Building a whiteboard application with Python and Tkinter

Python Tkinter Canvas and Graphics: Exercise-5 with Solution

Write a Python program that implements a Tkinter-based whiteboard application where users can draw, erase, and clear the canvas.

Sample Solution:

Python Code:

import tkinter as tk

class WhiteboardApp:
    def __init__(self, root):
        self.root = root
        self.root.title("Whiteboard")

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

        self.draw_button = tk.Button(root, text="Draw", command=self.start_draw)
        self.draw_button.pack(side=tk.LEFT)

        self.erase_button = tk.Button(root, text="Erase", command=self.start_erase)
        self.erase_button.pack(side=tk.LEFT)

        self.clear_button = tk.Button(root, text="Clear", command=self.clear_canvas)
        self.clear_button.pack(side=tk.LEFT)

        self.drawing = False
        self.erasing = False
        self.last_x, self.last_y = None, None

        self.canvas.bind("<Button-1>", self.start_action)
        self.canvas.bind("<B1-Motion>", self.draw_or_erase)
        self.canvas.bind("<ButtonRelease-1>", self.stop_action)

    def start_action(self, event):
        if self.drawing:
            self.start_draw(event)
        elif self.erasing:
            self.start_erase(event)

    def stop_action(self, event):
        if self.drawing:
            self.stop_draw(event)
        elif self.erasing:
            self.stop_erase(event)

    def start_draw(self, event=None):
        self.drawing = True
        self.erasing = False
        if event:
            self.last_x, self.last_y = event.x, event.y

    def stop_draw(self, event=None):
        self.drawing = False
        self.erasing = False

    def start_erase(self, event=None):
        self.erasing = True
        self.drawing = False
        if event:
            self.last_x, self.last_y = event.x, event.y

    def stop_erase(self, event=None):
        self.erasing = False
        self.drawing = False

    def draw_or_erase(self, event):
        if self.drawing:
            x, y = event.x, event.y
            self.canvas.create_line(self.last_x, self.last_y, x, y, fill="black", width=2)
            self.last_x, self.last_y = x, y
        elif self.erasing:
            x, y = event.x, event.y
            self.canvas.create_rectangle(x - 5, y - 5, x + 5, y + 5, fill="white", outline="white")

    def clear_canvas(self):
        self.canvas.delete("all")

if __name__ == "__main__":
    root = tk.Tk()
    app = WhiteboardApp(root)
    root.mainloop()

Explanation:

In the exercise above -

• Import the Tkinter library (tkinter).
• Create a WhiteboardApp class to manage the whiteboard application.
• Users can switch between drawing and erasing modes by clicking the "Draw" and "Erase" buttons.
• The clear_canvas method clears the entire canvas.
• Mouse events track drawing and erasing actions.
• The canvas is set up to capture mouse button events and motion events.
• The main event loop, root.mainloop(), starts the Tkinter application.

Output:

Flowchart:

Python Code Editor:

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