Answer
code
Work Step by Step
# 12.21 (Tkinter: display an n-sided regular polygon) In Exercise 12.20 you created the
# RegularPolygonCanvas subclass for displaying an n-sided regular polygon.
# Write a program that displays a regular polygon and uses two buttons named +1
# and -1 to increase or decrease the size of the polygon, as shown in Figure
# 12.31a–b. Also enable the user to increase or decrease the size by clicking the
# right or left mouse button and by pressing the UP and DOWN arrow keys.
import math
from tkinter import *
class RegularPolygonCanvas(Canvas):
def __init__(self, parent, numberOfSides=4, width=200, height=200):
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")
def reDraw(self, sides):
self.__numberOfSides = sides
self.drawPolygon()
class MainClass:
def __init__(self):
self.window = Tk() # Create a window
self.window.title("Regular Polygons") # Set title
self.sides = 3
self.canvas = RegularPolygonCanvas(self.window, self.sides)
self.canvas.pack()
frame = Frame(self.window)
frame.pack()
inc = Button(frame, text='+1', command=self.increase)
dec = Button(frame, text='-1', command=self.decrease)
self.canvas.bind("", self.clickIncrease)
self.canvas.bind("", self.clickDecrease)
self.canvas.bind("", self.clickIncrease)
self.canvas.bind("", self.clickDecrease)
self.canvas.focus_set()
inc.grid(row=1, column=1)
dec.grid(row=1, column=2)
self.window.mainloop() # Create an event loop
def increase(self):
self.sides += 1
self.canvas.reDraw(self.sides)
def decrease(self):
self.sides -= 1
self.canvas.reDraw(self.sides)
def clickIncrease(self,event):
self.increase()
def clickDecrease(self,event):
self.decrease()
MainClass()
