hook video driver

Keith T. Adeney keith.adeney "at" printsoft.de
Fri, 07 Sep 2001 12:22:27 +0000

Hello everybody,

I'm putting this information in the newsgroup, because people keep mailing
me directly about Win95/Win98 video driver hooks. There is a method for
hooking the video driver under Win95/Win98 called SetDDIHook. SetDDIHook
does exist, but Microsoft let it die most probably because it uses 32<-> 16
bit thunking. It is available in Win95 if you install the "MS Accessibility
Runtime", it is included out of the box with Win98/98SE. Microsoft
documentation (if you can get it) on SetDDIHook is in the "MS Accessibility
SDK" (my copy dates Sept 99).

I've talked to H. Lee [cyclent "at" bomun.kaist.ac.kr] quite a bit now, he took
my DDIWatch code and developed it further, but says "Although it's working,
it makes the system a bit unstable, so still looking at it time to time. (I
think win98 itself does not manage resource well. it's the cause of the
problem I think)."

The following have at least also had a look at my DDIWatch code: Daniel
Plakosh [dplakosh "at" sei.cmu.edu], reiter "at" nomadics.com,
stefanie.ballestra "at" fnac.net, and Thong Nguyen.

If you ask H. Lee nicely he might let you have a copy of his code. He wanted
to get it far enough to put it into VNC, so he probably would be grateful
for any help or advice.

Our company has moved to Win2000 now and is introducing UNIX as a Micro$oft
alternative, so Win98/98SE development isn't really on the radar anymore.
But VNC works on all the platforms anyway. Thanks for such a great piece of


> - -----Original Message-----
> From: Gianluca Bruni [mailto:gianluca "at" proximaautomation.com]
> Sent: Tuesday, September 04, 2001 7:20 PM
> To: Rudi De Vos
> Subject: R: hook video driver
> Hi,
> thaks for reply.
> I apologize I can't help you. I'm a Windows programmer but I have not
> tools to develop video drivers (I guess you use something like SDDK or
> similar).
> Your approach works in WinNT/Win2K.
> Do you know how to hook video driver under Win95/Win98?
Yes SetDDIHook
> Another strategy could be, as I read in WinVNC FAQ, to hook GDI32.DLL.
> What do you think?
> Bye
> Gianluca
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