From 0ae20c51f3eff13c16105188e7fdb439ccabb3c2 Mon Sep 17 00:00:00 2001
From: Eliot Jones <elioty@hotmail.co.uk>
Date: Sat, 31 Mar 2018 12:43:06 +0100
Subject: [PATCH] implement glyph index getter for the 3 implemented truetype
 cmap sub tables

---
 .../CMapSubTables/ByteEncodingCMapTable.cs    | 19 +++++++++++++----
 .../Tables/CMapSubTables/Format4CMapTable.cs  | 21 ++++++++++++++++++-
 .../CMapSubTables/HighByteMappingCMapTable.cs | 16 +++++++++++---
 3 files changed, 48 insertions(+), 8 deletions(-)

diff --git a/src/UglyToad.PdfPig/Fonts/TrueType/Tables/CMapSubTables/ByteEncodingCMapTable.cs b/src/UglyToad.PdfPig/Fonts/TrueType/Tables/CMapSubTables/ByteEncodingCMapTable.cs
index 3f3d5054..1f6360e5 100644
--- a/src/UglyToad.PdfPig/Fonts/TrueType/Tables/CMapSubTables/ByteEncodingCMapTable.cs
+++ b/src/UglyToad.PdfPig/Fonts/TrueType/Tables/CMapSubTables/ByteEncodingCMapTable.cs
@@ -6,29 +6,40 @@
     /// </summary>
     internal class ByteEncodingCMapTable : ICMapSubTable
     {
+        private const int GlyphMappingLength = 256;
+        private readonly byte[] glyphMapping;
+
         public int PlatformId { get; }
 
         public int EncodingId { get; }
 
-        private ByteEncodingCMapTable(int platformId, int encodingId)
+        private ByteEncodingCMapTable(int platformId, int encodingId, byte[] glyphMapping)
         {
+            this.glyphMapping = glyphMapping;
             PlatformId = platformId;
             EncodingId = encodingId;
         }
 
         public static ByteEncodingCMapTable Load(TrueTypeDataBytes data, int platformId, int encodingId)
         {
+            // ReSharper disable UnusedVariable
             var length = data.ReadUnsignedShort();
             var version = data.ReadUnsignedShort();
+            // ReSharper restore UnusedVariable
 
-            var glyphMapping = data.ReadByteArray(256);
+            var glyphMapping = data.ReadByteArray(GlyphMappingLength);
 
-            return new ByteEncodingCMapTable(platformId, encodingId);
+            return new ByteEncodingCMapTable(platformId, encodingId, glyphMapping);
         }
 
         public int CharacterCodeToGlyphIndex(int characterCode)
         {
-            throw new System.NotImplementedException();
+            if (characterCode < GlyphMappingLength || characterCode >= GlyphMappingLength)
+            {
+                return 0;
+            }
+
+            return glyphMapping[characterCode];
         }
     }
 }
\ No newline at end of file
diff --git a/src/UglyToad.PdfPig/Fonts/TrueType/Tables/CMapSubTables/Format4CMapTable.cs b/src/UglyToad.PdfPig/Fonts/TrueType/Tables/CMapSubTables/Format4CMapTable.cs
index 6e14e5e3..604a6df8 100644
--- a/src/UglyToad.PdfPig/Fonts/TrueType/Tables/CMapSubTables/Format4CMapTable.cs
+++ b/src/UglyToad.PdfPig/Fonts/TrueType/Tables/CMapSubTables/Format4CMapTable.cs
@@ -34,7 +34,26 @@ namespace UglyToad.PdfPig.Fonts.TrueType.Tables.CMapSubTables
 
         public int CharacterCodeToGlyphIndex(int characterCode)
         {
-            throw new NotImplementedException();
+            for (var i = 0; i < Segments.Count; i++)
+            {
+                var segment = Segments[i];
+
+                if (segment.EndCode < characterCode || segment.StartCode > characterCode)
+                {
+                    continue;
+                }
+
+                if (segment.IdRangeOffset == 0)
+                {
+                    return (characterCode + segment.IdDelta) % ushort.MaxValue;
+                }
+
+                var offset = segment.IdRangeOffset / 2 + (characterCode - segment.StartCode);
+
+                return GlyphIds[offset - Segments.Count + i];
+            }
+
+            return 0;
         }
 
         public static Format4CMapTable Load(TrueTypeDataBytes data, int platformId, int encodingId)
diff --git a/src/UglyToad.PdfPig/Fonts/TrueType/Tables/CMapSubTables/HighByteMappingCMapTable.cs b/src/UglyToad.PdfPig/Fonts/TrueType/Tables/CMapSubTables/HighByteMappingCMapTable.cs
index 605393bd..a0388a2a 100644
--- a/src/UglyToad.PdfPig/Fonts/TrueType/Tables/CMapSubTables/HighByteMappingCMapTable.cs
+++ b/src/UglyToad.PdfPig/Fonts/TrueType/Tables/CMapSubTables/HighByteMappingCMapTable.cs
@@ -10,25 +10,35 @@
     /// </summary>
     internal class HighByteMappingCMapTable : ICMapSubTable
     {
+        private readonly IReadOnlyDictionary<int, int> characterCodesToGlyphIndices;
+
         public int PlatformId { get; }
 
         public int EncodingId { get; }
 
-        public HighByteMappingCMapTable(int platformId, int encodingId)
+        private HighByteMappingCMapTable(int platformId, int encodingId, IReadOnlyDictionary<int, int> characterCodesToGlyphIndices)
         {
+            this.characterCodesToGlyphIndices = characterCodesToGlyphIndices ?? throw new ArgumentNullException(nameof(characterCodesToGlyphIndices));
             PlatformId = platformId;
             EncodingId = encodingId;
         }
 
         public int CharacterCodeToGlyphIndex(int characterCode)
         {
-            throw new NotImplementedException();
+            if (!characterCodesToGlyphIndices.TryGetValue(characterCode, out var index))
+            {
+                return 0;
+            }
+
+            return index;
         }
 
         public static HighByteMappingCMapTable Load(TrueTypeDataBytes data, int numberOfGlyphs, int platformId, int encodingId)
         {
+            // ReSharper disable UnusedVariable
             var length = data.ReadUnsignedShort();
             var version = data.ReadUnsignedShort();
+            // ReSharper restore UnusedVariable
 
             var subHeaderKeys = new int[256];
             var maximumSubHeaderIndex = 0;
@@ -83,7 +93,7 @@
                 }
             }
 
-            return new HighByteMappingCMapTable(platformId, encodingId);
+            return new HighByteMappingCMapTable(platformId, encodingId, characterCodeToGlyphId);
         }
 
         public struct SubHeader