ScrollBar controls outside MainWndProc

I have created scrollbar controls inside a window that actually does not belong to me (from a DLL). The problem is that I can't catch the messages (WM_HSCROLL and WM_VSCROLL). As far as I know, they end up in the main window process, which is out of my control. It responds with something like "Unknown exception..."

Is there any way to create a separate window process for the scrollbars, though they are children to the other window? I guess they have to be children, or...? How else should I solve this? - Please, help!!!

I don't know how much this could be worth... It ought to be fairly easy, but regarding windows programming - what is? I'll give you 100 points for it, anyway. Thanks in advance.
LVL 2
obgAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
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.

fasterCommented:
how do you put your scroll bat into the main window?
0
davmarcCommented:
The problem is that you must get your handling code into main window's process context - a hook is probably what you are looking for.

Davide Marcato.
0
obgAuthor Commented:
Thank you davmarc. A hook is probably what I am looking for, but how do I create a hook?
0
Become a Certified Penetration Testing Engineer

This CPTE Certified Penetration Testing Engineer course covers everything you need to know about becoming a Certified Penetration Testing Engineer. Career Path: Professional roles include Ethical Hackers, Security Consultants, System Administrators, and Chief Security Officers.

obgAuthor Commented:
I use the following to create the horizontal scrollbar:
hHScroll = CreateWindow("SCROLLBAR", NULL, WS_CHILD | WS_VISIBLE
                        | SBS_HORZ | SBS_BOTTOMALIGN, r.left,
                        r.top, r.right - r.left - iHThumb,
                        r.bottom - r.top, hWnd, (HMENU)10,
                        hInst, NULL);
SetScrollRange(hHScroll, SB_CTL, 0, 100, FALSE);
... as proposed in MSDN.
0
davmarcCommented:
The API to use to create hooks is:

HHOOK SetWindowsHookEx(
int idHook, // type of hook to install
HOOKPROC lpfn, // address of hook procedure
HINSTANCE hMod, // handle of application instance
DWORD dwThreadId // identity of thread to install hook for
);

Check it out in the documentation for more info...in any case you must put your code in a DLL to let it be mapped into the other process context. Use UnhookWindowsHookEx() to remove the hook.

A great source of info about how&why using hooks and subclassing to interfer with other apps (in Win32) is the book "Advanced Windows" by Jeff Richter. It even has a whole chapter on that topic.
An SDK sample on how to install system hooks is HOOKS

Davide Marcato.
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
obgAuthor Commented:
Thanks for your answer. I haven't fully tried it yet, but I think I can get it to work.
0
obgAuthor Commented:
I finally discovered that SetWindowLong contains a much easier way of intercepting messages...
0
davmarcCommented:
You used SetWindowLong() to subclass the control?
You must have another window procedure to handle the messages anyway, so I don't think it's that much easier.

Davide Marcato.
0
obgAuthor Commented:
Well, I don't know about "subclassing". All I did was:

OldWndProc = SetWindowLong(hWnd, GWL_WNDPROC, NewWndProc);

and then I ended the NewWndProc by calling OldWndProc, if the message wasn't WM_HSCROLL or WM_VSCROLL. Could it be simpler? I found it much simpler than my hooking (?) efforts. :-)

0
davmarcCommented:
What you've done is actually "subclassing" a window :-)

Davide Marcato.
0
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
Microsoft Development

From novice to tech pro — start learning today.