FIX: Errors are thrown when assigning Input Actions Asset that contains a custom InputProcessor or InputBindingComposite as Project-wide Input Actions (ISXB-856)

Assets/Samples/CustomComposite/CustomComposite.cs

@@ -27,61 +27,29 @@
 //       our composite will not be shown as our value type (Vector2) is
 //       incompatible with the value type of Axis (float).
 //
-// Also, we need to register our composite with the input system. And we
-// want to do it in a way that makes the composite visible in the action
-// editor of the input system.
-//
-// For that to happen, we need to call InputSystem.RegisterBindingComposite
-// sometime during startup. We make that happen by using [InitializeOnLoad]
-// in the editor and [RuntimeInitializeOnLoadMethod] in the player.
-#if UNITY_EDITOR
-[InitializeOnLoad]
-#endif
 // We can customize the way display strings are formed for our composite by
 // annotating it with DisplayStringFormatAttribute. The string is simply a
 // list with elements to be replaced enclosed in curly braces. Everything
 // outside those will taken verbatim. The fragments inside the curly braces
 // in this case refer to the binding composite parts by name. Each such
 // instance is replaced with the display text for the corresponding
 // part binding.
+//
+// NOTE: We don't supply a name for the composite here. The default logic
+//       will take the name of the type ("CustomComposite" in our case)
+//       and snip off "Composite" if used as a suffix (which is the case
+//       for us) and then use that as the name. So in our case, we are
+//       registering a composite called "Custom" here.
+//
+//       If we were to use our composite with the AddCompositeBinding API,
+//       for example, it would look like this:
+//
+//       myAction.AddCompositeBinding("Custom")
+//           .With("Stick", "<Gamepad>/leftStick")
+//           .With("Multiplier", "<Gamepad>/rightTrigger");
 [DisplayStringFormat("{multiplier}*{stick}")]
 public class CustomComposite : InputBindingComposite<Vector2>
 {
-    // In the editor, the static class constructor will be called on startup
-    // because of [InitializeOnLoad].
-    #if UNITY_EDITOR
-    static CustomComposite()
-    {
-        // Trigger our RegisterBindingComposite code in the editor.
-        Initialize();
-    }
-
-    #endif
-
-    // In the player, [RuntimeInitializeOnLoadMethod] will make sure our
-    // initialization code gets called during startup.
-    [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.BeforeSceneLoad)]
-    private static void Initialize()
-    {
-        // This registers the composite with the input system. After calling this
-        // method, we can have bindings reference the composite. Also, the
-        // composite will show up in the action editor.
-        //
-        // NOTE: We don't supply a name for the composite here. The default logic
-        //       will take the name of the type ("CustomComposite" in our case)
-        //       and snip off "Composite" if used as a suffix (which is the case
-        //       for us) and then use that as the name. So in our case, we are
-        //       registering a composite called "Custom" here.
-        //
-        //       If we were to use our composite with the AddCompositeBinding API,
-        //       for example, it would look like this:
-        //
-        //       myAction.AddCompositeBinding("Custom")
-        //           .With("Stick", "<Gamepad>/leftStick")
-        //           .With("Multiplier", "<Gamepad>/rightTrigger");
-        InputSystem.RegisterBindingComposite<CustomComposite>();
-    }
-
     // So, we need two parts for our composite. The part that delivers the stick
     // value and the part that delivers the axis multiplier. Note that each part
     // may be bound to multiple controls. The input system handles that for us

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -26,6 +26,7 @@ however, it has to be formatted properly to pass verification tests.
 
 ### Added
 - Added `InputSystemUIInputModule.scrollDeltaPerTick` property, a customizable multiplicative factor applied to the scroll wheel speed before it is sent to UI components. Note that this has no effect on UI Toolkit content, only uGUI.
+- Added automatic loading of custom extensions of InputProcessor, InputInteraction and InputBindingComposite [ISXB-856]](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-856).
 
 ## [1.9.0] - 2024-07-15
 

Packages/com.unity.inputsystem/InputSystem/Actions/IInputInteraction.cs

@@ -80,7 +80,7 @@ namespace UnityEngine.InputSystem
     /// </code>
     /// </example>
     ///
-    /// Custom interactions can be registered using <see cref="InputSystem.RegisterInteraction"/>. This can be
+    /// Custom interactions are automatically registed by reflexion but it can also be manually registered using <see cref="InputSystem.RegisterInteraction"/>. This can be
     /// done at any point during or after startup but has to be done before actions that reference the interaction
     /// are enabled or have their controls queried. A good point is usually to do it during loading like so:
     ///

Packages/com.unity.inputsystem/InputSystem/Actions/InputBindingComposite.cs

@@ -279,8 +279,8 @@ internal static string GetDisplayFormatString(string composite)
     ///
     /// The set of composites available in the system is extensible. While some composites are
     /// such as <see cref="Composites.Vector2Composite"/> and <see cref="Composites.ButtonWithOneModifier"/>
-    /// are available out of the box, new composites can be implemented by anyone and simply be
-    /// registered with <see cref="InputSystem.RegisterBindingComposite{T}"/>.
+    /// are available out of the box, new composites can be implemented by anyone and simply be autodiscover
+    /// or manually registered with <see cref="InputSystem.RegisterBindingComposite{T}"/>.
     ///
     /// See the "Custom Composite" sample (can be installed from package manager UI) for a detailed example
     /// of how to create a custom composite.

Packages/com.unity.inputsystem/InputSystem/Controls/InputProcessor.cs

@@ -117,10 +117,6 @@ public enum CachingPolicy
     ///
     /// <example>
     /// <code>
-    /// // To register the processor, call
-    /// //
-    /// //    InputSystem.RegisterProcessor&lt;ScalingProcessor&gt;("scale");
-    /// //
     /// public class ScalingProcessor : InputProcessor&lt;float&gt;
     /// {
     ///     // This field can be set as a parameter. See examples below.

Packages/com.unity.inputsystem/InputSystem/InputManager.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
+using System.Reflection;
 using System.Runtime.CompilerServices;
 using System.Text;
 using Unity.Collections;
@@ -1965,6 +1966,61 @@ internal void InitializeData()
             composites.AddTypeRegistration("ButtonWithTwoModifiers", typeof(ButtonWithTwoModifiers));
             composites.AddTypeRegistration("OneModifier", typeof(OneModifierComposite));
             composites.AddTypeRegistration("TwoModifiers", typeof(TwoModifiersComposite));
+
+            // Register custom types by reflection
+            RegisterCustomTypes();
+        }
+
+        void RegisterCustomTypes(Type[] types)
+        {
+            foreach (Type type in types)
+            {
+                if (!type.IsClass
+                    || type.IsAbstract
+                    || type.IsGenericType)
+                    continue;
+                if (typeof(InputProcessor).IsAssignableFrom(type))
+                {
+                    InputSystem.RegisterProcessor(type);
+                }
+                else if (typeof(IInputInteraction).IsAssignableFrom(type))
+                {
+                    InputSystem.RegisterInteraction(type);
+                }
+                else if (typeof(InputBindingComposite).IsAssignableFrom(type))
+                {
+                    InputSystem.RegisterBindingComposite(type, null);
+                }
+            }
+        }
+
+        void RegisterCustomTypes()
+        {
+            var inputSystemAssembly = typeof(InputProcessor).Assembly;
+            var inputSystemName = inputSystemAssembly.GetName().Name;
+            var assemblies = AppDomain.CurrentDomain.GetAssemblies();
+            foreach (var assembly in assemblies)
+            {
+                try
+                {
+                    // exclude InputSystem assembly which should be loaded first
+                    if (assembly == inputSystemAssembly) continue;
+
+                    // Only register types from assemblies that reference InputSystem
+                    foreach (var referencedAssembly in assembly.GetReferencedAssemblies())
+                    {
+                        if (referencedAssembly.Name == inputSystemName)
+                        {
+                            RegisterCustomTypes(assembly.GetTypes());
+                            break;
+                        }
+                    }
+                }
+                catch (ReflectionTypeLoadException)
+                {
+                    continue;
+                }
+            }
         }
 
         internal void InstallRuntime(IInputRuntime runtime)