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I am wrote a DLL to hook the TextOut calls to GDI32.dll. This works if the programs that run use ::TextOut but does not work if they do pDC->TextOut in OnDraw().
What is the difference between the two? What would I hook to get access to the CDC::TextOut calls?
Apijaking huh? :)
I havent bothered to troll the MFC source (which is available with VC++ BTW).....but I imagine CDC::TextOut does call TextOut and I guess its missed here because when you hook an API, you hook the symbols in your exe's import table....and if you use MFC, then I suppose the MFC runtime will call TextOut....not your app.....so that's why its being missed....
I havent tried this though....just guessing
Yes. I found the API hijacking info and have been tayloring it to my needs.
You answer was a little over my head. I don't know what that means about my exe's import table.
Currently I hook everything. I want to log all the text that ever appears on the screen. It wasn't working, so I wrote a little app that did a pDC->TextOut and that didnt work. Then I changed to ::TextOut and it did work.
I am hoping to use this to collect all the text in a given application. And I similarly hope to be able to read the cards in a solitaire game, a question I previusly posted.
Can you point me at something to help me understand why it's not working? I respect your opinions and advice, I just don't fully understand it this time ;). I am sure it will make perfect sense after I understand it.
You should have a knowledge on the PE executable format and if possible some basic ASM
The best person to learn this stuff from is the person that pioneered the methods you are using - Matt Pietrek. He's a win guru that's been writing for MSDN for years.....
I think this article touches on the subject, but do a search on his name and Api Hijack/hook and you will find other stuff
Happy reading!
Actually, that's not the best article...but its worth a read
Try this first