ControlGetHandle in AutoIT - autoit

Question

Can anyone tell me what ControlGetHandle() does behind the scenes? What Windows API function does it invoke? How can I see it? (logs/debug mode).
It sometimes succeeds and sometimes fails and I don't understand why. I looked all over the place, including AutoIT .au3 include files, but I couldn't find any information.

Answer 1

So, I discovered this amazing tool called "API Monitor". It shows you API calls made to the OS. You can filter etc. When running AutoIT with "ControlGetHandle" you can see that it actually calls two functions:
EnumWindows
EnumChildWindows
With the relevant parameters to get the handle you wish.
Thanks!

Answer 2

I believe it uses GetDlgCtrlID among other things. If you are having trouble getting it to return a handle sometimes changing the controlID parameter will fix it. Also, make sure you are waiting for the control to load first. If the control exists and you are using the right controlID parameters AutoIt will be able to get a controls handle 99.9999% of the time.

Answer 3

The first thing that comes to mind, the function finds the window with matching caption, lists the controls, finds the control with suitable criteria( class name and text), and returns his HWnd. This is done using the API EnumWindows/GetWindowTextLength/GetWindowText,GetWindowClassName.
Here, I wrote a small example, but it is in Pascal ( Excuse me. later rewritten in AutoIt. ;) ;) ;)
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
fhw:hwnd;
cls,txt:string;
wind:hwnd;
implementation
{$R *.dfm}
function GetText(wnd:hwnd):string;
var
len:integer;
begin
len:=GetWindowTextLength(wnd)+1;
SetLength(result,len);
SetLength(Result,GetWindowText(wnd,pchar(result),len));
end;
function GetClsName(wnd:hwnd):string;
begin
SetLength(result,5000);
SetLength(result,GetClassName(wnd,pchar(result),5000));
end;
function EnumChildProc(wnd:HWnd; param:Integer):bool;stdcall;
var
wintext,wincls:string;
ccmp,tcmp:boolean;
begin
wintext:=gettext(wnd);
wincls:=getclsname(wnd);
if cls <> '' then
ccmp:=(comparetext(cls,wincls)=0)
else
ccmp:=true;
if txt <> '' then
tcmp:=(comparetext(txt,wintext)=0)
else
tcmp:=true;
result:=not (tcmp and ccmp);
if not result then
wind:=wnd;
end;
procedure GetControlHandle(title:string; wtext:string; clsname:string);
var
hw:hwnd;
begin
wind:=0;
hw:=findwindow(nil,pchar(title));
if hw <> 0 then
begin
cls:=clsname;
txt:=wtext;
EnumChildWindows(hw,#EnumChildProc,integer(pointer(result)));
end;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
w:hwnd;
begin
getcontrolhandle('New Project','','Button');
w:=wind;
CloseWindow(w);
end;
end.