example on a system wide keyboard hook, allowing you to disable keys and such. msdn docs say hook procs must be in a dll, works here in the exe itself with no problems on win2k. in this example the right and left windows logo keys are disabled

Was it supposed to run in Win98? It doesn't...

cant test on anything but win2k, msdn says



possibly the hookproc must be in a dll on 95/98 systems. id like to make a dll, but ive no idea how to make a dll export a callback function, anyone have an example?

oh i see it now..


try using WH_KEYBOARD on 95/98, tho it may not capture all the same keys

Exported functions:

MakeHook(hwnd)
UnHook()

A hooked (witch MakeHook) function window receives WM_KEY message every time a key is depressed. wParam contains ASCII code. I wrote this a long time ago, so it may be buggy, but I think some parts may be useful.

[code]format PE GUI DLL
entry DLL_init

include '%fasminc%\win32a.inc'

WM_KEY=WM_USER+100d

section '.code' code readable executable shareable

proc DLL_init,hinstDLL,fdwReason,lpvReserved
enter
cmp [fdwReason],DLL_PROCESS_DETACH
je .cleanup
mov eax,[hinstDLL]
mov [hModule],eax
mov eax,1 ; successful initialization
.ex:
return
.cleanup:
call UnHook
jmp .ex
endp


proc MakeHook,hwnd ;returns 0 when error
enter
mov eax,[hwnd]
mov [hHookedWnd],eax
invoke SetWindowsHookEx,WH_KEYBOARD,HookProc,[hModule],0
mov [hHook],eax
return
endp

align 4
UnHook:
invoke UnhookWindowsHookEx,[hHook]
ret

proc HookProc,code,wParam,lParam

KeyState rb 256
cBufor rb 4

enter
push ebx
invoke CallNextHookEx,[hHook],[code],[wParam],[lParam]
push eax ;save return vaulue
cmp [code],HC_ACTION
jne .skip
test [lParam],80000000h ;is key being released
jnz .skip
lea ebx,[KeyState]
invoke GetKeyboardState,ebx
movzx eax,byte[lParam+2] ;scan code
lea ecx,[cBufor]
invoke ToAscii,[wParam],eax,ebx,ecx,0
test eax,eax
jz .skip
push eax ;push character count
movzx eax,[cBufor]
invoke PostMessage,[hHookedWnd],WM_KEY,eax,0
pop eax ;pop character count
cmp al,2
jz .skip
movzx eax,[cBufor+1]
invoke PostMessage,[hHookedWnd],WM_KEY,eax,0
.skip:
pop eax ;restore ruturn value
pop ebx
return
endp

section '.data' data readable writeable shareable

hModule dd ?
hHook dd ?
hHookedWnd dd ?

section '.idata' import data readable writeable

library user,'USER32.DLL'

import user,\
SetWindowsHookEx,'SetWindowsHookExA',\
UnhookWindowsHookEx,'UnhookWindowsHookEx',\
CallNextHookEx,'CallNextHookEx',\
PostMessage,'PostMessageA',\
ToAscii,'ToAscii',\
GetKeyboardState,'GetKeyboardState'

section '.edata' export data readable

export 'KEY.DLL',\ ;dll name
MakeHook,'MakeHook',\
UnHook,'UnHook'
section '.reloc' fixups data readable discardable[/code]

the reason for using a dll is due to it's ability to be accessed many times by many programs in a multitasking environment. Though, a dll is not required.

The reason most global hooks must be in DLLs is simple - the hooks need to execute in the context of multiple processes, and thus the OS has to inject hook DLLs into those process address spaces.

It's pretty easy to determine if a global hook needs to be put in a DLL or not - try keeping it in your app, and install the hook. If the system comes crashing down, you need to put it in a DLL

works fine on 2k/xp in this example, no dll used

PlatformSDK has this to say:

...so it sounds like, officially too, no DLL is needed for this hook.