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将树节点滚动到滚动窗格的顶部

发布于 2024-10-21 08:06:17 字数 194 浏览 1 评论 0原文

我有一个 JTree 大约有8个以上的树节点（叶子）。要求是如果用户单击树节点，所选树节点将自动从任何位置滚动到滚动窗格的顶部。请帮忙！

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德意的啸 2024-10-28 08:06:17

如前所述：所有的scrollXXToVisible方法都会滚动，使得给定的XX在某处可见，它们不支持更精细的控制，因为fi“应该是可见区域中的第一个节点”。

您必须自己实现该功能，例如

TreePath path = tree.getSelectionPath();
if (path == null) return;
Rectangle bounds = tree.getPathBounds(path);
// set the height to the visible height to force the node to top 
bounds.height = tree.getVisibleRect().height;
tree.scrollRectToVisible(bounds);

“注意：这样做以响应节点上的鼠标事件可能会让用户感到烦恼，因为它会将目标从其脚下移动”。

As already noted: all scrollXXToVisible methods scroll such that the given XX is visible somewhere, they don't support finer control as f.i. "should be first node in visible area".

You have to implement that functionality yourself, something like

TreePath path = tree.getSelectionPath();
if (path == null) return;
Rectangle bounds = tree.getPathBounds(path);
// set the height to the visible height to force the node to top 
bounds.height = tree.getVisibleRect().height;
tree.scrollRectToVisible(bounds);

Beware: doing so in reaction to a mouse event on the node might be annoying to the user as it moves the target from under its feet.

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皓月长歌 2024-10-28 08:06:17

在实际的JTree 上使用scrollRectToVisible 方法。

例子：

tree.scrollRectToVisible(new Rectangle(0,0));

Use the scrollRectToVisible method on the actual JTree.

Example:

tree.scrollRectToVisible(new Rectangle(0,0));

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茶底世界 2024-10-28 08:06:17

这个问题很久以前就被问过，我不知道你是否还需要这个......

我理解你遇到的问题，问题是这样的：树选择侦听器不能按你的预期工作。您必须通过注册鼠标侦听器来检测单击事件。像这样：

tree = new JTree();
    tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
    MouseListener ml = new MouseAdapter() {
        @Override
        public void mousePressed(MouseEvent e) {
            int selRow = tree.getRowForLocation(e.getX(), e.getY());
            currentRow = selRow;
            TreePath selPath = tree.getPathForLocation(e.getX(), e.getY());
            if (selRow != -1) {
                DefaultMutableTreeNode node = new DefaultMutableTreeNode(selPath.getLastPathComponent());
                if (node != null && node.isLeaf()) {
                    String stringId = '<sting-id-of-node-you-wish-to-scroll-to>';
                    TreePath tp = tree.getNextMatch(stringId, currentRow, Position.Bias.Forward);
                    if (tp == null) {
                        tp = tree.getNextMatch(stringId, currentRow, Position.Bias.Backward);
                    }
                    tree.setSelectionPath(tp);
                    tree.scrollPathToVisible(tp);
                }
            }
        }
    };
    tree.addMouseListener(ml);

干杯！

This question was asked a long time ago, and I don't know if you still need this...

I understand the problem you have, the issue is this: tree selection listeners don't work as you might expect. You have to detect the click event by registering a mouse listener. Something like this:

tree = new JTree();
    tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
    MouseListener ml = new MouseAdapter() {
        @Override
        public void mousePressed(MouseEvent e) {
            int selRow = tree.getRowForLocation(e.getX(), e.getY());
            currentRow = selRow;
            TreePath selPath = tree.getPathForLocation(e.getX(), e.getY());
            if (selRow != -1) {
                DefaultMutableTreeNode node = new DefaultMutableTreeNode(selPath.getLastPathComponent());
                if (node != null && node.isLeaf()) {
                    String stringId = '<sting-id-of-node-you-wish-to-scroll-to>';
                    TreePath tp = tree.getNextMatch(stringId, currentRow, Position.Bias.Forward);
                    if (tp == null) {
                        tp = tree.getNextMatch(stringId, currentRow, Position.Bias.Backward);
                    }
                    tree.setSelectionPath(tp);
                    tree.scrollPathToVisible(tp);
                }
            }
        }
    };
    tree.addMouseListener(ml);

Cheers!

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