wpftreeview:如何像在Explorer中那样实现键盘导航?

有趣的是,这似乎不是一个流行的话题。无论如何,在此期间,我已经找到了一个让我满意的解决方案:

我将一个行为附加到TreeViewItems。在这种行为中,我处理KeyUp事件。在KeyUp事件处理程序中,我从上到下搜索显示的可视化树。如果我找到第一个匹配的节点(其名称以按下键上的字母开头),我就选择该节点。

我知道这是一个老话题,但我想它对某些人来说仍然是相关的。我做了这个解决方案。它附加到wpftreeview上的KeyUp和TextInput事件。除了KeyUp之外,我还使用TextInput,因为我很难用KeyEventArgs将“national”字符翻译成真正的字符。使用TextInput会更加流畅。

// <TreeView Name="treeView1" KeyUp="treeView1_KeyUp" TextInput="treeView1_TextInput"/>

    private bool searchdeep = true;             // Searches in subitems
    private bool searchstartfound = false;      // true when current selected item is found. Ensures that you don't seach backwards and that you only search on the current level (if not searchdeep is true)
    private string searchterm = "";             // what to search for
    private DateTime LastSearch = DateTime.Now; // resets searchterm if last input is older than 1 second.

    private void treeView1_KeyUp(object sender, System.Windows.Input.KeyEventArgs e)
    {  
        // reset searchterm if any "special" key is pressed
        if (e.Key < Key.A)
            searchterm = "";

    }

    private void treeView1_TextInput(object sender, TextCompositionEventArgs e)
    {
        if ((DateTime.Now - LastSearch).Seconds > 1)
            searchterm = "";

        LastSearch = DateTime.Now;
        searchterm += e.Text;
        searchstartfound = treeView1.SelectedItem == null;

        foreach (var t in treeView1.Items)
            if (SearchTreeView((TreeViewItem) t, searchterm.ToLower()))
                break;
    }

   private bool SearchTreeView(TreeViewItem node, string searchterm)
    {
        if (node.IsSelected)
            searchstartfound = true;

        // Search current level first
        foreach (TreeViewItem subnode in node.Items)
        {
            // Search subnodes to the current node first
            if (subnode.IsSelected)
            {
                searchstartfound = true;
                if (subnode.IsExpanded)
                    foreach (TreeViewItem subsubnode in subnode.Items)
                        if (searchstartfound && subsubnode.Header.ToString().ToLower().StartsWith(searchterm))
                        {
                            subsubnode.IsSelected = true;
                            subsubnode.IsExpanded = true;
                            subsubnode.BringIntoView();
                            return true;
                        }
            }
            // Then search nodes on the same level
            if (searchstartfound && subnode.Header.ToString().ToLower().StartsWith(searchterm))
            {
                subnode.IsSelected = true;
                subnode.BringIntoView();
                return true;
            }
        }

        // If not found, search subnodes
        foreach (TreeViewItem subnode in node.Items)
        {
            if (!searchstartfound || searchdeep)
                if (SearchTreeView(subnode, searchterm))
                {
                    node.IsExpanded = true;
                    return true;
                }
        }

        return false;
    }

我也在寻找键盘导航,令人惊讶的是这个解决方案对于模板项目来说是多么的不明显。

在ListView或TreeView中设置SelectedValuePath会产生此行为。 如果项目已模板化,则设置附加属性:text搜索.text路径对路径上的属性进行搜索也会起到一定的作用。

希望这对我有帮助,它确实对我有用。

因为这个问题在搜索时最突出,所以我想发布一个答案。 当我使用带有HierarchicalDataTemplate的数据绑定TreeView时,lars的上述文章对我不起作用,因为Items集合返回的是实际的数据绑定项,而不是TreeViewItem。

下面是我的助手类:

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;

namespace TreeViewHelpers
{
    public static class TreeViewItemTextSearcher
    {
        private static bool checkIfMatchesText(TreeViewItem node, string searchterm, StringComparison comparison)
        {
            return node.Header.ToString().StartsWith(searchterm, comparison);
        }

        //https://stackoverflow.com/questions/26624982/get-parent-treeviewitem-of-a-selected-node-in-wpf
        public static TreeViewItem getParentItem(TreeViewItem item)
        {
            try
            {
                var parent = VisualTreeHelper.GetParent(item as DependencyObject);
                while ((parent as TreeViewItem) == null)
                {
                    parent = VisualTreeHelper.GetParent(parent);
                }
                return parent as TreeViewItem;
            }
            catch (Exception e)
            {
                //could not find a parent of type TreeViewItem
                return null;
            }
        }

        private static bool tryFindChild(
            int startindex,
            TreeViewItem node,
            string searchterm,
            StringComparison comparison,
            out TreeViewItem foundnode
            )
        {
            foundnode = null;
            if (!node.IsExpanded) { return false; }

            for (int i = startindex; i < node.Items.Count; i++)
            {
                object item = node.Items[i];
                object tviobj = node.ItemContainerGenerator.ContainerFromItem(item);
                if (tviobj is null)
                {
                    return false;
                }

                TreeViewItem tvi = (TreeViewItem)tviobj;
                if (checkIfMatchesText(tvi, searchterm, comparison))
                {
                    foundnode = tvi;
                    return true;
                }

                //recurse:
                if (tryFindChild(tvi, searchterm, comparison, out foundnode))
                {
                    return true;
                }
            }

            return false;
        }
        private static bool tryFindChild(TreeViewItem node, string searchterm, StringComparison comparison, out TreeViewItem foundnode)
        {
            return tryFindChild(0, node, searchterm, comparison, out foundnode);
        }

        public static bool SearchTreeView(TreeViewItem node, string searchterm, StringComparison comparison, out TreeViewItem found)
        {
            //search children:
            if (tryFindChild(node, searchterm, comparison, out found))
            {
                return true;
            }

            //search nodes same level as this:
            TreeViewItem parent = getParentItem(node);
            object boundobj = node.DataContext;
            if (!(parent is null || boundobj is null))
            {
                int startindex = parent.Items.IndexOf(boundobj);
                if (tryFindChild(startindex + 1, parent, searchterm, comparison, out found))
                {
                    return true;
                }
            }

            found = null;
            return false;
        }
    }
}

我还保存最后选定的节点,如中所述 this post

<TreeView ... TreeViewItem.Selected="TreeViewItemSelected" ... />
private TreeViewItem lastSelectedTreeViewItem;
private void TreeViewItemSelected(object sender, RoutedEventArgs e)
{
    TreeViewItem tvi = e.OriginalSource as TreeViewItem;
    this.lastSelectedTreeViewItem = tvi;
}

下面是上面的TextInput,修改为使用这个类:

private void treeView_TextInput(object sender, TextCompositionEventArgs e)
{
    if ((DateTime.Now - LastSearch).Seconds > 1) { searchterm = ""; }

    LastSearch = DateTime.Now;
    searchterm += e.Text;

    if (lastSelectedTreeViewItem is null)
    {
        return;
    }

    TreeViewItem found;
    if (TreeViewHelpers.TreeViewItemTextSearcher.SearchTreeView(
            node: lastSelectedTreeViewItem,
            searchterm: searchterm,
            comparison: StringComparison.CurrentCultureIgnoreCase, 
            out found
        ))
    {
        found.IsSelected = true;
        found.BringIntoView();
    }
}

请注意,此解决方案与上面的有点不同,因为我只搜索所选节点的子节点,以及与所选节点处于同一级别的节点。

http://www.codeproject.com/Articles/26288/Simplifying-the-WPF-TreeView-by-Using-the-ViewMode

如果你需要更多的细节,请告诉我。