fix path

QuickLook.Common/Helpers/DpiHelper.cs

@@ -0,0 +1,60 @@
+// Copyright © 2017 Paddy Xu
+// 
+// This file is part of QuickLook program.
+// 
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+// 
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+using System;
+using System.Drawing;
+using System.Runtime.InteropServices;
+
+namespace QuickLook.Common.Helpers
+{
+    public static class DpiHelper
+    {
+        public const float DefaultDpi = 96;
+
+        public static ScaleFactor GetCurrentScaleFactor()
+        {
+            var g = Graphics.FromHwnd(IntPtr.Zero);
+            var desktop = g.GetHdc();
+
+            var horizontalDpi = GetDeviceCaps(desktop, (int) DeviceCap.LOGPIXELSX);
+            var verticalDpi = GetDeviceCaps(desktop, (int) DeviceCap.LOGPIXELSY);
+
+            return new ScaleFactor {Horizontal = horizontalDpi / DefaultDpi, Vertical = verticalDpi / DefaultDpi};
+        }
+
+        [DllImport("gdi32.dll", CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]
+        private static extern int GetDeviceCaps(IntPtr hDC, int nIndex);
+
+        private enum DeviceCap
+        {
+            /// <summary>
+            ///     Logical pixels inch in X
+            /// </summary>
+            LOGPIXELSX = 88,
+            /// <summary>
+            ///     Logical pixels inch in Y
+            /// </summary>
+            LOGPIXELSY = 90
+        }
+
+        public struct ScaleFactor
+        {
+            public float Horizontal;
+            public float Vertical;
+        }
+    }
+}