The TListBox Delphi component displays a collection of items in a scrollable list. Delphi makes it easy to program into your applications.

Here's how to allow a user to rearrange (change item's position) the items of a ListBox using drag and drop:

1. Drop a TListBox (named ListBox1) on a form
2. Add several strings using the Items property
3. Set ListBox1's DragMode to dmAutomatic (in Form's OnCreate or using Object Inspector at design-time).
4. Handle LisBox-es MouseDown, DragOver and DragDrop events

var

// form level

   StartingPoint : TPoint;

implementation

...

procedure TForm1.FormCreate(Sender: TObject) ;

begin

   ListBox1.DragMode := dmAutomatic;

end;

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

var

   DropPosition, StartPosition: Integer;

   DropPoint: TPoint;

begin

   DropPoint.X := X;

   DropPoint.Y := Y;

  

with Source

as TListBox

do

  

begin

     StartPosition := ItemAtPos(StartingPoint,True) ;

     DropPosition := ItemAtPos(DropPoint,True) ;

     Items.Move(StartPosition, DropPosition) ;

  

end;

end;

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

var Accept: Boolean) ;

begin

   Accept := Source = ListBox1;

end;

procedure TForm1.ListBox1MouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer) ;

begin

   StartingPoint.X := X;

   StartingPoint.Y := Y;

end;

How to Move ListBox Items with the Mouse