有没有办法检查QRect在pyqt5中的边界内是否包含QGraphicspathitem？

Question

我在场景中有一个QGraphicspathitem。如果点击场景，我会得到网格的矩形。现在我需要做的是，检查QRect的边界内是否包含QGraphicspathitem

Answer 1

如果包含P的最小矩形包含在R中，则检查QPainterPath P是否在矩形R内(没有旋转)，为此，您必须使用boundingRect()。要知道一个矩形(R1)是否包含在另一个矩形( R2 )中，只要知道两个矩形的并集等于R2就足够了。考虑到解决方案是：

import math
import random
from PyQt5 import QtCore, QtGui, QtWidgets


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

        self._scene = QtWidgets.QGraphicsScene(QtCore.QRectF(0, 0, 400, 400), self)
        self.setScene(self._scene)

        self._rect = QtCore.QRectF(40, 40, 100, 100)

        rect_item = self._scene.addRect(self._rect)
        rect_item.setPen(QtGui.QPen(QtGui.QColor("green")))

        # create QGraphicsPathItems

        radius, number_of_sides = 40, 5

        for i in range(4):
            pos = QtCore.QPointF(*random.sample(range(0, 200), 2))
            center = QtCore.QPointF(*random.sample(range(0, 200), 2))
            poly = QtGui.QPolygonF()
            for j in range(number_of_sides + 1):
                angle = 2 * math.pi * j / number_of_sides
                poly << (
                    center + radius * QtCore.QPointF(math.cos(angle), math.sin(angle))
                )
            path = QtGui.QPainterPath()
            path.addPolygon(poly)
            path_item = QtWidgets.QGraphicsPathItem(path)
            path_item.setFlag(QtWidgets.QGraphicsItem.ItemIsMovable)
            path_item.setPos(pos)
            self._scene.addItem(path_item)

        timer = QtCore.QTimer(self, timeout=self.on_timeout, interval=60)
        timer.start()

    def on_timeout(self):
        for item in self._scene.items():
            if isinstance(item, QtWidgets.QGraphicsPathItem):
                color = (
                    QtGui.QColor("blue")
                    if self.verify_if_qgraphicspathitem_inside_qrectf(item, self._rect)
                    else QtGui.QColor("red")
                )
                item.setBrush(QtGui.QBrush(color))

    def verify_if_qgraphicspathitem_inside_qrectf(self, item, rect):
        """
        Check if a QGraphicsPathItem(item) is inside a rectangle(rect)
        """
        path = item.mapToScene(item.path())
        return rect == path.boundingRect().united(rect)


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    w = GraphicsView()
    w.show()
    w.resize(640, 480)
    sys.exit(app.exec_())