pyqt“ItemIgnoresParentOpacity”标志被忽略

Question

我已经花时间为我的问题做了一个最小可重现示例。

使用 PyQt5，我有一个经典的主窗口，其中 QGraphicsView 链接到 QGraphicsScene。

在场景中，我有一个 NodeHover 项目（绿色圆圈）和一个 TreeNode 孩子（正方形）。 NodeHover 项默认是透明的，悬停时变为不透明的。

我希望其子项 (TreeNode) 始终保持不透明，无论父项的不透明度如何。我已经尝试在这两个项目中设置标志，如下所示，但它们似乎不起作用。

import sys
from PyQt5.QtWidgets import QGraphicsScene, QGraphicsView, QMainWindow, QApplication, QToolBar, QStatusBar, QAction, QGraphicsItem, QGraphicsLineItem, QLabel, QGraphicsEllipseItem, QGraphicsTextItem

from PyQt5.QtCore import *
from PyQt5.QtGui import QPainter, QIcon, QPen, QBrush, QTransform


class NodeHover(QGraphicsItem):
    def __init__(self, *args, **kwargs):
        super(NodeHover, self).__init__(*args, **kwargs)
        self.setOpacity(0.1)
        self.setAcceptHoverEvents(True)
        # Setting the flag so Item doesn't propagate its opacity to children
        self.GraphicsItemFlag(QGraphicsItem.ItemDoesntPropagateOpacityToChildren)

    def hoverEnterEvent(self, event):
        self.setOpacity(1) # When mouse enters item, make it opaque
    def hoverLeaveEvent(self, event):
        self.setOpacity(0.1) # When mouse leaves item, make it transparent

    def boundingRect(self):
        return QRectF(0,0, 20, 20)

    def paint(self, painter, option, widget):
        painter.setBrush(QBrush(Qt.green))
        painter.drawEllipse(QPointF(10, 10), 10, 10)

    
class TreeNode(QGraphicsItem):
    def __init__(self, *args, **kwargs):
        super(TreeNode, self).__init__(*args, **kwargs)
        # Setting the flag to ignore parent's opacity
        self.GraphicsItemFlag(QGraphicsItem.ItemIgnoresParentOpacity)

    def boundingRect(self):
        return QRectF(100, 100, 100, 100)

    def paint(self, painter, option, widget):
        painter.drawRect(110,110,80,80)


class GView(QGraphicsView):
    def __init__(self, parent, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.parent = parent
        self.setGeometry(100, 100, 700, 450)
        self.show()


class Scene(QGraphicsScene):
    def __init__(self, parent):
        super().__init__(parent)
        self.parent = parent
        hoverItem = NodeHover() # create a NodeHover item
        self.addItem(hoverItem)
        nodeItem = TreeNode()   # create a TreeNode item and make it hoverItem's child
        nodeItem.setParentItem(hoverItem)


class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setGeometry(900, 70, 1000, 800)
        self.createGraphicView()
        self.show()

    def createGraphicView(self):
        self.scene = Scene(self)
        gView = GView(self)
        scene = Scene(gView)
        gView.setScene(scene)
        # Set the main window's central widget
        self.setCentralWidget(gView)

# Run program
if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = MainWindow()
    sys.exit(app.exec_())

Answer 1

要为 QGraphicsItem 设置标志，您必须使用 setFlag() 方法：

self.setFlag(QGraphicsItem.ItemDoesntPropagateOpacityToChildren)

self.setFlag(QGraphicsItem.ItemIgnoresParentOpacity)

注意：其中一个标志就足够了。