Building a paint application with Python and Tkinter

Last update on April 25 2025 12:53:14 (UTC/GMT +8 hours)

Write a Python program to design a paint application using Tkinter where the user can draw on the Canvas widget with different colors.

Sample Solution:

Python Code:

import tkinter as tk

# Global variables to track drawing state
drawing = False
last_x, last_y = None, None
pen_color = "black"

def start_drawing(event):
    global drawing
    drawing = True
    global last_x, last_y
    last_x, last_y = event.x, event.y

def stop_drawing(event):
    global drawing
    drawing = False

def draw(event):
    global last_x, last_y

    if drawing:
        x, y = event.x, event.y
        canvas.create_line((last_x, last_y, x, y), fill=pen_color, width=2)
        last_x, last_y = x, y

def change_color(new_color):
    global pen_color
    pen_color = new_color

root = tk.Tk()
root.title("Paint Application")

canvas = tk.Canvas(root, width=400, height=300, bg="white")
canvas.pack()

colors = ["red", "green", "blue", "black", "orange", "pink"]

color_buttons = []
for color in colors:
    color_buttons.append(tk.Button(root, text=color.capitalize(), bg=color, command=lambda c=color: change_color(c)))
    color_buttons[-1].pack(side=tk.LEFT)

canvas.bind("<Button-1>", start_drawing)
canvas.bind("<ButtonRelease-1>", stop_drawing)
canvas.bind("<B1-Motion>", draw)

root.mainloop()

Explanation:

In the exercise above -

Import the Tkinter library (tkinter).
Define global variables to track drawing state (drawing), last position ('last_x', 'last_y'), and pen color ('pen_color').
Define functions to handle drawing: start_drawing(event): Sets drawing to True and records the initial mouse position. stop_drawing(event): Sets drawing to False when the mouse button is released.
draw(event): Draws lines on the canvas if drawing is True, connecting the last recorded position to the current mouse position.
Create the main "Tkinter" window (root) with the title "Paint Application."
Create a canvas (canvas) for drawing with a white background.
Define a list of color names (colors) for the pen.
Create color buttons for each color in the list, associating each button with the change_color() function to change the pen color.
Bind mouse events to the canvas:
The main event loop, root.mainloop(), starts the Tkinter application.

Output:

Flowchart:

Go to:

Previous: Creating a Blue rectangle on a Tkinter canvas widget.
Next: Building a drawing program with Python and Tkinter.

Python Code Editor: