单击 PyQt 时的悬停事件

Question

在我的应用程序中，我有一个 QGraphicsScene，用户应该能够通过单击鼠标按钮并将鼠标悬停在项目上来更改项目的颜色。

下面是我从另一个问题借来的示例代码：

PyQt: hover and click events for graphicscene ellipse

from PyQt5 import QtGui, QtCore, QtWidgets

class MyFrame(QtWidgets.QGraphicsView):
    def __init__( self, parent = None ):
        super(MyFrame, self).__init__(parent)

        self.setScene(QtWidgets.QGraphicsScene())

        # add some items
        x = 0
        y = 0
        w = 15
        h = 15
        pen = QtGui.QPen(QtGui.QColor(QtCore.Qt.green))
        brush = QtGui.QBrush(pen.color().darker(150))

        # i want a mouse over and mouse click event for this ellipse
        for xi in range(3):
            for yi in range(3):
                item = callbackRect(x+xi*30, y+yi*30, w, h)
                item.setAcceptHoverEvents(True)
                item.setPen(pen)
                item.setBrush(brush)
                self.scene().addItem(item)
                item.setFlag(QtWidgets.QGraphicsItem.ItemIsMovable)

class callbackRect(QtWidgets.QGraphicsRectItem):
    '''
    Rectangle call-back class.
    '''

    def mouseReleaseEvent(self, event):
        # recolor on click
        color = QtGui.QColor(180, 174, 185)
        brush = QtGui.QBrush(color)
        QtWidgets.QGraphicsRectItem.setBrush(self, brush)

        return QtWidgets.QGraphicsRectItem.mouseReleaseEvent(self, event)

    def hoverMoveEvent(self, event):
        # Do your stuff here.
        pass

    def hoverEnterEvent(self, event):
        color = QtGui.QColor(0, 174, 185)
        brush = QtGui.QBrush(color)
        QtWidgets.QGraphicsRectItem.setBrush(self, brush)

    def hoverLeaveEvent(self, event):
        color = QtGui.QColor(QtCore.Qt.green)
        brush = QtGui.QBrush(color.darker(150))
        QtWidgets.QGraphicsRectItem.setBrush(self, brush)

if ( __name__ == '__main__' ):
    app = QtWidgets.QApplication([])
    f = MyFrame()
    f.show()
    app.exec_()

因此，在这段代码中，只有在没有按下鼠标按钮时才会调用悬停方法。如文档（对于 PySide）中所述，mousePressEvent“决定接收鼠标事件的图形项目”以某种方式阻止其他项目的鼠标事件。

https://deptinfo-ensip.univ-poitiers.fr/ENS/pyside-docs/PySide/QtGui/QGraphicsItem.html?highlight=graphicsitem#PySide.QtGui.PySide.QtGui.QGraphicsItem.mouseMoveEvent

但是，有没有办法同时按住鼠标按钮并调用不同项目的悬停事件？

Answer 1

问题在于使任务复杂化的事件组合，您可以传播mouseMoveEvent 事件，但不能对悬停事件执行相同的操作。一个简单的解决方案是实现QGraphicsView的方法mouseMoveEvent中的逻辑如下图：

class MyFrame(QtWidgets.QGraphicsView):
    def __init__( self, parent = None ):
        super(MyFrame, self).__init__(parent)    
        self.setScene(QtWidgets.QGraphicsScene())
        [...]

    itemsSelected = []
    def mouseMoveEvent(self, event):
        QtWidgets.QGraphicsView.mouseMoveEvent(self, event)
        items = self.items(event.pos())#, QtGui.QTransform())
        for item in self.itemsSelected:
            if item in items:
                item.enterColor()
            else:
                item.leaveColor()
        self.itemsSelected = items

class callbackRect(QtWidgets.QGraphicsRectItem):
    '''
    Rectangle call-back class.
    '''
    def enterColor(self):
        color = QtGui.QColor(0, 174, 185)
        brush = QtGui.QBrush(color)
        QtWidgets.QGraphicsRectItem.setBrush(self, brush)

    def leaveColor(self):
        color = QtGui.QColor(QtCore.Qt.green)
        brush = QtGui.QBrush(color.darker(150))
        QtWidgets.QGraphicsRectItem.setBrush(self, brush)

    def hoverEnterEvent(self, event):
        self.enterColor()

    def hoverLeaveEvent(self, event):
        self.leaveColor()