How to get Windows Display settings?

Both graphics.DpiX and DeviceCap.LOGPIXELSX return 96 on Surface Pro in all scaling levels.

Instead, I managed to calculate the scaling factor this way:

[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%
}

This setting is the screen DPI, or dots per inch.

Read it like so:

float dpiX, dpiY;
Graphics graphics = this.CreateGraphics();
dpiX = graphics.DpiX;
dpiY = graphics.DpiY;

I don't think it's possible at the moment for the X and Y values to be different. A value of 96 corresponds to 100% font scaling (smaller), 120 corresponds to 125% scaling (medium) and 144 corresponds to 150% scaling (larger). However, users are able to set values other than these standard ones.

Do be aware that unless your application is declared to be DPI aware, then the values you observe may be subject to DPI virtualization.