Drawing Circles with Canvas - Python GUI Tutorial

In the following, you will learn how to work with the Canvas in Python's GUI library Tkinter. This Tutorial guides you through the process of creating a small program where you display a circle on the canvas. Working with the canvas is not only a fundamental skill in GUI programming but also a fun way to interact creatively with code.

Main Insights

• A canvas serves as a "canvas" for displaying shapes and graphics.
• With Tkinter, you can create windows, canvases, and buttons.
• Colors can easily be specified using hexadecimal codes.
• Lambda functions allow you to pass parameters to functions, making programming more flexible.

Step-by-Step Guide

To understand the process, we will work on a simple example where we draw a circle and change its color through button clicks.

Step 1: Create the Window

First, you will create a window where the canvas will be placed. You can also set a title for the window.

root = tk.Tk() root.title("Circle on a Canvas")

Step 2: Set Background Color

You should assign a background color to your window. In our case, we will use pure white, defined by its hexadecimal code #FFFFFF.

Step 3: Create a Canvas

Now you create the canvas, determining its size (width and height). In this example, it should be 200 pixels.

Step 4: Drawing the Circle

Now we can start drawing the circle on our canvas. This is done through the create_oval method, which defines the position as well as the color of the circle. A circle in this case has the same X and Y values for the start and end positions.

Step 5: Add Buttons for Color Change

To change the color of the circle, we will add three buttons, each representing a different color (red, yellow, green). First, you create the area for the buttons.

Step 6: Create Buttons

For each button, you can use the Button class. A command is set that changes the color of the circle when the button is pressed.

red_button = tk.Button(button_frame, text="Red", command=lambda: draw_circle("red")) red_button.grid(row=0, column=0)

Step 7: Add More Buttons

Repeat the previous step for the colors yellow and green.

green_button = tk.Button(button_frame, text="Green", command=lambda: draw_circle("green")) green_button.grid(row=0, column=2)

Step 8: Start the Application

Finally, you need to start the main loop of Tkinter so that the window is displayed and responds to user interactions.

Summary - Python Canvas Programming: A Step-by-Step Tutorial

Creating GUI elements with Python and Tkinter can be both an interesting and educational experience. In this tutorial, you have learned how to create a simple window with a canvas and interactive buttons to work creatively and deepen programming skills.