Панель с изменяющимися размерами

unit Elastic;

interface

uses
  SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls,
  Forms, Dialogs, ExtCtrls;

type

  TElasticPanel = class(TPanel)
  private
    FHorz, FVert: boolean;
    nOldWidth, nOldHeight: integer;
    bResized: boolean;
  protected
    procedure WMSize(var message: TWMSize); message WM_SIZE;
  public
    nCount: integer;
    constructor Create(AOwner: TComponent); override;
  published
    property ElasticHorizontal: boolean read FHorz write FHorz default
      TRUE;

    property ElasticVertical: boolean read FVert write FVert default
      TRUE;

  end;

procedure Register;

implementation

constructor TElasticPanel.Create(AOwner: TComponent);
begin

  inherited Create(AOwner);
  FHorz := TRUE;
  FVert := TRUE;
  nOldWidth := Width;
  nOldHeight := Height;
  bResized := FALSE;
end;

procedure TElasticPanel.WMSize(var message: TWMSize);
var

  bResize: boolean;
  xRatio: real;
  i: integer;
  ctl: TWinControl;
begin

  Inc(nCount);
  if Align = alNone then
    bResize := TRUE
  else
    bResize := bResized;
  if not (csDesigning in ComponentState) and bResize then
  begin
    if FHorz then
    begin
      xRatio := Width / nOldWidth;
      for i := 0 to ControlCount - 1 do
      begin
        ctl := TWinControl(Controls[i]);
        ctl.Left := Round(ctl.Left * xRatio);
        ctl.Width := Round(ctl.Width * xRatio);
      end;
    end;
    if FVert then
    begin
      xRatio := Height / nOldHeight;
      for i := 0 to ControlCount - 1 do
      begin
        ctl := TWinControl(Controls[i]);
        ctl.Top := Round(ctl.Top * xRatio);
        ctl.Height := Round(ctl.Height * xRatio);
      end;
    end;
  end
  else
  begin
    nOldWidth := Width;
    nOldHeight := Height;
  end;
  bResized := TRUE;
  nOldWidth := Width;
  nOldHeight := Height;
end;

procedure Register;
begin

  RegisterComponents('Additional', [TElasticPanel]);
end;

end.