[Qt-interest] Screenshot

[MP]

>  This is almost certainly not worth the effort required. Not only would
>  you have to disable screenshots and screen-capture programs from
>  seeing your app, your app would have to be unusable over VNC or remote

This is close to impossible - even if you watch for common screen
capture programs, you will deter few newbies, but determined
"attacker" will be able to take screenshot (even without resorting to
hardware methods, like reading from VGA/DVI cable or using a camera)
no matter how hard you try not to allow it - easiest way would be to
write their own capture program that you can't detect.

Also, trying to lock/steal/disable any keys won't work, as most screen
capture programs come with a timer (capture image after X
seconds/every X seconds)

>  desktop (because otherwise someone could VNC to a computer running
>  your application and take a screenshot of the VNC session).
>
>  That being said, I believe it can be done. You need a way to bypass
>  the normal graphics system write directly to the video hardware. Movie

Won't work for capture programs reading the image directly from the
video hardware .... plus, most OS won't let you "just write to
videoram" as you wish ...

>  playback and OpenGL stuff used to have to do this, and if you tried to
>  take a screenshot of a movie playing, you would just see a blue block
>  where the movie was. This is no longer the case (taking a screenshot

This is because the movie is (with combination of some movie players
and some hardware) not stored in videoram, but it is mixed directly to
output in the videocard. I remembered one crash, when computer went to
BSOD and in the BSOD (which appears in text mode) I saw one frame from
the video :)

>  of a movie or OpenGL application works properly now), but it gives you
>  an idea of what you would need to do.

There are already tools that can work around such "tricks" to conceal the image.

Martin