draw elastic shapes on a canvas on drag, move on right click; : Canvas « Tkinker « Python Tutorial

1. Python Tutorial
2. Tkinker
3. Canvas

from Tkinter import *
trace = 0 
     
class CanvasEventsDemo: 
    def __init__(self, parent=None):
        canvas = Canvas(width=300, height=300, bg='white') 
        canvas.pack()
        canvas.bind('<ButtonPress-1>', self.onStart)  
        canvas.bind('<B1-Motion>',     self.onGrow)   
        canvas.bind('<Double-1>',      self.onClear)  
        canvas.bind('<ButtonPress-3>', self.onMove)   
        self.canvas = canvas
        self.drawn  = None

    def onStart(self, event):
        self.start = event
        self.drawn = None

    def onGrow(self, event):                          
        canvas = event.widget
        if self.drawn: canvas.delete(self.drawn)
        objectId = canvas.create_oval(self.start.x, self.start.y, event.x, event.y)
        if trace: print objectId
        self.drawn = objectId

    def onClear(self, event):
        event.widget.delete('all')

    def onMove(self, event):
        if self.drawn:            
            if trace: print self.drawn
            canvas = event.widget
            diffX, diffY = (event.x - self.start.x), (event.y - self.start.y)
            canvas.move(self.drawn, diffX, diffY)
            self.start = event
     
CanvasEventsDemo()
mainloop()

18.5.Canvas
	18.5.1.	Add CheckButon to frame
	18.5.2.	Canvas paint program.
	18.5.3.	Add Label to canvas
	18.5.4.	Draw line
	18.5.5.	Change line color
	18.5.6.	Draw oval
	18.5.7.	Draw arc
	18.5.8.	Draw rectangle
	18.5.9.	Draw text
	18.5.10.	Add gif image to canvas
	18.5.11.	Canvas click event
	18.5.12.	draw elastic shapes on a canvas on drag, move on right click;
	18.5.13.	Scrolled canvas
	18.5.14.	Add double click action to canvas