tidy up code in subsetting classes #98

removes some debugging code in the cmap replacer and moves the main glyph parsing logic in the glyph table subsetter to a method.

in the next commit we will delete the cmap replacer since it doesn't work and is no longer needed but we want a clean version of it in the commit history for reference.

src/UglyToad.PdfPig/Writer/Fonts/TrueTypeCMapReplacer.cs

@@ -45,7 +45,6 @@
             
             using (var stream = new MemoryStream())
             {
-
                 // Write the file header details and read the number of tables out.
                 CopyThroughBufferPreserveData(stream, buffer, fontBytes, SizeOfFraction + (SizeOfShort * 4));
 
@@ -86,7 +85,7 @@
                         CopyThroughBufferDiscardData(stream, buffer, fontBytes, gapFromPrevious);
                     }
 
-                    if (inputHeader.Value.IsTable(CMapTag) || inputHeader.Value.IsTable(TrueTypeHeaderTable.Os2))
+                    if (inputHeader.Value.IsTable(CMapTag))
                     {
                         // Skip the CMap table for now, move it to the end in the output so we can resize it dynamically.
                         inputOffset = location.Offset + location.Length;
@@ -112,8 +111,6 @@
                     inputOffset = fontBytes.CurrentOffset;
                 }
                 
-                inputTableHeaders.Remove("OS/2");
-
                 // Create a new cmap table here.
                 var table = GenerateWindowsSymbolTable(fontProgram, newEncoding);
                 var cmapLocation = inputTableHeaders[CMapTag];
@@ -159,19 +156,6 @@
                 result = stream.ToArray();
             }
 
-            // num tables
-            result[4] = 0;
-            result[5] = 16;
-            // search range
-            result[6] = 1;
-            result[7] = 0;
-            // entry selector
-            result[8] = 0;
-            result[9] = 4;
-            // range shift
-            result[10] = 0;
-            result[11] = 0;
-
             var inputBytes = new ByteArrayInputBytes(result);
 
             // Overwrite checksum values per table.
@@ -201,8 +185,6 @@
             // TODO: take andada regular with no modifications but removing the os/2 table and validate.
             var canParse = new TrueTypeFontParser().Parse(new TrueTypeDataBytes(new ByteArrayInputBytes(result)));
 
-            File.WriteAllBytes(@"C:\temp\no-os2-2.ttf", result);
-
             return result;
         }
 
@@ -264,11 +246,6 @@
                 throw new InvalidOperationException($"Failed to read {size} bytes starting at offset {input.CurrentOffset - read}.");
             }
 
-            if (buffer[0] == 'O' && buffer[1] == 'S')
-            {
-                return;
-            }
-
             destination.Write(buffer, 0, read);
         }
 

src/UglyToad.PdfPig/Writer/Fonts/TrueTypeGlyphTableSubsetter.cs

@@ -13,6 +13,52 @@
         {
             var data = new TrueTypeDataBytes(fontBytes);
 
+            var existingGlyphs = GetGlyphRecordsInFont(font, data);
+            
+            var newGlyphRecords = new GlyphRecord[mapping.Length];
+            var newGlyphTableLength = 0;
+
+            for (var i = 0; i < mapping.Length; i++)
+            {
+                var map = mapping[i];
+                var record = existingGlyphs[map.OldIndex];
+
+                newGlyphRecords[i] = record;
+                newGlyphTableLength += record.DataLength;
+            }
+
+            var newIndexToLoca = new uint[newGlyphRecords.Length + 1];
+
+            var outputIndex = 0u;
+            var output = new byte[newGlyphTableLength];
+            for (var i = 0; i < newGlyphRecords.Length; i++)
+            {
+                var newRecord = newGlyphRecords[i];
+                if (newRecord.Type == GlyphType.Composite)
+                {
+                    throw new NotSupportedException("TODO");
+                }
+
+                newIndexToLoca[i] = outputIndex;
+                if (newRecord.Type == GlyphType.Empty)
+                {
+                    continue;
+                }
+
+                data.Seek(newRecord.Offset);
+                for (var j = 0; j < newRecord.DataLength; j++)
+                {
+                    output[outputIndex++] = data.ReadByte();
+                }
+            }
+
+            newIndexToLoca[newIndexToLoca.Length - 1] = (uint)output.Length;
+            
+            return new NewGlyphTable(output, newIndexToLoca);
+        }
+
+        private static GlyphRecord[] GetGlyphRecordsInFont(TrueTypeFontProgram font, TrueTypeDataBytes data)
+        {
             var indexToLocationTable = font.TableRegister.IndexToLocationTable;
 
             var numGlyphs = indexToLocationTable.GlyphOffsets.Length - 1;
@@ -62,46 +108,7 @@
                 }
             }
 
-            var newGlyphRecords = new GlyphRecord[mapping.Length];
+            return glyphRecords;
-            var newGlyphTableLength = 0;
-
-            for (var i = 0; i < mapping.Length; i++)
-            {
-                var map = mapping[i];
-                var record = glyphRecords[map.OldIndex];
-
-                newGlyphRecords[i] = record;
-                newGlyphTableLength += record.DataLength;
-            }
-
-            var newIndexToLoca = new uint[newGlyphRecords.Length + 1];
-
-            var outputIndex = 0u;
-            var output = new byte[newGlyphTableLength];
-            for (var i = 0; i < newGlyphRecords.Length; i++)
-            {
-                var newRecord = newGlyphRecords[i];
-                if (newRecord.Type == GlyphType.Composite)
-                {
-                    throw new NotSupportedException("TODO");
-                }
-
-                newIndexToLoca[i] = outputIndex;
-                if (newRecord.Type == GlyphType.Empty)
-                {
-                    continue;
-                }
-
-                data.Seek(newRecord.Offset);
-                for (var j = 0; j < newRecord.DataLength; j++)
-                {
-                    output[outputIndex++] = data.ReadByte();
-                }
-            }
-
-            newIndexToLoca[newIndexToLoca.Length - 1] = (uint)output.Length;
-            
-            return new NewGlyphTable(output, newIndexToLoca);
         }
 
         private static void ReadSimpleGlyph(TrueTypeDataBytes data, int numberOfContours)

src/UglyToad.PdfPig/Writer/Fonts/TrueTypeWritingFont.cs

@@ -7,6 +7,7 @@
     using Core;
     using Filters;
     using Geometry;
+    using IO;
     using Logging;
     using Tokens;
     using PdfPig.Fonts;