PYQT5 drawing line

Question

def __init__(self):
    super().__init__()
    self.title = 'Main menu'
    self.left = 80
    self.top = 80
    self.width = 1500
    self.height = 1000
    self.initUI()


def initUI(self):
    self.setWindowTitle(self.title)
    self.setGeometry(self.left, self.top, self.width, self.height)

    painter = QPainter(self)
    painter.setBrush(Qt.black)
    painter.setPen(QPen(Qt.black, 2, Qt.SolidLine))
    painter.drawLine(200,200,400,400)

    self.show()

I am trying to draw a straight line but It is not drawing nothing. How can I draw it?

score 4 · Accepted Answer · edited Jun 20 '20 at 09:12

void QWidget::paintEvent(QPaintEvent *event)

This event handler can be reimplemented in a subclass to receive paint events passed in event.

import sys
from PyQt5.QtGui     import *
from PyQt5.QtCore    import *
from PyQt5.QtWidgets import *


class Widget(QWidget):
    def __init__(self):
        super().__init__()

    def paintEvent(self, event):
        painter = QPainter(self)
        painter.setPen(Qt.red)
        
        painter.drawLine(10,10,100,140)
        
        painter.setPen(Qt.blue)
        painter.drawRect(120,10,80,80)

        rectf = QRectF(230.0,10.0,80.0,80.0)
        painter.drawRoundedRect(rectf,20,20)

        p1 = [QPoint(10,100),QPoint(220,110),QPoint(220,190)]
        painter.drawPolyline(QPolygon(p1))

        p2 = [QPoint(120,110),QPoint(220,110),QPoint(220,190)]
        painter.drawPolygon(QPolygon(p2))


if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = Widget()
    ex.resize(400, 280)
    ex.show()
    sys.exit(app.exec_())

PYQT5 drawing line

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