Dialogs in Tkinter

In this part of the Tkinter tutorial, we will work with dialogs.

Dialog windows or dialogs are an indispensable part of most modern GUI applications. A dialog is defined as a conversation between two or more persons. In a computer application a dialog is a window which is used to "talk" to the application. A dialog is used to input data, modify data, change the application settings etc. Dialogs are important means of communication between a user and a computer program.

Message boxes

Message boxes are convenient dialogs that provide messages to the user of the application. The message consists of text and image data. Message boxes in Tkinter are located in the tkMessageBox module.

messagebox.py
#!/usr/bin/python3
# -*- coding: utf-8 -*-

"""
ZetCode Tkinter tutorial

In this program, we show various
message boxes.

Author: Jan Bodnar
Last modified: July 2017
Website: www.zetcode.com
"""

from tkinter import Tk, BOTH
from tkinter.ttk import Frame, Button
from tkinter import messagebox as mbox

class Example(Frame):
  
    def __init__(self):
        super().__init__()
         
        self.initUI()
        
        
    def initUI(self):
      
        self.master.title("Message boxes")    
        self.pack()
        
        error = Button(self, text="Error", command=self.onError)
        error.grid(padx=5, pady=5)
        warning = Button(self, text="Warning", command=self.onWarn)
        warning.grid(row=1, column=0)
        question = Button(self, text="Question", command=self.onQuest)
        question.grid(row=0, column=1)
        inform = Button(self, text="Information", command=self.onInfo)
        inform.grid(row=1, column=1)


    def onError(self):
        
        mbox.showerror("Error", "Could not open file")
        
    def onWarn(self):
        
        mbox.showwarning("Warning", "Deprecated function call")
        
    def onQuest(self):
        
        mbox.askquestion("Question", "Are you sure to quit?")
        
    def onInfo(self):
        
        mbox.showinfo("Information", "Download completed")
         

def main():
  
    root = Tk()
    ex = Example()
    root.geometry("300x150+300+300")
    root.mainloop()  


if __name__ == '__main__':
    main()     

We use the grid manager to set up a grid of four buttons. Each of the buttons shows a different message box.

from tkinter import messagebox as mbox

We import the messagebox which has the functions that show dialogs.

error = Button(self, text="Error", command=self.onError)

We create an error button, which calls the onError() method. Inside the method, we show the error message dialog.

def onError(self):

    mbox.showerror("Error", "Could not open file")

In case we pressed the error button, we show the error dialog. We use the showerror() function to show the dialog on the screen. The first parameter of this method is the title of the message box, the second parameter is the actual message.

Error message dialog
Figure: Error message dialog

Color chooser

The color chooser is a dialog for selecting a colour.

colorchooser.py
#!/usr/bin/python3
# -*- coding: utf-8 -*-

"""
ZetCode Tkinter tutorial

In this script, we use colorchooser
dialog to change the background of a frame.

Author: Jan Bodnar
Last modified: July 2017
Website: www.zetcode.com
"""

from tkinter import Tk, Frame, Button, BOTH, SUNKEN
from tkinter import colorchooser

class Example(Frame):
  
    def __init__(self):
        super().__init__()   
         
        self.initUI()
        
        
    def initUI(self):
      
        self.master.title("Color chooser")      
        self.pack(fill=BOTH, expand=1)
        
        self.btn = Button(self, text="Choose Color", 
            command=self.onChoose)
        self.btn.place(x=30, y=30)
        
        self.frame = Frame(self, border=1, 
            relief=SUNKEN, width=100, height=100)
        self.frame.place(x=160, y=30)


    def onChoose(self):
      
        (rgb, hx) = colorchooser.askcolor()
        self.frame.config(bg=hx)
         

def main():
  
    root = Tk()
    ex = Example()
    root.geometry("300x150+300+300")
    root.mainloop()  


if __name__ == '__main__':
    main()  
 

We have a button and a frame. Clicking on the button we show a color chooser dialog. We will change the background color of the frame by selecting a colour from the dialog.

(rgb, hx) = colorchooser.askcolor()
self.frame.config(bg=hx)

The askcolor() function shows the dialog. If we click OK, a tuple is returned. It is a colour value in RGB and hexadecimal format. In the second line we change the background colour of the frame with the returned colour value.

Color chooser
Figure: Color chooser

File dialog

tkFileDialog dialog allows a user to select a file from the filesystem.

filedialog.py
#!/usr/bin/python3
# -*- coding: utf-8 -*-

"""
ZetCode Tkinter tutorial

In this program, we use the
tkFileDialog to select a file from
a filesystem.

author: Jan Bodnar
last modified: July 2017
website: www.zetcode.com
"""

from tkinter import Frame, Tk, BOTH, Text, Menu, END
from tkinter import filedialog 

class Example(Frame):
  
    def __init__(self):
        super().__init__()   
         
        self.initUI()
        
        
    def initUI(self):
      
        self.master.title("File dialog")
        self.pack(fill=BOTH, expand=1)
        
        menubar = Menu(self.master)
        self.master.config(menu=menubar)
        
        fileMenu = Menu(menubar)
        fileMenu.add_command(label="Open", command=self.onOpen)
        menubar.add_cascade(label="File", menu=fileMenu)        
        
        self.txt = Text(self)
        self.txt.pack(fill=BOTH, expand=1)


    def onOpen(self):
      
        ftypes = [('Python files', '*.py'), ('All files', '*')]
        dlg = filedialog.Open(self, filetypes = ftypes)
        fl = dlg.show()
        
        if fl != '':
            text = self.readFile(fl)
            self.txt.insert(END, text)
            

    def readFile(self, filename):

        with open(filename, "r") as f:
            text = f.read()
            
        return text
         

def main():
  
    root = Tk()
    ex = Example()
    root.geometry("300x250+300+300")
    root.mainloop()  


if __name__ == '__main__':
    main()      

In our code example, we use the tkFileDialog dialog to select a file and display its contents in a Text widget.

self.txt = Text(self)

This is the Text widget in which we will show the contents of a selected file.

ftypes = [('Python files', '*.py'), ('All files', '*')]

These are file filters. The first shows only Python files, the other shows all files.

dlg = filedialog.Open(self, filetypes = ftypes)
fl = dlg.show()

The dialog is created and shown on the screen. We get the return value, which is the name of the selected file.

text = self.readFile(fl)

We read the contents of the file.

self.txt.insert(END, text)

The text is inserted into the Text widget.

File dialog
Figure: File dialog

In this part of the Tkinter tutorial, we worked with dialog windows.