Перетаскивание картинки мышью

Автор: Пётр Соболь

type
  TMouseState = (msNormal, msDragging);

var
  FMouseState: TMouseState;
  OldPos, NewPos: TPoint;
  MaxShift: TPoint;
  bar: integer;
  i: integer;

implementation

procedure TForm1.Image1MouseDown(Sender: TObject; Button:
  TMouseButton; Shift: TShiftState; X, Y: Integer);
begin
  with Image1 do
  begin
    MaxShift.X := Parent.Width - Width;
    MaxShift.Y := Parent.Height - Height;
  end;

  if (MaxShift.X > 0) and (MaxShift.Y > 0) then
    Exit;

  if MaxShift.X > 0 then
    MaxShift.X := 0;
  if MaxShift.Y > 0 then
    MaxShift.Y := 0;

  FMouseState := msDragging;
  OldPos := Point(X, Y);
end;

// обработка переноса
procedure TForm1.Image1MouseMove(Sender: TObject;
  Shift: TShiftState; X, Y: Integer);
begin
  if FMouseState = msDragging then
    with (Sender as TImage) do
    begin
      NewPos := Point(X - OldPos.X, Y - OldPos.Y);
      if Left + NewPos.X > 0 then
        NewPos.X := -Left;
      if Left + NewPos.X < MaxShift.X then
        NewPos.X := MaxShift.X - Left;
      if Top + NewPos.Y > 0 then
        NewPos.Y := -Top;
      if Top + NewPos.Y < MaxShift.Y then
        NewPos.Y := MaxShift.Y - Top;
      Parent.ScrollBy(NewPos.X, NewPos.Y);
    end;
end;

//возвращение исходных значений
procedure TForm1.Image1MouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  FMouseState := msNormal;
  Screen.Cursor := crDefault;
  with Sender as TImage do
    Label1.Caption := Format('(%d , %d)', [-Left, -Top]); // отображение координат
end;