Introduce multiple language based font fallback.

The motivation of this CL is enhance the font fallback score design
to support multiple language font fallback.

This CL contains following changes:
- Break language based font score into two: script-based score and
  primary-language-based score.
- The primary-language-based score is 0 if the script-based score is 0.
  If the script-based score is not 0 and the primary language is the
  as same as the requested one, the font gets an extra score of 1.
- The language score gets a higher multiplier for languages higher in
  the locale list.

Bug: 25122318
Bug: 26168983
Change-Id: Ib999997a88e6977e341f4c325e2a1b41a59db2d5

1 files changed, 10 insertions, 0 deletions

diff --git a/include/minikin/FontCollection.h b/include/minikin/FontCollection.h
index cd14261..294692f 100644
--- a/include/minikin/FontCollection.h
+++ b/include/minikin/FontCollection.h
@@ -67,6 +67,16 @@ private:
 
     FontFamily* getFamilyForChar(uint32_t ch, uint32_t vs, uint32_t langListId, int variant) const;
 
+    uint32_t calcFamilyScore(uint32_t ch, uint32_t vs, int variant, uint32_t langListId,
+                             FontFamily* fontFamily) const;
+
+    uint32_t calcCoverageScore(uint32_t ch, uint32_t vs, FontFamily* fontFamily) const;
+
+    static uint32_t calcLanguageMatchingScore(uint32_t userLangListId,
+                                              const FontFamily& fontFamily);
+
+    static uint32_t calcVariantMatchingScore(int variant, const FontFamily& fontFamily);
+
     // static for allocating unique id's
     static uint32_t sNextId;