Add support for the windows DPI scaling.

OpenRA.Platforms.Default/Sdl2GraphicsDevice.cs

@@ -31,11 +31,18 @@ namespace OpenRA.Platforms.Default
 		internal Size SurfaceSize { get; private set; }
 		public event Action<float, float> OnWindowScaleChanged = (before, after) => { };
 
+		[DllImport("user32.dll")]
+		static extern bool SetProcessDPIAware();
+
 		public Sdl2GraphicsDevice(Size windowSize, WindowMode windowMode)
 		{
 			Console.WriteLine("Using SDL 2 with OpenGL renderer");
 			WindowSize = windowSize;
 
+			// Disable legacy scaling on Windows
+			if (Platform.CurrentPlatform == PlatformType.Windows)
+				SetProcessDPIAware();
+
 			SDL.SDL_Init(SDL.SDL_INIT_NOPARACHUTE | SDL.SDL_INIT_VIDEO);
 			SDL.SDL_GL_SetAttribute(SDL.SDL_GLattr.SDL_GL_DOUBLEBUFFER, 1);
 			SDL.SDL_GL_SetAttribute(SDL.SDL_GLattr.SDL_GL_RED_SIZE, 8);
@@ -55,10 +62,7 @@ namespace OpenRA.Platforms.Default
 
 			Console.WriteLine("Using resolution: {0}x{1}", WindowSize.Width, WindowSize.Height);
 
-			var windowFlags = SDL.SDL_WindowFlags.SDL_WINDOW_OPENGL;
+			var windowFlags = SDL.SDL_WindowFlags.SDL_WINDOW_OPENGL | SDL.SDL_WindowFlags.SDL_WINDOW_ALLOW_HIGHDPI;
-			if (Platform.CurrentPlatform == PlatformType.OSX)
-				windowFlags |= SDL.SDL_WindowFlags.SDL_WINDOW_ALLOW_HIGHDPI;
-
 			window = SDL.SDL_CreateWindow("OpenRA", SDL.SDL_WINDOWPOS_CENTERED, SDL.SDL_WINDOWPOS_CENTERED,
 				WindowSize.Width, WindowSize.Height, windowFlags);
 
@@ -75,6 +79,15 @@ namespace OpenRA.Platforms.Default
 				SurfaceSize = new Size(width, height);
 				WindowScale = width * 1f / WindowSize.Width;
 			}
+			else if (Platform.CurrentPlatform == PlatformType.Windows)
+			{
+				float ddpi, hdpi, vdpi;
+				if (SDL.SDL_GetDisplayDPI(0, out ddpi, out hdpi, out vdpi) == 0)
+				{
+					WindowScale = ddpi / 96;
+					WindowSize = new Size((int)(SurfaceSize.Width / WindowScale), (int)(SurfaceSize.Height / WindowScale));
+				}
+			}
 
 			Console.WriteLine("Using window scale {0:F2}", WindowScale);
 

OpenRA.Platforms.Default/Sdl2Input.cs

@@ -40,6 +40,16 @@ namespace OpenRA.Platforms.Default
 				 | ((raw & (int)SDL.SDL_Keymod.KMOD_SHIFT) != 0 ? Modifiers.Shift : 0);
 		}
 
+		int2 EventPosition(Sdl2GraphicsDevice device, int x, int y)
+		{
+			// On Windows and Linux (X11) events are given in surface coordinates
+			// These must be scaled to our effective window coordinates
+			if (Platform.CurrentPlatform != PlatformType.OSX && device.WindowSize != device.SurfaceSize)
+				return new int2((int)(x / device.WindowScale), (int)(y / device.WindowScale));
+
+			return new int2(x, y);
+		}
+
 		public void PumpInput(Sdl2GraphicsDevice device, IInputHandler inputHandler)
 		{
 			var mods = MakeModifiers((int)SDL.SDL_GetModState());
@@ -88,8 +98,7 @@ namespace OpenRA.Platforms.Default
 							var button = MakeButton(e.button.button);
 							lastButtonBits |= button;
 
-							var pos = new int2(e.button.x, e.button.y);
+							var pos = EventPosition(device, e.button.x, e.button.y);
-
 							inputHandler.OnMouseInput(new MouseInput(
 								MouseInputEvent.Down, button, scrollDelta, pos, mods,
 								MultiTapDetection.DetectFromMouse(e.button.button, pos)));
@@ -108,7 +117,7 @@ namespace OpenRA.Platforms.Default
 							var button = MakeButton(e.button.button);
 							lastButtonBits &= ~button;
 
-							var pos = new int2(e.button.x, e.button.y);
+							var pos = EventPosition(device, e.button.x, e.button.y);
 							inputHandler.OnMouseInput(new MouseInput(
 								MouseInputEvent.Up, button, scrollDelta, pos, mods,
 								MultiTapDetection.InfoFromMouse(e.button.button)));
@@ -118,9 +127,10 @@ namespace OpenRA.Platforms.Default
 
 					case SDL.SDL_EventType.SDL_MOUSEMOTION:
 						{
+							var pos = EventPosition(device, e.motion.x, e.motion.y);
 							pendingMotion = new MouseInput(
 								MouseInputEvent.Move, lastButtonBits, scrollDelta,
-								new int2(e.motion.x, e.motion.y), mods, 0);
+								pos, mods, 0);
 
 							break;
 						}