Add cmap 3,0 (symbol) as Unicode fallback.

src/ports/SkFontHost_FreeType.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkAdvancedTypefaceMetrics.h"
 #include "SkBitmap.h"
 #include "SkCanvas.h"
@@ skipping 334 matching lines @@
     FT_Error err = FT_Open_Face(gFTLibrary->library(), &args, data->getIndex(), &rec->fFace);
     if (err) {
         SkDEBUGF(("ERROR: unable to open font '%x'\n", fontID));
         SkDELETE(rec);
         return NULL;
     }
     SkASSERT(rec->fFace);
 
     ft_face_setup_axes(rec->fFace, *data);
 
+    // FreeType will set the charmap to the "most unicode" cmap if it exists.
+    // If there are no unicode cmaps, the charmap is set to NULL.
+    // However, "symbol" cmaps should also be considered "fallback unicode" cmaps
+    // because they are effectively private use area only (even if they aren't).
+    // This is the last on the fallback list at
+    // https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6cmap.html
+    if (!rec->fFace->charmap) {
+        FT_Select_Charmap(rec->fFace, FT_ENCODING_MS_SYMBOL);
+    }
+
     rec->fNext = gFaceRecHead;
     gFaceRecHead = rec;
     return rec;
 }
 
 // Caller must lock gFTMutex before calling this function.
 static void unref_ft_face(FT_Face face) {
     gFTMutex.assertHeld();
 
     SkFaceRec*  rec = gFaceRecHead;
@@ skipping 74 matching lines @@
     FT_Fixed advance = 0;
     if (FT_Get_Advances(face, gId, 1, FT_LOAD_NO_SCALE, &advance)) {
         return false;
     }
     SkASSERT(data);
     *data = advance;
     return true;
 }
 
 static void populate_glyph_to_unicode(FT_Face& face, SkTDArray<SkUnichar>* glyphToUnicode) {
-    // Check and see if we have Unicode cmaps.
-    for (int i = 0; i < face->num_charmaps; ++i) {
-        // CMaps known to support Unicode:
-        // Platform ID   Encoding ID   Name
-        // -----------   -----------   -----------------------------------
-        // 0             0,1           Apple Unicode
-        // 0             3             Apple Unicode 2.0 (preferred)
-        // 3             1             Microsoft Unicode UCS-2
-        // 3             10            Microsoft Unicode UCS-4 (preferred)
-        //
-        // See Apple TrueType Reference Manual
-        // http://developer.apple.com/fonts/TTRefMan/RM06/Chap6cmap.html
-        // http://developer.apple.com/fonts/TTRefMan/RM06/Chap6name.html#ID
-        // Microsoft OpenType Specification
-        // http://www.microsoft.com/typography/otspec/cmap.htm
+    glyphToUnicode->setCount(face->num_glyphs);
+    sk_bzero(glyphToUnicode->begin(), sizeof((*glyphToUnicode)[0]) * face->num_glyphs);
 
-        FT_UShort platformId = face->charmaps[i]->platform_id;
-        FT_UShort encodingId = face->charmaps[i]->encoding_id;
-
-        if (platformId != 0 && platformId != 3) {
-            continue;
-        }
-        if (platformId == 3 && encodingId != 1 && encodingId != 10) {
-            continue;
-        }
-        bool preferredMap = ((platformId == 3 && encodingId == 10) ||
-                             (platformId == 0 && encodingId == 3));
-
-        FT_Set_Charmap(face, face->charmaps[i]);
-        if (glyphToUnicode->isEmpty()) {
-            glyphToUnicode->setCount(face->num_glyphs);
-            memset(glyphToUnicode->begin(), 0,
-                   sizeof(SkUnichar) * face->num_glyphs);
-        }
-
-        // Iterate through each cmap entry.
-        FT_UInt glyphIndex;
-        for (SkUnichar charCode = FT_Get_First_Char(face, &glyphIndex);
-             glyphIndex != 0;
-             charCode = FT_Get_Next_Char(face, charCode, &glyphIndex)) {
-            if (charCode &&
-                    ((*glyphToUnicode)[glyphIndex] == 0 || preferredMap)) {
-                (*glyphToUnicode)[glyphIndex] = charCode;
-            }
-        }
+    FT_UInt glyphIndex;
+    SkUnichar charCode = FT_Get_First_Char(face, &glyphIndex);
+    while (glyphIndex) {
+        (*glyphToUnicode)[glyphIndex] = charCode;
+        charCode = FT_Get_Next_Char(face, charCode, &glyphIndex);
     }
 }
 
 SkAdvancedTypefaceMetrics* SkTypeface_FreeType::onGetAdvancedTypefaceMetrics(
         PerGlyphInfo perGlyphInfo,
         const uint32_t* glyphIDs,
         uint32_t glyphIDsCount) const {
 #if defined(SK_BUILD_FOR_MAC)
     return NULL;
 #else
@@ skipping 996 matching lines @@
 
 static EncodingProc find_encoding_proc(SkTypeface::Encoding enc) {
     static const EncodingProc gProcs[] = {
         next_utf8, next_utf16, next_utf32
     };
     SkASSERT((size_t)enc < SK_ARRAY_COUNT(gProcs));
     return gProcs[enc];
 }
 
 int SkTypeface_FreeType::onCharsToGlyphs(const void* chars, Encoding encoding,
-                                      uint16_t glyphs[], int glyphCount) const {
+                                         uint16_t glyphs[], int glyphCount) const
+{
     AutoFTAccess fta(this);
     FT_Face face = fta.face();
     if (!face) {
         if (glyphs) {
             sk_bzero(glyphs, glyphCount * sizeof(glyphs[0]));
         }
         return 0;
     }
 
     EncodingProc next_uni_proc = find_encoding_proc(encoding);
@@ skipping 256 matching lines @@
             (*axes)[i].fTag = ftAxis.tag;
             (*axes)[i].fMinimum = ftAxis.minimum;
             (*axes)[i].fDefault = ftAxis.def;
             (*axes)[i].fMaximum = ftAxis.maximum;
         }
     }
 
     FT_Done_Face(face);
     return true;
 }