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# 12.20 (Tkinter: The RegularPolygonCanvas Class) Define a subclass of Canvas,
# named RegularPolygonCanvas, to paint an n-sided regular polygon. The class
# contains a property named numberOfSides, which specifies the number of sides
# in the polygon. The polygon is centered in the canvas, and the polygon’s size is
# proportional to the size of the canvas. Create a triangle, square, pentagon, hexagon,
# heptagon, and octagon from RegularPolygonCanvas and display them, as
# shown in Figure 12.30.
from tkinter import * # Import tkinter
import math
class RegularPolygonCanvas(Canvas):
def __init__(self, parent, numberOfSides=4, width=150, height=150):
super().__init__(parent, width=width, height=height)
self.setNumberOfSides(numberOfSides)
def getNumberOfSides(self):
return self.__numberOfSides
def setNumberOfSides(self, numberOfSides):
self.__numberOfSides = numberOfSides
self.drawPolygon()
def drawPolygon(self):
self.delete("polygon")
width = int(self["width"])
height = int(self["height"])
xCenter = width / 2
yCenter = height / 2;
radius = min(width, height) * 0.4
angle = 2 * math.pi / self.__numberOfSides
# Create a Polygon object
polygon = []
# Add points to the polygon
for i in range(self.__numberOfSides):
polygon.append([xCenter + radius * math.cos(i * angle),
yCenter - radius * math.sin(i * angle)])
# Draw the polygon
self.create_polygon(polygon, fill="green", tags="polygon")
class MainClass:
def __init__(self):
window = Tk() # Create a window
window.title("Regular Polygons") # Set title
canvas = RegularPolygonCanvas(window, 3)
canvas.pack(side=LEFT)
canvas = RegularPolygonCanvas(window, 4)
canvas.pack(side=LEFT)
canvas = RegularPolygonCanvas(window, 5)
canvas.pack(side=LEFT)
canvas = RegularPolygonCanvas(window, 6)
canvas.pack(side=LEFT)
canvas = RegularPolygonCanvas(window, 7)
canvas.pack(side=LEFT)
canvas = RegularPolygonCanvas(window, 8)
canvas.pack(side=LEFT)
window.mainloop() # Create an event loop
MainClass()
