Turning off plus/minus sign on specific TreeView nodes

Question

I have a System.Windows.Forms.TreeView control for which I would like to turn off the plus/minus sign for specific child TreeNode objects. I know I can do this at the entire TreeView level using the TreeView.ShowPlusMinus property, but I'm wondering if I can hide the signs only for selected TreeNode objects.

Answer 1

Alas, the Windows Forms TreeView class wraps the native tree view control, and that control only supports showing or hiding the plus/minus signs globally.

That's because, internally, that flag maps to the TVS_HASBUTTONS control style, which of course affects the whole control and not individual items.

To my knowledge, the only way to achieve what you want is to handle the DrawNode event and render everything yourself.

Answer 2

Each TreeViewItem (TVITEM) has an cChildren member. If 0 the plusminus sign is hidden. if 1, the + sign is shown.

See http://msdn.microsoft.com/en-us/library/windows/desktop/bb773456%28v=vs.85%29.aspx

Dont forget the TVIF_CHILDREN flag.

I answer, because I searched the the same question and found no answer.

Answer 3

Based on your edit above, you should override your TreeView's BeforeCollapse event to cancel the collapse if it is a non-collapsible node:

private void treeView1_BeforeCollapse(object sender, TreeViewCancelEventArgs e) {
  MyParameter myP = e.Node.Tag as MyParameter;
  if (myP != null) {
    if (myP.Type == MyParameterType.NonCollapsible) {
      e.Cancel = true;
    }
  }
}

Answer 4

To remove plus/minus sign setLoadOnDemand to false;

Telerik.WinControls.UI.RadTreeNode Node = new Telerik.WinControls.UI.RadTreeNode();
Node.LoadedOnDemand = false;