Реализовать перетаскивание чего либо

unit Unit1;
 
interface
 
uses
  Windows, SysUtils, Classes, Graphics, Controls, Forms,
  ExtCtrls, Messages, Math;
 
type
  TImage = class (ExtCtrls.TImage)
  private
    FDrag: BOOL;
    dX, dY: integer;
  public
    constructor Create(AOwner:TComponent); override;
    procedure WMLButtonUp(var Message: TWMLButtonUp);  message WM_LBUTTONUP;
    procedure WMLButtonDown(var Message: TWMLButtonDown); reintroduce; message WM_LBUTTONDOWN;
    procedure WMMouseMove(var Message: TWMMouseMove); reintroduce; message WM_MOUSEMOVE;
  end;
 
  TForm1 = class(TForm)
    Image1: TImage;
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
 
implementation
 
{$R *.dfm}
 
{ TImage }
 
constructor TImage.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
 
  Randomize;
  Canvas.TextOut(5, 5, Format('Picture №%d', [RandomRange(12345, 98765)]));
  FDrag := false;
end;
 
procedure TImage.WMLButtonDown(var Message: TWMLButtonDown);
begin
  inherited;
  
  FDrag := true;
 
  dX := Mouse.CursorPos.X;
  dY := Mouse.CursorPos.Y;
end;
 
procedure TImage.WMLButtonUp(var Message: TWMLButtonUp);
begin
  inherited;
 
  FDrag := false;
end;
 
procedure TImage.WMMouseMove(var Message: TWMMouseMove);
begin
  inherited;
 
  if FDrag then
  begin
    Left := Left + (Mouse.CursorPos.X - dX);
    Top := Top + (Mouse.CursorPos.Y - dY);
    dX := Mouse.CursorPos.X;
    dY := Mouse.CursorPos.Y;
  end;
end;
 
procedure TForm1.FormCreate(Sender: TObject);
var
  i, Count: integer;
begin
  Randomize;
 
  Count := RandomRange(5, 30);
  for i := 0 to Count - 1 do
    with TImage.Create(Self) do
    begin
      Parent := Self;
      Top := Random(Self.Height) + 1;
      Left := Random(Self.Width) + 1;
 
    end;
end;
 
end.