confused by WinGetTitle

[636C65616E]

Heyo,

I noticed something a bit weird.

I was playing with Kernel32 and User32, after creating a window and loging the mesages received, I noticed that WinGetTitle (native AutoIt) was sending a (2 !!) WM_NULL msg instead of WM_GETTEXT.

Quote

$hwnd = 0x04680908
call: U32_SetWindowTextA($hwnd,"foo")
[WndProc] hwnd:0x04680908 msg:0x000C
call: WinGetTitle($hwnd)
[WndProc] hwnd:0x04680908 msg:0x0000
[WndProc] hwnd:0x04680908 msg:0x0000
WinGetTitle > title = ""
call: U32_GetWindowTextA($hwnd,$ptr,256)
[WndProc] hwnd:0x04680908 msg:0x000D
GetWindowTextA > title = "foo"

I can provide the code ...

Edited January 20, 2021 by 636C65616E

[Nine]

2 hours ago, 636C65616E said:

I can provide the code ...

Please do so...

[636C65616E]

expandcollapse popup

local const $K32_HANDLE = DllOpen('kernel32.dll')
local const $NT_HANDLE  = DllOpen('ntdll.dll')
local const $U32_HANDLE = DllOpen('user32.dll')

func debug($msg)
    ConsoleWrite($msg & @CRLF)
endfunc
func WrapString($str, $wchar = FALSE)
    local $struct, $len = StringLen($str)
    if ($wchar) then
        $struct = DllStructCreate('WCHAR[' & ($len + 1) & ']')
    else
        $struct = DllStructCreate('CHAR[' & ($len + 1) & ']')
    endif
    DllStructSetData($struct, 1, $str)
    return $struct
endfunc


local const $STRUCTSTR_SYSTEM_INFO = ''  & _
    'DWORD dwOemId;'                     & _
    'DWORD dwPageSize;'                  & _
    'PTR   lpMinimumApplicationAddress;' & _
    'PTR   lpMaximumApplicationAddress;' & _
    'DWORD dwActiveProcessorMask;'       & _
    'DWORD dwNumberOfProcessors;'        & _
    'DWORD dwProcessorType;'             & _
    'DWORD dwAllocationGranularity;'     & _
    'WORD  wProcessorLevel;'             & _
    'WORD  wProcessorRevision;'

local const $STRUCTSTR_MSG = '' & _
    'HWND   hwnd;'    & _
    'UINT   message;' & _
    'WPARAM wParam;'  & _
    'LPARAM lParam;'  & _
    'DWORD  time;'    & _
    'LONG   pt_x;'    & _ ;'STRUCT;LONG x;LONG y;ENDSTRUCT pt;' & _
    'LONG   pt_y;'    & _
    'DWORD  lPrivate;'

local const $STRUCTSTR_WNDCLASSEXA = '' & _
    'UINT   cbSize;'        & _
    'UINT   style;'         & _
    'PTR    lpfnWndProc;'   & _
    'INT    cbClsExtra;'    & _
    'INT    cbWndExtra;'    & _
    'HANDLE hInstance;'     & _
    'HANDLE hIcon;'         & _
    'HANDLE hCursor;'       & _
    'HANDLE hbrBackground;' & _
    'PTR    lpszMenuName;'  & _
    'PTR    lpszClassName;' & _
    'HANDLE hIconSm;'

func CheckError($name, $prefix = 'DLLCALL', $error = @ERROR)
    if ($error <> 0) then
        debug('[ERROR:' & $prefix & '] ' & $name & ': ' & $error)
    endif
    SetError($error) ; to maintain the error flag after this call
endfunc

func K32_SetLastError($error)
    DllCall($K32_HANDLE, 'NONE', 'SetLastError', 'DWORD', $error)
    CheckError('K32_SetLastError')
endfunc
func K32_GetLastError()
    local $ret = DllCall($K32_HANDLE, 'DWORD', 'GetLastError')
    CheckError('K32_GetLastError')
    return $ret[0]
endfunc
func K32_OpenProcess($dwDesiredAccess,$bInheritHandle,$dwProcessId)
    K32_SetLastError(0)
    local $ret = DllCall($K32_HANDLE, 'HANDLE', 'OpenProcess', _
        'DWORD', $dwDesiredAccess, _
        'BOOL' , $bInheritHandle, _
        'DWORD', $dwProcessId)
    CheckError('K32_OpenProcess')
    return $ret[0]
endfunc
func K32_CloseHandle($hObject)
    K32_SetLastError(0)
    local $ret = DllCall($K32_HANDLE, 'BOOL', 'CloseHandle', 'HANDLE', $hObject)
    CheckError('K32_CloseHandle')
    return $ret[0]
endfunc

;HWND CreateWindowExA
;  DWORD     dwExStyle,
;  LPCSTR    lpClassName,
;  LPCSTR    lpWindowName,
;  DWORD     dwStyle,
;  int       X,
;  int       Y,
;  int       nWidth,
;  int       nHeight,
;  HWND      hWndParent,
;  HMENU     hMenu,
;  HINSTANCE hInstance,
;  LPVOID    lpParam
func U32_CreateWindowExA($dwExStyle,$lpClassName,$lpWindowName,$dwStyle,$X,$Y,$nWidth,$nHeight,$hWndParent,$hMenu,$hInstance,$lpParam)
    K32_SetLastError(0)
    local $ret = DllCall($U32_HANDLE, 'HWND', 'CreateWindowExA', _
        'DWORD', $dwExStyle, _
        'STR', $lpClassName, _
        'STR', $lpWindowName, _
        'DWORD', $dwStyle, _
        'INT', $X, _
        'INT', $Y, _
        'INT', $nWidth, _
        'INT', $nHeight, _
        'HWND', $hWndParent, _
        'HANDLE', $hMenu, _
        'HANDLE', $hInstance, _
        'PTR', $lpParam)
    CheckError('U32_CreateWindowExA')
    return $ret[0]
endfunc
func U32_DestroyWindow($hWnd)
    K32_SetLastError(0)
    local $ret = DllCall($U32_HANDLE, 'BOOL', 'DestroyWindow', 'HWND', $hWnd)
    CheckError('U32_DestroyWindow')
    return $ret[0]
endfunc
func U32_RegisterClassExA($arg)
    K32_SetLastError(0)
    local $ret = DllCall($U32_HANDLE, 'WORD', 'RegisterClassExA', 'PTR', $arg)
    CheckError('U32_RegisterClassExA')
    return $ret[0]
endfunc
;LRESULT LRESULT DefWindowProcA
;   HWND   hWnd,
;   UINT   Msg,
;   WPARAM wParam,
;   LPARAM lParam
func U32_DefWindowProcA($hWnd,$Msg,$wParam,$lParam)
    local $ret = DllCall($U32_HANDLE, 'LONG_PTR', 'DefWindowProcA', _
        'HWND', $hWnd, _
        'UINT', $Msg, _
        'WPARAM', $wParam, _
        'LPARAM', $lParam)
    CheckError('U32_DefWindowProcA')
    return $ret[0]
endfunc
;int GetWindowTextA
;   HWND  hWnd,
;   LPSTR lpString,
;   int   nMaxCount
func U32_GetWindowTextA($hWnd,$lpString,$nMaxCount)
    K32_SetLastError(0)
    local $ret = DllCall($U32_HANDLE, 'INT', 'GetWindowTextA', _
        'HWND', $hWnd, _
        'PTR', $lpString, _
        'INT', $nMaxCount)
    CheckError('U32_GetWindowTextA')
    return $ret[0]
endfunc
;BOOL SetWindowTextA
;   HWND   hWnd,
;   LPCSTR lpString
func U32_SetWindowTextA($hWnd,$lpString)
    K32_SetLastError(0)
    local $ret = DllCall($U32_HANDLE, 'BOOL', 'SetWindowTextA', _
        'HWND', $hWnd, _
        'STR', $lpString)
    CheckError('U32_SetWindowTextA')
    return $ret[0]
endfunc

global const $INVALID_HANDLE_VALUE = (-1)
global const $NULLPTR = ptr(0)
global const $PROCESS_ALL_ACCESS = 0x1FFFFF
global const $CW_USEDEFAULT = 0x80000000
global const $HWND_MESSAGE = ptr(-3)

; ---------------------------------------------------

;LRESULT CALLBACK WindowProc(
;   _In_ HWND   hwnd,
;   _In_ UINT   uMsg,
;   _In_ WPARAM wParam,
;   _In_ LPARAM lParam
func WndProcFunc($hwnd, $uMsg, $wParam, $lParam)
    debug('[WndProc] hwnd:' & ptr($hwnd) & ' msg:0x' & hex($uMsg,4))
    return U32_DefWindowProcA($hWnd,$uMsg,$wParam,$lParam)
endfunc
local $WndProc = DllCallbackRegister(WndProcFunc, 'LONG_PTR', 'HWND;UINT;WPARAM;LPARAM;')

local $className = 'MyWndMsg'
local $wrappedClassName = WrapString($className)

local $class_struct = DllStructCreate($STRUCTSTR_WNDCLASSEXA)
    $class_struct.cbSize = DllStructGetSize($class_struct)
    $class_struct.style = 0
    $class_struct.lpfnWndProc = DllCallbackGetPtr($WndProc)
    $class_struct.cbClsExtra = 0
    $class_struct.cbWndExtra = 0
    $class_struct.hInstance = null ; $proc
    $class_struct.hIcon = null
    $class_struct.hCursor = null
    $class_struct.hbrBackground = null
    $class_struct.lpszMenuName = null
    $class_struct.lpszClassName = DllStructGetPtr($wrappedClassName)
    $class_struct.hIconSm = null

local $res = U32_RegisterClassExA(DllStructGetPtr($class_struct))
if ($res = 0) then
    debug('U32_RegisterClassExA failed')
    local $err = K32_GetLastError()
    debug('LastError = ' & $err)
endif

debug('call: U32_CreateWindowExA(....)')
local $hwnd = U32_CreateWindowExA(0x0, $className, null, 0x0, $CW_USEDEFAULT, $CW_USEDEFAULT, 0, 0, 0, null, null, null)
if ($hwnd = $NULLPTR) then
    debug('U32_CreateWindowExA failed')
    local $err = K32_GetLastError()
    debug('LastError = ' & $err)
endif
debug('$hwnd = ' & $hwnd)

debug('call: U32_SetWindowTextA($hwnd,"foo")')
local $res = U32_SetWindowTextA($hwnd,'foo')
if ($res = 0) then
    debug('U32_SetWindowTextA failed')
    local $err = K32_GetLastError()
    debug('LastError = ' & $err)
endif

debug('call: WinGetTitle($hwnd)')
local $title = WinGetTitle($hwnd)
debug('WinGetTitle > title = "' & $title & '"')

local $title_struct = DllStructCreate('CHAR[256]')
debug('call: U32_GetWindowTextA($hwnd,$ptr,256)')
local $res = U32_GetWindowTextA($hwnd, DllStructGetPtr($title_struct), 256)
if ($res = 0) then
    debug('U32_GetWindowTextA failed')
    local $err = K32_GetLastError()
    debug('LastError = ' & $err)
endif
local $title = DllStructGetData($title_struct, 1)
debug('GetWindowTextA > title = "' & $title & '"')

here it is

[argumentum]

hmmm, changing this local $className = 'AutoIt v3' ; 'MyWndMsg' make it work 
Edit: 'AutoIt v3 GUI' also works

Edited January 20, 2021 by argumentum

[636C65616E]

13 minutes ago, argumentum said:

hmmm, changing this local $className = 'AutoIt v3' ; 'MyWndMsg' make it work 

yep, it works ... tryed with random stuff with spaces and other combinations, and still doesn't work ... im not a Microsoft expert so guess I miss something haha

edit: by changing the class name, you use the autoit class WndProc by overwriting the custom class (as this class already exists), but the DefWindowProc should handle the stuff (and it does for pure MS functions ...)

Edited January 20, 2021 by 636C65616E

[argumentum]

could you try CreateWindowExW instead of  CreateWindowExA ?

[636C65616E]

yes, but the only difference is the support of WCHAR ... it should change nothing

[argumentum]

Just now, 636C65616E said:

... it should change nothing

well, _WinAPI_CreateWindowEx() works, so, maybe ?

[636C65616E]

just tested, and still not working ...

but the real weirdy stuff is this 2 WM_NULL oO (the fact that it returns an empty string is only implied)

Edited January 20, 2021 by 636C65616E

[Nine]

Works for me on Win7 (without changing any of your code) but fails on Win10.

On Win7 there is that double WM_NULL also, but there is additional messages (WM_GETTEXTLENGTH + WM_GETTEXT).

Whereas in Win10 there are no additional messages...

[argumentum]

... tested _WinAPI_RegisterClassEx() and is basically what you'd like to do. Compare notes between the _WinAPI_RegisterClassEx() example and yours.
( since I'm clueless of all this DLL calling, I may be missing the point. In that case ... let me know )

Yes, WinGetTitle() fails.

debug( '! WinGetTitleByList > "' & WinGetTitleByList($hwnd) & '"')
Func WinGetTitleByList($hwnd)
    Local $aWinList = WinList()
    For $n = 1 To UBound($aWinList) -1
        If $hwnd = $aWinList[$n][1] Then
            Return SetError(0, UBound($aWinList) -1, $aWinList[$n][0])
            ConsoleWrite($n & @TAB & $aWinList[$n][1] & @TAB & $aWinList[$n][0] & @CRLF)
        EndIf
    Next
    Return SetError(1, UBound($aWinList) -1, "")
EndFunc

this WinGetTitleByList() works, so, there should be a ticket opened. What say you @Nine

Edited January 20, 2021 by argumentum

[Nine]

I believe there is bug with WinGetTitle under Win10 using parameter $hWnd.  If you replace $hWnd with "foo", it works.  If you use "[CLASS:MyWndMsg]", it works.  If you do a WinList(), it will appear in the list.  I don't see how it cannot be a bug...

Edit : tested on beta still same bug.

Edited January 20, 2021 by Nine

[argumentum]

20 minutes ago, Nine said:

tested on beta still same bug

...tested back to v3.3.6.1 with the same bug. So is not something newly introduced. I hope you open the ticket ( tho I saw jpm looking in this thread )

[Nine]

1 minute ago, argumentum said:

I hope you open the ticket ( tho I saw jpm looking in this thread )

I have asked the devs to look into it...before opening a ticket.

[636C65616E]

7 minutes ago, Nine said:

I have asked the devs to look into it...before opening a ticket.

well, keep us posted

[Nine]

Current Alpha version has resolved that issue