Python Tkinter canvas shape editor: Drawing and manipulating shapes

Python Tkinter Canvas and Graphics: Exercise-13 with Solution

Write a Python program that allows the user to draw and manipulate geometric shapes (e.g., rectangle, circle) on the "Canvas" using Tkinter.

Sample Solution:

Python Code:

import tkinter as tk
class ShapeEditorApp:
    def __init__(self, root):
        self.root = root
        self.root.title("Shape Editor")

        # Create Canvas widget
        self.canvas = tk.Canvas(root, bg="white")
        self.canvas.pack(fill=tk.BOTH, expand=True)

        # Initialize shape variables
        self.current_shape = None
        self.start_x = None
        self.start_y = None
        self.current_shape_item = None

        # Create buttons
        self.rect_button = tk.Button(root, text="Rectangle", command=self.create_rectangle)
        self.circle_button = tk.Button(root, text="Circle", command=self.create_circle)
        self.clear_button = tk.Button(root, text="Clear", command=self.clear_canvas)

        # Bind mouse events
        self.canvas.bind("<Button-1>", self.start_draw)
        self.canvas.bind("<B1-Motion>", self.draw_shape)
        self.canvas.bind("<ButtonRelease-1>", self.stop_draw)

    def create_rectangle(self):
        self.current_shape = "rectangle"

    def create_circle(self):
        self.current_shape = "circle"

    def start_draw(self, event):
        self.start_x = event.x
        self.start_y = event.y
        if self.current_shape == "rectangle":
            self.current_shape_item = self.canvas.create_rectangle(
                self.start_x, self.start_y, self.start_x, self.start_y, outline="black"
        elif self.current_shape == "circle":
            self.current_shape_item = self.canvas.create_oval(
                self.start_x, self.start_y, self.start_x, self.start_y, outline="black"

    def draw_shape(self, event):
        if self.current_shape_item:
            x, y = event.x, event.y
            self.canvas.coords(self.current_shape_item, self.start_x, self.start_y, x, y)

    def stop_draw(self, event):
        self.current_shape_item = None

    def clear_canvas(self):

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


In the exercise above -

  1. Import the Tkinter library (tkinter).
  2. Define the ShapeEditorApp class:
    • The constructor init initializes the application and creates the main window (root).
    • The main window's title is set to "Shape Editor."
  3. Create a Canvas widget:
    • A "Canvas" widget is created within the main window to serve as the drawing area. It's configured with a white background and expand to fill the available space.
  4. Initialize shape-related variables:
    • current_shape stores the currently selected shape ("rectangle" or "circle").
    • start_x and start_y store the starting coordinates when drawing shapes.
    • current_shape_item stores the currently drawn shape as a Canvas item.
  5. Create buttons:
    • Three buttons are created: "Rectangle," "Circle," and "Clear."
    • The buttons are associated with functions (create_rectangle, create_circle, and clear_canvas) that will be called when the buttons are clicked.
    • The buttons are packed (placed) on the main window in a horizontal layout using the pack method.
  6. Bind mouse events:
    • Three mouse events are bound to the Canvas widget:
      • <Button-1> is bound to the start_draw method when the left mouse button is clicked.
      • <B1-Motion> is bound to the draw_shape method when the left mouse button is moved.
      • <ButtonRelease-1> is bound to the stop_draw method when the left mouse button is released.
  7. Define functions for button actions:
    • create_rectangle and create_circle set the current_shape variable to "rectangle" or "circle" when the respective buttons are clicked.
    • start_draw initializes the drawing process by storing the starting coordinates and creating an initial shape (either a rectangle or a circle) at the starting point.
    • draw_shape updates the shape's coordinates as the mouse is moved, allowing the user to draw the shape.
    • stop_draw resets the current_shape_item to None when the drawing process is complete.
    • clear_canvas deletes all items on the "Canvas" to clear the drawing.
  8. Create the main application window:
    • The root window is created using tk.Tk().
    • An instance of the "ShapeEditorApp" class is created, which initializes the GUI and sets up the event handlers.
  9. Start the Tkinter main loop.


Tkinter: Python Tkinter canvas shape editor: Drawing and manipulating shapes. Part-1
Tkinter: Python Tkinter canvas shape editor: Drawing and manipulating shapes. Part-2


Flowchart: Python Tkinter canvas shape editor: Drawing and manipulating shapes.
Flowchart: Python Tkinter canvas shape editor: Drawing and manipulating shapes.
Flowchart: Python Tkinter canvas shape editor: Drawing and manipulating shapes.

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