我正在使用 Swing 开发一个应用程序。当用户与应用程序交互时，帮助数据可能会在屏幕的封闭部分中可用，当这种情况发生时，我想画一个指向该部分的小箭头。
为此，我扩展了一个 JPanel 并将其添加为应用程序 jframe 的玻璃窗格。自定义玻璃窗格类的名称是 AlertGlassPane。
AlertGlassPane 执行此操作：等待新的帮助数据可用。当发生这种情况并且帮助部分关闭时，它会在屏幕上找到帮助部分的位置，然后在其旁边绘制一个动画箭头。
为了绘制箭头，我扩展了玻璃窗格的 paintComponent 方法。
为了使箭头动画化，我创建了一个每 100 毫秒循环一次的小线程，在玻璃窗格上调用 repaint。
问题：Java 忽略了我的绘图……如果触发动画开始并静止不动，则什么也不会发生。应用程序上不显示任何绘图。
我知道循环正在运行并且正在调用paintComponent，但是自定义绘制没有生效。
但是，如果我将鼠标移到应该呈现箭头的区域上，它确实如此！但就在鼠标移动的时候。如果停止移动鼠标，动画也会停止，并且箭头会在鼠标停止（或离开该区域）之前的最后一个位置冻结。
我尝试了很多东西（例如设置绘图的剪辑区域），但似乎没有任何效果。唯一有效的是当我从paintComponent 内部错误地调用repaint 时。
此时我正在寻找一种方法来与渲染系统通信，即我的玻璃窗格的给定区域需要重新绘制（repaint(x, y, w, h) 不起作用......）。也许将自定义渲染移动到 JLabel，然后将此标签添加到玻璃窗格？我不喜欢这种方法...
在此处发布代码段之前，我将尝试清理代码。这会有帮助吗？
提前致谢！
片段：
package br.com.r4j.test;
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.awt.image.BufferedImage;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.text.JTextComponent;
/**
*
* @author
*/
public class TestGlassPaneAnimation extends JPanel
{
private static TestGlassPaneAnimation gvp = new TestGlassPaneAnimation();
public static void main(String args[])
{
SwingUtilities.invokeLater(new Runnable()
{
@Override
public void run()
{
JFrame f = new JFrame("Anitest in glass");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//f.setResizable(false);
f.setLayout(new GridLayout(5, 3));
f.add(new JLabel("First Name :"));
f.add(new JTextField(20));
f.add(new JLabel("Last Name :"));
f.add(new JTextField(20));
f.add(new JLabel("Phone Number :"));
f.add(new JTextField(20));
f.add(new JLabel("Email:"));
f.add(new JTextField(20));
f.add(new JLabel("Address :"));
f.add(new JTextField(20));
JButton btnStart = new JButton("Click me, please!");
f.add(btnStart);
btnStart.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
gvp.startAnimation();
}
});
f.setGlassPane(gvp);
f.pack();
f.setVisible(true);
gvp.setVisible(true);
}
});
}
private BufferedImage icon;
private boolean animate = false;
private long timeStart = 0;
private Thread thrLastActive = null;
public TestGlassPaneAnimation()
{
setLayout(null);//this is the exception to the rule case a layoutmanager might make setting Jlabel co-ords harder
setOpaque(false);
Icon icon1 = UIManager.getIcon("OptionPane.warningIcon");
int imgW = icon1.getIconWidth();
int imgH = icon1.getIconHeight();
this.icon = ImageUtilities.getBufferedImageOfIcon(icon1, imgW, imgH);
this.animate = false;
}
public void startAnimation()
{
this.animate = true;
this.timeStart = (new Date()).getTime();
if (this.thrLastActive != null)
this.thrLastActive.interrupt();
this.thrLastActive = new Thread(new Runnable()
{
public void run()
{
try
{
while (true)
{
// int x = 250, y = 250;
// int width = 60, height = 60;
Thread.currentThread().sleep(100);
// frmRoot.invalidate();
// repaint(x, y, width, height);
repaint(new Rectangle(x, y, width, height));
// repaint(new Rectangle(10, 10, 2000, 2000));
// repaint();
// paintComponent(getGraphics());
}
}
catch (Exception e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
this.thrLastActive.start();
}
protected void paintComponent(Graphics g)
{
try
{
// enables anti-aliasing
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
java.awt.Composite composite = g2.getComposite();
System.err.println("b1: " + g.getClipBounds());
if (this.animate)
{
long timeSpent = (new Date()).getTime() - timeStart;
int x = 10, y = 150;
int width = 60, height = 60;
float maxAlpha = 0.8f;
x += (-100*Math.sin(5*2*Math.PI*timeSpent/10000)+50)/15;
System.err.println("painting::x: " + x + ", y: " + y + ", sin: " + (Math.sin(6*2*Math.PI*timeSpent/10000)));
// g.setClip(x-10, y-10, width, height);
System.err.println("b2: " + g.getClipBounds());
AlphaComposite alpha2 = AlphaComposite.SrcOver.derive(maxAlpha);
g2.setComposite(alpha2);
g2.drawImage(this.icon, x, y, null);
g2.setComposite(composite);
g2.setComposite(composite);
}
}
catch (Throwable e)
{
System.err.println("Errr!");
e.printStackTrace();
}
}
}
class ImageUtilities {
public static BufferedImage resize(BufferedImage image, int width, int height) {
BufferedImage bi = new BufferedImage(width, height, BufferedImage.TRANSLUCENT);
Graphics2D g2d = (Graphics2D) bi.createGraphics();
g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY));
g2d.drawImage(image, 0, 0, width, height, null);
g2d.dispose();
return bi;
}
public static BufferedImage getBufferedImageOfIcon(Icon icon, int imgW, int imgH) {
BufferedImage img = new BufferedImage(imgW, imgH, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = (Graphics2D) img.getGraphics();
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
icon.paintIcon(null, g2d, 0, 0);
g2d.dispose();
return img;
}
}
