Windows CE Keyboard Hook

Windows CE Keyboard Hook

http://weibeltech.com/?p=110

March 9th, 2007 at 4:38 pm (Code, CE, Tech)

A teammate needed to write a Windows CE Keyboard Hook. So I gave them a hand, after doing a little digging I came across this posting. Many thanks to Prathamesh S Kulkarni for this post.

http://www.codeproject.com/ce/wincekbhook.asp?print=true

I duplicated the core of this sample code below so I don’t loose it in the future. Check out Prathamesh’s code for commented code. To make this work call activate() at the beginning of your app.

if (!activate(hInst, hook)) {
       return FALSE;
   }

And deactivate() at the end.

deactivate();

Then fill in the hook() with some interesting logic.

#include 
#include 
#include 

#define WH_KEYBOARD_LL          20

typedef LRESULT (CALLBACK* HOOKPROC)(int code, WPARAM wParam, LPARAM lParam);
typedef HHOOK   (WINAPI *_SetWindowsHookExW)(int, HOOKPROC, HINSTANCE, DWORD);
typedef LRESULT (WINAPI *_CallNextHookEx)(HHOOK, int, WPARAM, LPARAM);
typedef LRESULT (WINAPI *_UnhookWindowsHookEx)(HHOOK);

typedef struct {
   DWORD vkCode;
   DWORD scanCode;
   DWORD flags;
   DWORD time;
   ULONG_PTR dwExtraInfo;
} KBDLLHOOKSTRUCT, *PKBDLLHOOKSTRUCT;

static _SetWindowsHookExW   SetWindowsHookEx;
static _UnhookWindowsHookEx UnhookWindowsHookEx;
static _CallNextHookEx      CallNextHookEx;

HINSTANCE   gHook   = NULL;
HHOOK       gInst   = NULL;

BOOL activate(HINSTANCE, HOOKPROC);
BOOL deactivate();
LRESULT CALLBACK hook(int nCode, WPARAM wParam, LPARAM lParam);

//
// activate() -
//
BOOL
activate(HINSTANCE hInst, HOOKPROC hProc)
{
   SetWindowsHookEx        = NULL;
   CallNextHookEx          = NULL;
   UnhookWindowsHookEx     = NULL;

   gHook = LoadLibrary(_T("coredll.dll"));
   if(gHook == NULL) {
       return(false);
   } else {

       SetWindowsHookEx = (_SetWindowsHookExW)GetProcAddress(
           gHook, _T("SetWindowsHookExW"));
       if(SetWindowsHookEx == NULL) {
           return(false);
       } else {
           gInst = SetWindowsHookEx(WH_KEYBOARD_LL, hProc, hInst, 0);
           if(gInst == NULL) {
               return false;
           }
       }

       CallNextHookEx = (_CallNextHookEx)GetProcAddress(
           gHook, _T("CallNextHookEx"));
       if(CallNextHookEx == NULL) {
           return false;
       }

       UnhookWindowsHookEx = (_UnhookWindowsHookEx)GetProcAddress(
           gHook, _T("UnhookWindowsHookEx"));
       if(UnhookWindowsHookEx == NULL) {
           return(false);
       }
   }
   return(true);
}


//
// deactivate() -
//
BOOL
deactivate()
{
   if(gInst != NULL) {
       UnhookWindowsHookEx(gInst);
       gInst = NULL;
   }
   if(gHook != NULL) {
       FreeLibrary(gHook);
       gHook = NULL;
   }
   return(true);
}

//
// hook() -
//
LRESULT CALLBACK
hook(int nCode, WPARAM wParam, LPARAM lParam)
{
   // Do something interesting here
   return CallNextHookEx(gInst, nCode, wParam, lParam);
}