Windows scaling

Windows 8/10 has started to include a slider for how much GUI elements should scale, right click on desktop -> display. For a colleague with a laptop 4k-screen it’s 250% while another colleague using the same resolution on a 4k 28″ screen it’s 150%.

How do I read that value programmatically? I need to adjust some graphics so it looks the same on all screens.

I’m working in Java on a Eclipse RCP application, but a way that uses C or C++ through JNI works too. I’ve been looking around but can’t find anything.

Answer

Maybe this answer from here might help you:

[DllImport("gdi32.dll")]
static extern int GetDeviceCaps(IntPtr hdc, int nIndex);
public enum DeviceCap
{
    VERTRES = 10,
    DESKTOPVERTRES = 117,

    // http://pinvoke.net/default.aspx/gdi32/GetDeviceCaps.html
}  


private float getScalingFactor()
{
    Graphics g = Graphics.FromHwnd(IntPtr.Zero);
    IntPtr desktop = g.GetHdc();
    int LogicalScreenHeight = GetDeviceCaps(desktop, (int)DeviceCap.VERTRES);
    int PhysicalScreenHeight = GetDeviceCaps(desktop, (int)DeviceCap.DESKTOPVERTRES); 

    float ScreenScalingFactor = (float)PhysicalScreenHeight / (float)LogicalScreenHeight;

    return ScreenScalingFactor; // 1.25 = 125%
}