import tkinter
from tkinter import Canvas


# This function initializes a Canvas and display window, 
# then calls the recursive function triangle to do all the work
def start_triangle(size, color):
    window = tkinter.Tk()
    c = Canvas(window, width = size, height = size)
    c.pack()
    c.create_rectangle(1, 1, size + 1, size + 1, fill=color)
    triangle(c, 0, 0, size)


# draw a Sierpinski triangle with top left at (x,y) and 
# with height and width of size
def triangle(c, x, y, size):
    # stop when the size gets smaller than 2
    # (since we can't subdivide a pixel)
    if size < 2:
        return None
    half = size // 2
    draw_square(c, x, y, half)

    # recursively repeat the triangle
    # for each of the other three quadrants
    triangle(c,         ,          ,          ) # Fill in the missing parameters of this call
    triangle(c,         ,          ,          ) # Fill in the missing parameters of this call
    triangle(c,         ,          ,          ) # Fill in the missing parameters of this call


def draw_square(c, x, y, half):
    # draw a square in the upper left quadrant
    c.create_rectangle(1 + x,
                       1 + y,
                       1 + x + half,
                       1 + y + half, width=0, fill="white")