Add support for type (0,3) in TTF 'cmap' table

Platform 0, encoding 3 is one of the ways to represent the Unicode BMP,
and for our purposes can be handled in approximately the same way as (3, 1).
It's used (among other places) in some of the fonts that ship with
macOS.

DEVSIX-7110

Author: MatthiasValvekens

io/src/main/java/com/itextpdf/io/font/OpenTypeParser.java

@@ -819,6 +819,7 @@ private void readCmapTable() throws java.io.IOException {
         int map31 = 0;
         int map30 = 0;
         int mapExt = 0;
+        int map03 = 0;
         cmaps = new CmapTable();
         for (int k = 0; k < num_tables; ++k) {
             int platId = raf.readUnsignedShort();
@@ -833,6 +834,8 @@ private void readCmapTable() throws java.io.IOException {
                 mapExt = offset;
             } else if (platId == 1 && platSpecId == 0) {
                 map10 = offset;
+            } else if (platId == 0 && platSpecId == 3) {
+                map03 = offset;
             }
         }
         if (map10 > 0) {
@@ -850,6 +853,22 @@ private void readCmapTable() throws java.io.IOException {
                     break;
             }
         }
+        if (map03 > 0) {
+            // Unicode platform, Unicode >2.0 semantics, expect format 4 or 6 subtable
+            raf.seek(table_location[0] + map03);
+            int format = raf.readUnsignedShort();
+
+            // We treat this table as equivalent to (platformId = 3, encodingId = 1)
+            // for downstream processing, since both are intended to address the Unicode BMP
+            switch (format) {
+                case 4:
+                    cmaps.cmap31 = readFormat4(false);
+                    break;
+                case 6:
+                    cmaps.cmap31 = readFormat6();
+                    break;
+            }
+        }
         if (map31 > 0) {
             raf.seek(table_location[0] + map31);
             int format = raf.readUnsignedShort();

io/src/test/java/com/itextpdf/io/font/TrueTypeFontTest.java

@@ -94,4 +94,26 @@ public void notoSansScMapGlyphsCidsToGidsTest() throws IOException {
         Assertions.assertEquals(1, actualResult.size());
         Assertions.assertTrue(actualResult.contains(charGidInFont));
     }
+
+    @Test
+    public void cmapPlatform0PlatEnc3Format4Test() throws IOException {
+        FontProgram fontProgram = FontProgramFactory.createFont(SOURCE_FOLDER + "glyphs.ttf");
+        checkCmapTableEntry(fontProgram, 'f', 2);
+        checkCmapTableEntry(fontProgram, 'i', 3);
+    }
+
+    @Test
+    public void cmapPlatform0PlatEnc3Format6Test() throws IOException {
+        FontProgram fontProgram = FontProgramFactory.createFont(SOURCE_FOLDER + "glyphs-fmt-6.ttf");
+        checkCmapTableEntry(fontProgram, 'f', 2);
+        checkCmapTableEntry(fontProgram, 'i', 3);
+    }
+
+    private void checkCmapTableEntry(FontProgram fontProgram, char uniChar, int expectedGlyphId) {
+
+        Glyph glyph = fontProgram.getGlyph(uniChar);
+
+        Assertions.assertEquals(expectedGlyphId, glyph.getCode());
+        Assertions.assertArrayEquals(new char[]{uniChar}, glyph.getUnicodeChars());
+    }
 }

io/src/test/resources/com/itextpdf/io/font/sharedFontsResourceFiles/NOTICE.txt

@@ -3,4 +3,5 @@ This software uses the following test resources under the following licenses:
 | NotoSansTC-Regular.otf | OFL-1.1 | OFL.txt | Based on commit 165c01b46ea533872e002e0785ff17e44f6d97d8 (30.04.2021) from repository: "https://github.com/googlefonts/noto-cjk"
 | NotoSansSC-Regular.otf | OFL-1.1 | OFL.txt | Based on commit 165c01b46ea533872e002e0785ff17e44f6d97d8 (30.04.2021) from repository: "https://github.com/googlefonts/noto-cjk"
 | NotoSansCJKjp-Bold.otf | OFL-1.1 | OFL.txt | Based on commit 165c01b46ea533872e002e0785ff17e44f6d97d8 (30.04.2021) from repository: "https://github.com/googlefonts/noto-cjk"
-| Puritan2 | OFL-1.1 | OFL.txt |
+| Puritan2 | OFL-1.1 | OFL.txt |
+| glyphs.ttf, glyphs-fmt-6.ttf | MIT | Derived from https://github.com/RazrFalcon/ttf-parser/tree/337e7d1c08b06478a84c4345f4f289fc2cb9210c/tests/fonts-src |