Systemwide Mousehook

Hi!

I tried to install a systemwide mousehook with
SetWindowsHookEx(WH_MOUSE, MouseHookCallBack, HInstance, 0)
inside a DLL. According to any articles I read about hooking this usually installs a systemwide mousehook, but it does not!

I use the DLL from my application, both coded with Delphi3. Inside the DLL all mouseevents are filtered and if there is the right one, a WM_USER message is posted to my application to inform it of the event.
But this only recognizes mouseevents on the application's form and not on the desktop or somewhere else.

What's wrong?
Is there any other way than using a DLL and hook procedures?

I tried to subclass the desktop window, but it does not work (as I read later). I think I declared everything as it should be (export and stdcall).

I saw several applications that are obviously able to receive systemwide events, but I did not manage.

Thanks in advance,
Harro
LVL 1
tierAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

olmyCommented:
Hi Tier

This keyboard hook is systemwide. It calls another program, but that part you can change.

library hookdll;
uses
  SysUtils,
  Classes,
  Windows,
  Messages;
var
  MyHook: HHOOK;

function MyHookProc(code: Integer; wparam: WPARAM; lparam: LPARAM): LRESULT stdcall;
var
  h: HWND;
begin
  Result := CallNextHookEx(MyHook, code, wparam, lparam);
  if (code = HC_ACTION) and ((lparam and $80000000) = 0) then begin
    // this is a keypress - tell caller
    h := FindWindow(nil, 'HookCaller');
    if h <> 0 then
      PostMessage(h, WM_APP, 0, 0);
  end;
end;

procedure Hook;
begin
  MyHook:= SetWindowsHookEx(WH_KEYBOARD, MyHookProc, hInstance, 0);
end;

procedure UnHook;
begin
  UnhookWindowsHookEx(MyHook);
end;

exports
  Hook, UnHook;

begin
end.


I Hope this helps :)

0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Delphi

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.