Take screenshot of external OpenGL game C# with BitBlt (CopyFromScreen)

Question

I am trying to create some kind of antycheat for counter strike (hl) game. Of course funcionality of making a screenshot in-game is built-in, but exploited (detected) by antyss applications, so every time screenshot is taken from the game, antyss is disabling the cheats (so that no cheats are visible on the screenshots)

For the last few days, I've read dozens of threads regarding this topic. Most of them are outdated and are using libraries, that are obsolete right now.

I've read about the approach with mirage driver (which is not working on windows 10), about injecting to the application (of course application/game is not part of my code) and using/incjeting some code with OPEN GL/D3D library (to read backbuffer). Probably this could be in the end the only solution.

But right now I have almost a working solution. I write "almost" because it is working but giving me only some kind of "cached" data. It is giving me a correct screenshot, but if I take another screenshot - still the same screenshot is taken as last time. If while being in-game I minimize the application (full-screen mode) and then get back to the game, the new screenshot taken will have up to date screenshot, but then again, the next screenshot would be exactly the same.

I don't know if it is "by design" or is it "some sort of bug" Nevertheless my question is: Can I force somehow this "reloading" without having to programmatically call some kind of "alt+tab" and then focusing on the application once again?

In this topic: How to take screenshots of a game with OpenGL

@Andon M. Coleman wrote:

Are you on Windows? In fullscreen mode starting with Windows Vista, there is trouble with anything that tries to capture the front-buffer (including the built-in Alt + PrintScreen). The easiest solution is to change your buffer swap behavior to Copy Swap (PFD_SWAP_COPY, slower but guaranteed to work). Often if you Alt+TAB out and back in after making the fullscreen mode switch that will fix it too; though I have never been able to explain that ;) If you did not write the game in the question, then the second solution may be your only choice if you want to use that code.

This is exactly the problem I am facing. As he wrote: "Alt+Tab" is fixing the problem (although he did not know whether it is a feature or a bug) He proposed to change the buffer swap behavior to Copy Swap(PFD_SWAP_COPY) Any tips on how to change my code with that will also be most welcome (I can try this one) But if I understood correctly, this approach is the viable solution only if you can change this in the game (and this is not my case)

Here is my working code (which in topics about such scenarios was claiming that in this approach the screenshot is BLACK. But it is working for me)

private const int SW_RESTORE = 9;
public void TakeScreenShot()
{
    var guid = Guid.NewGuid();
    string procName = "hl";
    Process proc;

    try
    {
        proc = Process.GetProcessesByName(procName)[0];
    }
    catch (IndexOutOfRangeException e)
    {
        return;
    }


    // Focus on the application
    SetForegroundWindow(proc.MainWindowHandle);
    ShowWindow(proc.MainWindowHandle, SW_RESTORE);

    Thread.Sleep(1000);

    Rect rect = new Rect();
    IntPtr error = GetWindowRect(proc.MainWindowHandle, ref rect);

    while (error == (IntPtr)0)
    {
        error = GetWindowRect(proc.MainWindowHandle, ref rect);
    }

    int width = rect.right - rect.left;
    int height = rect.bottom - rect.top;

    using (Bitmap printscreen = new Bitmap(width, height, PixelFormat.Format32bppArgb))
    {
        using (var graphics = Graphics.FromImage(printscreen))
        {
            graphics.CopyFromScreen(rect.left,
                                               rect.top,
                                               0,
                                               0,
                                               new Size(width, height),
                                               CopyPixelOperation.SourceCopy);
            printscreen.Save($@"{Path.GetTempPath()}\{guid.ToString()}.jpg", ImageFormat.Jpeg);
        }
    }
}

I want this application to work on Windows7, Windows8, Windows 10. The best would be to cover full screen and windowed mode (but fullscreen is probably more important)

Any advice how to proceed (or why I am getting the "cached" data) would be nice :)

Of course if someone will say (with full authority), that what i want to achieve is impossible with CopyFromScreen (and there is no hack to fix that, apart from minimizing and maximazing the screen) i will consider option with injecting the code. But normally i would want to stay away from this one, as this could be treated as cheat and can lead to VAC ban.

====== UPDATE ======

You can try reproduce the process of taking screenshot by downloading the game (is small one, 260 MB): https://cssetti.pl/Api/GameDownload.php?GameDownloadId=v43

Then you can copy-paste my code to Linqpad (or any other editor) and run the code. The application after launching will launch the HL process which is then use to try to grab the screenshot.

====== UPDATE 2 ======

In windows mode everything works correctly (the printscreens are ok)