Project: CALLBACK.DPR

Project Structure

• CALLBACK.DPR
• CBACKF.PAS
• CBACKF.DFM

program Callback;

uses
  Forms,
  CbackF in 'CbackF.pas' {FormCallback};

{$R *.RES}

begin
  Application.Initialize;
  Application.CreateForm(TFormCallback, FormCallback);
  Application.Run;
end.

unit CbackF;

interface

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

type
  TFormCallback = class(TForm)
    ListBox1: TListBox;
    Panel1: TPanel;
    BtnTitles: TButton;
    procedure BtnTitlesClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  FormCallback: TFormCallback;

implementation

{$R *.DFM}

type
  EnumWindowsProc = function (Hwnd: THandle;
    Param: Pointer): Boolean; stdcall;

function GetTitle (Hwnd: THandle; Param: Pointer): Boolean; stdcall;
var
  Text: string;
begin
  SetLength (Text, 100);
  GetWindowText (Hwnd, PChar (Text), 100);
  FormCallBack.ListBox1.Items.Add (
    IntToStr (Hwnd) + ': ' + Text);
  Result := True;
end;

procedure TFormCallback.BtnTitlesClick(Sender: TObject);
var
  EWProc: EnumWindowsProc;
begin
  ListBox1.Items.Clear;
  EWProc := GetTitle;
  EnumWindows (@EWProc, 0);
end;


end.

object FormCallback: TFormCallback
  Left = 200
  Top = 108
  Width = 304
  Height = 352
  Caption = 'Callback Function Call'
  Font.Charset = ANSI_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'MS Sans Serif'
  Font.Style = []
  PixelsPerInch = 96
  TextHeight = 13
  object ListBox1: TListBox
    Left = 0
    Top = 41
    Width = 296
    Height = 284
    Align = alClient
    ItemHeight = 13
    TabOrder = 0
  end
  object Panel1: TPanel
    Left = 0
    Top = 0
    Width = 296
    Height = 41
    Align = alTop
    TabOrder = 1
    object BtnTitles: TButton
      Left = 72
      Top = 8
      Width = 153
      Height = 25
      Caption = 'Get Windows Titles'
      TabOrder = 0
      OnClick = BtnTitlesClick
    end
  end
end