unit PreviewFormUnit;

{$mode ObjFPC}{$H+}

interface

uses
  Classes, SysUtils, Forms, Controls, Graphics, Dialogs, LCLType,
  StdCtrls, LCLIntf, ExtCtrls,
  Windows;

type

  { TPreviewForm }

  TPreviewForm = class(TForm)
    Label1: TLabel;
    Timer1: TTimer;
    procedure FormCreate(Sender: TObject);
    procedure FormKeyDown(Sender: TObject; var Key: word; Shift: TShiftState);
    procedure Timer1Timer(Sender: TObject);
  private
    FParentHWND: HWND;
  protected
    procedure WndProc(var Message: TMessage); override;
  public
    procedure EmbedIntoParent(pHWND: HWND);

  end;

var
  PreviewForm: TPreviewForm;

implementation

{$R *.lfm}

{ TPreviewForm }

procedure TPreviewForm.FormCreate(Sender: TObject);
begin
  //FParentHWND := 0;
  BorderStyle := bsNone;
  Left := 0;
  Top := 0;
  Width := 152;
  Height := 112;

  Label1.Left := (ClientWidth - Label1.Width) div 2;
  Label1.Top := (ClientHeight - Label1.Height) div 2;
  Label1.Font.Color := clBlue;
end;

// 親ウインドウを指定
procedure TPreviewForm.EmbedIntoParent(pHWND: HWND);
var
  r: TRect;
begin
  FParentHWND := pHWND;

  if pHWND <> 0 then
  begin
    ParentWindow := pHWND;
    Windows.SetParent(self.Handle, pHWND);

    SetWindowLong(Self.Handle, GWL_STYLE, GetWindowLong(self.Handle, GWL_STYLE) or
      WS_CHILD);

    Windows.GetClientRect(pHWND, r);
    MoveWindow(Self.Handle, 0, 0, r.Right - r.Left, r.Bottom - r.Top, True);
    Visible := True;
  end;
end;

procedure TPreviewForm.Timer1Timer(Sender: TObject);
begin
  // 一定時間毎に自身が消えるべきかチェックする
  //Windows.Beep(440, 100);
  if (FParentHWND <> 0) and (not Windows.IsWindow(FParentHWND)) then
  begin
    // 親ウインドウが存在していないので終了
    //Windows.Beep(1000, 100);
    Application.Terminate;
  end
  else if not Windows.IsWindowVisible(self.Handle) then
  begin
    // 自分が非表示にされているなら終了
    //Windows.Beep(1000, 1000);
    Application.Terminate;
  end;
end;

procedure TPreviewForm.WndProc(var Message: TMessage);
begin
  //Windowsから閉じろとメッセージが来ているなら終了
  case Message.Msg of
    WM_CLOSE, WM_DESTROY, WM_NCDESTROY:
    begin
      //Windows.Beep(2000, 300);
      Application.Terminate;
    end;
  end;

  inherited WndProc(Message);
end;

procedure TPreviewForm.FormKeyDown(Sender: TObject; var Key: word; Shift: TShiftState);
begin
  if FParentHWND = 0 then
  begin
    // 開発時用。ESCキーで終了
    if Key = VK_ESCAPE then
      Application.Terminate;
  end;
end;

//initialization
//  RegisterClass(TPreviewForm);

end.