CODEWITHSUNDEEP
c#screenshot
Giorgio
Giorgio

Reputation: 1613

How can I know if the user has made a screenshot?

I'm writing a small c# program, I don't want the final user to take screenshots while using my program, is it possible? Or even if he takes one, how can I know it?

Thanks in advance and sorry if this is a poor-content question due to my lack of experience in c# coding.

Upvotes: 2

Views: 8974

Answers (3)

Abel
Abel

Reputation: 57169

You can create a system-wide keyboard hook using the low-level keyboard filter and cancel any printscreen keyboard combination. But if someone has also installed a helper application (like Gadwin or something) it'll become a lot more difficult because you won't know beforehand what keyboard shortcut you should catch (most tools allow to specify your own hooks).

On a side note: it's generally not preferred to change the system behavior. Screenshots are system behavior and serve a distinguished purpose for trouble shooting. If you prevent this, users will not be able to show you a screenshot of something wrong. But if you must do it, you can do it.

EDIT: on a deeper level, you can install an API hook. All screenshot applications use API calls to get the content of a (part of) the screen. But API hooks are hard to get right. A more trivial way is probably by writing a user-level driver. While you can prevent all this, it is really worth all the trouble?

Upvotes: 2

Sergii Kudriavtsev
Sergii Kudriavtsev

Reputation: 10512

General answer: No. It's not possible to detect this - especially from C#. There are dozens of ways to take screenshot and even applications written in C++/WinAPI can only detect some of them, but not all.

Also consider - what if user is running your app in virtual machine? He'll be able to take screenshots at host machine and you can do absolutely nothing to detect (not even prevent) this.

Upvotes: 1

ken2k
ken2k

Reputation: 48985

You might want a keyboard hook. But it'll tell you if the user pressed the "print screen" key, not if someone programmatically take a screenshot using some GDI function.

I doubt it's possible to prevent all the ways of taking a screenshot.

Upvotes: 2

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