java - 在面板顶部添加面板并且两者都可见

Question

我正在制作一个音乐/绘图应用程序，您可以用鼠标自由绘制线条，TrackBar 水平穿过它并读取线条并使用 x 和 y 坐标来修改音乐。

• 我遇到的问题是 TrackBar 类是一个 JPanel，而 DrawBoard 类是一个 JPanel，我将其添加到 Frame 中。但哪个在最上面，哪个就会显示，我想要的是它们都显示，并且 TrackBar 在绘制的线条之上传递。

下面是这3个类的源码，去掉了一些不必要的代码:

我添加它们的 MainFrame 类(在当前设置下，TrackBar 不会出现，但绘图板会出现，因为它与它重叠):

public class MainFrame extends JFrame {

public static ColourToolbar colourBar;
public static TrackBar tb;

public MainFrame(){

    super("VIPE by Prestige WorldWide");


    // Top colour toolbar for tones
    colourBar = new ColourToolbar();
    this.getContentPane().add(colourBar, BorderLayout.NORTH);

    // This class ImagePanel is a JPanel which I overite the paintCOmponent to have background
    ImagePanel bg = new ImagePanel();   
        bg.setLayout(new BorderLayout());
        Dimension size = getPreferredSize();
        size.setSize(1024,800); //w, h
        bg.setPreferredSize(size);
    this.getContentPane().add(bg, BorderLayout.CENTER);



    // I add the TrackBar to the ImagePanel since its the Background
    tb = new TrackBar();
    bg.add(tb, BorderLayout.CENTER);

    // I add the drawing board but It will overlap the Trackbar
    DrawBoard dboard =  new DrawBoard();
    bg.add(dboard, BorderLayout.CENTER);




    // The control toolbar where the settings and control buttons are.
    Toolbar toolBar = new Toolbar();
    this.getContentPane().add(toolBar, BorderLayout.SOUTH);
}

public static void main(String[] args){

    MainFrame frame = new MainFrame();

    frame.setBackground(Color.WHITE);
    frame.setSize(1024,768);
    frame.setLocationRelativeTo(null);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setResizable(false);
    //frame.pack();
    frame.setVisible(true);

}


}

现在是 TrackBar 类:

public class TrackBar extends JPanel{

private TrackBarAction tba = new TrackBarAction(this);
public static int TIME = 9;

public Timer t = new Timer(TIME, tba);
public static double x = 0, y = 0, velX = 1.0, velY = 0;

private int SKIP = 120;


public TrackBar(){

    this.setOpaque(false);
}

@Override
public void paintComponent(Graphics g){
            super.paintComponent(g);

            Graphics2D g2d = (Graphics2D)g;
            //g2d.drawRect((int)x, (int)y, 10, 800);

            Rectangle2D r2d = new Rectangle2D.Double(x, y, 8.0, 800.0);  // x,x, w, h
            g2d.setPaint(Color.DARK_GRAY);
            g2d.fill(r2d);
            g2d.draw(r2d);
}

public void reset(){

    t.stop();
    x = 0;
    y = 0;
    velX = 0.5;
    velY = 0;
    this.repaint();
}

public void skipForward(){

    if(x+SKIP <= 1024){
     x += SKIP;   
    } else {
        x = 1024 - x;
    }

    this.repaint();
}

public void skipBackwards(){

    if(x-SKIP >= 0){
    x -= SKIP;
    } else {
        x = 0;
    }

    this.repaint();
}

}

现在是 DrawBoard 类:

public class DrawBoard extends JPanel implements MouseListener, MouseMotionListener{


 (..)

public Color currentColor;

public static boolean eraser = false;

private int xX1, yY1;

public DrawBoard(){  



   Graphics2D g2d = bImage.createGraphics();
   g2d.dispose();

    Dimension size = getPreferredSize();
    size.setSize(1024,800); //w, h
    setPreferredSize(size);
    //status =  new JLabel("default");
    //add(status, BorderLayout.SOUTH);
    addMouseListener(this);
    addMouseMotionListener(this);  


     imgLabel = new JLabel(new ImageIcon(bImage)) {
     @Override
     protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        paintInLabel(g);
     }
   };
     imgLabel.setOpaque(false);
     setOpaque(false);
      add(imgLabel, BorderLayout.CENTER);

}

private void paintInLabel(Graphics g) {

    if(!eraser){
        Graphics2D g2d = (Graphics2D) g;
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2d.setColor(getColor()); // this colour is when mouse is pressed
        g2d.setStroke(new BasicStroke(STROKESIZE));
        if (points.size() < 1) {
            return;
        }
        for (int i = 1; i < points.size(); i++) {
            int x1 = points.get(i - 1).x;
            int y1 = points.get(i - 1).y;
            int x2 = points.get(i).x;
            int y2 = points.get(i).y;
            g2d.drawLine(x1, y1, x2, y2);
        }
    }

}


// Where the drawing happens
@Override
public void mousePressed(MouseEvent e) {
    //status.setText("you pressed down the mouse");
    if(!eraser){
        xX1 = e.getX();
        yY1 = e.getY();
        points.add(e.getPoint());
    }
}

@Override
public void mouseDragged(MouseEvent e) {
  //status.setText("you draged the mouse");
    Graphics2D g2d = bImage.createGraphics();

    // this is the eraser code
    if(eraser){
        //Graphics2D g2d = bImage.createGraphics();
        System.out.println("eraser = true");
        System.out.println("Stroke = " + STROKESIZE);
        g2d.setComposite(AlphaComposite.Clear);
        g2d.setColor(new Color(0, 0, 0, 0));
        g2d.drawRect(e.getX(), e.getY(), STROKESIZE, STROKESIZE);
        g2d.fillRect(e.getX(), e.getY(), STROKESIZE, STROKESIZE);
       // g2d.setColor(c);

        imgLabel.repaint();
    }else {
        //g2d.setComposite();
        points.add(e.getPoint());
        System.out.println("point = " + e.getPoint());
        imgLabel.repaint();
    }

}

@Override
public void mouseReleased(MouseEvent e) {
    //status.setText("you release the mouse click");
    if(!eraser){
        Graphics2D g2d = bImage.createGraphics();
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2d.setColor(getColor()); // this is the final colour
        g2d.setStroke(new BasicStroke(STROKESIZE));


        if (points.size() >= 2) {
            for (int i = 1; i < points.size(); i++) {
                int x1 = points.get(i - 1).x;
                int y1 = points.get(i - 1).y;
                int x2 = points.get(i).x;
                int y2 = points.get(i).y;
                g2d.drawLine(x1, y1, x2, y2);
            }
        }
     g2d.dispose();

     points.clear();
     imgLabel.repaint();
    }
    //imgLabel.repaint();

}
// End of where the drawing happens

public void clearDrawBoard() {

}

private Color getColor() {

    return ColourToolbar.selectedColor;
}

private void setColor(Color col){

    this.currentColor = col;
}

@Override
public void mouseClicked(MouseEvent e) {
    //throw new UnsupportedOperationException("Not supported yet.");
}

}

Answer 1

BorderLayout 只能有一个组件添加到每个组件的 5 个位置。通过将 DrawPanel 添加到中心位置，您可以有效地删除 TrackPanel。

相反，将 TrackBar 的布局管理器设置为 BorderLayout 并向其中添加 DrawPanel。

您也可以使用 JLayeredPane，但管理会变得更加复杂