Build a Basic Paint App in Python

Last update on October 15 2024 12:12:37 (UTC/GMT +8 hours)

Basic Paint App: Create a paint application with basic drawing tools and colors.

Input values:

User interacts with the paint application by selecting drawing tools, choosing colors, and drawing on the canvas.

Output value:

A visual representation of the canvas with the drawings created by the user using the tools and colors the user has chosen.

Example:

Input values:
1. Select a drawing tool: Pen
- User selects the pen tool for freehand drawing.
Output value:
Paint application switches to pen tool mode for drawing.
Input values:
2. Choose a color: Red
- User selects the color red for drawing.
Output value:
Selected color changes to red for drawing.
Input values:
3. Draw on the canvas
- User draws a freehand sketch on the canvas.
Output value:
Visual representation updates to display the freehand sketch drawn by the user in red color.
Input values:
4. Select the drawing tool: Rectangle
- User selects the rectangle tool for drawing shapes.
Output value:
Paint application switches to rectangle tool mode for drawing.
Input values:
5. Choose a color: Blue
- User selects blue for drawing rectangles.
Output value:
Selected color changes to blue for rectangles.
Input values:
6. Draw a rectangle on the canvas
- User draws a rectangle shape on the canvas.
Output value:
Visual representation updates to display the rectangle shape drawn by the user in blue color.
Input values:
7. Erase the drawing.
- User selects the eraser tool to erase part of the drawing.
Output value:
Visual representation updates to erase part of the drawing using the eraser tool.

Solution: Using tkinter for a Simple GUI Paint App

This solution uses tkinter, the standard GUI library in Python, to create a basic paint application. The app allows users to select different drawing tools, choose colors, and draw shapes on a canvas.

Code:

import tkinter as tk  # Import tkinter for GUI components
from tkinter import colorchooser  # Import colorchooser for color selection

class PaintApp:
    def __init__(self, root):
        """
        Initializes the Paint App with a canvas and drawing tools.
        Args:
            root: The main window of the application.
        """
        self.root = root
        self.root.title("Basic Paint App")

        # Create a canvas widget where the drawing will take place
        self.canvas = tk.Canvas(self.root, bg="white", width=600, height=400)
        self.canvas.pack()

        # Set initial color and tool
        self.color = "black"
        self.tool = "pen"

        # Create buttons for color, pen, rectangle, and eraser
        self.create_tools()

        # Bind mouse events to canvas methods
        self.canvas.bind("", self.paint)  # For drawing with left mouse button
        self.canvas.bind("", self.reset)  # Reset after drawing

    def create_tools(self):
        """Creates buttons for choosing colors, drawing tools, and clearing the canvas."""
        tools_frame = tk.Frame(self.root)
        tools_frame.pack()

        # Button for selecting pen tool
        pen_button = tk.Button(tools_frame, text="Pen", command=lambda: self.select_tool("pen"))
        pen_button.pack(side="left")

        # Button for selecting rectangle tool
        rect_button = tk.Button(tools_frame, text="Rectangle", command=lambda: self.select_tool("rectangle"))
        rect_button.pack(side="left")

        # Button for selecting eraser
        erase_button = tk.Button(tools_frame, text="Eraser", command=lambda: self.select_tool("eraser"))
        erase_button.pack(side="left")

        # Button for color picker
        color_button = tk.Button(tools_frame, text="Color", command=self.choose_color)
        color_button.pack(side="left")

    def select_tool(self, tool):
        """Sets the current drawing tool."""
        self.tool = tool

    def choose_color(self):
        """Opens a color chooser dialog and sets the selected color."""
        self.color = colorchooser.askcolor()[1]

    def paint(self, event):
        """Draws on the canvas based on the selected tool and color."""
        if self.tool == "pen":
            # Draws a line for the pen tool with the selected color
            self.canvas.create_line(event.x, event.y, event.x + 1, event.y + 1, fill=self.color)
        elif self.tool == "rectangle":
            # Draws a rectangle outline with the selected color
            self.canvas.create_rectangle(event.x, event.y, event.x + 50, event.y + 30, outline=self.color)
        elif self.tool == "eraser":
             # Draws with "white" color to simulate erasing by drawing over existing elements
            self.canvas.create_line(event.x, event.y, event.x + 10, event.y + 10, fill="white", width=10)


    def reset(self, event):
        """Resets the drawing process."""
        pass  # Can add functionality here if needed

# Initialize the application
root = tk.Tk()
app = PaintApp(root)
root.mainloop()

Output:

Explanation:

Initializes a tkinter window with a canvas for drawing.
Provides buttons to switch between drawing tools and color selection.
Uses mouse events to handle drawing operations on the canvas.