SVG/Source/SvgDocument.Win32.cs

using System;
using System.Runtime.InteropServices;

namespace Svg
{
    public partial class SvgDocument
    {
        [DllImport("gdi32.dll")]
        private static extern int GetDeviceCaps(IntPtr hdc, int nIndex);

        [DllImport("user32.dll")]
        private static extern IntPtr GetDC(IntPtr hWnd);

        [DllImport("user32.dll")]
        private static extern int ReleaseDC(IntPtr hWnd, IntPtr hDC);

        private static int GetWin32SystemDpi()
        {
            // NOTE: starting with Windows 8.1, the DPI is no longer system-wide but screen-specific
            IntPtr hDC = GetDC(IntPtr.Zero);
            const int LOGPIXELSY = 90;
            int result = GetDeviceCaps(hDC, LOGPIXELSY);
            ReleaseDC(IntPtr.Zero, hDC);
            return result;
        }
    }
}