Hooking Windows events in compact framework

[Ralph Flaugher]

In the full .NET framework you can hook Windows events
using the WIN32 function SetWindowsHookEx. This function
does not appear to be included in the CE API. Is there
another method which can be utilized to accomplish this in
the compact framework?

[Paul G. Tobey [eMVP]]

I think there's been substantial traffic on this before. Have you checked
the newsgroup archives?

http://groups.google.com/groups?hl=en&lr=lang_en&ie=UTF-8&oe=UTF-8&group=microsoft.public.dotnet.framework.compactframework

You can't have the hook be written in .NET CF, but you can write a C/C++
native DLL which calls SetWindowsHookEx(), implements the hook function and
maybe posts messages to a MessageWindow subclass in .NET CF. I've done this
to catch Tab keys in dialogs to move the focus around...

Paul T.

"Ralph Flaugher" <ralph.f...@us.asirobicon.com> wrote in message
news:040e01c352ec$8a4ce300$a101...@phx.gbl...

[Ralph Flaugher]

As I mentioned in my original posting, SetWindowHookEx does not appear
to be available in Windows CE. At least according to the documnetation
I have been able to find. Do you know differently? If it is available
then this should not be a problem.

Thanks,

Ralph

*** Sent via Developersdex http://www.developersdex.com ***
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[Ralph Flaugher]

Thanks. That was my first thought as well. However, as I
mentioned in my original email, I can't find anything in
the documentation for SetWindowsHookEx that indicates it
is available in Windows CE. From what you indicate it is
available. If so, do you know in which DLL it is located?

Ralph

>.
>

[Paul G. Tobey [eMVP]]

Yes, that's right. The documentation doesn't list it. However, it is
present and you can call it like this:

localHook = SetWindowsHookEx( WH_KEYBOARD_LL, ... );

I believe it's in coredll, but you would not want to call it directly from
.NET CF.

Paul T.

"Ralph Flaugher" <ralph.f...@us.asirobicon.com> wrote in message

news:07bc01c35506$89adf670$a101...@phx.gbl...

[Ralph Flaugher]

Thanks, that information makes things a lot easier.
However, just out of curiosity, why not call it from
within .NET CF?

Ralph

>-----Original Message-----
>Yes, that's right. The documentation doesn't list it.
However, it is
>present and you can call it like this:
>
> localHook = SetWindowsHookEx( WH_KEYBOARD_LL, ... );
>
>I believe it's in coredll, but you would not want to call
it directly from

>..NET CF.

>.
>

[Paul G. Tobey [eMVP]]

Because you can't specify the hook routine in managed code, so what would
you pass to it?

Paul T.

"Ralph Flaugher" <ralph.f...@us.asirobicon.com> wrote in message

news:351d01c35541$4c47e080$a001...@phx.gbl...

[Ralph Flaugher]

I was planning on using the technique in this artical:

http://msdn.microsoft.com/msdnmag/issues/02/10/CuttingEdge/

>.
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[Paul G. Tobey [eMVP]]

I don't believe that the necessary machinery is present in .NET CF to do
that. Also, since you'd have to define all of the message constants
(WM_KEYDOWN, WM_CHAR, etc.), plus do the message cracking, I think you'll
get done sooner if you just do the hooking in C++ and pass something to a
MessageWindow subclass in the .NET CF to handle communications from the hook
routine. It's not super fast, but it seems to be very reliable.

Paul T.

"Ralph Flaugher" <ralph.f...@us.asirobicon.com> wrote in message

news:049801c3554d$1895a950$a301...@phx.gbl...

[Ralph Flaugher]

I hate to bother you again on this but I don't know who
else to ask. I ahve written a DLL like you suggested.
(See code below) However, whenever I call the
SetWindowsHookExW function I get an error of invalid
parameter. I have tried every veriation I can think of
with the same result. Could you let kme know what I am
doing wrong?

Thanks again,

Ralph

#include "stdafx.h"
#include <kfuncs.h>

#define MSG (WM_USER+0)

HHOOK hhook = NULL;
HWND Form = NULL;
HANDLE hHandle = NULL;

BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
switch (ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
case DLL_THREAD_ATTACH:
hHandle = hModule;

case DLL_THREAD_DETACH:
case DLL_PROCESS_DETACH:
break;
}
return TRUE;
}

extern "C" HHOOK SetWindowsHookExW(int code, void *func,
HINSTANCE hInstance, DWORD threadId);
extern "C" int UnhookWindowsHookEx(HHOOK hhook);
extern "C" int CallNextHookEx(HHOOK hhook, int code,
WPARAM wParam, LPARAM lParam);

LRESULT CALLBACK MouseProc(int nCode, WPARAM wParam,
LPARAM lParam)
{
if (nCode < 0) // do not process the message
return CallNextHookEx(hhook, nCode, wParam,
lParam);

SendMessage(Form, MSG, wParam, lParam);

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

void _stdcall Initialize(HWND form)
{
Form = form;
}

int __stdcall UnInstall()
{
if (hhook == NULL)
{
return FALSE;
}

BOOL status = UnhookWindowsHookEx(hhook);

hhook = NULL;

if (status)
{
return FALSE;
}

return GetLastError();
}

int __stdcall Install(int code)
{
UnInstall();

hhook = SetWindowsHookExW(code, MouseProc,
(HINSTANCE) hHandle, 0);

if (hhook) return FALSE;

return GetLastError();
}

>.
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[Paul G. Tobey [eMVP]]

What code value are you passing to SetWindowsHookEx()? Not all of the Win32
desktop values are supported (I've only used the keyboard one for low-level
keyboard input).

Paul T.

"Ralph Flaugher" <ralph.f...@us.asirobicon.com> wrote in message

news:015c01c356ae$10ed6f00$a101...@phx.gbl...

[Ralph Flaugher]

I have tried them all including the keyboard low-level. I
always get an error 87 (Illegal parameter value). The
same is true if I call SetWindowsHookExW with the last two
parmeters set as "0, GetCurrentThreadId());".

For your DLL:

1. Are you running pocket PC 2002?

2. Did you compile the DLL with Visual C++ 3 or 4? I am
using 4.0 and using "editbin" to change the type to a 3.0
dll.

3. I am calling GetCurrentThreadId() in my DLL because
that appears the only way to do it, I know of. This is
because it is not a function call but a Macro. I don't
know if it works correctly in a dll.

4. Code you send me a code snipit?

Thanks

>.
>

[Paul G. Tobey [eMVP]]

Here's my call to SetWindowsHookEx():

localHook = SetWindowsHookEx( WH_KEYBOARD_LL,
&TabHook,
(HINSTANCE)hMod,
0 /* Associate with current thread */ );

This works fine for me, but I'm hooking from a C++ DLL and the hook routine
is in that DLL...

I'm running Windows CE.NET, so more like PPC 2003 than 2002, and I am using
eVC 4.

Paul T.

"Ralph Flaugher" <ralph.f...@us.asirobicon.com> wrote in message

news:024d01c356d5$13e23340$a501...@phx.gbl...

[Tibor Meinczinger]

Could you solve the problem?
I am using embedded Visual C++ 3.0, running PC 2002 and
have the same problem:
always get the error 87.
Does putting the hook-callback into a separate dll may
help??? (I haven't tried yet).
Thanks,
Tibor

>.
>

[Tibor Meinczinger]

It works now!
The problem was, that i used 13 as the value for
WH_KEYBOARD_LL, however the right value is 20.

Tibor

>.
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[Ralph Flaugher]

I am using 13 as well. Where did you find that the
correct value should be 20?

Ralph

>.
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[Tibor Meinczinger]

I don't remember, I have browsed a lot of newsgroups...
But now I have another problem. I have a MessageWindow
subclass in .net. I pass its hwnd to the unmanaged dll,
which sets the hook. When a keyboard event arrives, the
callback routine forwards it to that window. And it really
seems to be working: the managed WndProc is
called, but the wParam and lParam of the message are
always the same (lParam = 537130660, wParam = 256, and
then the when the WndProc is called for the second time
lParam = 537130680, wParam = 257).
Any idea?

>.
>

[Ralph Flaugher]

No, unfortuabtely I haven't gotten as far as you. I
haven't figured out what generates a keyboard event yet.
Does the SIP? It doesn't seem to me for me.

Incidently, I tried all values of event types from 0 to
63. 20 is the only value that will work in
SetWindowsHookEx. If this is for keyboard events there
must be no way of hooking mouse events then, which is what
I am trying to do. This whole area seems to be
undocumented and confusing for CE. Others have done it,
so it must be possible, but how is the question that never
seems to get answered in the threads I've seen.

I would appreciate you keeping me informed of any progress
you make. Feel free to email me directly, if you prefer.

Ralph

>.
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[Chris Tacke, eMVP]

The issue is that CE doesn't officially support *any* hooks. I think that
the keyboard is the only one that has any of the internals included in the
kernel.

--
Chris Tacke, eMVP
Advisory Board Member
www.OpenNETCF.org
---
Windows CE Product Manager
Applied Data Systems
www.applieddata.net

"Ralph Flaugher" <ralph.f...@us.asirobicon.com> wrote in message

news:0cbe01c3576f$24c3bd60$a501...@phx.gbl...

[Tibor Meinczinger]

Paul,

I have the same code, and it seems to work. But my
MessageWindow subclass gets always the same message.
I have logged the callback func it the unmanaged dll,
but the same, it gets always the same message (resp.
lParam is diferrent when pressing/releasing, but the
rest is the same).
Is it possible, that the os (Pocket PC in my case)
does not really support this
and send always the same dummy message?
Thanks,

Tibor

>.
>

[Tibor Meinczinger]

I have spent quite a lot of time on this topic,
and I have read several times in some newsgroups, that
mouse events are not supported at all. What kind of a
device do you have that you have some mouse?
I am trying to catch the keyboard events. The problem is,
that I always get the same message...

Tibor

>.
>

[Ralph Flaugher]

Ok, I'll buy that, but how then does the guy who is
selling the widgets controls accomplish what his product
accomplishes? He must be doing something "unofficial",
but what? I was hoping to not have to spend a $1000 just
to get a mouse click event in a treeview control.

Ralph

>.
>

[Paul G. Tobey [eMVP]]

It's up to you to send whatever message you want from your hook routine to
your MessageWindow subclass. I register my own message using
RegisterWindowMessage() (on both ends), and then pass that, along with
whatever information I need, to the MessageWindow.

Paul T.

"Tibor Meinczinger" <meinc...@web.de> wrote in message
news:0b3b01c35772$f86199a0$3501...@phx.gbl...

[Tibor Meinczinger]

Paul,

isn't the RegisterWindowMessage there to register new
messages? I would like to pass the keyboard events as a
message to my managed MessageWindow. Some extract of my
sources:

LRESULT CALLBACK Handler(int nCode, WPARAM wParam,
LPARAM lParam)
{
fprintf(_f, "%d:%d:%ld\n", nCode, wParam, lParam);
PostMessage(handle_to_notify, nCode, wParam, lParam);
return NextHookProc(hook, nCode, wParam, lParam);
}

HOOKLIB_API HHOOK SetKeyboardHook(HWND handle)
{
hook = (*SetHookProc)(WH_KEYBOARD_LL, Handler, hDll, 0);
return hook;
}

What I thougt is, that after setting the hook, the
function "Handler" will be always called, when the user
hits some key, lParam and wParam containing the
information, which key. The function is called, but lParam
and wParam always have the same value, nCode is always 0.

Maybe I have some general misunderstanding concerning the
whole issue.

Thanks,
Tibor

>.
>

[Tibor Meinczinger]

OK, my mistake.
I thought (have read somewhere), that lParam is just a
bitmask (which may be even true in case of WH_KEYBOARD).
But in case of WH_KEYBOARD_LL lParam is a pointer to a
structure:
typedef struct {
DWORD vkCode;
DWORD scanCode;
DWORD flags;
DWORD time;
ULONG_PTR dwExtraInfo;
} KBDLLHOOKSTRUCT, *PKBDLLHOOKSTRUCT;

So now it works.

Tibor

>.
>

[Tibor Meinczinger]

Paul,

I have again a problem, I hope you (or somebody else have
an idea). I try to implement two things:
- tabbing (focusing)
- shortcuts (like e.g. Ctrl-d for some action).
Both work, but...
I set the hook in an unmanaged dll and send the message
to a subclassed message window in managed code. This
subclassed message window has a list of (windows form,
delegate). The delegate is actually the keyboard message-
handler of the form. So when the message window revieves a
message, it searches for the enabled form in the list and
calls the delegate. In some cases the pressed button causes
to show up a new window. And then the pen doesn't work any
more.
For example I have a button (plus a shortcut) for logging
in. When the login fails, I show up a messagebox. If I
push the button with the pen, everything works well. But
if I use the shortcut, I can't close the messagebox with
the pen, actually I can't do anything with the pen. It is
strange, that I can close the messagebox with the Enter
button.
I have tried to use in the unmanaged dll both the
SendMessage and the SendNotifyMessage functions, there is
no difference. Is it some threading problem? Any other
idea?
Thanks,
Tibor

>.
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[Paul G. Tobey [eMVP]]

My thought is that you are not passing the event along to the next hook
routine in the list. This could, potentially, cause a problem with event
processing in the system. Also, I'd suggest that you send messages to the
MessageWindow subclass via PostMessage(), rather than something like
SendMessage().

Paul T.

"Tibor Meinczinger" <meinc...@web.de> wrote in message

news:12ff01c35b1f$edba01d0$7d02...@phx.gbl...