NEW: Throw error when extension for inputsystem needed (#2101)

Author: ritamerkl

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -49,6 +49,7 @@ however, it has to be formatted properly to pass verification tests.
 ### Added
 - Added new API `InputSystem.settings.useIMGUIEditorForAssets` that should be used in custom `InputParameterEditor` that use both IMGUI and UI Toolkit.
 - Added ProfilerMakers to `InputAction.Enable()` and `InputActionMap.ResolveBindings()` to enable gathering of profiling data.
+- Added throwing an error message when trying to use the Input System package on console without the extension package installed.
 
 ## [1.11.2] - 2024-10-16
 

Packages/com.unity.inputsystem/InputSystem/Editor/InputSystemPluginControl.cs

@@ -0,0 +1,98 @@
+#if ((UNITY_EDITOR && UNITY_2021_1_OR_NEWER) || PACKAGE_DOCS_GENERATION)
+using System;
+using System.Collections.Generic;
+using UnityEditor;
+
+namespace UnityEngine.InputSystem.Editor
+{
+    /// <summary>
+    /// This class controls all required plugins and extension packages are installed for the InputSystem.
+    /// </summary>
+    /// <remarks>
+    /// For some platforms, the InputSystem requires additional plugins to be installed. This class checks if the required plugins are installed and throws a warning if they are not.
+    /// </remarks>
+    public class InputSystemPluginControl
+    {
+        // Input system platform specific classes register with the input system via a class using InitializeOnLoad on static constructors.
+        // Static constructors in classes that are tagged with the InitializeOnLoad attribute are called before methods using the InitializeOnLoadMethod attribute.
+        // So the extra input system packages will be registered before this check which is done in InitializeOnLoadMethod.
+        [InitializeOnLoadMethod]
+        private static void CheckForExtension()
+        {
+            ThrowWarningOnMissingPlugin();
+        }
+
+        // This static HashSet will be reset OnDomainReload and so it will be reset every Domain Reload (at the time of InitializeOnLoad).
+        // This is pre-populated with the list of platforms that don't need a extra platform specific input system package to add platform specific functionality.
+        private static HashSet<BuildTarget> s_supportedBuildTargets = new HashSet<BuildTarget>()
+        {
+            BuildTarget.StandaloneOSX,
+            BuildTarget.StandaloneWindows,
+            BuildTarget.iOS,
+            BuildTarget.Android,
+            BuildTarget.StandaloneWindows64,
+            BuildTarget.WebGL,
+            BuildTarget.WSAPlayer,
+            BuildTarget.StandaloneLinux64,
+            BuildTarget.tvOS,
+            BuildTarget.LinuxHeadlessSimulation,
+            BuildTarget.EmbeddedLinux,
+            #if UNITY_2022_1_OR_NEWER
+            BuildTarget.QNX,
+            #endif
+            #if UNITY_2023_3_OR_NEWER
+            BuildTarget.VisionOS,
+            #endif
+            #if UNITY_6000_0_OR_NEWER
+            BuildTarget.ReservedCFE,
+            #endif
+            #if UNITY_6000_0_7_OR_NEWER
+            BuildTarget.Kepler
+            #endif
+            BuildTarget.NoTarget
+        };
+
+        static bool BuildTargetNeedsPlugin()
+        {
+            BuildTarget target = EditorUserBuildSettings.activeBuildTarget;
+            foreach (var platform in s_supportedBuildTargets)
+            {
+                if (platform == target) return false;
+            }
+            return true;
+        }
+
+        private const string PlugInName = "com.unity.inputsystem.";
+
+        /// <summary>
+        /// Used to register extensions externally to the InputSystem, this is needed for all Platforms that require a plugin to be installed.
+        /// </summary>
+        /// <remarks>
+        /// This method is internally called by the InputSystem package extensions to register the PlugIn. This can be called for custom extensions on custom platforms.
+        /// </remarks>
+        public static void RegisterPlatform(BuildTarget target)
+        {
+            s_supportedBuildTargets.Add(target);
+        }
+
+        private static bool IsPluginInstalled()
+        {
+            var registeredPackages = UnityEditor.PackageManager.PackageInfo.GetAllRegisteredPackages();
+            var plugInName = PlugInName + EditorUserBuildSettings.activeBuildTarget.ToString().ToLower();
+            foreach (var package in registeredPackages)
+            {
+                if (package.name.Equals(plugInName))
+                    return true;
+            }
+            return false;
+        }
+
+        private static void ThrowWarningOnMissingPlugin()
+        {
+            if (!BuildTargetNeedsPlugin())
+                return;
+            Debug.Assert(IsPluginInstalled(), "Active Input Handling is set to InputSystem, but no Plugin for " + EditorUserBuildSettings.activeBuildTarget + " was found. Please install the missing InputSystem package extensions.");
+        }
+    }
+}
+#endif