test_qpainter.py

import sys
import PyQt4.QtCore as QtCore
import PyQt4.QtGui as QtGui

class painter(QtGui.QWidget):
    
    def __init__(self, parent=None):
        super(painter,self).__init__(parent)
        
        self.resize(400,300)
        self.setWindowTitle('QPainter Test')

    def paintEvent(self, event):
        p = QtGui.QPainter()
        p.begin(self)
        p.setPen(QtGui.QColor(0, 0, 255))
        p.drawLine(0,0, 100,100)
        p.end()


app = QtGui.QApplication(sys.argv)
p = painter()
p.show()
app.exec_()