QGraphicsView的PyQt鼠标事件

我正在尝试从QGraphicsView获取各种鼠标事件的坐标，但是我不知道如何触发它们。最后，我想向graphicsView添加图片，然后在其上方绘制。

理想情况下，我希望坐标的原点位于左上角

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test.py

import sys
from PyQt4 import QtCore, QtGui, uic


class test(QtGui.QMainWindow):

    def __init__(self):
        QtGui.QMainWindow.__init__(self)
        self.ui = uic.loadUi('test.ui', self)

        self.connect(self.ui.graphicsView, QtCore.SIGNAL("mousePressEvent()"), self.mouse_pressed)
        self.connect(self.ui.graphicsView, QtCore.SIGNAL("mouseMoveEvent()"), self.mouse_moved)
        self.connect(self.ui.graphicsView, QtCore.SIGNAL("mouseReleaseEvent()"), self.mouse_released)

        self.ui.show()

    def mouse_pressed(self):
        p = QtGui.QCursor.pos()
        print "pressed here: " + p.x() + ", " + p.y()

    def mouse_moved(self):
        p = QtGui.QCursor.pos()
        print "moved here: " + p.x() + ", " + p.y()

    def mouse_released(self):
        p = QtGui.QCursor.pos()
        print "released here: " + p.x() + ", " + p.y()


def main():
    app = QtGui.QApplication(sys.argv)
    ui = test()
    sys.exit(app.exec_())

if __name__ == '__main__':
    main()

test.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>800</width>
    <height>600</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <layout class="QVBoxLayout" name="verticalLayout">
    <item>
     <widget class="QGraphicsView" name="graphicsView"/>
    </item>
   </layout>
  </widget>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>800</width>
     <height>22</height>
    </rect>
   </property>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <resources/>
 <connections/>
</ui>

编辑：

这似乎可行。椭圆不再可移动，因为click事件似乎接管了。有任何想法吗？

import sys
from PyQt4 import QtCore, QtGui, uic


class graphicsScene(QtGui.QGraphicsScene):
    def __init__ (self, parent=None):
        super(graphicsScene, self).__init__ (parent)

    def mousePressEvent(self, event):
        position = QtCore.QPointF(event.scenePos())
        print "pressed here: " + str(position.x()) + ", " + str(position.y())
        self.update()

    def mouseMoveEvent(self, event):
        position = QtCore.QPointF(event.scenePos())
        print "moved here: " + str(position.x()) + ", " + str(position.y())
        self.update()

    def mouseReleaseEvent(self, event):
        position = QtCore.QPointF(event.scenePos())
        print "released here: " + str(position.x()) + ", " + str(position.y())
        self.update()


class test(QtGui.QMainWindow):

    def __init__(self):
        QtGui.QMainWindow.__init__(self)
        self.ui = uic.loadUi('test.ui', self)

        self.scene = graphicsScene()
        self.ui.graphicsView.setScene(self.scene)

        pen = QtGui.QPen(QtCore.Qt.red)
        brush = QtGui.QBrush(QtCore.Qt.blue)
        e = self.scene.addEllipse(10,10,100,100, pen, brush)
        e.setFlag(QtGui.QGraphicsItem.ItemIsMovable, True)

        self.ui.show()


def main():
    app = QtGui.QApplication(sys.argv)
    ui = test()
    sys.exit(app.exec_())

if __name__ == '__main__':
    main()