Merge pull request #513 from SixLabors/js/fix-512

Ensure CFF table is present on load

Author: JimBobSquarePants

src/SixLabors.Fonts/StreamFontMetrics.Cff.cs

@@ -33,7 +33,9 @@ private static StreamFontMetrics LoadCompactFont(FontReader reader)
         NameTable name = reader.GetTable<NameTable>();
         CMapTable cmap = reader.GetTable<CMapTable>();
         PostTable post = reader.GetTable<PostTable>();
-        ICffTable? cff = reader.TryGetTable<Cff1Table>() ?? (ICffTable?)reader.TryGetTable<Cff2Table>();
+        ICffTable? cff =
+            (reader.TryGetTable<Cff1Table>() ?? (ICffTable?)reader.TryGetTable<Cff2Table>())
+            ?? throw new InvalidFontFileException("Missing required CFF table.");
 
         // TODO: VORG
         HorizontalMetricsTable htmx = reader.GetTable<HorizontalMetricsTable>();
@@ -63,18 +65,17 @@ private static StreamFontMetrics LoadCompactFont(FontReader reader)
         MVarTable? mVar = reader.TryGetTable<MVarTable>();
 
         GlyphVariationProcessor? glyphVariationProcessor = null;
-        if (cff?.ItemVariationStore != null)
+        if (cff.ItemVariationStore != null)
         {
             if (fVar is null)
             {
                 throw new InvalidFontFileException("missing fvar table required for glyph variations processing");
             }
 
-            // TODO: The docs say that hvar and vvar can be used for CFF fonts so how do we determine when to use them?
             glyphVariationProcessor = new GlyphVariationProcessor(cff.ItemVariationStore, fVar, aVar, gVar, hVar, vVar, mVar);
         }
 
-        CompactFontTables tables = new(cmap, head, hhea, htmx, maxp, name, os2, post, cff!)
+        CompactFontTables tables = new(cmap, head, hhea, htmx, maxp, name, os2, post, cff)
         {
             Kern = kern,
             Vhea = vhea,

tests/SixLabors.Fonts.Tests/Fonts/Issues/StreamFontMetri.CreateCffGlyphMetrics.otf

@@ -0,0 +1,22 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.Fonts.Tests.Issues;
+
+public class Issues_512
+{
+    [Fact]
+    public void MissingCffTableThrowsInvalidFontFileExceptionInsteadOfNullReferenceException()
+    {
+        const string text = "Hello";
+
+        FontFamily family = new FontCollection().Add(TestFonts.Issues.Issue512_CreateCffGlyphMetrics);
+
+        Font font = family.CreateFont(12);
+
+        TextOptions options = new(font);
+
+        InvalidFontFileException exception = Assert.Throws<InvalidFontFileException>(() => TextMeasurer.MeasureSize(text, options));
+        Assert.Equal("Missing required CFF table.", exception.Message);
+    }
+}

tests/SixLabors.Fonts.Tests/Issues/Issues_512.cs

@@ -411,6 +411,8 @@ public static class Issues
         public static string Issue97File => GetFullPath("Issues/Issue97.fuzz");
 
         public static string Issue298File => GetFullPath("Issues/StyleScript.ttf");
+
+        public static string Issue512_CreateCffGlyphMetrics => GetFullPath("Issues/StreamFontMetri.CreateCffGlyphMetrics.otf");
     }
 
     private static Stream OpenStream(string path) =>