PyQt，Qt: QGraphicsItemAniamtion 的问题

Question

我有下面这两段代码，但是只有第一段正常运行，我绞尽脑汁也想不出是为什么？求大神指点

这两端代码是关于QGraphicsItemAniamtion的应用，但是只有第一段会有动画效果，第二段就没有，也就是第二段代码中的ball 一直都不动。（第一段是文档中的一个例子，第二段是我自己改写的）

我个人觉得这两端代码几乎 等价 啊。。。还求大神指点

#! /usr/bin/python
# -*- coding:utf8 -*- 

from PyQt4 import QtCore, QtGui
from PyQt4.QtCore import *
from PyQt4.QtGui import *

import sys

app = QApplication(sys.argv)

ball = QGraphicsEllipseItem(0, 0, 20, 20)
timer = QTimeLine(5000)
timer.setFrameRange(0, 100)
animation = QGraphicsItemAnimation()
animation.setItem(ball)
animation.setTimeLine(timer)
for i in range(200):
    animation.setPosAt(i / 200.0, QPointF(i, i))
scene = QGraphicsScene()
scene.setSceneRect(0, 0, 250, 250);
scene.addItem(ball)
view = QGraphicsView(scene)

view.show()
timer.start()

sys.exit(app.exec_())

#! /usr/bin/python
# -*- coding:utf8 -*- 

from PyQt4 import QtCore, QtGui
from PyQt4.QtCore import *
from PyQt4.QtGui import *

import sys
class MainScene(QGraphicsScene):
    def __init__(self, parent=None):
        super(MainScene, self).__init__(parent)
        self.setSceneRect(0, 0, 250, 250);
        self.runPerson()

    def runPerson(self):
        print "person run"
        ball = QGraphicsEllipseItem(0, 0, 20, 20)
        timer = QTimeLine(50000)
        timer.setFrameRange(0,100)
        animation = QGraphicsItemAnimation()
        animation.setItem(ball)
        animation.setTimeLine(timer)
        for i in range(200):
            animation.setPosAt(i/200.0, QPointF(i,i))
        self.addItem(ball)
        timer.start()
        print "animation should started"

class MainView(QGraphicsView):
    def __init__(self, parent=None):
        super(MainView, self).__init__(parent)
        self.scene = MainScene(self)
        self.setScene(self.scene)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    mv = MainView()
    mv.show()
    sys.exit(app.exec_())

Answer 1

animation作为局部变量在函数退出后销掉了,用self.animation

问题就是出在这个地方

Answer 2

你这个在我的机子上,圆是会动的啊...你前面几行的import之类的加上去 我用的py2.7.5

Answer 3

回复
难道是我 ubuntu的原因么，@_@ 前面的import只是为了让代码看起来短一点，所以没贴上来. 谢谢了，

Answer 4

回复
的确会动，只是50000会动的非常慢.....我也是醉了

Answer 5

I writ it again in this way, but it still notwork, either.

class MainScene(QGraphicsScene):
    def __init__(self, parent=None):
        super(MainScene, self).__init__(parent)
        self.setSceneRect(0, 0, 250, 250);
        self.runPerson()
 
    def runPerson(self):
        print "person run"
        self.ball = QGraphicsEllipseItem(0, 0, 20, 20)
        self.timer = QTimeLine(50000)
        self.timer.setFrameRange(0,100)
        self.animation = QGraphicsItemAnimation()
        self.animation.setItem(self.ball)
        self.animation.setTimeLine(self.timer)
        for i in range(200):
            self.animation.setPosAt(i/200.0, QPointF(i,i))
        self.addItem(self.ball)
        self.timer.start()
        print "animation should started"
 
class MainView(QGraphicsView):
    def __init__(self, Scene=None, parent=None):
        super(MainView, self).__init__(Scene, parent)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    scene = MainScene()
    mv = MainView(scene)
    mv.show()
    sys.exit(app.exec_())

Answer 6

I writ it again in this way, but it still not work 

class MainScene(QGraphicsScene):
    def __init__(self, parent=None):
        super(MainScene, self).__init__(parent)
        self.setSceneRect(0, 0, 250, 250);
        self.runPerson()
 
    def runPerson(self):
        print "person run"
        self.ball = QGraphicsEllipseItem(0, 0, 20, 20)
        self.timer = QTimeLine(50000)
        self.timer.setFrameRange(0,100)
        self.animation = QGraphicsItemAnimation()
        self.animation.setItem(self.ball)
        self.animation.setTimeLine(self.timer)
        for i in range(200):
            self.animation.setPosAt(i/200.0, QPointF(i,i))
        self.addItem(self.ball)
        self.timer.start()
        print "animation should started"
 
class MainView(QGraphicsView):
    def __init__(self, parent=None):
        super(MainView, self).__init__(parent)
        self.scene = MainScene()
        self.setScene(self.scene)
if __name__ == "__main__":
    app = QApplication(sys.argv)
    mv = MainView(scene)
    mv.show()
    sys.exit(app.exec_())

Answer 7

还有一个问题,animation作为局部变量在函数退出后销掉了,用self.animation

Answer 8

回复
I writ it again in this way, but it still not work . can you correct it for me ? thanks

Answer 9

self.scene 把 scene函数覆盖掉了!