Drag and Drop со списками

Code:

{

This example shows how to drag&drop within a TListBox.

The Demo Program also shows how to implement an autoscroll-feature.

}

procedure TForm1.ListBox1DragOver(Sender, Source: TObject; X, Y: Integer;

  State: TDragState; var Accept: Boolean);

begin

  Accept := Sender is TListBox;

end;

procedure TForm1.ListBox1DragDrop(Sender, Source: TObject; X, Y: Integer);

var

  iTemp: Integer;

  ptTemp: TPoint;

  szTemp: string;

begin

  { change the x,y coordinates into a TPoint record }

  ptTemp.x := x;

  ptTemp.y := y;

  { Use a while loop instead of a for loop due to items possible being removed

  from listboxes this prevents an out of bounds exception }

  iTemp := 0;

   while iTemp <= TListBox(Source).Items.Count-1 do

  begin

    { look for the selected items as these are the ones we wish to move }

    if TListBox(Source).selected[iTemp] then

    begin

      { use a with as to make code easier to read }

      with Sender as TListBox do

      begin

      { need to use a temporary variable as when the item is deleted the

       indexing will change }

        szTemp := TListBox(Source).Items[iTemp];

        { delete the item that is being dragged  }

        TListBox(Source).Items.Delete(iTemp);

      { insert the item into the correct position in the listbox that it

      was dropped on }

        Items.Insert(itemAtPos(ptTemp, True), szTemp);

      end;

    end;

    Inc(iTemp);

  end;

end;