global low level keyboard hook being called when SendInput is made. how to prevent it? - c++

Question

I have a win 32 application written in c++ which sets the low level keyboard hook. now i want to sendInput to any app like word / notepad. how do i do this?
i have already done enough of using findwindow / sendmessage. for all these, i need to know edit controls. finding the edit control is very difficult.
since SendInput works for any windows application, i want to use it. the problem is i get a call to my callback function with the pressed key.
for e.g i pressed A and i want to send U+0BAF unicode character to the active applciation windows. in this case, assume it is notepad.
the problem is i get two characters U+0BAF and A in the notepad.
A is being sent because i am calling CallNextHookEx( NULL, nCode, wParam, lParam);
if i return 1 after sendInput, then nothing is sent to notepad.
any suggestion?

Answer 1

If I understood your problem correctly, you should ignore "injected" key events in your hook procedure, like this:
LRESULT CALLBACK
hook_proc( int code, WPARAM wParam, LPARAM lParam )
{
KBDLLHOOKSTRUCT* kbd = (KBDLLHOOKSTRUCT*)lParam;
// Ignore injected events
if (code < 0 || (kbd->flags & LLKHF_INJECTED)) {
return CallNextHookEx(kbdhook, code, wParam, lParam);
}
...
Update: additionally, you have to eat characters and notify some other routine for a character press through Windows messages.
Example:
...
// Pseudocode
if (kbd->vkCode is character) {
if (WM_KEYDOWN == wParam) {
PostMessage(mainwnd, WM_MY_KEYDOWN, kbd->vkCode, 0);
return 1; // eat the char, ie 'a'
}
}
return CallNextHookEx(kbdhook, code, wParam, lParam);
And, in some other module, you handle WM_MY_KEYDOWN:
ie, #define WM_MY_KEYDOWN (WM_USER + 1)
and call the appropriate routine that will generate new key events.