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.