Reputation: 12851
I have a simple TreeView with HotTracking Property set to True. It works when I move the mouse over an item. But it doesn't work when I use Drag&Drop and Drag something over a TreeView Item. Is there a way to use the HotTracking with DragDrop? Or any workarounds?
Upvotes: 1
Views: 814
Reputation: 148
Selecting a Node as @Hans suggested is a simple solution but can be unusable if there is some events on node selection, or if you just need keeping the selected node. The only way I found is custumDraw the node using VisualStylesRenderer.
private void plTree_DragOver(object sender, DragEventArgs e)
{
Point pt = plTree.PointToClient(new Point(e.X, e.Y));
var overNode = plTree.GetNodeAt(pt);
bool canMoveTo = overNode != null &&
TreeNodeIsFolder(overNode) &&
!IsFirstNodeParentToSecond(GetDraggedNodes(e)[0], overNode);// all dragged nodes are of the same parent
e.Effect = canMoveTo ? DragDropEffects.Move : DragDropEffects.None;
if (overNode == null) return;
if (_lastCustomDrawNode != overNode)
{
NormalDrawNode(_lastCustomDrawNode);
CustomDrawNode(overNode);
}
_lastCustomDrawNode = overNode;
}
private void NormalDrawNode(TreeNode aNode)
{
if (aNode == null) return;
if (_normalNodeRenderer == null)
_normalNodeRenderer = new VisualStyleRenderer("Explorer::TreeView", 1, 1);
Debug.WriteLine("normal render" + DateTime.Now);
RenderTreeNode(_normalNodeRenderer, aNode, true);
_lastCustomDrawNode = null;
}
private void CustomDrawNode(TreeNode aNode)
{
if (_hotNodeRenderer == null)
_hotNodeRenderer = new VisualStyleRenderer("Explorer::TreeView", 1, 2);
Debug.WriteLine("custom render" + DateTime.Now);
RenderTreeNode(_hotNodeRenderer, aNode, false);
}
private void RenderTreeNode(VisualStyleRenderer renderer, TreeNode aNode, bool drawDefaultBck)
{
if(_treeGraphics == null)
_treeGraphics = plTree.CreateGraphics();
const int iconShift = 21;
Rectangle aRec = aNode.Bounds;
var bckRec = new Rectangle(aRec.Location.X - iconShift, aRec.Location.Y, aRec.Width + iconShift, aRec.Height);
if (!drawDefaultBck)
renderer.DrawBackground(_treeGraphics, bckRec);
else
_treeGraphics.FillRectangle(_treebckgBrush, bckRec);
var textRec = new Rectangle(aRec.Location.X + 1, aRec.Location.Y - 1, aRec.Width, aRec.Height);
TextRenderer.DrawText(_treeGraphics, aNode.Text, GetTreeNodeFont(aNode), textRec, Color.FromKnownColor(KnownColor.ControlText));
var imgRec = new Rectangle(aRec.Location.X + 2 - iconShift, aRec.Location.Y, 16, 16);
renderer.DrawImage(_treeGraphics, imgRec, ImageListTree.Images[aNode.ImageIndex]);
}
this post helps a lot with theme drawing: VisualStyleRenderer and themes (WinForms)
Upvotes: 0
Reputation: 942428
By design, the control only gets D+D notifications, no mouse messages. You could simply select the node yourself:
private void treeView1_DragOver(object sender, DragEventArgs e) {
if (e.Data.GetDataPresent("something")) {
var pos = treeView1.PointToClient(new Point(e.X, e.Y));
var hit = treeView1.HitTest(pos);
if (hit.Location == TreeViewHitTestLocations.Label) {
treeView1.SelectedNode = hit.Node;
e.Effect = DragDropEffects.Copy;
}
else e.Effect = DragDropEffects.None;
}
}
You typically need to do more work to let the user scroll the view and expand nodes.
Upvotes: 1