The following application I have created is used to demonstrate multiple windows in tkinter. The main problem is that none of the Entry
controls, neither in the bmi-calculator or the converter, accept the values in the entry boxes - they get a ValueError
when I do a calculation.
from tkinter import *
from tkinter import ttk
from tkinter import messagebox
class App1(ttk.Frame):
def createWidgets(self):
#text variables
self.i_height = StringVar()
self.i_weight = StringVar()
self.o_bmi = StringVar()
#labels
self.label1 = ttk.Label(self, text="Enter your weight:").grid(row=0, column=0, sticky=W)
self.label2 = ttk.Label(self, text="Enter your height:").grid(row=1, column=0, sticky=W)
self.label3 = ttk.Label(self, text="Your BMI is:").grid(row=2, column=0, sticky=W)
#text boxes
self.textbox1 = ttk.Entry(self, textvariable=self.i_weight).grid(row=0, column=1, sticky=E)
self.textbox2 = ttk.Entry(self, textvariable=self.i_height).grid(row=1, column=1, sticky=E)
self.textbox3 = ttk.Entry(self, textvariable=self.o_bmi).grid(row=2, column=1, sticky=E)
#buttons
self.button1 = ttk.Button(self, text="Cancel/Quit", command=self.quit).grid(row=3, column=1, sticky=E)
self.button1 = ttk.Button(self, text="Ok", command=self.calculateBmi).grid(row=3, column=2, sticky=E)
def calculateBmi(self):
try:
self.weight = float(self.i_weight.get())
self.height = float(self.i_height.get())
self.bmi = self.weight / self.height ** 2.0
self.o_bmi.set(self.bmi)
except ValueError:
messagebox.showinfo("Error", "You can only use numbers.")
finally:
self.i_weight.set("")
self.i_height.set("")
def __init__(self, master=None):
ttk.Frame.__init__(self, master)
self.grid()
self.createWidgets()
class App2(ttk.Frame):
def create_widgets(self):
"""Create the widgets for the GUI"""
#1 textbox (stringvar)
self.entry= StringVar()
self.textBox1= ttk.Entry(self, textvariable=self.entry).grid(row=0, column=1)
#5 labels (3 static, 1 stringvar)
self.displayLabel1 = ttk.Label(self, text="feet").grid(row=0, column=2, sticky=W)
self.displayLabel2 = ttk.Label(self, text="is equivalent to:").grid(row=1, column=0)
self.result= StringVar()
self.displayLabel3 = ttk.Label(self, textvariable=self.result).grid(row=1, column=1)
self.displayLabel4 = ttk.Label(self, text="meters").grid(row=1, column=2, sticky=W)
#2 buttons
self.quitButton = ttk.Button(self, text="Quit", command=self.quit).grid(row=2, column=1, sticky=(S,E))
self.calculateButton = ttk.Button(self, text="Calculate", command=self.convert_feet_to_meters).grid(row=2, column=2, sticky=(S,E))
def convert_feet_to_meters(self):
"""Converts feet to meters, uses string vars and converts them to floats"""
self.measurement = float(self.entry.get())
self.meters = self.measurement * 0.3048
self.result.set(self.meters)
def __init__(self, master=None):
ttk.Frame.__init__(self, master)
self.grid()
self.create_widgets()
def button1_click():
root = Tk()
app = App1(master=root)
app.mainloop()
def button2_click():
root = Tk()
app = App2(master=root)
app.mainloop()
def main():
window = Tk()
button1 = ttk.Button(window, text="bmi calc", command=button1_click).grid(row=0, column=1)
button2 = ttk.Button(window, text="feet conv", command=button2_click).grid(row=1, column=1)
window.mainloop()
if __name__ == '__main__':
main()
How can I fix this, but still maintaining the class structure and the use of python3? BTW - Anything similar to C#'s form1.Show()
?
You have to convert the StringVar()
to an integer/float or use IntVar()
or DoubleVar()
There are other problems as well. Statements like the following return "None" since it is a grid()
object and not a Label()
object:
self.label1 = ttk.Label(self, text="Enter your weight:").grid(row=0, column=0, sticky=W)
I think you will also have problems with two Tk()
windows open at the same time. Use Toplevel()
or separate frames instead.
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