Move coverage bitmap from FontCollection to FontFamily

This will significantly reduce memory usage and also speed the creation
of new font families. In particular, the coverage bitmaps for the fonts
in the fallback stack will be computed once in the Zygote, rather than
separately in each app process.

Bug: 17756900
Change-Id: I66f5706bddd4658d78fe5b709f7251ca9d2ff4f8

2 files changed, 10 insertions, 9 deletions

diff --git a/include/minikin/FontCollection.h b/include/minikin/FontCollection.h
index 12700c6..ffdb4d1 100644
--- a/include/minikin/FontCollection.h
+++ b/include/minikin/FontCollection.h
@@ -21,7 +21,6 @@
 
 #include <minikin/MinikinRefCounted.h>
 #include <minikin/MinikinFont.h>
-#include <minikin/SparseBitSet.h>
 #include <minikin/FontFamily.h>
 
 namespace android {
@@ -52,17 +51,12 @@ private:
     static const int kLogCharsPerPage = 8;
     static const int kPageMask = (1 << kLogCharsPerPage) - 1;
 
-    struct FontInstance {
-        SparseBitSet* mCoverage;
-        FontFamily* mFamily;
-    };
-
     struct Range {
         size_t start;
         size_t end;
     };
 
-    const FontInstance* getInstanceForChar(uint32_t ch, FontLanguage lang, int variant) const;
+    FontFamily* getFamilyForChar(uint32_t ch, FontLanguage lang, int variant) const;
 
     // static for allocating unique id's
     static uint32_t sNextId;
@@ -74,10 +68,10 @@ private:
     uint32_t mMaxChar;
 
     // This vector has ownership of the bitsets and typeface objects.
-    std::vector<FontInstance> mInstances;
+    std::vector<FontFamily*> mFamilies;
 
     // This vector contains pointers into mInstances
-    std::vector<const FontInstance*> mInstanceVec;
+    std::vector<FontFamily*> mFamilyVec;
 
     // These are offsets into mInstanceVec, one range per page
     std::vector<Range> mRanges;
diff --git a/include/minikin/FontFamily.h b/include/minikin/FontFamily.h
index bcc2e3a..08c7a2c 100644
--- a/include/minikin/FontFamily.h
+++ b/include/minikin/FontFamily.h
@@ -23,6 +23,7 @@
 #include <utils/TypeHelpers.h>
 
 #include <minikin/MinikinRefCounted.h>
+#include <minikin/SparseBitSet.h>
 
 namespace android {
 
@@ -139,6 +140,9 @@ public:
     size_t getNumFonts() const;
     MinikinFont* getFont(size_t index) const;
     FontStyle getStyle(size_t index) const;
+
+    // Get Unicode coverage. Lifetime of returned bitset is same as receiver.
+    const SparseBitSet* getCoverage();
 private:
     void addFontLocked(MinikinFont* typeface, FontStyle style);
 
@@ -152,6 +156,9 @@ private:
     FontLanguage mLang;
     int mVariant;
     std::vector<Font> mFonts;
+
+    SparseBitSet mCoverage;
+    bool mCoverageValid;
 };
 
 }  // namespace android