我想要一个可以在其中平移和缩放的 QWidget。
设想 :
- 当用户使用他的鼠标中键向上/向下滚动时,所有子级都从小部件的中心缩放。
- 如果用户按住 Alt 并同时按下鼠标中键,则所有子项都将使用鼠标产生的距离进行平移。
这个想法是通过继承另一个 QWidget 来创建一个新的 QWidget。所以我用 QGraphicsView 作为例子:
更新 :
class MyQGraphicsView(QGraphicsView):
def __init__(self):
QGraphicsView.__init__(self)
self.setFocusPolicy(Qt.WheelFocus)
self.setRenderHints(QPainter.Antialiasing)
self.altPressed = False
self.middlePressed = False
self.rightPressed = False
def wheelEvent(self, event):
self.newScale(event.delta(), 1.15)
def keyPressEvent(self, event):
if event.key() == Qt.Key_Alt:
self.altPressed = True
QApplication.setOverrideCursor(Qt.OpenHandCursor)
def keyReleaseEvent(self, event):
if event.key() == Qt.Key_Alt:
self.altPressed = False
QApplication.setOverrideCursor(Qt.ArrowCursor)
def mousePressEvent(self, event):
self._dragPos = event.pos()
if event.button() == Qt.MidButton:
self.middlePressed = True
if event.button() == Qt.RightButton:
self.rightPressed = True
def mouseReleaseEvent(self, event):
if event.button() == Qt.MidButton:
self.middlePressed = False
if event.button() == Qt.RightButton:
self.rightPressed = False
def mouseMoveEvent(self, event):
if self.altPressed:
newPos = event.pos()
if self.middlePressed:
diff = newPos - self._dragPos
self._dragPos = newPos
QApplication.setOverrideCursor(Qt.ClosedHandCursor)
self.horizontalScrollBar().setValue(self.horizontalScrollBar().value() - diff.x())
self.verticalScrollBar().setValue(self.verticalScrollBar().value() - diff.y())
event.accept()
if self.rightPressed:
diff = newPos - self._dragPos
self._dragPos = newPos
QApplication.setOverrideCursor(Qt.SizeAllCursor)
self.newScale(diff.x(), 1.01)
def newScale(self, operator, factor):
if operator > 0:
self.scale(factor, factor)
if operator < 0:
self.scale(1.0/factor, 1.0/factor)
此类适用于平移和缩放,但是当我像这样使用它时:
view = MyQGraphicsView()
scene = QGraphicsScene()
view.setScene(scene)
view.setSceneRect(0, 0, 1000, 1000)
button = QPushButton('Hello !')
button.clicked.connect(self.sayHello)
scene.addWidget(button)
我无法点击按钮。我该如何解决?