Added platform overrides

XRTK-Core/Packages/com.xrtk.core/Definitions/Platforms/BasePlatform.cs

@@ -17,5 +17,8 @@ public abstract class BasePlatform : IMixedRealityPlatform
 
         /// <inheritdoc />
         public virtual bool IsBuildTargetAvailable => false;
+
+        /// <inheritdoc />
+        public virtual IMixedRealityPlatform[] PlatformOverrides { get; } = new IMixedRealityPlatform[0];
     }
 }

XRTK-Core/Packages/com.xrtk.core/Definitions/Platforms/CurrentBuildTargetPlatform.cs

@@ -22,27 +22,25 @@ public sealed class CurrentBuildTargetPlatform : BasePlatform
         /// <returns>True, if any build target is active.</returns>
         public static bool IsBuildTargetActive(List<IMixedRealityPlatform> platforms)
         {
+            if (!Application.isEditor) { return false; }
+
             var isEditor = false;
             var isBuildTargetActive = false;
             var isEditorPlatformActive = false;
 
-            for (var i = 0; i < platforms.Count; i++)
+            foreach (var platform in platforms)
             {
-                var platform = platforms[i];
-
-                if (platform is AllPlatforms)
-                {
-                    return true;
-                }
-
-                if (platform is CurrentBuildTargetPlatform)
-                {
-                    isEditor = true;
-                    isEditorPlatformActive = platform.IsAvailable;
-                }
-                else
+                switch (platform)
                 {
-                    isBuildTargetActive |= platform.IsBuildTargetAvailable;
+                    case AllPlatforms _:
+                        return true;
+                    case CurrentBuildTargetPlatform _:
+                        isEditor = true;
+                        isEditorPlatformActive = platform.IsAvailable;
+                        break;
+                    default:
+                        isBuildTargetActive |= platform.IsBuildTargetAvailable;
+                        break;
                 }
             }
 

XRTK-Core/Packages/com.xrtk.core/Interfaces/IMixedRealityPlatform.cs

@@ -20,5 +20,10 @@ public interface IMixedRealityPlatform
         /// Only returns true in editor.
         /// </remarks>
         bool IsBuildTargetAvailable { get; }
+
+        /// <summary>
+        /// The list of platforms that this specific platform will override and make the others return not available.
+        /// </summary>
+        IMixedRealityPlatform[] PlatformOverrides { get; }
     }
 }

XRTK-Core/Packages/com.xrtk.core/Services/MixedRealityToolkit.cs

@@ -536,27 +536,46 @@ private static void EnsureMixedRealityRequirements()
                 .Where(type => typeof(IMixedRealityPlatform).IsAssignableFrom(type) && type.IsClass && !type.IsAbstract)
                 .OrderBy(type => type.Name);
 
+            var platformOverrides = new List<Type>();
+
             foreach (var platformType in platformTypes)
             {
-                IMixedRealityPlatform platformInstance = null;
+                IMixedRealityPlatform platform = null;
 
                 try
                 {
-                    platformInstance = Activator.CreateInstance(platformType) as IMixedRealityPlatform;
+                    platform = Activator.CreateInstance(platformType) as IMixedRealityPlatform;
                 }
                 catch (Exception e)
                 {
                     Debug.LogError(e);
                 }
 
-                if (platformInstance == null) { continue; }
+                if (platform == null) { continue; }
 
-                availablePlatforms.Add(platformInstance);
+                availablePlatforms.Add(platform);
 
-                if (platformInstance.IsAvailable ||
-                    platformInstance.IsBuildTargetAvailable)
+                if (platform.IsAvailable ||
+                    platform.IsBuildTargetAvailable)
                 {
-                    activePlatforms.Add(platformInstance);
+                    foreach (var platformOverride in platform.PlatformOverrides)
+                    {
+                        platformOverrides.Add(platformOverride.GetType());
+                    }
+                }
+            }
+
+            foreach (var platform in availablePlatforms)
+            {
+                if (platformOverrides.Contains(platform.GetType()))
+                {
+                    continue;
+                }
+
+                if (platform.IsAvailable ||
+                    platform.IsBuildTargetAvailable)
+                {
+                    activePlatforms.Add(platform);
                 }
             }
 
@@ -886,23 +905,17 @@ public static bool TryCreateAndRegisterService<T>(Type concreteType, IReadOnlyLi
 
             Debug.Assert(ActivePlatforms.Count > 0);
 
-            for (var i = 0; i < runtimePlatforms?.Count; i++)
+            for (var i = 0; i < ActivePlatforms.Count; i++)
             {
-                var runtimePlatform = runtimePlatforms[i].GetType();
-
-                if (runtimePlatform == typeof(AllPlatforms))
-                {
-                    platforms.Add(runtimePlatforms[i]);
-                    break;
-                }
+                var activePlatform = ActivePlatforms[i].GetType();
 
-                for (var j = 0; j < ActivePlatforms.Count; j++)
+                for (var j = 0; j < runtimePlatforms?.Count; j++)
                 {
-                    var activePlatform = ActivePlatforms[j].GetType();
+                    var runtimePlatform = runtimePlatforms[j].GetType();
 
                     if (activePlatform == runtimePlatform)
                     {
-                        platforms.Add(runtimePlatforms[i]);
+                        platforms.Add(runtimePlatforms[j]);
                         break;
                     }
                 }