如何在jlayeredpane Java中划一条线

I want to draw line in my jLayeredPane and this is my project from netbeans.

我想在jLayeredPane中画一条线，这是我来自netbeans的项目。

https://drive.google.com/file/d/0B6e6jjVl5-sCMkJFcEI3MkZEZ1E/view

I have problem when i clicked my button why i can't draw line in my jlayeredpane??where's my wrong with this code?

当我点击按钮时我有问题为什么我不能在jlayeredpane中画线?这段代码哪里出错了?

I want to draw some line in my jlayeredpane when click button draw.I try to add jlayerpane1.add some component.and i set this for visible.

单击“绘制”按钮时，我想在jlayeredpane中画一些线。我尝试添加jlayerpane1。添加一些组件。我把它设为可见。

how to fix it?

如何修复它吗?

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    jLayeredPane1.add(new JComponent(){                                   
     ArrayList<Shape> linesList = new ArrayList<Shape>();
    private Shape line = null;
    {
    MouseAdapter mouseAdapter = new MouseAdapter(){
                @Override
        public void mousePressed (MouseEvent e){                       
        line = new Line2D.Double(e.getPoint(), e.getPoint());
        linesList.add(line);
        repaint();
        }
                @Override
        public void mouseDragged(MouseEvent e){
        Line2D shape =(Line2D)line;
        shape.setLine(shape.getP1(), e.getPoint());
        repaint();
        }
                @Override
        public void mouseReleased(MouseEvent e){
        line = null;
        repaint();
        }
    };
    addMouseListener(mouseAdapter);
    addMouseMotionListener(mouseAdapter);
    }
        @Override
    protected void paintComponent(Graphics g){
    Graphics2D g2d = (Graphics2D) g;
    g2d.setPaint(Color.BLUE);
    g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
    for(Shape content : linesList){
        g2d.draw(content);
    }
  }          
    });
    jLayeredPane1.setVisible(true); // set for visible
}

1 个解决方案

#1

A JLayeredPane uses a null layout. So when you add your custom painting panel to the layered pane you need to give the panel a size otherwise the size is (0, 0) so there is nothing to paint.

JLayeredPane使用空布局。所以当你将自定义的绘图面板添加到层叠的面板中时，你需要给面板一个尺寸，否则面板的尺寸是(0,0)所以没有什么可画的。

So the code should be something like:

所以代码应该是这样的:

JPanel panel = new CustomPaintingPanel();
panel.setSize(300, 300);
layeredPane.add(panel, ...);
frame.add(layeredPane);

#1