Drawing Rectangles in a Permanent Manner

In your JPanel implementation, rectangles disappear because the paint() method overwrites previous drawings. To prevent this, we modify our approach:

Using a BufferedImage as Painting Surface

Instead of directly drawing on the JPanel, we use a BufferedImage (canvasImage) as our painting surface. This allows us to modify the image permanently without affecting previous drawings.

Customized paint() Method

Here's a modified paint() method that uses canvasImage for drawing:

@Override
public void paint(Graphics g) {
    super.paint(g); // Handle inherited painting tasks

    Graphics2D bg = (Graphics2D) g;
    bg.drawImage(canvasImage, 0, 0, this);
}

Creating the BufferedImage and Setting It Up

Initialize canvasImage in your JPanel constructor like so:

canvasImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

And set its graphics context for drawing:

Graphics2D cg = canvasImage.createGraphics();
cg.setColor(Color.WHITE);
cg.fillRect(0, 0, width, height);

Drawing Rectangles on the BufferedImage

Now, your DrawRect() method can modify canvasImage directly:

public void DrawRect(int x, int y, int size, Color c) {
    Graphics2D cg = canvasImage.createGraphics();
    cg.setColor(c);
    cg.fillRect(x, y, size, size);
}

Additional Features

This approach provides several benefits:

• Persistent Draw: Rectangles are permanently drawn on the BufferedImage.
• Optimized Drawing: Instead of repainting the entire JPanel, only the modified portions of the image are updated.
• Supports Undo/Redo (Potential): By keeping track of changes to the image, you can implement undo/redo functionality.