创建一个消失的JPanel？

Question

我正在尝试创建一个扩展的JPanel，用作突出显示屏幕某些区域的方法。我已经从this SO answer获取了一些代码，但我想进一步扩展它，但我不知道如何去做。

我希望能够在达到指定的超时后让JPanel（MatchAreaPanel以下）消失。那就是JPanel将其visible属性设置为false并随后自行处理。

这样做最好的方法是什么？

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JPanel;

public class MatchAreaPanel extends JPanel
{
    public MatchAreaPanel()
    {

    }

    @Override
    protected void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D) g.create();
        g2d.setColor(new Color(128, 128, 128, 64));
        g2d.fillRect(0, 0, getWidth(), getHeight());

        float dash1[] = {10.0f};
        BasicStroke dashed = new BasicStroke(3.0f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_MITER, 10.0f, dash1, 0.0f);
        g2d.setColor(Color.BLACK);
        g2d.setStroke(dashed);
        g2d.drawRect(0, 0, getWidth() - 3, getHeight() - 3);
        g2d.dispose();
    }
}

Answer 1

您可以使用Swing Timer在给定延迟后简单地安排回调并关闭相关窗口或根据您的需要隐藏组件，例如......

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.Random;
import javax.swing.JPanel;
import javax.swing.JWindow;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                Rectangle bounds = getVirtualBounds();
                Random rnd = new Random();
                int x = bounds.x + (rnd.nextInt(bounds.width) - 100);
                int y = bounds.y + (rnd.nextInt(bounds.height) - 100);

                MatchAreaPanel pane = new MatchAreaPanel();
                JWindow frame = new JWindow();
                frame.setBackground(new Color(0, 0, 0, 0));
                frame.add(pane);
                frame.setBounds(x, y, 100, 100);
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
                pane.start();
            }
        });
    }

    public static Rectangle getVirtualBounds() {

        Rectangle bounds = new Rectangle(0, 0, 0, 0);

        GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
        GraphicsDevice gd = ge.getDefaultScreenDevice();
        bounds.add(gd.getDefaultConfiguration().getBounds());

        return bounds;

    }

    public class MatchAreaPanel extends JPanel {

        public MatchAreaPanel() {
            setOpaque(false);
            addMouseListener(new MouseAdapter() {
                @Override
                public void mouseClicked(MouseEvent e) {
                    SwingUtilities.windowForComponent(MatchAreaPanel.this).dispose();
                }
            });
        }

        public void start() {
            Timer timer = new Timer(5000, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    SwingUtilities.windowForComponent(MatchAreaPanel.this).dispose();
                }
            });
            timer.start();
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.setColor(new Color(128, 128, 128, 64));
            g2d.fillRect(0, 0, getWidth(), getHeight());

            float dash1[] = {10.0f};
            BasicStroke dashed = new BasicStroke(3.0f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_MITER, 10.0f, dash1, 0.0f);
            g2d.setColor(Color.BLACK);
            g2d.setStroke(dashed);
            g2d.drawRect(0, 0, getWidth() - 3, getHeight() - 3);
            g2d.dispose();
        }
    }

}

有关详细信息，请参阅How to use Swing Timers

<强>更新...

现在，简单地“隐藏”面板，很无聊，用户也可能错过面板，因为突然出现并不能保证用户会看到它，所以相反，你可以添加一个淡出效果。

在这个例子中，您可以通过单击它来淡出面板（但我在测试过程中这样做，因此您不需要它）或在指定的超时后...

import java.awt.AlphaComposite;
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.Random;
import javax.swing.JPanel;
import javax.swing.JWindow;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                Rectangle bounds = getVirtualBounds();
                Random rnd = new Random();
                int x = bounds.x + (rnd.nextInt(bounds.width) - 100);
                int y = bounds.y + (rnd.nextInt(bounds.height) - 100);

                MatchAreaPanel pane = new MatchAreaPanel();
                JWindow frame = new JWindow();
                frame.setBackground(new Color(0, 0, 0, 0));
                frame.add(pane);
                frame.setBounds(x, y, 100, 100);
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
                pane.start();
            }
        });
    }

    public static Rectangle getVirtualBounds() {

        Rectangle bounds = new Rectangle(0, 0, 0, 0);

        GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
        GraphicsDevice gd = ge.getDefaultScreenDevice();
        bounds.add(gd.getDefaultConfiguration().getBounds());

        return bounds;

    }

    public static class MatchAreaPanel extends JPanel {

        protected static final long FADE_OUT_TIME = 2500;

        private float alpha = 1f;
        private long fadeStartAt;
        private Timer fadeTimer;
        private Timer waitTimer;

        public MatchAreaPanel() {
            setOpaque(false);
            addMouseListener(new MouseAdapter() {
                @Override
                public void mouseClicked(MouseEvent e) {
                    fadeOut();
                }
            });
            fadeTimer = new Timer(40, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    long runTime = System.currentTimeMillis() - fadeStartAt;
                    float progress = 0f;
                    if (runTime >= FADE_OUT_TIME) {
                        progress = 1f;
                    } else {
                        progress = (float) runTime / (float) FADE_OUT_TIME;
                        if (progress > 1f) {
                            progress = 1f;
                        }
                    }
                    alpha = 1f - progress;

                    if (progress >= 1f) {
                        ((Timer) e.getSource()).stop();
                        SwingUtilities.windowForComponent(MatchAreaPanel.this).dispose();
                    }
                    repaint();
                }
            });
            waitTimer = new Timer(5000, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    ((Timer) e.getSource()).stop();
                    fadeOut();
                }
            });
        }

        protected void fadeOut() {
            waitTimer.stop();
            fadeStartAt = System.currentTimeMillis();
            fadeTimer.start();
        }

        public void start() {
            if (!waitTimer.isRunning() && !fadeTimer.isRunning()) {
                waitTimer.start();
            }
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.setComposite(AlphaComposite.SrcOver.derive(alpha));
            g2d.setColor(new Color(128, 128, 128, 64));
            g2d.fillRect(0, 0, getWidth(), getHeight());

            float dash1[] = {10.0f};
            BasicStroke dashed = new BasicStroke(3.0f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_MITER, 10.0f, dash1, 0.0f);
            g2d.setColor(Color.BLACK);
            g2d.setStroke(dashed);
            g2d.drawRect(0, 0, getWidth() - 3, getHeight() - 3);
            g2d.dispose();
        }
    }

}