#!/usr/bin/env python
          #-*- coding:utf-8 -*-
          from PyQt4.QtCore import *
          from PyQt4.QtGui import *
          
          class Caculator(QDialog):
              def __init__(self):
                  super(Caculator, self).__init__()
                  #widgets
                  self.leInput = QLineEdit()
                  self.lwResult = QListWidget()
                  #layouts
                  l = QVBoxLayout(self)
                  for w in self.leInput, self.lwResult:
                      l.addWidget(w)
                  #events
                  self.leInput.returnPressed.connect(self.caculate)
          
              def caculate(self):
                  data = unicode(self.leInput.text())
                  if not data: return
                  self.leInput.clear()
          
                  try:
                      result = unicode(eval(data))
                  except Exception as e:
                      result = unicode(e)
          
                  self.lwResult.addItem(result)
          
          
          def main():
              app = QApplication([])
              Caculator().exec_()
          
          if __name__=="__main__":
              main()
          

l = QVBoxLayout(self)
          for w in self.leInput, self.lwResult:
              l.addWidget(w)
          

this->connect(leInput, SINGAL(returnPressed()), this, caculate))
          

self.leInput.returnPressed.connect(self.caculate)
          

form, base = uic.loadUiType("score.ui")
          class ScoreDlg(QDialog, form):
              def __init__(self):
                  super(ScoreDlg, self).__init__()
                  self.setupUi(self)
          

def mouseReleaseEvent(self, event):
              if event.button() == Qt.LeftButton:
                  ...
          
          def paintEvent(self, event=None):
              p = QPainter(self)
              ...
              p.drawLine(mx+i*sx, my, mx+i*sx, my+y*sy)