem(self.item) 
     self.a.setTimeLine(self.tl) 

     # Each method determining an animation state (e.g. setPosAt, setRotationAt etc.) 
     # takes as a first argument a step which is a value between 0 (the beginning of the 
     # animation) and 1 (the end of the animation) 
     self.a.setPosAt(0, QtCore.QPointF(0, -10)) 
     self.a.setRotationAt(1, 360) 

     self.tl.start() 

#create the graphicsView which contains the graphicsScene 
class GraphicsView(QtGui.QGraphicsView): 
    #initialize and set dragMode and renderHints for everything inside the view 
    def __init__(self, parent=None): 
     super(GraphicsView, self).__init__(parent) 

     #the dragMode should be changed to use the rihgt-mousebutton 
     self.setDragMode(QtGui.QGraphicsView.ScrollHandDrag) 

     self.setRenderHint(QtGui.QPainter.Antialiasing) 
     self.setRenderHint(QtGui.QPainter.TextAntialiasing) 

    #crate a zoom function for the mouse-wheel 
    def wheelEvent(self, event): 
     factor = 1.5 ** (event.delta()/240.0) 
     self.scale(factor, factor) 

#create the GraphicsScene containing the main graphics 
class GraphicsScene(QtGui.QGraphicsScene): 

    def animate(self): 

     self.animations = range(3) 

     #move item to position(x,y) at time t 
     def animate_to(item,x,y,t): 

      animation = QtGui.QGraphicsItemAnimation() 
      #create a timeline of 1 second 
      timeline = QtCore.QTimeLine(2000) 
      #number of steps in timeline (100) 
      timeline.setFrameRange(0,100) 
      #set position at time t 
      animation.setPosAt(t, QtCore.QPointF(x,y)) 
      #apply this to "item" 
      animation.setItem(item) 
      #add timeline to the animation 
      animation.setTimeLine(timeline) 

      #output of this definition is "animation" 
      return animation 

     self.animations[0] = animate_to(self.geos[0],200,200,0.2) 
     self.animations[1] = animate_to(self.geos[1],200,200,0.2) 
     self.animations[2] = animate_to(self.geos[2],200,200,0.2) 

     #animation.timeline().start() 
     self.animator.start(2000) 


    def __init__(self, parent=None): 
     QtGui.QGraphicsScene.__init__(self, parent) 
     #set the size of the scene 
     self.setSceneRect(0,0,2000,2000) 

     #self.addRect(QtCore.QRectF(800,800,200,200)) 

     #---create the scene-geometries --- 

     #empty list to hold the geometries 
     self.geos = [] 

     #create stuff to add to the scene 
     geo_01 = QtGui.QGraphicsEllipseItem(800,800,200,200) 
     geo_02 = QtGui.QGraphicsEllipseItem(850,850,300,300) 
     geo_03 = QtGui.QGraphicsEllipseItem(900,900,400,400) 
     #add stuff to the scene 
     self.addItem(geo_01) 
     self.addItem(geo_02) 
     self.addItem(geo_03) 

     #put stuff into list so it can be referenced 
     self.geos.append(geo_01) 
     self.geos.append(geo_02) 
     self.geos.append(geo_03) 

     #----do the animation thing--- 
     self.animator = QtCore.QTimer() 

     self.animator.timeout.connect(self.animate) 

     self.animate() 


#Create a new class which inherrits from "QtGui.QMainWindow" 
class Example(QtGui.QMainWindow): 

    def __init__(self): 
     #The "super()"-method returns the parrent object of the example-class 
     #and it's constructor is called ("__init__") 
     super(Example, self).__init__() 

     self.initUI() 

    #create the GUI 
    def initUI(self): 

     """---create the buttons---""" 

     #set a font for the tool-tips 
     QtGui.QToolTip.setFont(QtGui.QFont('SansSerif', 10)) 

     #create a button and a tool-tip for the button 
     btn_01 = QtGui.QPushButton('Button', self) 
     btn_01.setToolTip('This is a <b>QPushButton</b> widget') 
     #resize the button with a recommended size (.sizeHint()) 
     btn_01.resize(btn_01.sizeHint()) 

     #create a button and a tool-tip for the button 
     btn_02 = QtGui.QPushButton('Button', self) 
     btn_02.setToolTip('This is a <b>QPushButton</b> widget') 
     #resize the button with a recommended size (.sizeHint()) 
     btn_02.resize(btn_02.sizeHint()) 

     """----create a layout----""" 

     #create the main widget, which holds the layout 
     self.main_widget = QtGui.QWidget(self) 

     #create a vertical box layout to hold the buttons on the right 
     vbox = QtGui.QVBoxLayout() 
     vbox.addStretch(1) 
     vbox.addWidget(btn_01) 
     vbox.addWidget(btn_02) 

     #create horizontal box layout to hold the vbox and the main area 
     hbox = QtGui.QHBoxLayout() 

     #store the GraphicsScene in a variable so it is not destroyed 
     self.scene = GraphicsScene() 
     #add the scene to the GraphicsView 
     view = GraphicsView(self.scene) 

     hbox.addWidget(view) 
     hbox.addStretch(1) 
     hbox.addLayout(vbox) 

     self.main_widget.setLayout(hbox) 
     self.setCentralWidget(self.main_widget) 

     #set the possition and size of the window, then set the window title 
     #these methods have been inherited by the "QtGui.QWidget"-class 
     self.setGeometry(100, 100, 700, 500) 
     self.setWindowTitle("PatternNexus...Maybe?") 
     #self.setWindowIcon(QtGui.QIcon('web.png')) 

     self.show() 

    def closeEvent(self, event): 
     #create a messagebox to confirm quit 
     # when QtGui.QWidget is closed the QtGui.QCloseEvent is generated 
     # to modify its behaviour the event handler (closeEvent()) must be reinplemented 

     #create a msgBox with 2 buttons 
     #4th argument is the button combination 
     #5th argument is the button with initial ketboard focus 
     reply = QtGui.QMessageBox.question(self, 'Message', 
      "Are you leaving?", QtGui.QMessageBox.Yes | 
      QtGui.QMessageBox.No, QtGui.QMessageBox.No) 

     #test the return value, is "yes" the event is accepted 
     if reply == QtGui.QMessageBox.Yes: 
      event.accept() 
     else: 
      event.ignore() 

def main(): 
    #start the application 
    app = QtGui.QApplication(sys.argv) 
    ex = Example() 
    sys.exit(app.exec_()) 

#if this module (.py-file) is run as the main program the statement is true 
#if this module is imported the statement will return false 
if __name__ == '__main__': 
    main() 

我的編碼這個主要參考是「快速的GUI編程Python和QT - 第12章」，而這些鏈接：http://lateral.netmanagers.com.ar/stories/BBS53.html，並http://www.diotavelli.net/PyQtWiki/GraphicsView_-_SimpleAnimation

Answer 1

這樣回答我的問題是：通過添加啓動timelne：
[animation.timeLine（）開始（）在self.animations動畫] 在生命的定義