BorlandTalk.com

Vladimir Stefanovic · Guest

Hi Remy,

I wanted to avoid getting HWND of some APP from my DLL
by FindWindow() because of some problems I reported before.

Then you suggested me to pass the APP HWND to a DLL directly,
and so avoid determining the APP HWND all the time by
FindWindow().

You also suggested me to store the HWND in the shared memory
because that every DLL instance can have a valid HWND, but in my
case the APP can have in fact only *one* instance, so I suppose that
is not necessary.

That concept works *almost* fine for me, but... The funy thing
is that if my APP is in tray - nothing happens, ie. my APP
KeyHook() function that should be triggered by DLL's:

// Send key information to the main window
SendMessage( hAppWnd, WM_KEYHOOK, 0, lParam );

.... simply is not executed. I placed a fake ShowMessage("?"),
but it's not reached if the APP is in tray.

If the app is on screen, it is triggered.

Whay I'm missing? Is there anything I can do to avoid FindWindow()
which indeed works if the APP is in tray?

--- DLL ---

// ...
HWND hAppWnd;
// ...
void __stdcall SetHook( HWND hWnd )
{
ghhookKB = SetWindowsHookEx( WH_KEYBOARD, (HOOKPROC)CheckKey, ghInst,
NULL );
hAppWnd = hWnd;
}
// ...
DWORD __stdcall CheckKey( int nCode, WORD wParam, LONG lParam )
{
if ( ( nCode < 0 ) || ( nCode == HC_NOREMOVE ) )
return CallNextHookEx( ghhookKB, nCode, wParam, lParam );

// Skip if it's a repeat
if ( lParam & 0x40000000 )
return CallNextHookEx( ghhookKB, nCode, wParam, lParam );

// Check if Alt is pressed
if ( !( lParam & ( 1<<29 ) ) )
return CallNextHookEx( ghhookKB, nCode, wParam, lParam );

// Send key information to the main window
SendMessage( hAppWnd, WM_KEYHOOK, 0, lParam );

return CallNextHookEx( ghhookKB, nCode, wParam, lParam );
}
/************************************************************/

--
Best regards,
Vladimir Stefanovic

Remy Lebeau (TeamB) · Guest

"Vladimir Stefanovic" <antivari (AT) po (DOT) sbb.co.yu> wrote

Vladimir Stefanovic · Guest

Hi Remy,

Following your instructions I completely redesigned my DLL, and
now I have placed HWND in the shared memory, at least I think I did.

The code now works as I expect, and so far I haven't noticed crashes
of other VCL programs on their termination like it was the case when
I used FindWindow (from a DLL) to get the App HWND.

Anyway, can you please take a short look at the code and see if
I should make any (maybe code security) corrections to it.

Also, I have few questions:

1) Is there any sigifficant difference if I use SendMessage() or
PostMessage() from my DLL, in my case?

2) In the API CreateFileMapping(), I named a last argument "DiHook",
and I never used it after that. Is that OK? Should I use NULL?

3) Is that normal that I haven't any chages (because of shared memory
changes in y DLL) at my App side, except that I passed the HWND
argument to install a DLL?

--- DLL CODE ---

#include <vcl.h>
#include <windows.h>
#pragma hdrstop

#define WM_KEYHOOK (WM_USER + 1002)

HINSTANCE ghInst;

typedef struct _HookInfo
{
HHOOK ghhookKB;
HWND hAppWnd;

} HOOKINFO, *PHOOKINFO;

HANDLE hFileMapping = NULL;
PHOOKINFO pHookInfo = NULL;

#pragma argsused

//---------------------------------------------------------------------------
extern "C" __declspec(dllexport) __stdcall void SetHook(HWND);
extern "C" __declspec(dllexport) __stdcall void RemoveHook(void);
extern "C" __declspec(dllexport) __stdcall DWORD CheckKey(int, WORD,LONG);
//---------------------------------------------------------------------------

int WINAPI DllEntryPoint(HINSTANCE hinst, unsigned long reason, void
*lpReserved)
{
ghInst = hinst;

switch ( reason )
{
case DLL_PROCESS_ATTACH:
hFileMapping = CreateFileMapping( INVALID_HANDLE_VALUE,
NULL,
PAGE_READWRITE,
0,
sizeof(HOOKINFO),
"DiHook" );
if ( hFileMapping )
pHookInfo = (PHOOKINFO)MapViewOfFile( hFileMapping,
FILE_MAP_WRITE,
0,
0,
0 );
break;

case DLL_PROCESS_DETACH:
UnmapViewOfFile( pHookInfo );
pHookInfo = NULL;
CloseHandle( hFileMapping );
hFileMapping = NULL;
break;

}

return ( 1 );
}

void __stdcall SetHook( HWND hWnd )
{
if ( pHookInfo )
{
if( pHookInfo->ghhookKB == NULL )
pHookInfo->ghhookKB = SetWindowsHookEx( WH_KEYBOARD,
(HOOKPROC)CheckKey, ghInst, NULL );
pHookInfo->hAppWnd = hWnd;
}
}

void __stdcall RemoveHook( void )
{
if ( pHookInfo )
{
if ( pHookInfo->ghhookKB )
{
UnhookWindowsHookEx( pHookInfo->ghhookKB );
pHookInfo->ghhookKB = NULL;
}
}

}

DWORD __stdcall CheckKey( int nCode, WORD wParam, LONG lParam )
{
if ( ( nCode < 0 ) || ( nCode == HC_NOREMOVE ) )
return CallNextHookEx( pHookInfo->ghhookKB, nCode, wParam, lParam );

// Skip if it's a repeat
if ( lParam & 0x40000000 )
return CallNextHookEx( pHookInfo->ghhookKB, nCode, wParam, lParam );

// Check if Alt is pressed
if ( !( lParam & ( 1<<29 ) ) )
return CallNextHookEx( pHookInfo->ghhookKB, nCode, wParam, lParam );

// Send key information to the main window
if ( pHookInfo && pHookInfo->hAppWnd )
PostMessage( pHookInfo->hAppWnd, WM_KEYHOOK, 0, lParam );

return CallNextHookEx( pHookInfo->ghhookKB, nCode, wParam, lParam );
}

--
Best regards,
Vladimir Stefanovic
"Remy Lebeau (TeamB)" <no.spam (AT) no (DOT) spam.com> wrote

Remy Lebeau (TeamB) · Guest

"Vladimir Stefanovic" <antivari (AT) po (DOT) sbb.co.yu> wrote

Vladimir Stefanovic · Guest

Thanks,

I'll implement all that tomorrow...

--
Best regards,
Vladimir Stefanovic
"Remy Lebeau (TeamB)" <no.spam (AT) no (DOT) spam.com> wrote