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# 15.35 (Tkinter: Sierpinski triangle) Revise Listing 15.9, SierpinskiTriangle.py, to display
# the filled Sierpinski triangles, as shown in Figure 15.21.
from tkinter import * # Import tkinter
class SierpinskiTriangle:
def __init__(self):
window = Tk() # Create a window
window.title("Sierpinski Triangle") # Set a title
self.width = 200
self.height = 200
self.canvas = Canvas(window,
width=self.width, height=self.height)
self.canvas.pack()
# Add a label, an entry, and a button to frame1
frame1 = Frame(window) # Create and add a frame to window
frame1.pack()
Label(frame1,
text="Enter an order: ").pack(side=LEFT)
self.order = StringVar()
entry = Entry(frame1, textvariable=self.order,
justify=RIGHT).pack(side=LEFT)
Button(frame1, text="Display Sierpinski Triangle",
command=self.display).pack(side=LEFT)
window.mainloop() # Create an event loop
def display(self):
self.canvas.delete("line")
p1 = [self.width / 2, 10]
p2 = [10, self.height - 10]
p3 = [self.width - 10, self.height - 10]
self.canvas.create_polygon([p1, p2, p3], fill='white',tags="line")
self.displayTriangles(int(self.order.get()), p1, p2, p3)
def displayTriangles(self, order, p1, p2, p3):
if order == 0: # Base condition
self.canvas.create_polygon([p1, p2, p3], fill='black',tags="line")
else:
# Get the midpoint of each triangle's edge
p12 = self.midpoint(p1, p2)
p23 = self.midpoint(p2, p3)
p31 = self.midpoint(p3, p1)
# Recursively display three triangles
self.displayTriangles(order - 1, p1, p12, p31)
self.displayTriangles(order - 1, p12, p2, p23)
self.displayTriangles(order - 1, p31, p23, p3)
# Return the midpoint between two points
def midpoint(self, p1, p2):
p = 2 * [0]
p[0] = (p1[0] + p2[0]) / 2
p[1] = (p1[1] + p2[1]) / 2
return p
SierpinskiTriangle() # Create GUI
