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

4 files changed, 63 insertions, 60 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
diff --git a/libs/minikin/FontCollection.cpp b/libs/minikin/FontCollection.cpp
index ca5b1d1..7b6b950 100644
--- a/libs/minikin/FontCollection.cpp
+++ b/libs/minikin/FontCollection.cpp
@@ -23,7 +23,6 @@
 #include "unicode/unorm2.h"
 
 #include "MinikinInternal.h"
-#include <minikin/CmapCoverage.h>
 #include <minikin/FontCollection.h>
 
 using std::vector;
@@ -54,28 +53,12 @@ FontCollection::FontCollection(const vector<FontFamily*>& typefaces) :
             continue;
         }
         family->RefLocked();
-        FontInstance dummy;
-        mInstances.push_back(dummy);  // emplace_back would be better
-        FontInstance* instance = &mInstances.back();
-        instance->mFamily = family;
-        instance->mCoverage = new SparseBitSet;
-#ifdef VERBOSE_DEBUG
-        ALOGD("closest match = %p, family size = %d\n", typeface, family->getNumFonts());
-#endif
-        const uint32_t cmapTag = MinikinFont::MakeTag('c', 'm', 'a', 'p');
-        size_t cmapSize = 0;
-        bool ok = typeface->GetTable(cmapTag, NULL, &cmapSize);
-        UniquePtr<uint8_t[]> cmapData(new uint8_t[cmapSize]);
-        ok = typeface->GetTable(cmapTag, cmapData.get(), &cmapSize);
-        CmapCoverage::getCoverage(*instance->mCoverage, cmapData.get(), cmapSize);
-#ifdef VERBOSE_DEBUG
-        ALOGD("font coverage length=%d, first ch=%x\n", instance->mCoverage->length(),
-                instance->mCoverage->nextSetBit(0));
-#endif
-        mMaxChar = max(mMaxChar, instance->mCoverage->length());
-        lastChar.push_back(instance->mCoverage->nextSetBit(0));
+        mFamilies.push_back(family);  // emplace_back would be better
+        const SparseBitSet* coverage = family->getCoverage();
+        mMaxChar = max(mMaxChar, coverage->length());
+        lastChar.push_back(coverage->nextSetBit(0));
     }
-    nTypefaces = mInstances.size();
+    nTypefaces = mFamilies.size();
     LOG_ALWAYS_FATAL_IF(nTypefaces == 0,
         "Font collection must have at least one valid typeface");
     size_t nPages = (mMaxChar + kPageMask) >> kLogCharsPerPage;
@@ -90,10 +73,10 @@ FontCollection::FontCollection(const vector<FontFamily*>& typefaces) :
         range->start = offset;
         for (size_t j = 0; j < nTypefaces; j++) {
             if (lastChar[j] < (i + 1) << kLogCharsPerPage) {
-                const FontInstance* instance = &mInstances[j];
-                mInstanceVec.push_back(instance);
+                FontFamily* family = mFamilies[j];
+                mFamilyVec.push_back(family);
                 offset++;
-                uint32_t nextChar = instance->mCoverage->nextSetBit((i + 1) << kLogCharsPerPage);
+                uint32_t nextChar = family->getCoverage()->nextSetBit((i + 1) << kLogCharsPerPage);
 #ifdef VERBOSE_DEBUG
                 ALOGD("nextChar = %d (j = %d)\n", nextChar, j);
 #endif
@@ -105,9 +88,8 @@ FontCollection::FontCollection(const vector<FontFamily*>& typefaces) :
 }
 
 FontCollection::~FontCollection() {
-    for (size_t i = 0; i < mInstances.size(); i++) {
-        delete mInstances[i].mCoverage;
-        mInstances[i].mFamily->UnrefLocked();
+    for (size_t i = 0; i < mFamilies.size(); i++) {
+        mFamilies[i]->UnrefLocked();
     }
 }
 
@@ -117,7 +99,7 @@ FontCollection::~FontCollection() {
 // 3. If a font matches just language, it gets a score of 2.
 // 4. Matching the "compact" or "elegant" variant adds one to the score.
 // 5. Highest score wins, with ties resolved to the first font.
-const FontCollection::FontInstance* FontCollection::getInstanceForChar(uint32_t ch,
+FontFamily* FontCollection::getFamilyForChar(uint32_t ch,
             FontLanguage lang, int variant) const {
     if (ch >= mMaxChar) {
         return NULL;
@@ -126,15 +108,14 @@ const FontCollection::FontInstance* FontCollection::getInstanceForChar(uint32_t
 #ifdef VERBOSE_DEBUG
     ALOGD("querying range %d:%d\n", range.start, range.end);
 #endif
-    const FontInstance* bestInstance = NULL;
+    FontFamily* bestFamily = NULL;
     int bestScore = -1;
     for (size_t i = range.start; i < range.end; i++) {
-        const FontInstance* instance = mInstanceVec[i];
-        if (instance->mCoverage->get(ch)) {
-            FontFamily* family = instance->mFamily;
+        FontFamily* family = mFamilyVec[i];
+        if (family->getCoverage()->get(ch)) {
             // First font family in collection always matches
-            if (mInstances[0].mFamily == family) {
-                return instance;
+            if (mFamilies[0] == family) {
+                return family;
             }
             int score = lang.match(family->lang()) * 2;
             if (variant != 0 && variant == family->variant()) {
@@ -142,11 +123,11 @@ const FontCollection::FontInstance* FontCollection::getInstanceForChar(uint32_t
             }
             if (score > bestScore) {
                 bestScore = score;
-                bestInstance = instance;
+                bestFamily = family;
             }
         }
     }
-    if (bestInstance == NULL && !mInstanceVec.empty()) {
+    if (bestFamily == NULL && !mFamilyVec.empty()) {
         UErrorCode errorCode = U_ZERO_ERROR;
         const UNormalizer2* normalizer = unorm2_getNFDInstance(&errorCode);
         if (U_SUCCESS(errorCode)) {
@@ -155,12 +136,12 @@ const FontCollection::FontInstance* FontCollection::getInstanceForChar(uint32_t
             if (U_SUCCESS(errorCode) && len > 0) {
                 int off = 0;
                 U16_NEXT_UNSAFE(decomposed, off, ch);
-                return getInstanceForChar(ch, lang, variant);
+                return getFamilyForChar(ch, lang, variant);
             }
         }
-        bestInstance = &mInstances[0];
+        bestFamily = mFamilies[0];
     }
-    return bestInstance;
+    return bestFamily;
 }
 
 const uint32_t NBSP = 0xa0;
@@ -183,7 +164,7 @@ void FontCollection::itemize(const uint16_t *string, size_t string_size, FontSty
         vector<Run>* result) const {
     FontLanguage lang = style.getLanguage();
     int variant = style.getVariant();
-    const FontInstance* lastInstance = NULL;
+    FontFamily* lastFamily = NULL;
     Run* run = NULL;
     int nShorts;
     for (size_t i = 0; i < string_size; i += nShorts) {
@@ -197,17 +178,17 @@ void FontCollection::itemize(const uint16_t *string, size_t string_size, FontSty
             }
         }
         // Continue using existing font as long as it has coverage and is whitelisted
-        if (lastInstance == NULL
-                || !(isStickyWhitelisted(ch) && lastInstance->mCoverage->get(ch))) {
-            const FontInstance* instance = getInstanceForChar(ch, lang, variant);
-            if (i == 0 || instance != lastInstance) {
+        if (lastFamily == NULL
+                || !(isStickyWhitelisted(ch) && lastFamily->getCoverage()->get(ch))) {
+            FontFamily* family = getFamilyForChar(ch, lang, variant);
+            if (i == 0 || family != lastFamily) {
                 size_t start = i;
                 // Workaround for Emoji keycap until we implement per-cluster font
                 // selection: if keycap is found in a different font that also
                 // supports previous char, attach previous char to the new run.
                 // Only handles non-surrogate characters.
                 // Bug 7557244.
-                if (ch == KEYCAP && i && instance && instance->mCoverage->get(string[i - 1])) {
+                if (ch == KEYCAP && i && family && family->getCoverage()->get(string[i - 1])) {
                     run->end--;
                     if (run->start == run->end) {
                         result->pop_back();
@@ -217,12 +198,12 @@ void FontCollection::itemize(const uint16_t *string, size_t string_size, FontSty
                 Run dummy;
                 result->push_back(dummy);
                 run = &result->back();
-                if (instance == NULL) {
+                if (family == NULL) {
                     run->fakedFont.font = NULL;
                 } else {
-                    run->fakedFont = instance->mFamily->getClosestMatch(style);
+                    run->fakedFont = family->getClosestMatch(style);
                 }
-                lastInstance = instance;
+                lastFamily = family;
                 run->start = start;
             }
         }
@@ -235,10 +216,10 @@ MinikinFont* FontCollection::baseFont(FontStyle style) {
 }
 
 FakedFont FontCollection::baseFontFaked(FontStyle style) {
-    if (mInstances.empty()) {
+    if (mFamilies.empty()) {
         return FakedFont();
     }
-    return mInstances[0].mFamily->getClosestMatch(style);
+    return mFamilies[0]->getClosestMatch(style);
 }
 
 uint32_t FontCollection::getId() const {
diff --git a/libs/minikin/FontFamily.cpp b/libs/minikin/FontFamily.cpp
index f688a33..d2e5867 100644
--- a/libs/minikin/FontFamily.cpp
+++ b/libs/minikin/FontFamily.cpp
@@ -23,6 +23,7 @@
 #include "MinikinInternal.h"
 #include <minikin/MinikinFont.h>
 #include <minikin/AnalyzeStyle.h>
+#include <minikin/CmapCoverage.h>
 #include <minikin/FontFamily.h>
 #include <UniquePtr.h>
 
@@ -128,6 +129,7 @@ void FontFamily::addFont(MinikinFont* typeface, FontStyle style) {
 
 void FontFamily::addFontLocked(MinikinFont* typeface, FontStyle style) {    typeface->RefLocked();
     mFonts.push_back(Font(typeface, style));
+    mCoverageValid = false;
 }
 
 // Compute a matching metric between two styles - 0 is an exact match
@@ -183,4 +185,23 @@ FontStyle FontFamily::getStyle(size_t index) const {
     return mFonts[index].style;
 }
 
+const SparseBitSet* FontFamily::getCoverage() {
+    if (!mCoverageValid) {
+        const FontStyle defaultStyle;
+        MinikinFont* typeface = getClosestMatch(defaultStyle).font;
+        const uint32_t cmapTag = MinikinFont::MakeTag('c', 'm', 'a', 'p');
+        size_t cmapSize = 0;
+        bool ok = typeface->GetTable(cmapTag, NULL, &cmapSize);
+        UniquePtr<uint8_t[]> cmapData(new uint8_t[cmapSize]);
+        ok = typeface->GetTable(cmapTag, cmapData.get(), &cmapSize);
+        CmapCoverage::getCoverage(mCoverage, cmapData.get(), cmapSize);
+#ifdef VERBOSE_DEBUG
+        ALOGD("font coverage length=%d, first ch=%x\n", mCoverage->length(),
+                mCoverage->nextSetBit(0));
+#endif
+        mCoverageValid = true;
+    }
+    return &mCoverage;
+}
+
 }  // namespace android