Using variable size IME events

Author: StayTalm

Assets/Tests/InputSystem/CoreTests_Devices.cs

@@ -5235,9 +5235,31 @@ public void Devices_CanListenForIMECompositionEvents()
             Assert.AreEqual(composition.ToString(), imeCompositionCharacters);
         };
 
-        var inputEvent = IMECompositionEvent.Create(keyboard.deviceId, imeCompositionCharacters,
+        IMECompositionEventVariableSize.QueueEvent(keyboard.deviceId, imeCompositionCharacters,
+            InputRuntime.s_Instance.currentTime);
+        InputSystem.Update();
+
+        Assert.That(callbackWasCalled, Is.True);
+    }
+
+    [Test]
+    [Category("Devices")]
+    public void Devices_CanReadEmptyIMECompositionEvents()
+    {
+        const string imeCompositionCharacters = "";
+        var callbackWasCalled = false;
+
+        var keyboard = InputSystem.AddDevice<Keyboard>();
+        keyboard.onIMECompositionChange += composition =>
+        {
+            Assert.That(callbackWasCalled, Is.False);
+            callbackWasCalled = true;
+            Assert.AreEqual(composition.Count, 0);
+            Assert.AreEqual(composition.ToString(), imeCompositionCharacters);
+        };
+
+        IMECompositionEventVariableSize.QueueEvent(keyboard.deviceId, imeCompositionCharacters,
             InputRuntime.s_Instance.currentTime);
-        InputSystem.QueueEvent(ref inputEvent);
         InputSystem.Update();
 
         Assert.That(callbackWasCalled, Is.True);

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

@@ -8,7 +8,7 @@ namespace UnityEngine.InputSystem.LowLevel
     /// input through <see cref="TextEvent"/>.
     /// </remarks>
     /// <seealso cref="TextEvent"/>
-    /// <seealso cref="IMECompositionEvent"/>
+    /// <seealso cref="IMECompositionEventVariableSize"/>
     public interface ITextInputReceiver
     {
         /// <summary>
@@ -32,7 +32,7 @@ public interface ITextInputReceiver
         /// Called when an IME composition is in-progress or finished.
         /// </summary>
         /// <param name="compositionString">The current composition.</param>
-        /// <seealso cref="IMECompositionEvent"/>
+        /// <seealso cref="IMECompositionEventVariableSize"/>
         /// <seealso cref="Keyboard.onIMECompositionChange"/>
         /// <remarks>
         /// The method will be repeatedly called with the current string while composition is in progress.

Packages/com.unity.inputsystem/InputSystem/Events/IMECompositionEvent.cs

@@ -2,16 +2,15 @@
 using System.Collections;
 using System.Collections.Generic;
 using System.Runtime.InteropServices;
+using Unity.Collections;
+using Unity.Collections.LowLevel.Unsafe;
 using UnityEngine.InputSystem.Utilities;
 
 namespace UnityEngine.InputSystem.LowLevel
 {
-    /// <summary>
-    /// A specialized event that contains the current IME Composition string, if IME is enabled and active.
-    /// This event contains the entire current string to date, and once a new composition is submitted will send a blank string event.
-    /// </summary>
+    [Obsolete("IMECompositionEvent is obsolete, please use IMECompositionEventVariableSize")]
     [StructLayout(LayoutKind.Explicit, Size = InputEvent.kBaseEventSize + sizeof(int) + (sizeof(char) * kIMECharBufferSize))]
-    public struct IMECompositionEvent : IInputEventTypeInfo
+    public unsafe struct IMECompositionEvent : IInputEventTypeInfo
     {
         // These needs to match the native ImeCompositionStringInputEventData settings
         internal const int kIMECharBufferSize = 64;
@@ -21,19 +20,95 @@ public struct IMECompositionEvent : IInputEventTypeInfo
         public InputEvent baseEvent;
 
         [FieldOffset(InputEvent.kBaseEventSize)]
-        public IMECompositionString compositionString;
+        private int length;
+
+        [FieldOffset(InputEvent.kBaseEventSize + sizeof(int))]
+        private fixed char buffer[kIMECharBufferSize];
+
+        public IMECompositionString compositionString
+        {
+            get
+            {
+                fixed(char* ptr = buffer)
+                return new IMECompositionString(ptr, length);
+            }
+        }
 
         public FourCC typeStatic => Type;
 
         public static IMECompositionEvent Create(int deviceId, string compositionString, double time)
         {
             var inputEvent = new IMECompositionEvent();
             inputEvent.baseEvent = new InputEvent(Type, InputEvent.kBaseEventSize + sizeof(int) + (sizeof(char) * kIMECharBufferSize), deviceId, time);
-            inputEvent.compositionString = new IMECompositionString(compositionString);
+            inputEvent.length = compositionString.Length > kIMECharBufferSize ? kIMECharBufferSize : compositionString.Length;
+            fixed(char* dst = compositionString)
+            fixed(char* src = compositionString)
+            UnsafeUtility.MemCpy(dst, src, inputEvent.length * sizeof(char));
             return inputEvent;
         }
     }
 
+    /// <summary>
+    /// A specialized event that contains the current IME Composition string, if IME is enabled and active.
+    /// This event contains the entire current string to date, and once a new composition is submitted will send a blank string event.
+    /// </summary>
+    [StructLayout(LayoutKind.Explicit, Size = InputEvent.kBaseEventSize + sizeof(int))]
+    public struct IMECompositionEventVariableSize : IInputEventTypeInfo
+    {
+        // Before we had 0x494D4553 which corresponds to ImeCompositionStringInputEventData fixed size event with 64 character payload.
+        // 0x494D4543 corresponds to ImeCompositionInputEventData and is a different event which provides variable size array of characters after the event.
+        public const int Type = 0x494D4543;
+
+        [FieldOffset(0)]
+        public InputEvent baseEvent;
+
+        [FieldOffset(InputEvent.kBaseEventSize)]
+        internal int length;
+
+        internal static unsafe char* GetCharsPtr(IMECompositionEventVariableSize* ev)
+        {
+            return (char*)((byte*)ev + InputEvent.kBaseEventSize + sizeof(int));
+        }
+
+        public FourCC typeStatic => Type;
+
+        /// <summary>
+        /// Returns composition string for the given event.
+        /// </summary>
+        /// <param name="ev">Pointer to the event.</param>
+        /// <returns></returns>
+        public static unsafe IMECompositionString GetIMECompositionString(IMECompositionEventVariableSize* ev)
+        {
+            return new IMECompositionString(GetCharsPtr(ev), ev->length);
+        }
+
+        /// <summary>
+        /// Queues up an IME Composition Event. IME Event sizes are variable, and this simplifies the process of aligning up the Input Event information and actual IME composition string.
+        /// </summary>
+        /// <param name="deviceId">ID of the device (see <see cref="InputDevice.deviceId") to which the composition event should be sent to. Should be an <see cref="ITextInputReceiver"/> device. Will trigger <see cref="ITextInputReceiver.OnIMECompositionChanged"/> call when processed.</param>
+        /// <param name="str">The IME characters to be sent. This can be any length, or left blank to represent a resetting of the IME dialog.</param>
+        /// <param name="time">The time in seconds, the event was generated at.  This uses the same timeline as <see cref="Time.realtimeSinceStartup"/></param>
+        public static unsafe void QueueEvent(int deviceId, string str, double time)
+        {
+            var sizeInBytes = (InputEvent.kBaseEventSize + sizeof(int)) + sizeof(char) * str.Length;
+            var eventBuffer = new NativeArray<byte>(sizeInBytes, Allocator.Temp, NativeArrayOptions.UninitializedMemory);
+
+            var ev = (IMECompositionEventVariableSize*)eventBuffer.GetUnsafePtr();
+
+            ev->baseEvent = new InputEvent(Type, sizeInBytes, deviceId, time);
+            ev->length = str.Length;
+
+            if (str.Length > 0)
+                fixed(char* p = str)
+                UnsafeUtility.MemCpy(GetCharsPtr(ev), p, str.Length * sizeof(char));
+
+            InputSystem.QueueEvent(new InputEventPtr((InputEvent*)ev));
+
+            eventBuffer.Dispose();
+        }
+    }
+
+    //// TODO for v2 remove and replace with just string.
     /// <summary>
     /// A struct representing an string of characters generated by an IME for text input.
     /// </summary>
@@ -42,36 +117,31 @@ public static IMECompositionEvent Create(int deviceId, string compositionString,
     /// <see cref="ITextInputReceiver.OnIMECompositionChanged"/> method. It can easily be converted to a normal C# string using
     ///  <see cref="ToString"/>, but is exposed as the raw struct to avoid allocating memory by default.
     /// </remarks>
-    [StructLayout(LayoutKind.Explicit, Size = sizeof(int) + sizeof(char) * LowLevel.IMECompositionEvent.kIMECharBufferSize)]
     public unsafe struct IMECompositionString : IEnumerable<char>
     {
-        internal struct Enumerator : IEnumerator<char>
+        private const int kLegacyIMEEventCharBufferSize = 64;
+
+        private readonly string m_ManagedString;
+        private readonly int m_Size;
+        private fixed char m_FixedBuffer[kLegacyIMEEventCharBufferSize];
+
+        private struct FixedBufferEnumerator : IEnumerator<char>
         {
-            IMECompositionString m_CompositionString;
-            char m_CurrentCharacter;
-            int m_CurrentIndex;
+            private IMECompositionString m_CompositionString;
+            private int m_CurrentIndex;
 
-            public Enumerator(IMECompositionString compositionString)
+            public FixedBufferEnumerator(IMECompositionString compositionString)
             {
                 m_CompositionString = compositionString;
-                m_CurrentCharacter = '\0';
                 m_CurrentIndex = -1;
             }
 
             public bool MoveNext()
             {
-                int size = m_CompositionString.Count;
-
-                m_CurrentIndex++;
-
-                if (m_CurrentIndex == size)
+                if (m_CurrentIndex + 1 >= m_CompositionString.Count)
                     return false;
 
-                fixed(char* ptr = m_CompositionString.buffer)
-                {
-                    m_CurrentCharacter = *(ptr + m_CurrentIndex);
-                }
-
+                m_CurrentIndex++;
                 return true;
             }
 
@@ -84,58 +154,73 @@ public void Dispose()
             {
             }
 
-            public char Current => m_CurrentCharacter;
+            public char Current => m_CompositionString[m_CurrentIndex];
 
             object IEnumerator.Current => Current;
         }
 
-        public int Count => size;
+        public int Count => m_Size;
 
         public char this[int index]
         {
             get
             {
+                if (m_ManagedString != null)
+                    return m_ManagedString[index];
+
                 if (index >= Count || index < 0)
                     throw new ArgumentOutOfRangeException(nameof(index));
 
-                fixed(char* ptr = buffer)
-                {
-                    return *(ptr + index);
-                }
+                return m_FixedBuffer[index];
             }
         }
 
-        [FieldOffset(0)]
-        int size;
-
-        [FieldOffset(sizeof(int))]
-        fixed char buffer[IMECompositionEvent.kIMECharBufferSize];
-
-        public IMECompositionString(string characters)
+        public IMECompositionString(char* characters, int length)
         {
-            if (string.IsNullOrEmpty(characters))
+            // only allocate string if we can't fit into fixed buffer
+            if (length <= kLegacyIMEEventCharBufferSize)
+            {
+                m_ManagedString = null;
+                m_Size = length;
+                if (m_Size > 0)
+                {
+                    Debug.Assert(characters != null);
+                    fixed(char* dst = m_FixedBuffer)
+                    UnsafeUtility.MemCpy(dst, characters, m_Size * sizeof(char));
+                }
+            }
+            else
             {
-                size = 0;
-                return;
+                m_ManagedString = new string(characters, 0, length);
+                m_Size = length;
             }
+        }
 
-            Debug.Assert(characters.Length < IMECompositionEvent.kIMECharBufferSize);
-            size = characters.Length;
-            for (var i = 0; i < size; i++)
-                buffer[i] = characters[i];
+        public IMECompositionString(string characters)
+        {
+            // string is already allocated on the heap, so reuse it
+            m_ManagedString = characters;
+            m_Size = characters.Length;
         }
 
         public override string ToString()
         {
-            fixed(char* ptr = buffer)
-            {
-                return new string(ptr, 0, size);
-            }
+            if (m_Size == 0)
+                return string.Empty;
+
+            if (m_ManagedString != null)
+                return m_ManagedString;
+
+            fixed(char* ptr = m_FixedBuffer)
+            return new string(ptr, 0, m_Size);
         }
 
         public IEnumerator<char> GetEnumerator()
         {
-            return new Enumerator(this);
+            if (m_ManagedString != null)
+                return m_ManagedString.GetEnumerator();
+
+            return new FixedBufferEnumerator(this);
         }
 
         IEnumerator IEnumerable.GetEnumerator()

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

@@ -3252,11 +3252,11 @@ private unsafe void OnUpdate(InputUpdateType updateType, ref InputEventBuffer ev
                             break;
                         }
 
-                        case IMECompositionEvent.Type:
+                        case IMECompositionEventVariableSize.Type:
                         {
-                            var imeEventPtr = (IMECompositionEvent*)currentEventReadPtr;
+                            var imeEventPtr = (IMECompositionEventVariableSize*)currentEventReadPtr;
                             var textInputReceiver = device as ITextInputReceiver;
-                            textInputReceiver?.OnIMECompositionChanged(imeEventPtr->compositionString);
+                            textInputReceiver?.OnIMECompositionChanged(IMECompositionEventVariableSize.GetIMECompositionString(imeEventPtr));
                             break;
                         }