


JTextFields on Top of Active Drawing on JPanel: Threading Issues
Question:
Can Swing construct a multi-buffered rendering environment where Swing user interface elements can be added on top of it?
In this scenario, a red rectangle animates on a green background. The background remains static, so it's rendered onto a BufferedImage and redrawn only for the necessary portions to clear the rectangle's previous location.
However, adding a JTextField leads to repaint fails on cursor blinks.
Answer:
The key to this issue lies in JPanel's paintComponent() method.
Solution:
To fix this, invoke the superclass's method and erase the old drawing:
@Override protected void paintComponent(Graphics g) { super.paintComponent(g); int width = this.getWidth(); int height = this.getHeight(); g.setColor(Color.black); g.fillRect(0, 0, width, height); ... }
Additional Notes:
- Setting the background color in the constructor eliminates the need for filling the panel in paintComponent().
- Using super.paintComponent() ensures that text fields function correctly.
- Note that super.paintComponent() updates the delegate's background color, which can be avoided by setting setOpaque(false).
Improved Code:
import java.awt.Color; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.GraphicsConfiguration; import java.awt.GraphicsEnvironment; import java.awt.Rectangle; import java.awt.Transparency; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.ComponentAdapter; import java.awt.event.ComponentEvent; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import java.awt.image.BufferedImage; import java.util.Random; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JTextField; import javax.swing.Timer; /** @see http://stackoverflow.com/questions/3256941 */ public class AnimationTest extends JPanel implements ActionListener { private static final int WIDE = 640; private static final int HIGH = 480; private static final int RADIUS = 25; private static final int FRAMES = 24; private final Timer timer = new Timer(20, this); private final Rectangle rect = new Rectangle(); private BufferedImage background; private int index; private long totalTime; private long averageTime; private int frameCount; public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { @Override public void run() { new AnimationTest().create(); } }); } private void create() { JFrame f = new JFrame("AnimationTest"); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.add(this); f.pack(); f.setLocationRelativeTo(null); f.setVisible(true); timer.start(); } public AnimationTest() { super(true); this.setOpaque(false); this.setPreferredSize(new Dimension(WIDE, HIGH)); this.addMouseListener(new MouseHandler()); this.addComponentListener(new ComponentHandler()); } @Override protected void paintComponent(Graphics g) { long start = System.nanoTime(); int w = this.getWidth(); int h = this.getHeight(); g.drawImage(background, 0, 0, this); double theta = 2 * Math.PI * index++ / 64; g.setColor(Color.blue); rect.setRect( (int) (Math.sin(theta) * w / 3 + w / 2 - RADIUS), (int) (Math.cos(theta) * h / 3 + h / 2 - RADIUS), 2 * RADIUS, 2 * RADIUS); g.fillOval(rect.x, rect.y, rect.width, rect.height); g.setColor(Color.white); if (frameCount == FRAMES) { averageTime = totalTime / FRAMES; totalTime = 0; frameCount = 0; } else { totalTime += System.nanoTime() - start; frameCount++; } String s = String.format("%1.3f", averageTime / 1000000d); g.drawString(s, 5, 16); } @Override public void actionPerformed(ActionEvent e) { this.repaint(); } private class MouseHandler extends MouseAdapter { @Override public void mousePressed(MouseEvent e) { super.mousePressed(e); JTextField field = new JTextField("test"); Dimension d = field.getPreferredSize(); field.setBounds(e.getX(), e.getY(), d.width, d.height); add(field); } } private class ComponentHandler extends ComponentAdapter { private final GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment(); private final GraphicsConfiguration gc = ge.getDefaultScreenDevice().getDefaultConfiguration(); private final Random r = new Random(); @Override public void componentResized(ComponentEvent e) { super.componentResized(e); int w = getWidth(); int h = getHeight(); background = gc.createCompatibleImage(w, h, Transparency.OPAQUE); Graphics2D g = background.createGraphics(); g.clearRect(0, 0, w, h); g.setColor(Color.green.darker()); for (int i = 0; i
The above is the detailed content of How Can I Overlay Swing Components (e.g., JTextFields) on a Multi-Buffered Animated JPanel Without Repaint Issues?. For more information, please follow other related articles on the PHP Chinese website!

The article discusses using Maven and Gradle for Java project management, build automation, and dependency resolution, comparing their approaches and optimization strategies.

The article discusses creating and using custom Java libraries (JAR files) with proper versioning and dependency management, using tools like Maven and Gradle.

The article discusses implementing multi-level caching in Java using Caffeine and Guava Cache to enhance application performance. It covers setup, integration, and performance benefits, along with configuration and eviction policy management best pra

The article discusses using JPA for object-relational mapping with advanced features like caching and lazy loading. It covers setup, entity mapping, and best practices for optimizing performance while highlighting potential pitfalls.[159 characters]

Java's classloading involves loading, linking, and initializing classes using a hierarchical system with Bootstrap, Extension, and Application classloaders. The parent delegation model ensures core classes are loaded first, affecting custom class loa

This article explains Java's Remote Method Invocation (RMI) for building distributed applications. It details interface definition, implementation, registry setup, and client-side invocation, addressing challenges like network issues and security.

This article details Java's socket API for network communication, covering client-server setup, data handling, and crucial considerations like resource management, error handling, and security. It also explores performance optimization techniques, i

This article details creating custom Java networking protocols. It covers protocol definition (data structure, framing, error handling, versioning), implementation (using sockets), data serialization, and best practices (efficiency, security, mainta


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment

Atom editor mac version download
The most popular open source editor

Safe Exam Browser
Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

SublimeText3 Linux new version
SublimeText3 Linux latest version

SublimeText3 Chinese version
Chinese version, very easy to use