使用 QSignalMapper 进行 QGraphicsItems 之间的通信
Using QSignalMapper for communication between QGraphicsItems
下面的代码显示了我试图让几个可移动的 VerticalLineSegment 对象（派生自 QGraphicsLineItem 和 QObject）向一个（使用 QSignalMapper）另一个发出信号他们移动。对于 VerticalLineSegment 插槽 updateX 未被触发的原因，我将不胜感激。
（未来的目标是让 VerticalLineSegment 出现在不同的 QGraphicsScene 中，但我认为现在最好保持简单。）
from PySide import QtGui, QtCore
import sys
class VerticalLineSegment( QtCore.QObject , QtGui.QGraphicsLineItem ):
onXMove = QtCore.Signal()
def __init__(self, x , y0 , y1 , parent=None):
QtCore.QObject.__init__(self)
QtGui.QGraphicsLineItem.__init__( self , x , y0 , x , y1 , parent)
self.setFlag(QtGui.QGraphicsLineItem.ItemIsMovable)
self.setFlag(QtGui.QGraphicsLineItem.ItemSendsGeometryChanges)
self.setCursor(QtCore.Qt.SizeAllCursor)
def itemChange( self , change , value ):
if change is QtGui.QGraphicsItem.ItemPositionChange:
self.onXMove.emit()
value.setY(0) # Restrict movements along horizontal direction
return value
return QtGui.QGraphicsLineItem.itemChange(self, change , value )
def shape(self):
path = super(VerticalLineSegment, self).shape()
stroker = QtGui.QPainterPathStroker()
stroker.setWidth(5)
return stroker.createStroke(path)
def boundingRect(self):
return self.shape().boundingRect()
# slot
def updateX(self , object ):
print "slot"
class CustomScene(QtGui.QGraphicsScene):
def __init__(self , parent=None):
super(CustomScene, self).__init__(parent)
self.signalMapper = QtCore.QSignalMapper()
def addItem( self , item ):
self.signalMapper.setMapping( item , item )
item.onXMove.connect(self.signalMapper.map )
self.signalMapper.mapped.connect(item.updateX)
return QtGui.QGraphicsScene.addItem(self,item)
class Editor(QtGui.QMainWindow):
def __init__(self, parent=None):
super(Editor, self).__init__(parent)
scene = CustomScene()
line0 = VerticalLineSegment( 10 , 210 , 300 )
line1 = VerticalLineSegment( 10 , 110 , 200 )
line2 = VerticalLineSegment( 10 , 10 , 100 )
scene.addItem( line0 )
scene.addItem( line1 )
scene.addItem( line2 )
view = QtGui.QGraphicsView()
view.setScene( scene )
self.setGeometry( 250 , 250 , 600 , 600 )
self.setCentralWidget(view)
self.show()
if __name__=="__main__":
app=QtGui.QApplication(sys.argv)
myapp = Editor()
sys.exit(app.exec_())
在PySide（以及PySide2、PyQt4和PyQt5）中，不可能从QGraphicsItem和QObject继承（特殊情况下只允许双重继承）
所以一个可能的解决方案是使用组合，也就是说，将 QObject 作为属性并且它具有信号：
import sys
import uuid
from PySide import QtGui, QtCore
class Signaller(QtCore.QObject):
onXMove = QtCore.Signal()
class VerticalLineSegment(QtGui.QGraphicsLineItem):
def __init__(self, _id, x, y0, y1, parent=None):
super(VerticalLineSegment, self).__init__(x, y0, x, y1, parent)
self._id = _id
self.signaller = Signaller()
self.setFlag(QtGui.QGraphicsLineItem.ItemIsMovable)
self.setFlag(QtGui.QGraphicsLineItem.ItemSendsGeometryChanges)
self.setCursor(QtCore.Qt.SizeAllCursor)
def itemChange(self, change, value):
if change is QtGui.QGraphicsItem.ItemPositionChange:
self.signaller.onXMove.emit()
value.setY(0) # Restrict movements along horizontal direction
return value
return QtGui.QGraphicsLineItem.itemChange(self, change, value)
def shape(self):
path = super(VerticalLineSegment, self).shape()
stroker = QtGui.QPainterPathStroker()
stroker.setWidth(5)
return stroker.createStroke(path)
def boundingRect(self):
return self.shape().boundingRect()
def updateX(self, _id):
print("slot", _id)
class CustomScene(QtGui.QGraphicsScene):
def __init__(self, parent=None):
super(CustomScene, self).__init__(parent)
self.signalMapper = QtCore.QSignalMapper(self)
def addItem(self, item):
if hasattr(item, "_id"):
item.signaller.onXMove.connect(self.signalMapper.map)
self.signalMapper.setMapping(item.signaller, item._id)
self.signalMapper.mapped[str].connect(item.updateX)
super(CustomScene, self).addItem(item)
class Editor(QtGui.QMainWindow):
def __init__(self, parent=None):
super(Editor, self).__init__(parent)
scene = CustomScene()
line0 = VerticalLineSegment(str(uuid.uuid4()), 10.0, 210.0, 300.0)
line1 = VerticalLineSegment(str(uuid.uuid4()), 10.0, 110.0, 200.0)
line2 = VerticalLineSegment(str(uuid.uuid4()), 10.0, 10.0, 100.0)
scene.addItem(line0)
scene.addItem(line1)
scene.addItem(line2)
view = QtGui.QGraphicsView()
view.setScene(scene)
self.setGeometry(250, 250, 600, 600)
self.setCentralWidget(view)
self.show()
或者使用QGraphicsObject:
import sys
from PySide import QtCore, QtGui
class VerticalLineSegment(QtGui.QGraphicsObject):
onXMove = QtCore.Signal()
def __init__(self, x, y0, y1, parent=None):
super(VerticalLineSegment, self).__init__(parent)
self._line = QtCore.QLineF(x, y0, x, y1)
self.setFlag(QtGui.QGraphicsLineItem.ItemIsMovable)
self.setFlag(QtGui.QGraphicsLineItem.ItemSendsGeometryChanges)
self.setCursor(QtCore.Qt.SizeAllCursor)
def paint(self, painter, option, widget=None):
painter.drawLine(self._line)
def shape(self):
path = QtGui.QPainterPath()
path.moveTo(self._line.p1())
path.lineTo(self._line.p2())
stroker = QtGui.QPainterPathStroker()
stroker.setWidth(5)
return stroker.createStroke(path)
def boundingRect(self):
return self.shape().boundingRect()
def itemChange(self, change, value):
if change is QtGui.QGraphicsItem.ItemPositionChange:
self.onXMove.emit()
value.setY(0) # Restrict movements along horizontal direction
return value
return QtGui.QGraphicsLineItem.itemChange(self, change, value)
def updateX(self , obj):
print("slot", obj)
class CustomScene(QtGui.QGraphicsScene):
def __init__(self, parent=None):
super(CustomScene, self).__init__(parent)
self.signalMapper = QtCore.QSignalMapper(self)
def addItem(self, item):
if isinstance(item, QtCore.QObject):
item.onXMove.connect(self.signalMapper.map)
self.signalMapper.setMapping(item, item)
self.signalMapper.mapped[QtCore.QObject].connect(item.updateX)
super(CustomScene, self).addItem(item)
class Editor(QtGui.QMainWindow):
def __init__(self, parent=None):
super(Editor, self).__init__(parent)
scene = CustomScene()
line0 = VerticalLineSegment(10.0, 210.0, 300.0)
line1 = VerticalLineSegment(10.0, 110.0, 200.0)
line2 = VerticalLineSegment(10.0, 10.0, 100.0)
scene.addItem(line0)
scene.addItem(line1)
scene.addItem(line2)
view = QtGui.QGraphicsView()
view.setScene(scene)
self.setGeometry(250, 250, 600, 600)
self.setCentralWidget(view)
self.show()
这是我想出的解决方案。与@eyllanesc 的第一个解决方案一样，它使用了一个信号器，我将其称为 Broadcaster 而不是 QSignalMapper，现在是 obsolete/deprecated。以下是相关更改：
class VerticalLineSegment( QtCore.QObject , QtGui.QGraphicsLineItem ):
onXMove = QtCore.Signal( int , int )
def __init__(self, x , y0 , y1 , parent=None):
...
self.index = -1
...
def updateX( self , id , x ):
if id is not self.index:
# Disconnect and reconnect to avoid a signal cycle
self.onXMove.disconnect()
self.setX( x )
self.onXMove.connect( self.sender().onXMove )
# Alternative to signal mapper
class Broadcaster( QtCore.QObject ):
onXMove = QtCore.Signal( int , int )
class CustomScene(QtGui.QGraphicsScene):
def __init__(self , parent=None):
super(CustomScene, self).__init__(parent)
self.broadcaster = Broadcaster()
self.count = 0
def addItem( self , item ):
item.index = self.count
self.count = self.count + 1
item.onXMove.connect( self.broadcaster.onXMove )
self.broadcaster.onXMove.connect( item.updateX )
return QtGui.QGraphicsScene.addItem(self,item)
这是完整的程序
from PySide import QtGui, QtCore
import sys
class VerticalLineSegment( QtCore.QObject , QtGui.QGraphicsLineItem ):
onXMove = QtCore.Signal( int , int )
def __init__(self, x , y0 , y1 , parent=None):
QtCore.QObject.__init__(self)
QtGui.QGraphicsLineItem.__init__( self , x , y0 , x , y1 , parent)
self.index = -1
self.setFlag(QtGui.QGraphicsLineItem.ItemIsMovable)
self.setFlag(QtGui.QGraphicsLineItem.ItemSendsGeometryChanges)
self.setCursor(QtCore.Qt.SizeAllCursor)
def itemChange( self , change , value ):
if change is QtGui.QGraphicsItem.ItemPositionChange:
self.onXMove.emit( self.index , value.x() )
value.setY(0) # Restrict movements along horizontal direction
return value
return QtGui.QGraphicsLineItem.itemChange(self, change , value )
def shape(self):
path = super(VerticalLineSegment, self).shape()
stroker = QtGui.QPainterPathStroker()
stroker.setWidth(5)
return stroker.createStroke(path)
def boundingRect(self):
return self.shape().boundingRect()
def updateX( self , id , x ):
if id is not self.index:
self.onXMove.disconnect()
self.setX( x )
self.onXMove.connect( self.sender().onXMove )
class Broadcaster( QtCore.QObject ):
onXMove = QtCore.Signal( int , int )
class CustomScene(QtGui.QGraphicsScene):
def __init__(self , parent=None):
super(CustomScene, self).__init__(parent)
self.broadcaster = Broadcaster()
self.count = 0
def addItem( self , item ):
item.index = self.count
self.count = self.count + 1
item.onXMove.connect( self.broadcaster.onXMove )
self.broadcaster.onXMove.connect( item.updateX )
return QtGui.QGraphicsScene.addItem(self,item)
class Editor(QtGui.QMainWindow):
def __init__(self, parent=None):
super(Editor, self).__init__(parent)
scene = CustomScene()
line0 = VerticalLineSegment( 10 , 210 , 300 )
line1 = VerticalLineSegment( 10 , 110 , 200 )
line2 = VerticalLineSegment( 10 , 10 , 100 )
scene.addItem( line0 )
scene.addItem( line1 )
scene.addItem( line2 )
view = QtGui.QGraphicsView()
view.setScene( scene )
self.setGeometry( 250 , 250 , 600 , 600 )
self.setCentralWidget(view)
self.show()
if __name__=="__main__":
app=QtGui.QApplication(sys.argv)
myapp = Editor()
sys.exit(app.exec_())
下面的代码显示了我试图让几个可移动的 VerticalLineSegment 对象（派生自 QGraphicsLineItem 和 QObject）向一个（使用 QSignalMapper）另一个发出信号他们移动。对于 VerticalLineSegment 插槽 updateX 未被触发的原因，我将不胜感激。
（未来的目标是让 VerticalLineSegment 出现在不同的 QGraphicsScene 中，但我认为现在最好保持简单。）
from PySide import QtGui, QtCore
import sys
class VerticalLineSegment( QtCore.QObject , QtGui.QGraphicsLineItem ):
onXMove = QtCore.Signal()
def __init__(self, x , y0 , y1 , parent=None):
QtCore.QObject.__init__(self)
QtGui.QGraphicsLineItem.__init__( self , x , y0 , x , y1 , parent)
self.setFlag(QtGui.QGraphicsLineItem.ItemIsMovable)
self.setFlag(QtGui.QGraphicsLineItem.ItemSendsGeometryChanges)
self.setCursor(QtCore.Qt.SizeAllCursor)
def itemChange( self , change , value ):
if change is QtGui.QGraphicsItem.ItemPositionChange:
self.onXMove.emit()
value.setY(0) # Restrict movements along horizontal direction
return value
return QtGui.QGraphicsLineItem.itemChange(self, change , value )
def shape(self):
path = super(VerticalLineSegment, self).shape()
stroker = QtGui.QPainterPathStroker()
stroker.setWidth(5)
return stroker.createStroke(path)
def boundingRect(self):
return self.shape().boundingRect()
# slot
def updateX(self , object ):
print "slot"
class CustomScene(QtGui.QGraphicsScene):
def __init__(self , parent=None):
super(CustomScene, self).__init__(parent)
self.signalMapper = QtCore.QSignalMapper()
def addItem( self , item ):
self.signalMapper.setMapping( item , item )
item.onXMove.connect(self.signalMapper.map )
self.signalMapper.mapped.connect(item.updateX)
return QtGui.QGraphicsScene.addItem(self,item)
class Editor(QtGui.QMainWindow):
def __init__(self, parent=None):
super(Editor, self).__init__(parent)
scene = CustomScene()
line0 = VerticalLineSegment( 10 , 210 , 300 )
line1 = VerticalLineSegment( 10 , 110 , 200 )
line2 = VerticalLineSegment( 10 , 10 , 100 )
scene.addItem( line0 )
scene.addItem( line1 )
scene.addItem( line2 )
view = QtGui.QGraphicsView()
view.setScene( scene )
self.setGeometry( 250 , 250 , 600 , 600 )
self.setCentralWidget(view)
self.show()
if __name__=="__main__":
app=QtGui.QApplication(sys.argv)
myapp = Editor()
sys.exit(app.exec_())
在PySide（以及PySide2、PyQt4和PyQt5）中，不可能从QGraphicsItem和QObject继承（特殊情况下只允许双重继承）
所以一个可能的解决方案是使用组合，也就是说，将 QObject 作为属性并且它具有信号：
import sys
import uuid
from PySide import QtGui, QtCore
class Signaller(QtCore.QObject):
onXMove = QtCore.Signal()
class VerticalLineSegment(QtGui.QGraphicsLineItem):
def __init__(self, _id, x, y0, y1, parent=None):
super(VerticalLineSegment, self).__init__(x, y0, x, y1, parent)
self._id = _id
self.signaller = Signaller()
self.setFlag(QtGui.QGraphicsLineItem.ItemIsMovable)
self.setFlag(QtGui.QGraphicsLineItem.ItemSendsGeometryChanges)
self.setCursor(QtCore.Qt.SizeAllCursor)
def itemChange(self, change, value):
if change is QtGui.QGraphicsItem.ItemPositionChange:
self.signaller.onXMove.emit()
value.setY(0) # Restrict movements along horizontal direction
return value
return QtGui.QGraphicsLineItem.itemChange(self, change, value)
def shape(self):
path = super(VerticalLineSegment, self).shape()
stroker = QtGui.QPainterPathStroker()
stroker.setWidth(5)
return stroker.createStroke(path)
def boundingRect(self):
return self.shape().boundingRect()
def updateX(self, _id):
print("slot", _id)
class CustomScene(QtGui.QGraphicsScene):
def __init__(self, parent=None):
super(CustomScene, self).__init__(parent)
self.signalMapper = QtCore.QSignalMapper(self)
def addItem(self, item):
if hasattr(item, "_id"):
item.signaller.onXMove.connect(self.signalMapper.map)
self.signalMapper.setMapping(item.signaller, item._id)
self.signalMapper.mapped[str].connect(item.updateX)
super(CustomScene, self).addItem(item)
class Editor(QtGui.QMainWindow):
def __init__(self, parent=None):
super(Editor, self).__init__(parent)
scene = CustomScene()
line0 = VerticalLineSegment(str(uuid.uuid4()), 10.0, 210.0, 300.0)
line1 = VerticalLineSegment(str(uuid.uuid4()), 10.0, 110.0, 200.0)
line2 = VerticalLineSegment(str(uuid.uuid4()), 10.0, 10.0, 100.0)
scene.addItem(line0)
scene.addItem(line1)
scene.addItem(line2)
view = QtGui.QGraphicsView()
view.setScene(scene)
self.setGeometry(250, 250, 600, 600)
self.setCentralWidget(view)
self.show()
或者使用QGraphicsObject:
import sys
from PySide import QtCore, QtGui
class VerticalLineSegment(QtGui.QGraphicsObject):
onXMove = QtCore.Signal()
def __init__(self, x, y0, y1, parent=None):
super(VerticalLineSegment, self).__init__(parent)
self._line = QtCore.QLineF(x, y0, x, y1)
self.setFlag(QtGui.QGraphicsLineItem.ItemIsMovable)
self.setFlag(QtGui.QGraphicsLineItem.ItemSendsGeometryChanges)
self.setCursor(QtCore.Qt.SizeAllCursor)
def paint(self, painter, option, widget=None):
painter.drawLine(self._line)
def shape(self):
path = QtGui.QPainterPath()
path.moveTo(self._line.p1())
path.lineTo(self._line.p2())
stroker = QtGui.QPainterPathStroker()
stroker.setWidth(5)
return stroker.createStroke(path)
def boundingRect(self):
return self.shape().boundingRect()
def itemChange(self, change, value):
if change is QtGui.QGraphicsItem.ItemPositionChange:
self.onXMove.emit()
value.setY(0) # Restrict movements along horizontal direction
return value
return QtGui.QGraphicsLineItem.itemChange(self, change, value)
def updateX(self , obj):
print("slot", obj)
class CustomScene(QtGui.QGraphicsScene):
def __init__(self, parent=None):
super(CustomScene, self).__init__(parent)
self.signalMapper = QtCore.QSignalMapper(self)
def addItem(self, item):
if isinstance(item, QtCore.QObject):
item.onXMove.connect(self.signalMapper.map)
self.signalMapper.setMapping(item, item)
self.signalMapper.mapped[QtCore.QObject].connect(item.updateX)
super(CustomScene, self).addItem(item)
class Editor(QtGui.QMainWindow):
def __init__(self, parent=None):
super(Editor, self).__init__(parent)
scene = CustomScene()
line0 = VerticalLineSegment(10.0, 210.0, 300.0)
line1 = VerticalLineSegment(10.0, 110.0, 200.0)
line2 = VerticalLineSegment(10.0, 10.0, 100.0)
scene.addItem(line0)
scene.addItem(line1)
scene.addItem(line2)
view = QtGui.QGraphicsView()
view.setScene(scene)
self.setGeometry(250, 250, 600, 600)
self.setCentralWidget(view)
self.show()
这是我想出的解决方案。与@eyllanesc 的第一个解决方案一样，它使用了一个信号器，我将其称为 Broadcaster 而不是 QSignalMapper，现在是 obsolete/deprecated。以下是相关更改：
class VerticalLineSegment( QtCore.QObject , QtGui.QGraphicsLineItem ):
onXMove = QtCore.Signal( int , int )
def __init__(self, x , y0 , y1 , parent=None):
...
self.index = -1
...
def updateX( self , id , x ):
if id is not self.index:
# Disconnect and reconnect to avoid a signal cycle
self.onXMove.disconnect()
self.setX( x )
self.onXMove.connect( self.sender().onXMove )
# Alternative to signal mapper
class Broadcaster( QtCore.QObject ):
onXMove = QtCore.Signal( int , int )
class CustomScene(QtGui.QGraphicsScene):
def __init__(self , parent=None):
super(CustomScene, self).__init__(parent)
self.broadcaster = Broadcaster()
self.count = 0
def addItem( self , item ):
item.index = self.count
self.count = self.count + 1
item.onXMove.connect( self.broadcaster.onXMove )
self.broadcaster.onXMove.connect( item.updateX )
return QtGui.QGraphicsScene.addItem(self,item)
这是完整的程序
from PySide import QtGui, QtCore
import sys
class VerticalLineSegment( QtCore.QObject , QtGui.QGraphicsLineItem ):
onXMove = QtCore.Signal( int , int )
def __init__(self, x , y0 , y1 , parent=None):
QtCore.QObject.__init__(self)
QtGui.QGraphicsLineItem.__init__( self , x , y0 , x , y1 , parent)
self.index = -1
self.setFlag(QtGui.QGraphicsLineItem.ItemIsMovable)
self.setFlag(QtGui.QGraphicsLineItem.ItemSendsGeometryChanges)
self.setCursor(QtCore.Qt.SizeAllCursor)
def itemChange( self , change , value ):
if change is QtGui.QGraphicsItem.ItemPositionChange:
self.onXMove.emit( self.index , value.x() )
value.setY(0) # Restrict movements along horizontal direction
return value
return QtGui.QGraphicsLineItem.itemChange(self, change , value )
def shape(self):
path = super(VerticalLineSegment, self).shape()
stroker = QtGui.QPainterPathStroker()
stroker.setWidth(5)
return stroker.createStroke(path)
def boundingRect(self):
return self.shape().boundingRect()
def updateX( self , id , x ):
if id is not self.index:
self.onXMove.disconnect()
self.setX( x )
self.onXMove.connect( self.sender().onXMove )
class Broadcaster( QtCore.QObject ):
onXMove = QtCore.Signal( int , int )
class CustomScene(QtGui.QGraphicsScene):
def __init__(self , parent=None):
super(CustomScene, self).__init__(parent)
self.broadcaster = Broadcaster()
self.count = 0
def addItem( self , item ):
item.index = self.count
self.count = self.count + 1
item.onXMove.connect( self.broadcaster.onXMove )
self.broadcaster.onXMove.connect( item.updateX )
return QtGui.QGraphicsScene.addItem(self,item)
class Editor(QtGui.QMainWindow):
def __init__(self, parent=None):
super(Editor, self).__init__(parent)
scene = CustomScene()
line0 = VerticalLineSegment( 10 , 210 , 300 )
line1 = VerticalLineSegment( 10 , 110 , 200 )
line2 = VerticalLineSegment( 10 , 10 , 100 )
scene.addItem( line0 )
scene.addItem( line1 )
scene.addItem( line2 )
view = QtGui.QGraphicsView()
view.setScene( scene )
self.setGeometry( 250 , 250 , 600 , 600 )
self.setCentralWidget(view)
self.show()
if __name__=="__main__":
app=QtGui.QApplication(sys.argv)
myapp = Editor()
sys.exit(app.exec_())