将 mouseMoved() 事件转发到 JTree 节点？

Question

如果我将 JCheckBox 放在 JTree 之外，它会在我将鼠标悬停在它上面时播放动画。当我在 JTree 节点中放置相同的 JCheckbox 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() 事件转发给共享实例时，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有两个原因：

1. 无论何时修改外观，JCheckBox UI 类（例如 BasicCheckBoxUI）都会调用 repaint()，但您不会看到这些更改，除非您使用 DefaultTreeModel.nodeChanged(TreeNode) 请求 JTree 重绘节点。
2. 即使您侦听与 UI 类相同的模型事件并在 repaint() 之后触发 DefaultTreeModel.nodeChanged(TreeNode)，一些 L&F（尤其是 Insubstantial）也会检查 JCheckBox 是否在 CellRendererPane 内并在这种情况下禁用动画（可能是出于性能原因）。

总之，JTree 设计使得动画节点变得不切实际。

对于它的价值，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

Answer 2

以下是我认为您正在寻找的内容，但如果您正在做更复杂的事情，您可能需要考虑创建一个 CellEditor。：

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
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;
import javax.swing.tree.TreePath;

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());
        checkbox.setText("Row:" + row);
        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);
    final DefaultTreeModel model = new DefaultTreeModel(root);

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

    tree.addMouseListener(new MouseListener() {
        @Override
        public void mouseClicked(MouseEvent e) {
            TreePath pathForLocation = tree.getPathForLocation(e.getX(), e.getY());
            Object lastPathComponent = pathForLocation.getLastPathComponent();
            if(lastPathComponent instanceof DefaultMutableTreeNode){
                Boolean oldObject = (Boolean) ((DefaultMutableTreeNode)lastPathComponent).getUserObject();
                ((DefaultMutableTreeNode)lastPathComponent).setUserObject(!oldObject);
                model.nodeChanged((DefaultMutableTreeNode)lastPathComponent);
            }
        }

        @Override
        public void mousePressed(MouseEvent e) {

        }

        @Override
        public void mouseReleased(MouseEvent e) {

        }

        @Override
        public void mouseEntered(MouseEvent e) {

        }

        @Override
        public void mouseExited(MouseEvent e) {

        }
    });


    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);
}
}