Sample code of custom widget using PyQt

pyqt4_custom_widget.py

#!/usr/bin/python
# coding: UTF-8

from PyQt4 import QtGui, QtCore
import sys


class MyWidget(QtGui.QWidget):
	def __init__(self):
		super(MyWidget, self).__init__()


	def paintEvent(self, event):
		p = QtGui.QPainter()
		p.begin(self)
		self.onPaint(p)
		p.end()

	def onPaint(self, p):
		p.drawLine(0,0,self.size().width(),self.size().height())

		


def main():
	app = QtGui.QApplication(sys.argv)
	main_window = QtGui.QMainWindow()
	main_window.setWindowTitle('Custom Widget Test')
	d = MyWidget()
	main_window.setCentralWidget(d)
	main_window.show()
	app.exec_()

if __name__ == '__main__':
	main()