JTree - 將節點向右移動

Question

我有一個JTree與幾個節點級別。我將根節點的圖標更改爲更大的圖標。問題是，現在圖標大於默認圖標，垂直虛線和相應的子節點不位於根節點圖標下方。

見下圖：

我的問題是：是否有可能除根節點一點點向右側移動的一切嗎？

Answer 1

在JTree中設置左邊距，並在JLayer中分別繪製真實的根節點圖標。

import java.awt.*; 
import javax.swing.*; 
import javax.swing.plaf.*; 
import javax.swing.tree.*; 

public class MiddleXOfRootNodeIconTest { 
    public JComponent makeUI() { 
    int ow = UIManager.getIcon("Tree.openIcon").getIconWidth(); 
    int iw = 32; 

    Icon icon1 = new ColorIcon(Color.GREEN, new Dimension(ow, iw)); 
    Icon icon2 = new ColorIcon(new Color(0x550000AA, true), new Dimension(iw, iw)); 

    JTree tree = new JTree(); 
    tree.setBorder(BorderFactory.createEmptyBorder(1, 1 + iw/2, 1, 1)); 
    //TEST: 
    //tree.setBorder(BorderFactory.createMatteBorder(1, 1 + iw/2, 1, 1, Color.RED)); 
    tree.setCellRenderer(new CompoundTreeCellRenderer(icon1, iw)); 
    LayerUI<JTree> layerUI = new LayerUI<JTree>() { 
     @Override public void paint(Graphics g, JComponent c) { 
     super.paint(g, c); 
     Graphics2D g2 = (Graphics2D) g.create(); 
     icon2.paintIcon(c, g2, 1 + ow/2, 1); 
     g2.dispose(); 
     } 
    }; 

    JPanel p = new JPanel(new GridLayout(1, 3)); 
    p.add(new JScrollPane(new JTree())); 
    p.add(new JScrollPane(new JLayer<JTree>(tree, layerUI))); 
    return p; 
    } 
    public static void main(String... args) { 
    EventQueue.invokeLater(() -> { 
     JFrame f = new JFrame(); 
     f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); 
     f.getContentPane().add(new MiddleXOfRootNodeIconTest().makeUI()); 
     f.setSize(320, 240); 
     f.setLocationRelativeTo(null); 
     f.setVisible(true); 
    }); 
    } 
} 
class CompoundTreeCellRenderer extends DefaultTreeCellRenderer { 
    private static final Color ALPHA_ZERO = new Color(0x0, true); 
    private final JPanel p = new JPanel(new GridBagLayout()); 
    private final GridBagConstraints ci = new GridBagConstraints(); 
    private final GridBagConstraints cl = new GridBagConstraints(); 
    private final JLabel icon = new JLabel(); 
    private final Icon gap1 = new ColorIcon(ALPHA_ZERO, new Dimension(2, 10)); 
    private final Icon gap2; 
    private final Icon rootIcon; 
    public CompoundTreeCellRenderer(Icon rootIcon, int iw) { 
    super(); 
    Dimension d = new Dimension(2 + (iw - rootIcon.getIconWidth())/2, 10); 
    this.rootIcon = rootIcon; 
    //TEST: this.gap2 = new ColorIcon(Color.BLUE, d); 
    this.gap2 = new ColorIcon(ALPHA_ZERO, d); 
    this.setOpaque(false); 
    p.setOpaque(false); 
    ci.gridx = 0; 
    ci.weightx = 1.0; 
    cl.gridx = 1; 
    cl.anchor = GridBagConstraints.WEST; 
    } 
    @Override public Component getTreeCellRendererComponent(
     JTree tree, Object value, boolean selected, boolean expanded, 
     boolean leaf, int row, boolean hasFocus) { 
    JLabel l = (JLabel) super.getTreeCellRendererComponent(
     tree, value, selected, expanded, leaf, row, hasFocus); 
    l.setOpaque(false); 
    p.removeAll(); 

    if (value.equals(tree.getModel().getRoot())) { 
     icon.setIcon(rootIcon); 
     l.setIcon(gap2); 
    } else { 
     icon.setIcon(l.getIcon()); 
     l.setIcon(gap1); 
    } 
    p.add(icon, ci); 
    p.add(l, cl); 
    return p; 
    } 
} 
class ColorIcon implements Icon { 
    private final Color color; 
    private final Dimension dim; 
    public ColorIcon(Color color, Dimension dim) { 
    this.color = color; 
    this.dim = dim; 
    } 
    @Override public void paintIcon(Component c, Graphics g, int x, int y) { 
    Graphics2D g2 = (Graphics2D) g.create(); 
    g2.translate(x, y); 
    g2.setColor(color); 
    g2.fillRect(1, 1, dim.width - 2, dim.height - 2); 
    g2.dispose(); 
    } 
    @Override public int getIconWidth() { 
    return dim.width; 
    } 
    @Override public int getIconHeight() { 
    return dim.height; 
    } 
}