Alternatives for taking a screenshot

Question

I'm doing a bot to read images and transform it in text using Tesseract, but I have a problem with the target application named Tibia (Its a game in window mode screen), because it have a anti-screenshot protection. If I try, I got a black screen picture.

A already have try CopyFromScreen(), user32.dll, and gdi.dll functions but without success.

I tried these ways:

Bitmap printscreen = new Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height);
Graphics graphics = Graphics.FromImage(printscreen as Image);
graphics.CopyFromScreen(0, 0, 0, 0, printscreen.Size);

And:

public static Bitmap GetDesktopImage()
{
    WIN32_API.SIZE size;

    IntPtr hDC = WIN32_API.GetDC(WIN32_API.GetDesktopWindow());
    IntPtr hMemDC = WIN32_API.CreateCompatibleDC(hDC);

    size.cx = WIN32_API.GetSystemMetrics(WIN32_API.SM_CXSCREEN);
    size.cy = WIN32_API.GetSystemMetrics(WIN32_API.SM_CYSCREEN);

    m_HBitmap = WIN32_API.CreateCompatibleBitmap(hDC, size.cx, size.cy);

    if (m_HBitmap != IntPtr.Zero)
    {
        IntPtr hOld = (IntPtr)WIN32_API.SelectObject(hMemDC, m_HBitmap);
        WIN32_API.BitBlt(hMemDC, 0, 0, size.cx, size.cy, hDC, 0, 0, WIN32_API.SRCCOPY);
        WIN32_API.SelectObject(hMemDC, hOld);
        WIN32_API.DeleteDC(hMemDC);
        WIN32_API.ReleaseDC(WIN32_API.GetDesktopWindow(), hDC);
        return System.Drawing.Image.FromHbitmap(m_HBitmap);
    }
    return null;
}

public class WIN32_API
{
    public struct SIZE
    {
        public int cx;
        public int cy;
    }
    public const int SRCCOPY = 13369376;
    public const int SM_CXSCREEN = 0;
    public const int SM_CYSCREEN = 1;

    [DllImport("gdi32.dll", EntryPoint = "DeleteDC")]
    public static extern IntPtr DeleteDC(IntPtr hDc);

    [DllImport("gdi32.dll", EntryPoint = "DeleteObject")]
    public static extern IntPtr DeleteObject(IntPtr hDc);

    [DllImport("gdi32.dll", EntryPoint = "BitBlt")]
    public static extern bool BitBlt(IntPtr hdcDest, int xDest, int yDest, int wDest, int hDest, IntPtr hdcSource, int xSrc, int ySrc, int RasterOp);

    [DllImport("gdi32.dll", EntryPoint = "CreateCompatibleBitmap")]
    public static extern IntPtr CreateCompatibleBitmap(IntPtr hdc, int nWidth, int nHeight);

    [DllImport("gdi32.dll", EntryPoint = "CreateCompatibleDC")]
    public static extern IntPtr CreateCompatibleDC(IntPtr hdc);

    [DllImport("gdi32.dll", EntryPoint = "SelectObject")]
    public static extern IntPtr SelectObject(IntPtr hdc, IntPtr bmp);

    [DllImport("user32.dll", EntryPoint = "GetDesktopWindow")]
    public static extern IntPtr GetDesktopWindow();

    [DllImport("user32.dll", EntryPoint = "GetDC")]
    public static extern IntPtr GetDC(IntPtr ptr);

    [DllImport("user32.dll", EntryPoint = "GetSystemMetrics")]
    public static extern int GetSystemMetrics(int abc);

    [DllImport("user32.dll", EntryPoint = "GetWindowDC")]
    public static extern IntPtr GetWindowDC(Int32 ptr);

    [DllImport("user32.dll", EntryPoint = "ReleaseDC")]
    public static extern IntPtr ReleaseDC(IntPtr hWnd, IntPtr hDc);
}

Can anyone help me?

Have anyone api to capture print direct from GPU?

Answer 1

In order to get the screenshot you need to go a layer lower than device contexts and Gdi. The game is not doing the rendering on the device context of the hWnd and instead talking to the graphic card driver. So when you call CreateCompatibleBitmap there is essentially nothing rendered there. I am not sure if there are any public APIs to capture what is being rendered directly. Some games do this because they would like to have faster rendering and would prefer to skip GDI or GDI+.

Answer 2

DISCLAIMER: I am not responsible in any way for anything that anyone does with any code shared or made accessible from this answer.

I agree that the concept of screen capturing video games that feature any type of anti-cheat software is sketchy. The other side of that coin is that there could be any number of valid personal reasons to have a separate utility that can capture screenshots or video and process the content (i.e. custom notifications of in game activity, making the game more accessible to disabled persons by parsing messages and playing them through a synthesizer API, etc...).

All that being said, I downloaded and installed Tibia, copied the FullScreenshot code snippet from this article into a simple WinForms app project, and was able to save a screenshot of the game (shown below).

The WinForms app can be downloaded from here to test before playing with the code yourself.

Screenshot of Tibia from custom app: