Question

我试图创建一个自定义的JComponent，它将成为一个自定义的进度条，但是我无法让它显示在现有的JPanel（确实显示正确）上，不确定是什么问题。

public class JCustomProgressBar extends JComponent{

private final Dimension SIZE = new Dimension( 120, 120 );

public JCustomProgressBar() {
    super();
    this.setVisible(true);
}

int progress = 50; // temporary keeps progress at 50% for now while I debug

public void updateProgress (int progress){
    this.progress = progress;
}

 @Override
   public Dimension getPreferredSize() {
      return SIZE;
   }

 @Override
 public void paintComponent (Graphics g){
   //super.paintComponent(g);
   System.out.println("called");
   Graphics2D g2D = (Graphics2D) g.create();
   g2D.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
   g2D.translate(this.getWidth()/2, this.getHeight()/2);
   g2D.rotate(Math.toRadians(270));
   Arc2D.Float arc = new Arc2D.Float (Arc2D.PIE);
   Ellipse2D circle = new Ellipse2D.Float(0, 0, 110, 110);
   arc.setFrameFromCenter (new Point(0,0), new Point (120, 120));
   circle.setFrameFromCenter(new Point(0,0), new Point (110, 110));
   arc.setAngleExtent(progress*360/100);
   g2D.setColor(Color.green);
   g2D.draw(arc);
   g2D.fill(arc);

   g2D.setColor(Color.gray);
   g2D.draw(circle);
   g2D.fill(circle);

   g2D.setColor(Color.black);
   g2D.rotate(Math.toRadians(90));
   g2D.setFont(new Font("Verdana", Font.PLAIN, 50));
   FontMetrics fm = g2D.getFontMetrics();
   Rectangle2D r = fm.getStringBounds(progress + "%", g);
   int x = (0 - (int) r.getWidth())/2;
   int y = (0 - (int) r.getHeight())/2 +fm.getAscent();
   g2D.drawString(progress + "%", x, y);
   g2D.dispose();
}

编辑

这样我就在单击按钮时调用了我的draw方法（可以正常工作并正确绘制我的JPanel）。

/**Called when a button created using createButton() is clicked. This method 
should return true if it handled the click event, and false if the click 
should be passed on to the parent.

Overrides: onButtonClick(...) in GuiScreen*/


@Override
protected boolean onButtonClick(String id) {

    if(id.equals("btnIDConfirmL")) {
        drawLeftFillProgressBar();
    }
    return false;
}

在我的draw方法中，我将JPanel添加到我的父级JPanel中，为其指定了边界，颜色和边框。它可以正确显示在屏幕上，并且此时一切都很好，但是当我尝试添加自己制作的JComponent时，它永远不会显示在屏幕上。我可以在此处创建的JPanel中添加另一个JPanel，也可以出于我的JComponent不会显示的原因而添加JLabel。

    private JComponent customProgressBarL;
    private JPanel backgroundPanel;

private void drawLeftFillProgressBar(){
    leftFillProgressJPanel = createPanel(this.backgroundPanel, new Rectangle(0,backgroundPanel.getHeight()/2 - (this.getPanel().getWidth()/3 - 2*10)/2, this.getPanel().getWidth()/3 - 2*10, this.getPanel().getWidth()/3 + 87));
    leftFillProgressJPanel.setBackground(Color.white);
    leftFillProgressJPanel.setBorder(BorderFactory.createLineBorder(Color.black, 1));

    customProgressBarL = new JCustomProgressBar();
    leftFillProgressJPanel.add(customProgressBarL);
    customProgressBarL.setVisible(true);
    customProgressBarL.validate();

}

我的createPanel方法位于我的GuiScreen类内部，如下所示：

protected JPanel createPanel(JComponent parent, Rectangle bounds){
    JPanel panel = new JPanel();
    panel.setLayout(null);

    if(bounds != null){
        panel.setBounds(bounds);
    }
    if(parent != null){
        parent.add(panel);
    }

    return panel;
}

Answer 1

（代表问题作者发布了解决方案）。

我通过在draw方法中添加以下内容解决了这个问题：事实证明，我必须使用setBounds方法指定范围，以便在将其添加到我的父级JPanel后，范围包含整个JComponent。

    customProgressBarL = new JCustomProgressBar();
    leftFillProgressJPanel.add(customProgressBarL);

    int width = 190;
    int height = 290;

    customProgressBarL.setBounds(new Rectangle(leftFillProgressJPanel.getWidth()/2 - width/2,leftFillProgressJPanel.getHeight()/2 - height/2, width, height));

为什么在现有JPanel上绘制我的自定义JComponent时什么都没显示？

编辑

1 个答案: