FIX: useStateFrom not working with injected controls (#1067).

Author: Rene Damm

Assets/Tests/InputSystem/CoreTests_Layouts.cs

@@ -1369,6 +1369,60 @@ public void Layouts_CanAddChildControlToExistingControl()
         Assert.That(device.leftStick["enabled"].parent, Is.SameAs(device.leftStick));
     }
 
+    [Test]
+    [Category("Layouts")]
+    public void Layouts_CanAddChildControlToExistingControl_UsingStateFromOtherControl()
+    {
+        InputSystem.RegisterLayout(@"
+            {
+                ""name"" : ""TestDevice"",
+                ""controls"" : [
+                    { ""name"" : ""noise"", ""layout"" : ""Button"" },
+                    { ""name"" : ""scroll"", ""layout"" : ""Vector2"" },
+                    { ""name"" : ""scroll/up"", ""layout"" : ""Button"", ""useStateFrom"" : ""scroll/y"", ""parameters"" : ""clamp=1,clampMin=0,clampMax=99999"" },
+                    { ""name"" : ""scroll/down"", ""layout"" : ""Button"", ""useStateFrom"" : ""scroll/y"", ""parameters"" : ""clamp=1,clampMin=-99999,clampMax=0,invert"" },
+                    { ""name"" : ""scroll/left"", ""layout"" : ""Button"", ""useStateFrom"" : ""scroll/x"", ""parameters"" : ""clamp=1,clampMin=-99999,clampMax=0,invert"" },
+                    { ""name"" : ""scroll/right"", ""layout"" : ""Button"", ""useStateFrom"" : ""scroll/x"", ""parameters"" : ""clamp=1,clampMin=0,clampMax=99999"" }
+                ]
+            }
+        ");
+
+        var device = InputSystem.AddDevice("TestDevice");
+        var scroll = (Vector2Control)device["scroll"];
+
+        // Left.
+        Set(scroll, new Vector2(-123, 0));
+
+        Assert.That(device["scroll/up"].ReadValueAsObject(), Is.Zero);
+        Assert.That(device["scroll/down"].ReadValueAsObject(), Is.Zero);
+        Assert.That(device["scroll/left"].ReadValueAsObject(), Is.EqualTo(123).Within(0.00001));
+        Assert.That(device["scroll/right"].ReadValueAsObject(), Is.Zero);
+
+        // Right.
+        Set(scroll, new Vector2(234, 0));
+
+        Assert.That(device["scroll/up"].ReadValueAsObject(), Is.Zero);
+        Assert.That(device["scroll/down"].ReadValueAsObject(), Is.Zero);
+        Assert.That(device["scroll/left"].ReadValueAsObject(), Is.Zero);
+        Assert.That(device["scroll/right"].ReadValueAsObject(), Is.EqualTo(234).Within(0.00001));
+
+        // Up.
+        Set(scroll, new Vector2(0, 123));
+
+        Assert.That(device["scroll/up"].ReadValueAsObject(), Is.EqualTo(123).Within(0.00001));
+        Assert.That(device["scroll/down"].ReadValueAsObject(), Is.Zero);
+        Assert.That(device["scroll/left"].ReadValueAsObject(), Is.Zero);
+        Assert.That(device["scroll/right"].ReadValueAsObject(), Is.Zero);
+
+        // Down.
+        Set(scroll, new Vector2(0, -432));
+
+        Assert.That(device["scroll/up"].ReadValueAsObject(), Is.Zero);
+        Assert.That(device["scroll/down"].ReadValueAsObject(), Is.EqualTo(432).Within(0.00001));
+        Assert.That(device["scroll/left"].ReadValueAsObject(), Is.Zero);
+        Assert.That(device["scroll/right"].ReadValueAsObject(), Is.Zero);
+    }
+
     [Test]
     [Category("Layouts")]
     [Ignore("TODO")]

Packages/com.unity.inputsystem/Documentation~/Touch.md

@@ -3,6 +3,7 @@
 * [`Touchscreen` Device](#touchscreen-device)
 * [`Touch` class](#enhancedtouchtouch-class)
     * [Using Touch with Actions](#using-touch-with-actionsactionsmd)
+* [Touch Simulation](#touch-simulation)
 
 Touch support is divided into:
 * low-level support implemented in the [`Touchscreen`](#touchscreen-device) class.
@@ -76,3 +77,18 @@ The [`EnhancedTouch.Touch`](../api/UnityEngine.InputSystem.EnhancedTouch.Touch.h
 See [`EnhancedTouch.Touch` API documentation](../api/UnityEngine.InputSystem.EnhancedTouch.Touch.html) for more details.
 
 >__Note__: The [`Touch`](../api/UnityEngine.InputSystem.EnhancedTouch.Touch.html) and [`Finger`](../api/UnityEngine.InputSystem.EnhancedTouch.Finger.html) APIs don't generate GC garbage. The bulk of the data is stored in unmanaged memory that is indexed by wrapper structs. All arrays are pre-allocated.
+
+## Touch Simulation
+
+Touch input can be simulated from input on other kinds of [Pointer](./Pointers.md) devices such as [Mouse](./Mouse.md) and [Pen](./Pen.md) devices. To enable this, you can either add the [`TouchSimulation`](../api/UnityEngine.InputSystem.EnhancedTouch.TouchSimulation.html) `MonoBehaviour` to a `GameObject` in your scene or simply call [`TouchSimulation.Enable`](../api/UnityEngine.InputSystem.EnhancedTouch.TouchSimulation.html#UnityEngine_InputSystem_EnhancedTouch_TouchSimulation_Enable) somewhere in your startup code.
+
+```CSharp
+    void OnEnable()
+    {
+        TouchSimulation.Enable();
+    }
+```
+
+In the editor, you can also enable touch simulation by toggling "Simulate Touch Input From Mouse or Pen" on in the "Options" dropdown of the [Input Debugger](./Debugging.md).
+
+[`TouchSimulation`](../api/UnityEngine.InputSystem.EnhancedTouch.TouchSimulation.html) will add a [`Touchscreen`](../api/UnityEngine.InputSystem.Touchscreen.html) device and automatically mirror input on any [`Pointer`](../api/UnityEngine.InputSystem.Pointer.html) device to the virtual touchscreen device.

Packages/com.unity.inputsystem/InputSystem/Devices/InputDeviceBuilder.cs

@@ -17,8 +17,6 @@
 ////TODO: ensure that things are aligned properly for ARM; should that be done on the reading side or in the state layouts?
 ////       (make sure that alignment works the same on *all* platforms; otherwise editor will not be able to process events from players properly)
 
-////FIXME: looks like `useStateFrom` is not working properly in combination with isModifyingExistingControl
-
 namespace UnityEngine.InputSystem.Layouts
 {
     /// <summary>
@@ -202,28 +200,13 @@ private InputControl InstantiateLayout(InputControlLayout layout, InternedString
             // controls, assign them their blocks now.
             if (haveChildrenUsingStateFromOtherControl)
             {
-                foreach (var controlLayout in layout.controls)
+                var controls = layout.m_Controls;
+                for (var i = 0; i < controls.Length; ++i)
                 {
-                    if (string.IsNullOrEmpty(controlLayout.useStateFrom))
+                    ref var item = ref controls[i];
+                    if (string.IsNullOrEmpty(item.useStateFrom))
                         continue;
-
-                    var child = InputControlPath.TryFindChild(control, controlLayout.name);
-                    Debug.Assert(child != null, "Could not find child control which should be present at this point");
-
-                    // Find the referenced control.
-                    var referencedControl = InputControlPath.TryFindChild(control, controlLayout.useStateFrom);
-                    if (referencedControl == null)
-                        throw new InvalidOperationException(
-                            $"Cannot find control '{controlLayout.useStateFrom}' referenced in 'useStateFrom' of control '{controlLayout.name}' in layout '{layout.name}'");
-
-                    // Copy its state settings.
-                    child.m_StateBlock = referencedControl.m_StateBlock;
-
-                    // At this point, all byteOffsets are relative to parents so we need to
-                    // walk up the referenced control's parent chain and add offsets until
-                    // we are at the same level that we are at.
-                    for (var parentInChain = referencedControl.parent; parentInChain != control; parentInChain = parentInChain.parent)
-                        child.m_StateBlock.byteOffset += parentInChain.m_StateBlock.byteOffset;
+                    ApplyUseStateFrom(control, ref item, layout);
                 }
             }
 
@@ -574,6 +557,28 @@ private InputControl InsertChildControl(InputControlLayout layout, InternedStrin
             return control;
         }
 
+        private static void ApplyUseStateFrom(InputControl parent, ref InputControlLayout.ControlItem controlItem, InputControlLayout layout)
+        {
+            var child = InputControlPath.TryFindChild(parent, controlItem.name);
+            Debug.Assert(child != null, "Could not find child control which should be present at this point");
+
+            // Find the referenced control.
+            var referencedControl = InputControlPath.TryFindChild(parent, controlItem.useStateFrom);
+            if (referencedControl == null)
+                throw new InvalidOperationException(
+                    $"Cannot find control '{controlItem.useStateFrom}' referenced in 'useStateFrom' of control '{controlItem.name}' in layout '{layout.name}'");
+
+            // Copy its state settings.
+            child.m_StateBlock = referencedControl.m_StateBlock;
+
+            // At this point, all byteOffsets are relative to parents so we need to
+            // walk up the referenced control's parent chain and add offsets until
+            // we are at the same level that we are at.
+            if (child.parent != referencedControl.parent)
+                for (var parentInChain = referencedControl.parent; parentInChain != parent; parentInChain = parentInChain.parent)
+                    child.m_StateBlock.byteOffset += parentInChain.m_StateBlock.byteOffset;
+        }
+
         private static void ShiftChildIndicesInHierarchyOneUp(InputDevice device, int startIndex, InputControl exceptControl)
         {
             var controls = device.m_ChildrenForEachControl;