C / C++ / MFC

Keyboard Hook in MFC -- Minor Syntax

26-Jul-05 11:22

While there's probably a better/cleaner solution, you might check the HKEY_CURRENT_USER\AppEvents\Schemes\Apps\Explorer\Navigating\.current registry key.

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

namespace and DLL issues

Joris van der Pol26-Jul-05 8:25

Joris van der Pol

26-Jul-05 8:25

Hey

Atm i'm working on a image processing project and i hit some snags. The interface of the program is created with MFC and GDI+, for the processing bit i created my own classes and functions and shoved them in one DLL. Since my classes and GDI+ have some similarities i tried to put my stuff in a namespace. So in stdafx.h i put the headers of the classes i want to import, in a namespace (implicit linking). This gives linker errors saying it cannot find certain functions. A solution would be to place all my code in a namespace already before compiling the dll. Is there a way around this, like that you choose between placing it in a namespace or not?
There is another strange thing. Apparently, when having this dll and calling for example 'bitmap = new Bitmap(..)', new returns NULL, while directly placing all my stuff in the project without the dll it works fine. Any thoughts on that?

c121hains26-Jul-05 7:06

c121hains

26-Jul-05 7:06

Every example of using Keyboard hooks with MFC seems to be in a DLL. Is there any reason for this? I'm trying to do it in a separate class so my program will be all together. How do you do this? I've pasted what I have so far but the error i get is:

error C2664: 'SetWindowsHookExA' : cannot convert parameter 2 from 'long (int,unsigned int,long)' to 'long (__stdcall *)(int,unsigned int,long)'
None of the functions with this name in scope match the target type

//Keyboard hook callback
LRESULT CALLBACK CKeyboardHook::KeyboardProc(int nCode, WPARAM wParam, LPARAM lParam)
{
try
{
KBDLLHOOKSTRUCT *pkbhs = (KBDLLHOOKSTRUCT *) lParam;

if (nCode >= 0)
{
if (wParam == WM_KEYDOWN)
{

BOOL bControlKeyDown = FALSE;

// Check to see if the CTRL key is pressed
bControlKeyDown = GetAsyncKeyState (VK_CONTROL) >> ((sizeof(SHORT) * 8) - 1);

if ((pkbhs->vkCode == VK_F) && bControlKeyDown)
{
SendMessage(hWnd,UWM_SETVISIBLE, 0, 0);
ShowWindow(hWnd, SW_RESTORE);
}
}
}
}
catch(...)
{
}

return CallNextHookEx( hkb, nCode, wParam, lParam );
}

BOOL CKeyboardHook::InstallHook()
{
HINSTANCE ppI = AfxGetInstanceHandle();
hkb=SetWindowsHookEx(WH_KEYBOARD_LL, KeyboardProc,ppI,0);

return TRUE;
}

---- and in the header:
class CKeyboardHook
{
public:
CKeyboardHook();

LRESULT CALLBACK KeyboardProc(int nCode, WPARAM wParam, LPARAM lParam);

BOOL InstallHook();
... Confused | :confused:

David Crow26-Jul-05 8:04

26-Jul-05 8:04

c121hains wrote:
Every example of using Keyboard hooks with MFC seems to be in a DLL. Is there any reason for this?

Yes. Global hooks are part of a chain. The hook procedure must be exported in a DLL in order for Windows to call it.

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

c121hains26-Jul-05 8:14

c121hains

26-Jul-05 8:14

Ohhh i see.

There's a setting in visual studio (statically link objects or something) so that i can compile my EXE and DLL into one EXE right? How do i do this?

David Crow26-Jul-05 9:10

26-Jul-05 9:10

"Dynamic linking" is the process that Windows uses to link a function call in one module to the actual function in the library module. "Static linking" occurs at compile/link time when you link various object (.OBJ) modules, run-time library (.LIB) files to create a Windows .EXE file. Dynamic linking occurs at run time. With static linking, the linker copies the code for the function into the application's executable file. With dynamic linking, a link is established when the program is loaded into memory or while it is running. So even though you can static link your DLL to your EXE, you still need a DLL that contains the exported hook function.

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

Kuniva26-Jul-05 12:41

Kuniva

26-Jul-05 12:41

That's not true. You can export the function in your EXE just as well, a DLL and EXE are basically the same, they just have different entry points and are treated differently by Windows' PE loader. I tried the exact same thing with the keyboardhook once this guy is trying and it worked fine, in one EXE. The problem is, when I tried it without MFC for some reason it didn't work, but it did work with MFC. The hook function was simply in my EXE's export table, so windows just loaded the same EXE that made the call for the hooking registration in memory (or used the same copy i dunno what it does exactly) and used that function as the hook procedure.

Kuniva
--------------------------------------------

David Crow27-Jul-05 2:46

27-Jul-05 2:46

Kuniva wrote:
I tried the exact same thing with the keyboardhook once this guy is trying and it worked fine, in one EXE.

Did you use a local or a global hook? The former will work in both a DLL and an EXE, while the latter will only work in a DLL.

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

Does anybody know any good WIN32 SDK sites?

Anonymous26-Jul-05 13:04

Anonymous

26-Jul-05 13:04

The keyboard hook proc must be either a global function or a static member of your class.

Also, hooks are in dll's if they are global hooks (work no matter where teh input focus is). If the hook is in your .exe then it will only catch keyboard events when the exe has the keyboard focus.

jinzhecheng26-Jul-05 6:51

jinzhecheng

26-Jul-05 6:51

Thanks alot!

David Crow26-Jul-05 7:59

26-Jul-05 7:59

Aside from msdn.microsoft.com[^], can you be a bit more specific? Win32 SDK is a very broad term.

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

Anonymous26-Jul-05 13:05

Anonymous

26-Jul-05 13:05

http://www.codeproject.com[^] Big Grin | :-D

Jack Puppy26-Jul-05 15:01

Jack Puppy

26-Jul-05 15:01

I've used this small site in the past:
Catch 22

Painted on the side of a dog trainer's van: SIT HAPPENS