java - 将 mouseMoved() 事件转发到 JTree 节点？

Question

如果我将 JCheckBox 放在 JTree 之外，当我将鼠标悬停在它上面时它会播放动画。当我将相同的 JCheckbox 放置在 JTree 节点内时，它不再接收任何 mouseMoved() 事件并且不播放动画。我尝试将这些事件从 JTree 转发到 JCheckBox，但没有任何显示。

我猜问题是同一个 JCheckBox 实例被 JTree“标记”(每个节点一次)。当我将 mouseMoved() 事件转发到共享实例时，它不知道在哪里重新绘制自己。

有什么想法吗？

编辑:这是一个独立的测试用例。请注意，使 JCheckBox 可点击超出了这个问题的范围(我已经在我的应用程序中使用 TreeCellEditor 这样做了)。

import java.awt.BorderLayout;
import java.awt.Component;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreeCellRenderer;

public class HoverBug
{
    public static class TreeRenderer implements TreeCellRenderer
    {
        private final JCheckBox checkbox = new JCheckBox();

        @Override
        public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected,
            boolean expanded, boolean leaf, int row, boolean hasFocus)
        {
            DefaultMutableTreeNode node = (DefaultMutableTreeNode) value;
            checkbox.setSelected((Boolean) node.getUserObject());
            return checkbox;
        }
    }

    public static void main(String[] args)
    {
        JCheckBox checkbox = new JCheckBox("See... this works!");

        DefaultMutableTreeNode root = new DefaultMutableTreeNode(Boolean.TRUE);
        DefaultMutableTreeNode child1 = new DefaultMutableTreeNode(Boolean.FALSE);
        DefaultMutableTreeNode child2 = new DefaultMutableTreeNode(Boolean.FALSE);
        root.add(child1);
        root.add(child2);
        DefaultTreeModel model = new DefaultTreeModel(root);

        JTree tree = new JTree(model);
        tree.setCellRenderer(new TreeRenderer());

        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.getContentPane().setLayout(new BorderLayout());
        frame.getContentPane().add(checkbox, BorderLayout.NORTH);
        frame.getContentPane().add(tree, BorderLayout.CENTER);
        frame.setSize(800, 600);
        frame.setVisible(true);
    }

Answer 1

我认为没有解决方案，原因有二:

1. JCheckBox UI 类(例如 BasicCheckBoxUI)在修改外观时调用 repaint()，但您不会看到这些更改，除非您要求 JTree 使用 DefaultTreeModel.nodeChanged(TreeNode) 重绘节点。 .
2. 即使您监听与 UI 类相同的模型事件并触发 DefaultTreeModel.nodeChanged(TreeNode)在 repaint() 之后，一些 L&F(特别是 Insubstantial)检查 JCheckBox 是否在 CellRendererPane 内，并在这种情况下禁用动画(可能出于性能原因)。

总而言之，JTree 设计使得为节点设置动画变得不切实际。

就其值(value)而言，这是我将事件转发到底层节点的尝试(它有问题，但你明白了):

[...]
    MouseAdapterImpl listener = new MouseAdapterImpl(tree);
    tree.addMouseListener(listener);
    tree.addMouseMotionListener(listener);
    tree.addMouseWheelListener(listener);
[...]
private class MouseAdapterImpl implements MouseListener, MouseWheelListener, MouseMotionListener
{
    private final JTree tree;
    private int lastRow = -1;

    public MouseAdapterImpl(JTree tree)
    {
        this.tree = tree;
    }

    /**
     * Returns the mouse position relative to the JTree row.
     * <p/>
     * @param e the mouse event
     */
    private void forwardEvent(MouseEvent e)
    {
        int row = tree.getRowForLocation(e.getX(), e.getY());
        Rectangle bounds;
        Point point;
        if (row == -1)
        {
            bounds = null;
            point = null;
        }
        else
        {
            bounds = tree.getRowBounds(row);
            point = new Point(e.getX() - bounds.x, e.getY() - bounds.y);
        }
        if (lastRow != row)
        {
            if (lastRow != -1)
            {
                Rectangle lastBounds = tree.getRowBounds(lastRow);
                if (lastBounds != null)
                {
                    Point lastPoint = new Point(e.getX() - lastBounds.x, e.getY() - lastBounds.y);
                    dispatchEvent(new MouseEvent(checkbox, MouseEvent.MOUSE_EXITED,
                        System.currentTimeMillis(), 0, lastPoint.x, lastPoint.y, 0, false, 0), lastRow);
                }
            }
            if (row != -1)
            {
                dispatchEvent(new MouseEvent(checkbox, MouseEvent.MOUSE_ENTERED,
                    System.currentTimeMillis(), 0, point.x, point.y, 0, false, 0), row);
            }
        }
        lastRow = row;
        if (row == -1)
            return;
        dispatchEvent(new MouseEvent(checkbox, e.getID(),
            System.currentTimeMillis(), e.getModifiers(), point.x, point.y, e.getClickCount(),
            e.isPopupTrigger(), e.getButton()), row);
    }

    private void dispatchEvent(MouseEvent e, int row)
    {
        checkbox.dispatchEvent(e);
        TreePath pathForLocation = tree.getPathForRow(row);
        if (pathForLocation == null)
            return;
        Object lastPathComponent = pathForLocation.getLastPathComponent();
        if (lastPathComponent instanceof DefaultMutableTreeNode)
        {
            DefaultTreeModel model = (DefaultTreeModel) tree.getModel();
            model.nodeChanged((DefaultMutableTreeNode) lastPathComponent);
        }
    }

    @Override
    public void mouseEntered(MouseEvent e)
    {
        forwardEvent(e);
    }

    @Override
    public void mouseMoved(MouseEvent e)
    {
        forwardEvent(e);
    }

    @Override
    public void mouseExited(MouseEvent e)
    {
        forwardEvent(e);
    }

    @Override
    public void mouseClicked(MouseEvent e)
    {
        forwardEvent(e);
    }

    @Override
    public void mousePressed(MouseEvent e)
    {
        forwardEvent(e);
    }

    @Override
    public void mouseReleased(MouseEvent e)
    {
        forwardEvent(e);
    }

    @Override
    public void mouseWheelMoved(MouseWheelEvent e)
    {
        forwardEvent(e);
    }

    @Override
    public void mouseDragged(MouseEvent e)
    {
        forwardEvent(e);
    }
}

编辑:好消息。他们在 JavaFX 中修复了这个问题:http://javafx-jira.kenai.com/browse/RT-19027