Make TextFlowContainer wrap on individual characters as a last resort

osu.Framework.Tests/Visual/Containers/TestSceneTextFlowContainer.cs

@@ -24,7 +24,9 @@
         private TextFlowContainer textContainer = null!;
 
         [SetUp]
-        public void Setup() => Schedule(() =>
+        public void Setup() => Schedule(() => createContainer(default_text));
+
+        private void createContainer(string text = default_text)
         {
             Child = topLevelContainer = new Container
             {
@@ -43,11 +45,11 @@
                     {
                         RelativeSizeAxes = Axes.X,
                         AutoSizeAxes = Axes.Y,
-                        Text = default_text
+                        Text = text
                     }
                 }
             };
-        });
+        }
 
         [TestCase(Anchor.TopLeft)]
         [TestCase(Anchor.TopCentre)]
@@ -123,6 +125,53 @@
             AddStep("set cjk text", () => textContainer.Text = "日本の桜は世界中から観光客を引きつけています。寿司は美味しい伝統的な日本食です。東京タワーは景色が美しいです。速い新幹線は、便利な交通手段です。富士山は、その美しさと完全な形状で知られています。日本文化は、優雅さと繊細さを象徴しています。抹茶は特別な日本の茶です。着物は、伝統的な日本の衣装で、特別な場面でよく着用されます。");
         }
 
+        [Test]
+        public void TestOverflowCharacterSplitting()
+        {
+            string overflowText = "LoremipsumdolorsitametconsecteturadipiscingelitIntegermattiseuturpisvitaeposuereOrcivariusnatoquepenatibusetmagnisdisparturientmontesnasceturridiculusmusEtiammaurisnibhfaucibusmaximusornareeuultricesutipsumProinrhoncusnuncetfaucibuspretiumnislnuncdapibusmassaetscelerisquenibhligulaidodioPraesentdapibusexsednuncegestasinplaceratrisusmattisNullasedligulavelitVestibulumauctorportaerosetcondimentumEtiamlaoreetnuncneclaciniapulvinarMaurishendreritmiataliquetcondimentumexexcursusdolornonportaeraterosidjustoCrasmalesuadatinciduntnuncattinciduntrisuseleifendidMaecenashendreritvenenatismietlobortisEtiamsemtortorelementumegetlacusnonportatristiquequamMorbisedlaciniaodioPhasellusutpretiumnuncFuscevitaemollismagnavelscelerisquedui";
+
+            AddStep("set text to overflow on creation", () =>
+            {
+                createContainer(overflowText);
+            });
+            assertSpriteTextCount(overflowText.Length);
+
+            AddStep("set overflow text post-creation", () => textContainer.Text = overflowText);
+            assertSpriteTextCount(overflowText.Length);
+
+            AddStep("set overflow text mid-sentence", () =>
+            {
+                textContainer.Text = "start/" + overflowText + "/end";
+            });
+            assertSpriteTextCount(overflowText.Length + 3);
+
+            AddStep("set relative width", () =>
+            {
+                topLevelContainer.AutoSizeAxes = textContainer.AutoSizeAxes = Axes.Y;
+                topLevelContainer.RelativeSizeAxes = textContainer.RelativeSizeAxes = Axes.X;
+                topLevelContainer.Width = textContainer.Width = 0.5f;
+                textContainer.Text = overflowText;
+            });
+            assertSpriteTextCount(overflowText.Length);
+
+            AddStep("set absolute width", () =>
+            {
+                topLevelContainer.AutoSizeAxes = textContainer.AutoSizeAxes = Axes.Y;
+                topLevelContainer.RelativeSizeAxes = textContainer.RelativeSizeAxes = Axes.None;
+                topLevelContainer.Width = textContainer.Width = 200f;
+                textContainer.Text = overflowText;
+            });
+            assertSpriteTextCount(overflowText.Length);
+
+            AddStep("set autosize width", () =>
+            {
+                topLevelContainer.RelativeSizeAxes = textContainer.RelativeSizeAxes = Axes.None;
+                topLevelContainer.AutoSizeAxes = textContainer.AutoSizeAxes = Axes.Both;
+                textContainer.Text = overflowText;
+            });
+            assertSpriteTextCount(1);
+        }
+
         [Test]
         public void TestSizing()
         {

osu.Framework.Tests/Visual/Sprites/TestSceneTextFlow.cs

@@ -73,6 +73,7 @@ public TestSceneTextFlow()
             textFlowContainer.AddText(" (and so are inline styles!)", t => t.Colour = Color4.Yellow);
             textFlowContainer.AddParagraph("There's 2 line breaks\n\ninside this paragraph!", t => t.Colour = Color4.GreenYellow);
             textFlowContainer.AddParagraph("Make\nTextFlowContainer\ngreat\nagain!", t => t.Colour = Color4.Red);
+            textFlowContainer.AddText("\ntext overflowwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww", t => t.Colour = Color4.Blue);
 
             paragraphContainer.Add(new TextFlowContainer
             {
@@ -106,6 +107,28 @@ public TestSceneTextFlow()
                 Text = "Test icons [RedBox] interleaved\n[GreenBox] with other [0] text, also [[0]] escaping stuff is possible."
             });
 
+            paragraphContainer.Add(new CustomText
+            {
+                RelativeSizeAxes = Axes.X,
+                AutoSizeAxes = Axes.Y,
+                Placeholders = new Drawable[]
+                {
+                    new LineBaseBox
+                    {
+                        Colour = Color4.Purple,
+                        LineBaseHeight = 25f,
+                        Size = new Vector2(25, 25)
+                    }.WithEffect(new OutlineEffect
+                    {
+                        Strength = 20f,
+                        PadExtent = true,
+                        BlurSigma = new Vector2(5f),
+                        Colour = Color4.White
+                    })
+                },
+                Text = "Test icons interleaved with wrapping overflowwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww[0]wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww"
+            });
+
             paragraphContainer.Add(new Container
             {
                 Size = new Vector2(300),

osu.Framework/Graphics/Containers/TextChunk.cs

@@ -73,12 +73,31 @@
 
                     var textSprite = CreateSpriteText(textFlowContainer);
                     textSprite.Text = word;
-                    sprites.Add(textSprite);
+
+                    // Avoid splitting if we don't know what the container's size will be (this check will short circut if so)
+                    if (textFlowContainer.Parent != null && !textFlowContainer.TextFitsInFlow(textSprite))
+                    {
+                        addCharacters(word);
+                    }
+                    else
+                    {
+                        sprites.Add(textSprite);
+                    }
                 }
 
                 first = false;
             }
 
+            void addCharacters(string text)
+            {
+                foreach (char character in text)
+                {
+                    var characterSprite = CreateSpriteText(textFlowContainer);
+                    characterSprite.Text = character.ToString();
+
+                    sprites.Add(characterSprite);
+                }
+            }
             return sprites;
         }
 

osu.Framework/Graphics/Containers/TextFlowContainer.cs

@@ -194,7 +194,6 @@
             base.LoadAsyncComplete();
 
             localisationParameters.Value = Localisation.CurrentParameters.Value;
-            RecreateAllParts();
         }
 
         protected override void LoadComplete()
@@ -203,6 +202,7 @@
 
             localisationParameters.BindValueChanged(_ => partsCache.Invalidate());
             ((IBindable<LocalisationParameters>)localisationParameters).BindTo(Localisation.CurrentParameters);
+            RecreateAllParts();
         }
 
         protected override void Update()
@@ -287,6 +287,26 @@
 
         protected internal virtual SpriteText CreateSpriteText() => new SpriteText();
 
+        /// <summary>
+        /// Checks whether the width of a <see cref="SpriteText"/> would fit within the bounds of this TextFlowContainer when drawn.
+        /// </summary>
+        /// <param name="spriteText">The <see cref="SpriteText"/> to check.</param>
+        /// <returns>Whether the text fits within the bounds of this TextFlowContainer.</returns>
+        /// <exception cref="InvalidOperationException">If this container's <see cref="RelativeSizeAxes"/> == <see cref="Axes.X"/> and/or it hasn't loaded (Parent == null)</exception>
+        /// <remarks>The <paramref name="spriteText"/> provided will be pre-loaded by being passed into <see cref="CompositeDrawable.LoadComponent{TLoadable}(TLoadable)"/> to get its width.</remarks>
+        public bool TextFitsInFlow(SpriteText spriteText)
+        {
+            if (AutoSizeAxes.HasFlagFast(Axes.X))
+                return true;
+            if (Parent == null)
+                throw new InvalidOperationException($"Cannot invoke {nameof(TextFitsInFlow)} before this {nameof(TextFlowContainer)} has a parent. Consider calling after this container has loaded.");
+            if (Flow.LoadState < LoadState.Ready)
+                throw new InvalidOperationException($"Cannot invoke {nameof(TextFitsInFlow)} before this container's {nameof(InnerFlow)} is ready. Consider calling after this container has loaded.");
+
+            Flow.LoadSpriteTextComponent(spriteText);
+            return spriteText.Width <= Flow.ChildSize.X;
+        }
+
         internal void ApplyDefaultCreationParameters(SpriteText spriteText) => defaultCreationParameters?.Invoke(spriteText);
 
         public void Clear(bool disposeChildren = true)
@@ -347,6 +367,11 @@
 
         protected partial class InnerFlow : FillFlowContainer
         {
+            protected internal void LoadSpriteTextComponent(SpriteText item)
+            {
+                LoadComponent(item);
+            }
+
             private float firstLineIndent;
 
             /// <summary>