Question

When drag / dropping text between two components, is there a simple way to show the text that I am dragging as the drag cursor?

Answer 1

To drag an item from a listbox, and show its text representation along with the drag cursor:

type
  TTextDragObject = class(TDragControlObjectEx)
  private
    FDragImages: TDragImageList;
    FText: String;
  protected
    function GetDragImages: TDragImageList; override;
  end;

{ TTextDragObject }

function TTextDragObject.GetDragImages: TDragImageList;
var
  Bmp: TBitmap;
begin
  if FDragImages = nil then
  begin
    FDragImages := TDragImageList.Create(Control);
    Bmp := TBitmap.Create;
    try
      Bmp.Width := Bmp.Canvas.TextWidth(FText);
      Bmp.Height := Bmp.Canvas.TextHeight(FText);
      Bmp.Canvas.TextOut(0, 0, FText);
      FDragImages.Width := Bmp.Width;
      FDragImages.Height := Bmp.Height;
      FDragImages.SetDragImage(FDragImages.Add(Bmp, nil), 0, 0);
    finally
      Bmp.Free;
    end;
  end;
  Result := FDragImages;
end;

{ TForm1 }

procedure TForm1.FormCreate(Sender: TObject);
begin
  ControlStyle := ControlStyle + [csDisplayDragImage];
  ListBox1.ControlStyle := ListBox1.ControlStyle + [csDisplayDragImage];
end;

procedure TForm1.ListBox1StartDrag(Sender: TObject;
  var DragObject: TDragObject);
var
  List: TListbox absolute Sender;
begin
  DragObject := TTextDragObject.Create(List);
  if List.ItemIndex > -1 then
    TTextDragObject(DragObject).FText := List.Items[List.ItemIndex];
end;