add TransformPoint impl for NDS

src/BizHawk.Client.Common/DisplayManager/Filters/Gui.cs

@@ -197,11 +197,7 @@ namespace BizHawk.Client.Common.Filters
 		}
 
 		public override Vector2 TransformPoint(string channel, Vector2 point)
-		{
-			// TODO
-			Console.WriteLine($"TODO ScreenControlNDS TransformPoint {point.X} / {point.Y}");
-			return base.TransformPoint(channel, point);
-		}
+			=> _nds.GetScreenCoords(point.X, point.Y);
 	}
 
 	/// <summary>

src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/LibMelonDS.cs

@@ -294,5 +294,8 @@ namespace BizHawk.Emulation.Cores.Consoles.Nintendo.NDS
 
 		[BizImport(CC)]
 		public abstract void GetTouchCoords(ref int x, ref int y);
+
+		[BizImport(CC)]
+		public abstract void GetScreenCoords(ref float x, ref float y);
 	}
 }

src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/MelonDS.cs

@@ -71,6 +71,8 @@ namespace BizHawk.Emulation.Cores.Consoles.Nintendo.NDS
 		private IntPtr GetGLProcAddressCallback(string proc)
 			=> _openGLProvider.GetGLProcAddress(proc);
 
+		// TODO: Probably can make these into an interface (ITouchScreen with UntransformPoint/TransformPoint methods?)
+		// Which case the hackiness of the current screen controls wouldn't be as bad
 		public Vector2 GetTouchCoords(int x, int y)
 		{
 			if (_glContext != null)
@@ -86,6 +88,21 @@ namespace BizHawk.Emulation.Cores.Consoles.Nintendo.NDS
 			return new(x, y);
 		}
 
+		public Vector2 GetScreenCoords(float x, float y)
+		{
+			if (_glContext != null)
+			{
+				_core.GetScreenCoords(ref x, ref y);
+			}
+			else
+			{
+				// no GL context, so nothing fancy can be applied
+				y = Math.Min(256, y + 192);
+			}
+
+			return new(x, y);
+		}
+
 		[CoreConstructor(VSystemID.Raw.NDS)]
 		public NDS(CoreLoadParameters<NDSSettings, NDSSyncSettings> lp)
 			: base(lp.Comm, new()