from tkinter import *
from tkinter import messagebox
from tkinter import filedialog
from PIL import ImageGrab

def locate(event):
	global x
	global y
	x = event.x
	y = event.y

def draw(event):
	canvas.create_line(x, y, event.x, event.y, fill="black", width=3)
	locate(event)

def get_img(event):
	x1 = root.winfo_rootx() + widget.winfo_x()
	y1 = root.winfo_rooty() + widget.winfo_y()
	x2 = x + widget.winfo_width()
	y2 = y + widget.winfo_height()
	ImageGrab.grab().crop((x1,y1,x2,y2)).save("file.png") #Windows only

def maximize(event):
	root.attributes("-fullscreen", True)
	root.bind("<F11>", minimize)

def minimize(event):
	root.attributes("-fullscreen", False)
	root.bind("<F11>", maximize)

root = Tk()
root.geometry("600x480")
menu = Menu(root)
canvas = Canvas(root, cursor="cross")

root.bind("<F11>", maximize)
canvas.bind("<Motion>", locate)
canvas.bind("<B1-Motion>", draw)
root.bind("<Control-S>", get_img)

if __name__ == '__main__':
	canvas.pack(fill="both", expand=True)
	root.config(menu=menu)
	root.mainloop()