Check if a program creates prt scrs

**Livijn** · 09-10-2008

Hi! Long time, no see.

I wonder how to check if a program creates print screens. The program, which create print screens at random set of time, is needed to play at some servers. So, I want to check if a program creates a print screen in just that second, if now, continue as normal, but if, then I'd like to do 1 thing which is a secret.

Example:

Code:

Time: 12:21:22 Normal
Time: 12:21:23 Normal
Time: 12:21:24 Normal
Time: 12:21:25 Normal
Time: 12:21:26 A program is trying to create a screenshot. Do blabla();
Time: 12:21:27 Normal
Time: 12:21:28 Normal
Time: 12:21:29 Normal

I hope you all understand. It was kind of hard to explain since there are no such program right know. If you don't understand, please tell me, otherwise I won't understand that.

Greetings,
Fredrik.

**matsp** · 09-10-2008

"a program create print screens" does not make sense. Prt Scrn is a key on the keyboard. It causes the screen data to be copied to the clipboard.

An application can perform a similar operation in several ways, but it is not using "Prt Scrn" to do that.

So can you please explain what you actually want to know about? When some application copies the entire screen? If so, which of the half a dozen or more variants of doing that would you like to know about? How much driver writing experience do you have [you probably need to write a Display Filter Driver to capture those]? Does it make a difference that you will incur a penalty on any "read from frame buffer to system memory" oeprations?

Does the application you have in mind run in a window or as a full-screen application, is it using GDI, DirectX, OpenGL API's?

--
Mats

**Livijn** · 09-10-2008

Thank you for your answer!

Okey, what i meant with "a program create print screens" was that the program - as you said - copies the entire screen. Is there any way a program can know when the other program takes the capture of the screen? I don't know in what way the program will copy the screen. The program copies the screen from a game called "Counter-Strike" which is usually played with OpenGL and full-screen.

Is there anything you need to know before you can give me a hint?

**matsp** · 09-10-2008

Well, to detect that something is copying the screen requires that you intercept the system calls or driver calls that are involved in copying the screen. Since there are at least half a dozen different system calls that can possibly be used for this purpose, it would be much easier to do if you can determine which system call it is that is being used.

Once you know which system call it is, you will need to "trap" that system call in such a way that you can see that the system call is happening, then inspect the parameters, and determine if it's copying the screen or doing something else that you don't care about. Most of the time, it will probably be the latter. And the chances of crashing the system if you get it wrong is HUGE.

--
Mats

**~~master5001~~** · 09-10-2008

I will assume you are using windows since you are using c#. You can reasonably easily just poll for changes in the clipboard content, check what the content type is, and then do your thing from there--OR what may actually prove more fruitful in actually determining if someone hit Print Screen as opposed to just copying and pasting something from Photoshop would be to implement a system hook that monitors keys and have your program do its thing if Print Screen is pressed. Which should effectively avoid you crashing your computer whilst tinking with system messages and trying to inject information into them (which is generally best avoided anyway).

**matsp** · 09-11-2008

Originally Posted by master5001

I will assume you are using windows since you are using c#. You can reasonably easily just poll for changes in the clipboard content, check what the content type is, and then do your thing from there--OR what may actually prove more fruitful in actually determining if someone hit Print Screen as opposed to just copying and pasting something from Photoshop would be to implement a system hook that monitors keys and have your program do its thing if Print Screen is pressed. Which should effectively avoid you crashing your computer whilst tinking with system messages and trying to inject information into them (which is generally best avoided anyway).

But he's actually trying to determine if an application is capturing the screen for it's own purposes, not the actual "PrntScrn" button that copies to the clipboard.

--
Mats

**BobS0327** · 09-11-2008

I'm not sure it would be a wise idea to use C# for this application since you'll be pinvoking a lot of Win32 functions. But anyway, one possible option is to intercept the target app's api to determine whether or not a screen capture has occured. MS has a Detours library that may be of some use to you.

Thread: Check if a program creates prt scrs

Thread Tools

Search Thread

Display

Check if a program creates prt scrs

Similar Threads

Program I made check it out if you want...... comment.... whatever

Suggestions for my Check Book program

HELP!!!!emergency ~expert please help

Can someone check my program?

My program, anyhelp