我试图让用户TreeViewItems在 a 周围移动TreeView（特别是通过按住控制键并按下箭头键）。我可以将节点移入和移出其他节点，并且可以在顶层上下移动节点，但是当我尝试在子节点内向上移动节点时，它什么也不做，如果我尝试在一个子节点内向下移动节点子节点，我得到以下异常：
元素已经有一个逻辑父级。在附加到新的父级之前，它必须与旧的父级分离。
当我尝试将节点添加回其原始集合时会发生这种情况（当然是在删除它之后）。这是原始实现：
private TreeViewItem getParent(TreeViewItem item)
{
for (int i=0; i<fragment_tree.Items.Count; ++i)
{
TreeViewItem r = getParent((TreeViewItem)(fragment_tree.Items[i]), item);
if (r != null)
{
return r;
}
}
return null;
}
private TreeViewItem getParent(TreeViewItem test, TreeViewItem item)
{
for (int i=0; i<test.Items.Count; ++i)
{
if (test.Items[i] == item)
{
return test;
}
}
for (int i=0; i<test.Items.Count; ++i)
{
TreeViewItem r = getParent((TreeViewItem)(test.Items[i]), item);
if (r != null)
{
return r;
}
}
return null;
}
private ItemCollection getContainingList(TreeViewItem item, out int id)
{
return getContainingList(fragment_tree.Items, item, out id);
}
private ItemCollection getContainingList(ItemCollection test, TreeViewItem item, out int id)
{
for (int i=0; i<test.Count; ++i)
{
if (test[i] == item)
{
id = i;
return test;
}
}
for (int i=0; i<test.Count; ++i)
{
ItemCollection r = getContainingList((TreeViewItem)(test[i]), out id);
if (r != null)
{
return r;
}
}
id = -1;
return null;
}
private void fragment_tree_PreviewKeyDown(object sender, KeyEventArgs e)
{
TreeViewItem selected_item = (TreeViewItem)(fragment_tree.SelectedItem);
if (selected_item.Header is String)
{
if (e.KeyboardDevice.IsKeyDown(Key.LeftCtrl) || e.KeyboardDevice.IsKeyDown(Key.RightCtrl))
{
if (e.Key == Key.Up)
{
int id;
ItemCollection collection = getContainingList(selected_item, out id);
if (collection != null) // it'll never be null, but w/e
{
if (id > 0)
{
collection.RemoveAt(id);
collection.Insert(id-1, selected_item);
selected_item.IsSelected = true;
}
}
e.Handled = true;
}
else if (e.Key == Key.Down)
{
int id;
ItemCollection collection = getContainingList(selected_item, out id);
if (collection != null) // it'll never be null, but w/e
{
if (id < collection.Count)
{
collection.RemoveAt(id);
collection.Insert(id+1, selected_item); // here is the exception
selected_item.IsSelected = true;
}
}
e.Handled = true;
}
else if (e.Key == Key.Left)
{
TreeViewItem parent = getParent(selected_item);
if (parent != null)
{
int id;
ItemCollection collection = getContainingList(parent, out id);
parent.Items.RemoveAt(id);
collection.Insert(id, selected_item);
selected_item.IsSelected = true;
}
e.Handled = true;
}
else if (e.Key == Key.Right)
{
int id;
ItemCollection collection = getContainingList(selected_item, out id);
if (id+1 < collection.Count)
{
TreeViewItem next_item = (TreeViewItem)(collection[id+1]);
collection.RemoveAt(id);
next_item.Items.Insert(0, selected_item);
next_item.IsExpanded = true;
selected_item.IsSelected = true;
}
e.Handled = true;
}
}
}
我尝试对所选内容进行深度克隆TreeViewItem（尽管我不想承担开销），但出现了一些奇怪的行为。当我尝试在它的子树中向上或向下移动一个项目时，它会跳到父级。当我尝试向上或向下移动顶层节点时，它会删除其邻居。我觉得好像缺少一些基本的东西
private TreeViewItem cloneTreeViewItem(TreeViewItem item)
{
TreeViewItem r = new TreeViewItem();
r.Header = item.Header;
r.Tag = item.Tag;
for (int i=0; i<item.Items.Count; ++i)
{
r.Items.Add(cloneTreeViewItem((TreeViewItem)(item.Items[i])));
}
return r;
}
....
if (e.Key == Key.Up)
{
int id;
ItemCollection collection = getContainingList(selected_item, out id);
if (collection != null) // it'll never be null, but w/e
{
if (id > 0)
{
collection.RemoveAt(id);
TreeViewItem clone = cloneTreeViewItem(selected_item);
collection.Insert(id-1, clone);
clone.IsSelected = true;
}
}
e.Handled = true;
}
else if (e.Key == Key.Down)
{
int id;
ItemCollection collection = getContainingList(selected_item, out id);
if (collection != null) // it'll never be null, but w/e
{
if (id < collection.Count)
{
collection.RemoveAt(id);
TreeViewItem clone = cloneTreeViewItem(selected_item);
collection.Insert(id+1, clone);
clone.IsSelected = true;
}
}
e.Handled = true;
}
.....
我确实花了至少一个小时研究这个主题，我知道TreeViewItem必须将其与其逻辑父级分离，并且我从测试中知道 a 的父级TreeViewItem始终是 a TreeView，我只是不知道如何分离它。我知道你试图让网站没有无聊的问题，我希望我的不是。任何见解将不胜感激。