java - drawString() 方法上的 MouseListener

Question

如何检测我用 drawString() 绘制的文本(“Resume”、“Restart”、“Quit”)方法被点击？

到目前为止我的代码:

public class Pause {

    public Pause() {

    }


    public void draw(Graphics2D g) {

        g.setFont(new Font("Arial", Font.BOLD, 14));
        int intValue = Integer.parseInt( "ff5030",16);      
        g.setColor(new Color(intValue));

        g.drawString("Resume", 200, 156);
        g.drawString("Restart", 200, 172);
        g.drawString("Quit", 200, 188);    
    }
}

我希望你能帮助我。谢谢

@aioobe 我试着把它写得尽可能简单。这里是 SSCCE:

GameFrame.java

public class GameFrame extends JFrame implements Runnable { 
    /**
     * 
     */
    private static final long serialVersionUID = 1L;


    // dimensions
    public static final int WIDTH = 448;
    public static final int HEIGHT = 288;
    public static final double SCALE = 2.5; 

    // game thread
    private Thread thread;
    private boolean running;

    private int FPS = 60;
    private long targetTime = 1000 / FPS;

    // image
    private BufferedImage image;
    private Graphics2D g;

    //displays
    private Pause pauseDisplay;


    public GameFrame() {
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setResizable(false);
        this.pack();
        this.setLocationRelativeTo(null);
        this.setPreferredSize(new Dimension((int)(WIDTH * SCALE), (int)(HEIGHT * SCALE)));
        this.setBounds(100, 100, (int)(WIDTH * SCALE), (int)(HEIGHT * SCALE));
        this.setLocationRelativeTo(null);
        this.setFocusable(true);
        this.requestFocus();
        this.setVisible(true);
    }

    public void addNotify() {
        super.addNotify();
        if(thread == null) {
            thread = new Thread(this);
            thread.start();
        }
    }

    private void init() {       
        image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
        g = (Graphics2D) image.getGraphics();

        running = true;     
    }

    public void run() {     
        init();

        long start;
        long elapsed;
        long wait;

        // game loop
        while(running) {
            start = System.nanoTime();          
            elapsed = System.nanoTime() - start;            
            wait = targetTime - elapsed / 1000000;
            if(wait < 0) wait = 5;

            try {
                Thread.sleep(wait);
            }
            catch(Exception e) {
                e.printStackTrace();
            }

            pauseDisplay = new Pause(this);
            drawToScreen();
            draw();         
        }       
    }


    private void draw() {               
        pauseDisplay.draw(g);
    }


    private void drawToScreen() {
        Graphics g2 = getGraphics();
        g2.drawImage(image, 0, 0, (int)(WIDTH * SCALE), (int)(HEIGHT * SCALE), null);
        g2.dispose();
    }       


    public static void main(String[] args) {
        GameFrame game = new GameFrame();
    }    
}

Pause.java

public class Pause implements MouseListener{

    private Rectangle2D resumeRect;
    private Rectangle2D restartRect;

    public Pause(GameFrame GameFrame) {
        GameFrame.addMouseListener(this);
    }


    public void draw(Graphics2D g) {        
        g.setFont(new Font("Arial", Font.BOLD, 14));
        int intValue = Integer.parseInt( "ff5030",16);      
        g.setColor(new Color(intValue));

        g.drawString("Resume", 200, 156);
        resumeRect= g.getFontMetrics().getStringBounds("Resume", g);

        g.drawString("Restart", 200, 172);
        restartRect = g.getFontMetrics().getStringBounds("Restart", g);

        g.drawString("Quit", 200, 188);
    }


    public void mouseClicked(MouseEvent e) {
        if (resumeRect.contains(e.getPoint())) {
            System.out.println("clicked");
        }

        System.out.println(resumeRect);
        System.out.println(restartRect);
        System.out.println(e.getPoint());
    }


    public void mousePressed(MouseEvent e) {}
    public void mouseReleased(MouseEvent e) {}
    public void mouseEntered(MouseEvent e) {}
    public void mouseExited(MouseEvent e) {}

}

Answer 1

你必须记住你画线的位置。您可以为每个字符串设置一个 Rectangle2D。

String 的矩形可以计算如下:

Rectangle2D r = g.getFontMetrics().getStringBounds(str, g);

(您需要根据绘制字符串的位置调整矩形位置。)

然后您将注册一个鼠标监听器来检查针对这些矩形的点击坐标:

if (resumeRect.contains(mouseEvent.getPoint())) {
    ...
}

话虽如此，我建议您重新考虑您的 GUI 代码，看看您是否不能为此目的使用 JLabel 或 JButton。

---

关于您的修改:

您的 NullPointerException 是由于您可以在渲染图像之前(即在初始化矩形之前)单击框架。

除此之外，您还需要进行两项编辑:

1. 您需要考虑SCALE。

   if (resumeRect.contains(e.getPoint().getX() / GameFrame.SCALE,
                           e.getPoint().getY() / GameFrame.SCALE)) {
   

   和

2. 您需要补偿 drawString 在基线上绘制字符串的事实，因此矩形应该从基线提升到文本的左上角:

   g.drawString("Resume", 200, 156);
   resumeRect= g.getFontMetrics().getStringBounds("Resume", g);
   
   // Add this:
   resumeRect.setRect(200,
                      156 - g.getFontMetrics().getAscent(),
                      resumeRect.getWidth(),
                      resumeRect.getHeight());