TTreeGetNodeAt (Delphi)

Description

The following code uses GetNodeAt to add a dragged node as a child of the node under the mouse when it is dropped. This example requires a populated TreeView. Also, the TTreeView DragMode property must be set to dmAutomatic, and the TTreeView OnDragOver event handler must be implemented to accept the drop.

Code

procedure TForm1.TreeView1DragDrop(Sender, Source: TObject; X, Y: Integer);
var 
  AnItem: TTreeNode;
  AttachMode: TNodeAttachMode;
  HT: THitTests;
begin
  if TreeView1.Selected = nil then Exit;
  HT := TreeView1.GetHitTestInfoAt(X, Y);
  AnItem := TreeView1.GetNodeAt(X, Y);
  if (HT - [htOnItem, htOnIcon, htNowhere, htOnIndent] <> HT) then 
  begin
    if (htOnItem in HT) or (htOnIcon in HT) then
      AttachMode := naAddChild
    else if htNowhere in HT then AttachMode := naAdd
    else if htOnIndent in HT then AttachMode := naInsert;
    TreeView1.Selected.MoveTo(AnItem, AttachMode); 
  end;
end;

procedure TForm1.TreeView1DragOver(Sender, Source: TObject; X, Y: Integer;
  State: TDragState; var Accept: Boolean);
begin
  Accept := Source is TTreeView;
end;

Uses

• Vcl.ComCtrls.TCustomTreeView.GetNodeAt ( fr | de | ja )
• Vcl.ComCtrls.TTreeNode.MoveTo ( fr | de | ja )
• Vcl.ComCtrls.TCustomTreeView.Selected ( fr | de | ja )
• Vcl.ComCtrls.TCustomTreeView.GetHitTestInfoAt ( fr | de | ja )
• Vcl.Controls.TControl.DragMode ( fr | de | ja )
• Vcl.ComCtrls.TNodeAttachMode ( fr | de | ja )
• Vcl.ComCtrls.THitTest ( fr | de | ja )