Canvas paint program: drag and draw，canvasdrag,from Tkinter

Canvas paint program: drag and draw，canvasdrag,from Tkinter

from Tkinter import *class PaintBox( Frame ):   def __init__( self ):      Frame.__init__( self )      self.pack( expand = YES, fill = BOTH )      self.master.title( 'A simple paint program' )      self.master.geometry( '300x150' )      self.message = Label( self, text = 'Drag the mouse to draw' )      self.message.pack( side = BOTTOM )      # create Canvas component      self.myCanvas = Canvas( self )      self.myCanvas.pack( expand = YES, fill = BOTH )      # bind mouse dragging event to Canvas      self.myCanvas.bind( '<B1-Motion>', self.paint )   def paint( self, event ):      x1, y1 = ( event.x - 4 ), ( event.y - 4 )      x2, y2 = ( event.x + 4 ), ( event.y + 4 )      self.myCanvas.create_oval( x1, y1, x2, y2, fill = 'red' )def main():   PaintBox().mainloop()if __name__ == '__main__':   main()