PyQt5 object bouncing effect.py

import sys
from PyQt5.QtWidgets import (QApplication, QWidget)
from PyQt5.QtGui import QColor, QPainter
from PyQt5.QtCore import Qt, QRect, QPoint, QTimer


class AppDemo(QWidget):
	def __init__(self):
		super().__init__()
		self.resize(1200, 800)
		self.color = QColor(Qt.red)

		self.rect_circle = QRect(0, 0, 50, 50)
		self.rect_circle.moveCenter(QPoint(self.width() / 2, self.rect_circle.height() / 2))

		self.step = QPoint(0, 5)
		self.y_direction = 1

		timer = QTimer(self, interval=10)
		timer.timeout.connect(self.update_position)
		timer.start()

	def paintEvent(self, event):
		bounce = QPainter(self)
		bounce.setPen(Qt.black)
		bounce.setBrush(Qt.red)
		bounce.drawEllipse(self.rect_circle)

	def update_position(self):
		if self.rect_circle.bottom() > self.height() and self.y_direction == 1:
			self.y_direction = -1
		if self.rect_circle.top() < 0 and self.y_direction == -1:
			self.y_direction = 1

		self.rect_circle.translate(self.step * self.y_direction)
		self.update()


if __name__ == '__main__':
	app = QApplication(sys.argv)

	demo = AppDemo()
	demo.show()

	sys.exit(app.exec_())