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# 9.20 (Geometry: inside a circle?) Write a program that draws a fixed circle centered at
# (100, 60) with radius 50. Whenever the mouse is moved while the left button is
# pressed, display the message indicating whether the mouse pointer is inside the
# circle, as shown in Figure 9.31.
from tkinter import * # Import tkinter
width = 240
height = 120
class MainGUI:
def __init__(self):
window = Tk() # Create a window
window.title("Inside the circle?") # Set a title
self.canvas = Canvas(window, bg="white", width=width, height=height)
self.canvas.pack()
self.canvas.create_oval(100 - 50, 60 - 50, 100 + 50, 60 + 50, tags="circle")
self.canvas.bind("", self.isInside)
window.mainloop() # Create an event loop
def isInside(self, event):
self.canvas.delete("text")
if isInsideCircle(100, 60, 50, event.x, event.y):
self.canvas.create_text(event.x, event.y - 5,
text="Mouse pointer is in the circle", tags="text")
else:
self.canvas.create_text(event.x, event.y - 5,
text="Mouse pointer is not in the circle", tags="text")
def isInsideCircle(xCenter, yCenter, radius, x, y):
return distance(xCenter, yCenter, x, y) <= radius
def distance(xCenter, yCenter, x, y):
return ((xCenter - x) * (xCenter - x) + (yCenter - y) * (yCenter - y)) ** 0.5;
MainGUI()
