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Develop GUI application with Python Tkinter

3 min read

There are at least two reasons that you should develop GUI-based application with Python. GUI applications developed with Python are cross-platform, which you can run them on Mac, Linux and Windows and Python is easy to learn with much simpler syntax than any other programming languages.

Tkinter is the standard GUI library for Python and it is easy to use. Basically, to create a GUI application main window, just need a few lines as follows

from tkinter import Tk
window = Tk()
window.mainloop()

  • Line 1 – import the Tk, which is the GUI window from tkinter
  • Line 2 – create an instance of Tk()
  • Line 3 – and then call the mainloop() method of Tk, a window will be presented as shown above
  • Here is an example of a simple application, which consists of a container, which inherits from the main container of tkinter librarry, Frame and has two buttons in the container, which the first button will show a message when it’s clicked and the second button will quit the application when it’s clicked. As shown in the image below:

    from tkinter import Button, Frame, Tk, messagebox as mbox
    from datetime import datetime
    class MyGuiApp(Frame) :
    	
    	def __init__(self, window=None): 
    		super().__init__(window)
    		self.window = window
    		self.pack(expand=True, fill='both')
    		self.createButtons()
    
    	def createButtons(self): 
    		...
    	def showMessageBox(self):
    		... 
    

  • Line 1 – we need to import the components we need in Tkinter library, which are Button, Frame, Tk and the messagebox
  • Line 2 – import the datetime from datetime library as we need this in the showMessageBox() method to show the current date and time
  • From line 5 to line 10, the special constructor init() method, which we pass in the parent widget window and assign it an instance variable and we have some setup here by calling method pack(), which add itself to the parent with the parameters, expand and fill set to true and both respectively, meaning to expand it to fill up the space. And then call the createButtons() method to layout the buttons.
  • Details of the createButtons() and showMessageBox() methods are as follows:

    The createButtons() method is which we layout the two buttons.

    def createButtons(self): 
       self.actionButton = Button(self, text = 'Click Me To Show Message')
       self.actionButton["command"] = self.showMessageBox
       self.actionButton.pack()
       self.actionButton.place(x=50, y=50, width=200, height = 30)
    		
       self.quitButton = Button(self, text='Quit', fg='red')
       self.quitButton["command"] = self.window.destroy
       self.quitButton.pack()
       self.quitButton.place(x=75, y=120, width=150, height = 30)

    The first button, create an instance variable actionButton, set its text label as ‘Click Me To Show Message’ and command, which is what the method showMessageBox() will be called when it’s clicked. And then call the pack() to add it to the parent widget and then we use the place() method to place it in a specific position.

    The same goes to the second button, quitButton, the little difference is its command set to self.window.destroy, which will quit the application when it’s clicked.

    The showMessageBox() method basically displays the message and shows the current date and time

    def showMessageBox(self):
       now = datetime.now()
       date = now.strftime("%d/%b/%Y")
       time = now.strftime("%H:%M:%S")
       mbox.showinfo("New Message!", "Hello World! Today's Date is "+ date + ", current time is "+ time)

    Finally, we have a self-contained application Frame, we need to create a window and add the frame to it to show it.

    window = Tk()
    window.geometry('300x250') 
    window.configure(bg='grey')
    window.title('My First Python GUI App Example')
    app = MyGuiApp(window=window)
    window.mainloop()

    The above lines of code, create a window object, set its size (300×250), background color (grey) and title and runs the event loop to listen for events such as button clicks.

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    Posted on December 5, 2020 By Christopher Chee

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