Python Check Buttons

Question

I'm using python 3.5.1 for a Programming with Python class.

The assignment is:

(Select geometric figures) Write a program that draws a rectangle or an oval, as shown in figure 9.23. The user selects a figure from a radio button and specifies whether is it filled by selecting a check button.

from tkinter import *

class geometricFig:
    def __init__(self):
        window = Tk()
        window.title("Geometric Figures") 

        self.canvas = Canvas(window, width = 200, height = 100, bg = "white")
        self.canvas.pack()

        frame = Frame(window)
        frame.pack()
        self.v1 = StringVar()
        rbRect = Radiobutton(frame, text = "Rectangle", command = self.displayRect, variable = self.v1, value = '1')
        rbOval = Radiobutton(frame, text = "Oval", command = self.displayOval, variable = self.v1, value = '2')
        self.v2 = StringVar()
        cbtFill = Checkbutton(frame, text = "Fill", command = self.processFill, variable = self.v2)

        rbRect.grid(row = 1, column = 1)
        rbOval.grid(row = 1, column = 2)
        cbtFill.grid(row = 1, column = 3)

        window.mainloop()

   def displayRect(self):
       self.canvas.delete("rect", "oval")
       self.canvas.create_rectangle(10, 10, 190, 90, tags = "rect")
   def displayOval(self):
       self.canvas.delete("rect", "oval")
       self.canvas.create_oval(10, 10, 190, 90, tags = "oval")
   def processFill(self):
       if self.v1.get() == '1':
           self.canvas.delete("rect", "oval")
           self.canvas.create_rectangle(10, 10, 190, 90, tags = "rect", fill = "red")
       elif self.v1.get() == '2':
           self.canvas.delete("rect", "oval")
           self.canvas.create_oval(10, 10, 190, 90, tags = "oval", fill = "red")
       else:
           self.canvas.delete("rect", "oval")

geometricFig()

What I was able to do was create the window and have the radio buttons draw the rectangle and oval. I was also able to implement the check button to draw a filled rectangle or oval, depending on which radio button was ticked.

However, when I build the program, it starts the program with all radio and check buttons filled in. I have to uncheck everything for the program to start working properly. Also, when I uncheck the fill button, it does not unfill the shapes, but leaves a filled shape on the canvas.

What can I do to fix these problems?

Kevin · Accepted Answer · 2016-01-21 18:58:59Z

Try explicitly setting values for your StringVars before you enter the mainloop.

self.v1.set("1")
self.v2.set("0")

Unchecking the "fill" button doesn't cause a hollow shape to be drawn, because hollow shapes are only drawn during displayRect and displayOval, but you aren't calling either one of those from within processFill. I suggest just having a single function that serves as the callback for all three of your widgets.

    self.v1 = StringVar()
    rbRect = Radiobutton(frame, text = "Rectangle", command = self.optionChanged, variable = self.v1, value = '1')
    rbOval = Radiobutton(frame, text = "Oval", command = self.optionChanged, variable = self.v1, value = '2')
    self.v2 = StringVar()
    cbtFill = Checkbutton(frame, text = "Fill", command = self.optionChanged, variable = self.v2)

#later on in the class definition...
def optionChanged(self):
    self.canvas.delete("rect", "oval")
    color = "white" if self.v2.get() == "0" else "red"
    if self.v1.get() == '1':
        self.canvas.create_rectangle(10, 10, 190, 90, tags = "rect", fill = color)
    else:
       self.canvas.create_oval(10, 10, 190, 90, tags = "oval", fill = color)

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