from PyQt5.QtWidgets import QGraphicsView
from PyQt5.QtGui import QPolygonF
from PyQt5.QtCore import QPoint, QRectF

class GraphicsView(QGraphicsView):
    def __init__(self, window):
        super().__init__(window)

    def mousePressEvent(self, QMouseEvent):
        rect = self.mapToScene(QMouseEvent.x(), QMouseEvent.y(), self.width()/20, self.width()/20)
        self.scene().addPolygon(rect)