# Tk_snap2grid.py

# Tk_snap2grid.py

import tkinter as tk

def Snap2Grid(width=300, height=300):
    canvas.config(width=width, height=height)
    for x in range(1,width,50):
        canvas.create_line(x,0, x,height)
    for y in range(1,height,50):
        canvas.create_line(0,y, width,y)
    canvas.create_rectangle(51,51, 101,101, fill="red",
                          activefill='green', tag="R")
0
root = tk.Tk()
canvas = tk.Canvas()
canvas.pack()
canvas.click = None

def onClick1(event):
    canvas.click = event.x, event.y
    canvas.delete('cpoint')
def onMotion1(event):
    x, y = canvas.click
    dx = event.x - x
    dy = event.y - y
    canvas.move('current' ,dx ,dy)
    canvas.click = event.x, event.y
def onRelease1(event):
    mx, my = event.x, event.y
    x, y = mx-(mx%50)+1, my-(my%50)+1
    canvas.coords("R", x,y, x+50,y+50)
canvas.tag_bind("R", "<Button-1>", onClick1)
canvas.tag_bind("R", "<B1-Motion>", onMotion1)
canvas.tag_bind("R", "<ButtonRelease-1>",onRelease1)

Snap2Grid()
root.mainloop()