unit CallBack;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  EnumWindowsProcedure = function (Hwnd: THandle;Param: Pointer): Boolean; stdcall;
  TForm1 = class(TForm)
    ListBox1: TListBox;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

function GetAllRuningWindowTitle(Hwnd: THandle; Param: Pointer): Boolean; stdcall;
var
  WindowCaptionText: string;
begin
  SetLength (WindowCaptionText, 100);
  GetWindowText(Hwnd, PChar (WindowCaptionText), 100);
  Form1.ListBox1.Items.Add ('句柄為'+IntToStr (Hwnd) + '的窗體的標題為：'+WindowCaptionText);
  Result := True;
end;


procedure TForm1.Button1Click(Sender: TObject);
var
  MYEWProc: EnumWindowsProcedure;
begin
  ListBox1.Items.Clear;
  MYEWProc := GetAllRuningWindowTitle;
  EnumWindows(@MYEWProc, 0);
  ShowMessage('當前系統中正在運行的窗體一共有：'+IntToStr(Listbox1.Items.Count)+'個.');
end;

end.