cpython/Demo/tkinter/matt/rubber-line-demo-1.py

from Tkinter import *

class Test(Frame):
    def printit(self):
	print "hi"

    def createWidgets(self):
	self.QUIT = Button(self, text='QUIT', 
				  background='red', 
				  foreground='white', 
				  height=3, 
				  command=self.quit)
	self.QUIT.pack(side=BOTTOM, fill=BOTH)

	self.canvasObject = Canvas(self, width="5i", height="5i")
	self.canvasObject.pack(side=LEFT)

    def mouseDown(self, event):
	# canvas x and y take the screen coords from the event and translate
	# them into the coordinate system of the canvas object
	self.startx = self.canvasObject.canvasx(event.x)
	self.starty = self.canvasObject.canvasy(event.y)

    def mouseMotion(self, event):
	# canvas x and y take the screen coords from the event and translate
	# them into the coordinate system of the canvas object
	x = self.canvasObject.canvasx(event.x)
	y = self.canvasObject.canvasy(event.y)

	if (self.startx != event.x)  and (self.starty != event.y) : 
	    self.canvasObject.delete(self.rubberbandLine)
	    self.rubberbandLine = self.canvasObject.create_line(
		self.startx, self.starty, x, y)
	    # this flushes the output, making sure that 
	    # the rectangle makes it to the screen 
	    # before the next event is handled
	    self.update_idletasks()

    def __init__(self, master=None):
	Frame.__init__(self, master)
	Pack.config(self)
	self.createWidgets()
	# this is a "tagOrId" for the rectangle we draw on the canvas
	self.rubberbandLine = None
	Widget.bind(self.canvasObject, "<Button-1>", self.mouseDown)
	Widget.bind(self.canvasObject, "<Button1-Motion>", self.mouseMotion)
	

test = Test()

test.mainloop()