pdf: write only ToUnicode mappings needed by the font, trimming anything out of [firstChar, lastCha…

tests/ToUnicode.cpp

Index: tests/ToUnicode.cpp
===================================================================
--- tests/ToUnicode.cpp	(revision 11153)
+++ tests/ToUnicode.cpp	(working copy)
@@ -27,7 +27,9 @@
 
 void append_cmap_sections(const SkTDArray<SkUnichar>& glyphToUnicode,
                           const SkPDFGlyphSet* subset,
-                          SkDynamicMemoryWStream* cmap);
+                          SkDynamicMemoryWStream* cmap,
+                          uint16_t firstGlypthID,
+                          uint16_t lastGlypthID);
 
 static void TestToUnicode(skiatest::Reporter* reporter) {
     SkTDArray<SkUnichar> glyphToUnicode;
@@ -70,7 +72,7 @@
 
     SkDynamicMemoryWStream buffer;
     subset.set(glyphsInSubset.begin(), glyphsInSubset.count());
-    append_cmap_sections(glyphToUnicode, &subset, &buffer);
+    append_cmap_sections(glyphToUnicode, &subset, &buffer, 0, 0xFFFF);
 
     char expectedResult[] =
 "4 beginbfchar\n\
@@ -89,6 +91,38 @@
     REPORTER_ASSERT(reporter, stream_equals(buffer, 0, expectedResult,
                                             buffer.getOffset()));
 
+    // Remove characters and ranges.
+    buffer.reset();
+
+    append_cmap_sections(glyphToUnicode, &subset, &buffer, 8, 0x00FF);
+
+    char expectedResultChop1[] =
+"2 beginbfchar\n\
+<0008> <002F>\n\
+<0009> <0033>\n\
+endbfchar\n\
+2 beginbfrange\n\
+<000B> <000C> <0035>\n\
+<00FE> <00FF> <1010>\n\
+endbfrange\n";
+
+    REPORTER_ASSERT(reporter, stream_equals(buffer, 0, expectedResultChop1,
+                                            buffer.getOffset()));
+
+    // Remove characters from range to downdrade it to one char.
+    buffer.reset();
+
+    append_cmap_sections(glyphToUnicode, &subset, &buffer, 0x00C, 0x00FE);
+
+    char expectedResultChop2[] =
+"2 beginbfchar\n\
+<000C> <0035>\n\
+<00FE> <1010>\n\
+endbfchar\n";
+
+    REPORTER_ASSERT(reporter, stream_equals(buffer, 0, expectedResultChop2,
+                                            buffer.getOffset()));
+
     glyphToUnicode.reset();
     glyphsInSubset.reset();
     SkPDFGlyphSet subset2;
@@ -110,7 +144,7 @@
 
     SkDynamicMemoryWStream buffer2;
     subset2.set(glyphsInSubset.begin(), glyphsInSubset.count());
-    append_cmap_sections(glyphToUnicode, &subset2, &buffer2);
+    append_cmap_sections(glyphToUnicode, &subset2, &buffer2, 0, 0xffff);
 
     char expectedResult2[] =
 "4 beginbfchar\n\