# Tk_mouse_rectangle_draw.py

# Tk_mouse_rectangle_draw.py

from PIL import Image, ImageTk
from Tkinter import *

root=Tk()
canvas = Canvas(root)
canvas.pack()

def on_button_press(event):
    global start_x, start_y, rect
    # save mouse drag start position
    start_x = canvas.canvasx(event.x)
    start_y = canvas.canvasy(event.y)

    # create rectangle if not yet exist
    if not rect:
        rect = canvas.create_rectangle(x, y, 1, 1, outline='red')

def on_move_press(event):
    global start_x, start_y, curX, curY, rect
    curX = canvas.canvasx(event.x)
    curY = canvas.canvasy(event.y)

    # expand rectangle as you drag the mouse
    canvas.coords(rect, start_x, start_y, curX, curY)

def on_button_release(event):
    global start_x, start_y, curX, curY, rect
    try:
        canvas.create_rectangle(start_x, start_y, curX, curY, fill='green')
    except: pass
    rect = None

x = y = 0

canvas.grid(row=0,column=0,sticky=N+S+E+W)

canvas.bind("<ButtonPress-1>", on_button_press)
canvas.bind("<B1-Motion>", on_move_press)
canvas.bind("<ButtonRelease-1>", on_button_release)

rect = None

start_x = None
start_y = None

root.mainloop()