add charsToGlyphs to SkTypeface

include/core/SkTypeface.h

Index: include/core/SkTypeface.h
diff --git a/include/core/SkTypeface.h b/include/core/SkTypeface.h
index d34854d329fa6ab33c686c6b5de480fee5483511..9c23fb200ba7aca3db006fc3388dca428716bef4 100644
--- a/include/core/SkTypeface.h
+++ b/include/core/SkTypeface.h
@@ -148,6 +148,36 @@ public:
             const uint32_t* glyphIDs = NULL,
             uint32_t glyphIDsCount = 0) const;
 
+    enum Encoding {
+        kUTF8_Encoding,
+        kUTF16_Encoding,
+        kUTF32_Encoding
+    };
+
+    /**
+     *  Given an array of character codes, of the specified encoding,
+     *  optionally return their corresponding glyph IDs (if glyphs is not NULL).
+     *
+     *  @param chars pointer to the array of character codes
+     *  @param encoding how the characteds are encoded
+     *  @param glyphs (optional) returns the corresponding glyph IDs for each
+     *          character code, up to glyphCount values. If a character code is
+     *          not found in the typeface, the corresponding glyph ID will be 0.
+     *  @param glyphCount number of code points in 'chars' to process. If glyphs
+     *          is not NULL, then it must point sufficient memory to write
+     *          glyphCount values into it.
+     *  @return the number of number of continuous non-zero glyph IDs computed
+     *          from the beginning of chars. This value is valid, even if the
+     *          glyphs parameter is NULL.
+     */
+    int charsToGlyphs(const void* chars, Encoding encoding, uint16_t glyphs[],
+                      int glyphCount) const;
+
+    /**
+     *  Return the number of glyphs in the typeface.
+     */
+    int countGlyphs() const;
+
     // Table getters -- may fail if the underlying font format is not organized
     // as 4-byte tables.
 
@@ -233,6 +263,10 @@ protected:
     virtual SkStream* onOpenStream(int* ttcIndex) const = 0;
     virtual void onGetFontDescriptor(SkFontDescriptor*, bool* isLocal) const = 0;
 
+    virtual int onCharsToGlyphs(const void* chars, Encoding, uint16_t glyphs[],
+                                int glyphCount) const;
+    virtual int onCountGlyphs() const;
+
     virtual int onGetUPEM() const;
 
     virtual int onGetTableTags(SkFontTableTag tags[]) const;