Use of the Windows desktop by Modern UI apps

[langweg]

This is more of a side project.

Modern UI apps draw on a surface that seems to be drawn on the regular default desktop. Can the visible content of a Modern UI app be retrieved from the desktop surface? It has been demonstrated that access to user input (e.g. a keylogger) works well for applications that are executed in the same session. An open question is how easy it is to find out what a Modern UI app draws on the screen.

[DonatJR]

just a small and in no way exhaustive test: capturing the contents of the windows weather app (https://www.microsoft.com/en-us/p/msn-weather/9wzdncrfj3q2) works without any problems using the built in capture (print key) as well as with a little C# code (Windows 10, non admin user):

Rectangle bounds = Screen.GetBounds(Point.Empty);
using (Bitmap bitmap = new Bitmap(bounds.Width, bounds.Height))
{
    using (Graphics g = Graphics.FromImage(bitmap))
    {
        g.CopyFromScreen(Point.Empty, Point.Empty, bounds.Size);
    }
    bitmap.Save("test.jpg", ImageFormat.Jpeg);
}

[langweg]

Can the C# code be used from a Modern UI app?

[DonatJR]

I never worked with UWP apps before so I just tested it for the first time. It could be that I am missing something, but it seems the necessary namespaces for the code are not available when developing UWP apps. However, there is an official (different) solution for capturing screen contents from Microsoft: https://docs.microsoft.com/en-us/windows/uwp/audio-video-camera/screen-capture