How Can I Render HTML Markup Using Swing's `drawString` Method?

Swing HTML Draw String: Beyond the Basic

In Swing, the drawString method is commonly used to display text on components. However, it may fall short when attempting to render HTML markup. Let's delve into a workaround to overcome this limitation.

The Draw String Dilemma

As illustrated in the provided sample code, drawString treats HTML tags as plain text. This behavior can be frustrating when you need to format text using HTML elements.

A Flyweight Renderer Approach

Instead of relying solely on drawString, consider using a flyweight renderer approach:

• Create a component to handle HTML rendering, such as a JLabel.
• Use a CellRendererPane to control the painting and caching of the component.

By utilizing this technique, you can specify HTML tags in your JLabel and control its rendering location and style.

A Simplified Flyweight Renderer Example

The code snippet below demonstrates a simplified implementation of a flyweight renderer:

import javax.swing.*;
import javax.swing.plaf.ComponentUI;
import java.awt.*;

public class FlyweightRenderer {

    private JLabel renderer = new JLabel("<b>Hello World</b>");
    private CellRendererPane crp = new CellRendererPane();
    private Component parent;

    public FlyweightRenderer(Component parent) {
        this.parent = parent;
    }

    public void render(Graphics g, int x, int y) {
        crp.paintComponent(g, renderer, parent, x, y,
                renderer.getPreferredSize().width,
                renderer.getPreferredSize().height);
    }
}

In the paintComponent method of your custom component, you can use the flyweight renderer to draw the HTML-formatted text:

@Override
protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    flyweightRenderer.render(g, 10, 10);
}

Conclusion

This flyweight renderer approach enables you to render HTML-formatted text within Swing components. By manipulating the rendering location and style of the JLabel, you can achieve the desired visual effects.

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