如何检测从paintComponent的drawImage（）中绘制的图像上的鼠标悬停;方法

Question

我是Java新手，需要帮助。我正在使用从photoshop制作的图像为应用程序制作GUI，并希望使用图像创建菜单，当用户将鼠标悬停在它们上方时，这些图像会突出显示。我通过获取鼠标x，y坐标尝试mouseEntered();方法，但它不起作用。这是代码。

public class GUI extends JComponent{

    public void paintComponent(Graphics g){

        super.paintComponent(g);
        ImageIcon exitBtnImg = new ImageIcon("src/images/userInterface/exitBtn.png");
        g.drawImage(exitBtnImg.getImage(), 0, 5, this);
        mouseHandler handler = new mouseHandler();
        addMouseListener(handler);
    }
}


public class mouseHandler implements MouseListener{

    @Override
    public void mouseClicked(MouseEvent e) {

   }

    @Override
    public void mousePressed(MouseEvent e) {

    }

    @Override
    public void mouseReleased(MouseEvent e) {

    }

    @Override
    public void mouseEntered(MouseEvent e) {
        if((e.getX()>100&&e.getX()<300)&&(e.getY()>50&&e.getY()<196)){

            repaint();
        }
    }

    @Override
   public void mouseExited(MouseEvent e) {

    }

}

Answer 1

1. 不要在Thread中加载资源，您的绘制方法应该尽可能快地运行
2. 不要在paintComponent方法中添加听众，这会被大量调用，因此每次绘制组件时，您只需重复添加新的侦听器
3. 使用paint代替MouseMotionListener，您想要MouseListener事件
4. 您需要某种方式来了解图像的绘制位置，以便确定鼠标是否在其范围内移动。

有关详细信息，请查看How to Write a Mouse-Motion Listener和Painting in AWT and Swing。

此示例使用简单的mouseMoved来定义图像在其中绘制的位置，当鼠标在Rectangle的范围内移动时，设置标志并重新绘制组件，在图像上绘制基于alpha的高光效果



Rectangle

现在，说了这么多，你可能最好使用import java.awt.AlphaComposite; import java.awt.Color; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Rectangle; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import javax.imageio.ImageIO; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.UIManager; import javax.swing.UnsupportedLookAndFeelException; public class Example { public static void main(String[] args) { new Example(); } public Example() { EventQueue.invokeLater(new Runnable() { @Override public void run() { try { try { UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) { ex.printStackTrace(); } JFrame frame = new JFrame("Testing"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.add(new TestPane()); frame.pack(); frame.setLocationRelativeTo(null); frame.setVisible(true); } catch (IOException ex) { ex.printStackTrace(); } } }); } public class TestPane extends JPanel { private BufferedImage img; private Rectangle drawRectangle; private boolean highlight = false; public TestPane() throws IOException { img = ImageIO.read(...); addMouseMotionListener(new MouseAdapter() { @Override public void mouseMoved(MouseEvent e) { highlight = drawRectangle.contains(e.getPoint()); repaint(); } }); int width = getPreferredSize().width; int height = getPreferredSize().height; int x = (width - img.getWidth()) / 2; int y = (height - img.getHeight()) / 2; drawRectangle = new Rectangle(x, y, img.getWidth(), img.getHeight()); } @Override public Dimension getPreferredSize() { return new Dimension(400, 400); } @Override protected void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g.create(); g2d.drawImage(img, drawRectangle.x, drawRectangle.y, this); if (highlight) { g2d.setColor(Color.RED); g2d.setComposite(AlphaComposite.SrcOver.derive(0.5f)); g2d.fill(drawRectangle); } g2d.dispose(); } } } rollover的功能，这基本上会做同样的事情。

有关详细信息，请参阅How to Use Buttons, Check Boxes, and Radio Buttons