pyqt5 graphicview 点击坐标后，在周围框选一个100*100的红色矩形 完整代码

以下是一个完整的示例代码，实现了在 QGraphicsView 中点击鼠标后在指定位置周围框选一个 100*100 的红色矩形：

from PyQt5.QtWidgets import QApplication, QGraphicsView, QGraphicsScene, QGraphicsRectItem
from PyQt5.QtGui import QBrush, QColor
from PyQt5.QtCore import Qt

class MyGraphicsView(QGraphicsView):
    def __init__(self):
        super().__init__()
        self.setScene(QGraphicsScene(self))
        self.setRenderHint(QPainter.Antialiasing)
        self.setRenderHint(QPainter.SmoothPixmapTransform)
        self.setDragMode(QGraphicsView.ScrollHandDrag)
        self.setTransformationAnchor(QGraphicsView.AnchorUnderMouse)
        self.setResizeAnchor(QGraphicsView.AnchorUnderMouse)
        self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.setViewportUpdateMode(QGraphicsView.FullViewportUpdate)
        self.setOptimizationFlag(QGraphicsView.DontAdjustForAntialiasing, True)
        self.setOptimizationFlag(QGraphicsView.DontSavePainterState, True)
        self.setOptimizationFlag(QGraphicsView.DontAdjustForDrag, True)

    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton:
            pos = self.mapToScene(event.pos())
            rect = self.scene().addRect(pos.x()-50, pos.y()-50, 100, 100)
            rect.setBrush(QBrush(QColor("red")))
            rect.setPen(Qt.NoPen)

if __name__ == '__main__':
    app = QApplication([])
    view = MyGraphicsView()
    view.show()
    app.exec_()

运行以上代码，点击 QGraphicsView 中的任意位置，即可在该位置周围框选一个 100*100 的红色矩形。