Move solution and projects to src

src/Ryujinx.Common/SystemInterop/GdiPlusHelper.cs

@@ -0,0 +1,76 @@
+using System;
+using System.Runtime.InteropServices;
+using System.Runtime.Versioning;
+
+namespace Ryujinx.Common.SystemInterop
+{
+    [SupportedOSPlatform("windows")]
+    public static partial class GdiPlusHelper
+    {
+        private const string LibraryName = "gdiplus.dll";
+
+        private static readonly IntPtr _initToken;
+
+        static GdiPlusHelper()
+        {
+            CheckStatus(GdiplusStartup(out _initToken, StartupInputEx.Default, out _));
+        }
+
+        private static void CheckStatus(int gdiStatus)
+        {
+            if (gdiStatus != 0)
+            {
+                throw new Exception($"GDI Status Error: {gdiStatus}");
+            }
+        }
+
+        private struct StartupInputEx
+        {
+            public int GdiplusVersion;
+
+#pragma warning disable CS0649
+            public IntPtr DebugEventCallback;
+            public int SuppressBackgroundThread;
+            public int SuppressExternalCodecs;
+            public int StartupParameters;
+#pragma warning restore CS0649
+
+            public static StartupInputEx Default => new StartupInputEx
+            {
+                // We assume Windows 8 and upper
+                GdiplusVersion = 2,
+                DebugEventCallback = IntPtr.Zero,
+                SuppressBackgroundThread = 0,
+                SuppressExternalCodecs = 0,
+                StartupParameters = 0,
+            };
+        }
+
+        private struct StartupOutput
+        {
+            public IntPtr NotificationHook;
+            public IntPtr NotificationUnhook;
+        }
+
+        [LibraryImport(LibraryName)]
+        private static partial int GdiplusStartup(out IntPtr token, in StartupInputEx input, out StartupOutput output);
+
+        [LibraryImport(LibraryName)]
+        private static partial int GdipCreateFromHWND(IntPtr hwnd, out IntPtr graphics);
+
+        [LibraryImport(LibraryName)]
+        private static partial int GdipDeleteGraphics(IntPtr graphics);
+
+        [LibraryImport(LibraryName)]
+        private static partial int GdipGetDpiX(IntPtr graphics, out float dpi);
+
+        public static float GetDpiX(IntPtr hwnd)
+        {
+            CheckStatus(GdipCreateFromHWND(hwnd, out IntPtr graphicsHandle));
+            CheckStatus(GdipGetDpiX(graphicsHandle, out float result));
+            CheckStatus(GdipDeleteGraphics(graphicsHandle));
+
+            return result;
+        }
+    }
+}