Demo/tkinter/guido/paint.py

   1 """"Paint program by Dave Michell.
   2
   3 Subject: tkinter "paint" example
   4 From: Dave Mitchell <davem@magnet.com>
   5 To: python-list@cwi.nl
   6 Date: Fri, 23 Jan 1998 12:18:05 -0500 (EST)
   7
   8   Not too long ago (last week maybe?) someone posted a request
   9 for an example of a paint program using Tkinter. Try as I might
  10 I can't seem to find it in the archive, so i'll just post mine
  11 here and hope that the person who requested it sees this!
  12
  13   All this does is put up a canvas and draw a smooth black line
  14 whenever you have the mouse button down, but hopefully it will
  15 be enough to start with.. It would be easy enough to add some
  16 options like other shapes or colors...
  17
  18                                                 yours,
  19                                                 dave mitchell
  20                                                 davem@magnet.com
  21 """
  22
  23 from Tkinter import *
  24
  25 """paint.py: not exactly a paint program.. just a smooth line drawing demo."""
  26
  27 b1 = "up"
  28 xold, yold = None, None
  29
  30 def main():
  31   root = Tk()
  32   drawing_area = Canvas(root)
  33   drawing_area.pack()
  34   drawing_area.bind("<Motion>", motion)
  35   drawing_area.bind("<ButtonPress-1>", b1down)
  36   drawing_area.bind("<ButtonRelease-1>", b1up)
  37   root.mainloop()
  38
  39 def b1down(event):
  40   global b1
  41   b1 = "down"           # you only want to draw when the button is down
  42                         # because "Motion" events happen -all the time-
  43
  44 def b1up(event):
  45   global b1, xold, yold
  46   b1 = "up"
  47   xold = None           # reset the line when you let go of the button
  48   yold = None
  49
  50 def motion(event):
  51   if b1 == "down":
  52     global xold, yold
  53     if xold != None and yold != None:
  54       event.widget.create_line(xold,yold,event.x,event.y,smooth=TRUE)
  55                         # here's where you draw it. smooth. neat.
  56     xold = event.x
  57     yold = event.y
  58
  59 if __name__ == "__main__":
  60   main()