TDBLookupComboBox.DragMode Property

Determines how the control initiates drag-and-drop or drag-and-dock operations.

Pascal

property DragMode: TDragMode;

C++

__property TDragMode DragMode;

Description

Use DragMode to control when the user can drag the control. Disable the drag-and-drop or drag-and-dock capability at runtime by setting the DragMode property value to dmManual. Enable automatic dragging by setting DragMode to dmAutomatic.

C++ Examples:

Copy Code

/*
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 set to dmAutomatic, and the TTreeView
OnDragOver event handler must be implemented to accept the
drop.
*/
void __fastcall TForm1::TreeView1DragDrop(TObject *Sender, TObject *Source,
      int X, int Y)
{
  if (Source != dynamic_cast<TObject *>(TreeView1) || TreeView1->Selected == NULL)
    return;
  THitTests HT = TreeView1->GetHitTestInfoAt(X, Y);
  TNodeAttachMode AttachMode;
  TTreeNode *Item = TreeView1->GetNodeAt(X, Y);
  if (HT.Contains(htOnItem) || HT.Contains(htOnIcon))
    AttachMode = naAddChild;
  else if (HT.Contains(htNowhere))
    AttachMode = naAdd;
  else if (HT.Contains(htOnIndent))
    AttachMode = naInsert;
  else
    return;
  TreeView1->Selected->MoveTo(Item, AttachMode);
}

void __fastcall TForm1::TreeView1DragOver(TObject *Sender, TObject *Source,
      int X, int Y, TDragState State, bool &Accept)
{
  Accept = (Source == dynamic_cast<TObject *>(TreeView1));
}

Delphi Examples:

Copy Code

{
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.
}
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;