Make IActionMarkupHandler.OnLineDisplayComplete asynchronous

Runtime/Views/ActionMarkupHandler.cs

@@ -71,7 +71,7 @@ public interface IActionMarkupHandler
         /// <param name="text">A <see cref="TMP_Text"/> object that the line is
         /// being displayed in.</param>
         /// <param name="cancellationToken">A cancellation token representing
-        /// whether the </param>
+        /// whether cancellation has been requested.</param>
         /// <returns>A task that completes when the <see
         /// cref="ActionMarkupHandler"/> has completed presenting this
         /// character. Dialogue presenters will wait until this task is complete
@@ -85,7 +85,13 @@ public interface IActionMarkupHandler
         /// <remarks>This method is an opportunity for a <see
         /// cref="ActionMarkupHandler"/> to finalise its presentation after
         /// all of the characters in the line have been presented.</remarks>
-        public void OnLineDisplayComplete();
+        /// <param name="cancellationToken">A cancellation token representing
+        /// whether cancellation has been requested.</param>
+        /// <returns>A task that completes when the <see
+        /// cref="ActionMarkupHandler"/> has completed presenting this
+        /// character. Dialogue presenters will wait until this task is complete
+        /// before proceeding to dismiss the line.</returns>
+        public YarnTask OnLineDisplayComplete(CancellationToken cancellationToken);
 
         /// <summary>
         /// Called right before the line will dismiss itself.
@@ -117,7 +123,7 @@ public abstract class ActionMarkupHandler : MonoBehaviour, IActionMarkupHandler
         public abstract YarnTask OnCharacterWillAppear(int currentCharacterIndex, MarkupParseResult line, CancellationToken cancellationToken);
 
         /// <inheritdoc/>
-        public abstract void OnLineDisplayComplete();
+        public abstract YarnTask OnLineDisplayComplete();
 
         /// <inheritdoc/>
         public abstract void OnLineWillDismiss();

Runtime/Views/LineAdvancer.cs

@@ -769,7 +769,7 @@ public YarnTask OnCharacterWillAppear(int currentCharacterIndex, MarkupParseResu
             return YarnTask.CompletedTask;
         }
 
-        public void OnLineDisplayComplete()
+        public YarnTask OnLineDisplayComplete(CancellationToken cancellationToken)
         {
             if (status == PresentationStatus.LineBegan)
             {
@@ -779,6 +779,8 @@ public void OnLineDisplayComplete()
             {
                 status = PresentationStatus.OptionsWaiting;
             }
+
+            return YarnTask.CompletedTask;
         }
 
         public void OnLineWillDismiss()

Runtime/Views/LinePresenterButtonHandler.cs

@@ -69,9 +69,9 @@ public override YarnTask OnCharacterWillAppear(int currentCharacterIndex, Markup
             return YarnTask.CompletedTask;
         }
 
-        public override void OnLineDisplayComplete()
+        public override YarnTask OnLineDisplayComplete()
         {
-            return;
+            return YarnTask.CompletedTask;
         }
 
         public override void OnLineWillDismiss()

Runtime/Views/PauseEventProcessor.cs

@@ -23,9 +23,10 @@ namespace Yarn.Unity
     public sealed class PauseEventProcessor : IActionMarkupHandler
     {
         private Dictionary<int, float> pauses = new();
-        public void OnLineDisplayComplete()
+        public YarnTask OnLineDisplayComplete(CancellationToken cancellationToken)
         {
             pauses.Clear();
+            return YarnTask.CompletedTask;
         }
 
         public void OnLineDisplayBegin(MarkupParseResult line, TMP_Text text)

Runtime/Views/Typewriter/InstantTypewriter.cs

@@ -4,6 +4,7 @@ namespace Yarn.Unity
 {
     using System;
     using System.Collections.Generic;
+    using System.Linq;
     using System.Threading;
     using UnityEngine;
     using Yarn.Markup;
@@ -75,10 +76,9 @@ await processor
             Text.maxVisibleCharacters = visibleCharacterCount;
 
             // Let each markup handler know the line has finished displaying
-            foreach (var markupHandler in ActionMarkupHandlers)
-            {
-                markupHandler.OnLineDisplayComplete();
-            }
+            await YarnTask.WhenAll(
+                ActionMarkupHandlers.Select(handler => handler.OnLineDisplayComplete(cancellationToken))
+            );
         }
 
         public void PrepareForContent(MarkupParseResult line)

Runtime/Views/Typewriter/LetterTypewriter.cs

@@ -4,6 +4,7 @@ namespace Yarn.Unity
 {
     using System;
     using System.Collections.Generic;
+    using System.Linq;
     using System.Threading;
     using UnityEngine;
 #if USE_TMP
@@ -105,10 +106,9 @@ await processor
             }
 
             // Let each markup handler know the line has finished displaying
-            foreach (var markupHandler in ActionMarkupHandlers)
-            {
-                markupHandler.OnLineDisplayComplete();
-            }
+            await YarnTask.WhenAll(
+                ActionMarkupHandlers.Select(handler => handler.OnLineDisplayComplete(cancellationToken))
+            );
         }
 
         public void PrepareForContent(Markup.MarkupParseResult line)

Runtime/Views/Typewriter/WordTypewriter.cs

@@ -4,6 +4,7 @@ namespace Yarn.Unity
 {
     using System;
     using System.Collections.Generic;
+    using System.Linq;
     using System.Threading;
     using UnityEngine;
 #if USE_TMP
@@ -131,10 +132,9 @@ await processor
             }
 
             // Let each markup handler know the line has finished displaying
-            foreach (var markupHandler in ActionMarkupHandlers)
-            {
-                markupHandler.OnLineDisplayComplete();
-            }
+            await YarnTask.WhenAll(
+                ActionMarkupHandlers.Select(handler => handler.OnLineDisplayComplete(cancellationToken))
+            );
         }
 
         public void PrepareForContent(Markup.MarkupParseResult line)