Merge pull request #454 from SixLabors/js/additional-linebreak-fixes

Fix #448 and #450

Author: JimBobSquarePants

src/SixLabors.Fonts/TextLayout.cs

@@ -1179,7 +1179,28 @@ VerticalOrientationType.Rotate or
         List<LineBreak> lineBreaks = new();
         while (lineBreakEnumerator.MoveNext())
         {
-            lineBreaks.Add(lineBreakEnumerator.Current);
+            // URLs are now so common in regular plain text that they need to be taken into account when
+            // assigning general-purpose line breaking properties.
+            //
+            // To handle this we disallow breaks after solidus (U+002F) entirely.
+            // Testing seems to indicate Chrome and other browsers do this as well.
+            //
+            // We do this outside of the line breaker so that the expected results from the Unicode
+            // tests are not affected.
+            // https://www.unicode.org/reports/tr14/#SY
+            LineBreak current = lineBreakEnumerator.Current;
+            int i = current.PositionMeasure;
+            if (i < textLine.Count)
+            {
+                CodePoint c = textLine[i].CodePoint;
+                CodePoint p = textLine[Math.Max(0, i - 1)].CodePoint;
+                if (c.Value == 0x002F || p.Value == 0x002F)
+                {
+                    continue;
+                }
+            }
+
+            lineBreaks.Add(current);
         }
 
         int processed = 0;

src/SixLabors.Fonts/Unicode/LineBreakEnumerator.cs

@@ -347,11 +347,52 @@ private bool GetPairTableBreak(LineBreakClass lastClass)
                 }
 
                 // LB25
-                if (this.lb25ex && (this.nextClass == LineBreakClass.PR || this.nextClass == LineBreakClass.NU))
+                if (this.lb25ex)
                 {
-                    shouldBreak = true;
-                    this.lb25ex = false;
-                    break;
+                    switch (lastClass)
+                    {
+                        case LineBreakClass.PO:
+                        case LineBreakClass.PR:
+                            if (this.currentClass == LineBreakClass.NU)
+                            {
+                                this.lb25ex = false;
+                                return false;
+                            }
+
+                            LineBreakClass ahead = this.PeekNextCharClass();
+                            if (ahead == LineBreakClass.NU && this.nextClass is LineBreakClass.OP or LineBreakClass.HY)
+                            {
+                                this.lb25ex = false;
+                                return false;
+                            }
+
+                            break;
+                        case LineBreakClass.HY:
+                        case LineBreakClass.OP:
+                            if (this.currentClass == LineBreakClass.NU)
+                            {
+                                this.lb25ex = false;
+                                return false;
+                            }
+
+                            break;
+
+                        case LineBreakClass.NU:
+                            if (this.currentClass is LineBreakClass.PO or LineBreakClass.PR or LineBreakClass.NU)
+                            {
+                                this.lb25ex = false;
+                                return false;
+                            }
+
+                            break;
+                    }
+
+                    if (this.nextClass is LineBreakClass.PR or LineBreakClass.NU)
+                    {
+                        shouldBreak = true;
+                        this.lb25ex = false;
+                        break;
+                    }
                 }
 
                 // LB24

tests/Images/ReferenceOutput/Issue_448__WrappingLength_150_.png

@@ -0,0 +1,22 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.Fonts.Tests.Issues;
+public class Issues_448
+{
+    [Fact]
+    public void Issue_448()
+    {
+        if (SystemFonts.TryGet("Arial", out FontFamily family))
+        {
+            Font font = family.CreateFont(20);
+
+            TextLayoutTestUtilities.TestLayout(
+                "aaaaa bbbbb/ccccc ddddd",
+                new TextOptions(font)
+                {
+                    WrappingLength = 150
+                });
+        }
+    }
+}

tests/Images/ReferenceOutput/Issue_450__WrappingLength_960_.png

@@ -0,0 +1,25 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using System.Numerics;
+
+namespace SixLabors.Fonts.Tests.Issues;
+public class Issues_450
+{
+    [Fact]
+    public void Issue_450()
+    {
+        if (SystemFonts.TryGet("Arial", out FontFamily family))
+        {
+            Font font = family.CreateFont(92);
+
+            TextLayoutTestUtilities.TestLayout(
+                "Super, Smash Bros (1999)",
+                new TextOptions(font)
+                {
+                    Origin = new Vector2(50, 20),
+                    WrappingLength = 960,
+                });
+        }
+    }
+}

tests/SixLabors.Fonts.Tests/Issues/Issues_448.cs

@@ -46,6 +46,43 @@ public void BasicLatinTest()
         Assert.False(lineBreaker.MoveNext());
     }
 
+    [Fact]
+    public void NumericTests()
+    {
+        const string text1 = "Super Smash Bros (1999)";
+        const string text2 = "Super, Smash Bros (1999)";
+        List<LineBreak> breaks1 = new();
+
+        foreach (LineBreak lineBreak in new LineBreakEnumerator(text1.AsSpan()))
+        {
+            breaks1.Add(lineBreak);
+        }
+
+        Assert.Equal(5, breaks1[0].PositionMeasure);
+        Assert.Equal(6, breaks1[0].PositionWrap);
+        Assert.Equal(11, breaks1[1].PositionMeasure);
+        Assert.Equal(12, breaks1[1].PositionWrap);
+        Assert.Equal(16, breaks1[2].PositionMeasure);
+        Assert.Equal(17, breaks1[2].PositionWrap);
+        Assert.Equal(23, breaks1[3].PositionMeasure);
+        Assert.Equal(23, breaks1[3].PositionWrap);
+
+        List<LineBreak> breaks2 = new();
+        foreach (LineBreak lineBreak in new LineBreakEnumerator(text2.AsSpan()))
+        {
+            breaks2.Add(lineBreak);
+        }
+
+        Assert.Equal(6, breaks2[0].PositionMeasure);
+        Assert.Equal(7, breaks2[0].PositionWrap);
+        Assert.Equal(12, breaks2[1].PositionMeasure);
+        Assert.Equal(13, breaks2[1].PositionWrap);
+        Assert.Equal(17, breaks2[2].PositionMeasure);
+        Assert.Equal(18, breaks2[2].PositionWrap);
+        Assert.Equal(24, breaks2[3].PositionMeasure);
+        Assert.Equal(24, breaks2[3].PositionWrap);
+    }
+
     [Fact]
     public void ForwardTextWithOuterWhitespace()
     {