wpf 在树视图中拖放
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时间：2020-09-08 20:35:55 来源:igfitidea点击:
Drag & Drop in Treeview
提问by don
I'm trying to drag and drop files in my treeview but I have no idea why it's breaking down if I run it and try dragging a file.
我正在尝试在我的树视图中拖放文件，但我不知道为什么如果我运行它并尝试拖动文件它会崩溃。
The code below is what I tried. Please help.
下面的代码是我试过的。请帮忙。
private void TreeViewItem_Drop( object sender, DragEventArgs e)
{
TreeViewItem treeViewItem = e.Source as TreeViewItem;
TreeViewItem obj = e.Data.GetData(typeof(TreeViewItem)) as TreeViewItem;
if ((obj.Parent as TreeViewItem) != null)
{
(obj.Parent as TreeViewItem).Items.Remove(obj);
}
else
{
treeViewItem.Items.Remove(obj);
treeViewItem.Items.Insert(0, obj);
e.Handled = true;
}
}
private void TreeViewItem_MouseLeftButtonDown( object sender,MouseButtonEventArgs e)
{
DependencyObject dependencyObject = _treeview.InputHitTest(e.GetPosition(_treeview)) as DependencyObject;
Debug.Write(e.Source.GetType().ToString());
if (dependencyObject is TextBlock)
{
TreeViewItem treeviewItem = e.Source as TreeViewItem;
DragDrop.DoDragDrop(_treeview, _treeview.SelectedValue, DragDropEffects.Move);
e.Handled = true;
}
}
回答by Erin
This article is very helpful. Drag drop wpf
这篇文章很有帮助。拖放 wpf
This code may be of use to you as well.
此代码也可能对您有用。
Point _startPoint;
bool _IsDragging = false;
void TemplateTreeView_PreviewMouseMove(object sender, MouseEventArgs e)
{
if (e.LeftButton == MouseButtonState.Pressed ||
e.RightButton == MouseButtonState.Pressed && !_IsDragging)
{
Point position = e.GetPosition(null);
if (Math.Abs(position.X - _startPoint.X) >
SystemParameters.MinimumHorizontalDragDistance ||
Math.Abs(position.Y - _startPoint.Y) >
SystemParameters.MinimumVerticalDragDistance)
{
StartDrag(e);
}
}
}
void TemplateTreeView_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
_startPoint = e.GetPosition(null);
}
private void StartDrag(MouseEventArgs e)
{
_IsDragging = true;
object temp = this.TemplateTreeView.SelectedItem;
DataObject data = null;
data = new DataObject("inadt", temp);
if (data != null)
{
DragDropEffects dde = DragDropEffects.Move;
if (e.RightButton == MouseButtonState.Pressed)
{
dde = DragDropEffects.All;
}
DragDropEffects de = DragDrop.DoDragDrop(this.TemplateTreeView, data, dde);
}
_IsDragging = false;
}
