向图像添加动作侦听器

Question

我将图片插入JPanel。我写这段代码。

public void paint(Graphics g)
{

    img1=getToolkit().getImage("/Users/Boaz/Desktop/Piece.png");
    g.drawImage(img1, 200, 200,null);

}

我想向该图片添加一个动作监听器，但是它没有addActionListener()方法。如何在不将图像放入按钮或标签的情况下做到这一点？

Answer 1

有一些选择。

使用MouseListener在直接JPanel

一种简单但肮脏的方法是MouseListener直接在JPanel中添加一个，您将在其中覆盖该paintComponent方法，并实现一个mouseClicked方法来检查是否单击了图像存在的区域。

一个例子可能是：

class ImageShowingPanel extends JPanel {

  // The image to display
  private Image img;

  // The MouseListener that handles the click, etc.
  private MouseListener listener = new MouseAdapter() {
    public void mouseClicked(MouseEvent e) {
      // Do what should be done when the image is clicked.
      // You'll need to implement some checks to see that the region where
      // the click occurred is within the bounds of the `img`
    }
  }

  // Instantiate the panel and perform initialization
  ImageShowingPanel() {
    addMouseListener(listener);
    img = ... // Load the image.
  }

  public void paintComponent(Graphics g) {
    g.drawImage(img, 0, 0, null);
  }
}

注意：ActionListener无法将添加到中JPanel，因为JPanel本身不适合创建“动作”。

创建一个JComponent以显示图像，然后添加一个MouseListener

更好的方法是创建一个新的子类，JComponent其唯一目的是显示图像。本JComponent应大小本身对图片的大小，使一点击的任何部分JComponent可以考虑在图像上点击。再次，建立MouseListener在JComponent以捕获点击。

class ImageShowingComponent extends JComponent {

  // The image to display
  private Image img;

  // The MouseListener that handles the click, etc.
  private MouseListener listener = new MouseAdapter() {
    public void mouseClicked(MouseEvent e) {
      // Do what should be done when the image is clicked.
    }
  }

  // Instantiate the panel and perform initialization
  ImageShowingComponent() {
    addMouseListener(listener);
    img = ... // Load the image.
  }

  public void paintComponent(Graphics g) {
    g.drawImage(img, 0, 0, null);
  }

  // This method override will tell the LayoutManager how large this component
  // should be. We'll want to make this component the same size as the `img`.
  public Dimension getPreferredSize() {
    return new Dimension(img.getWidth(), img.getHeight());
  }
}