Bug 921858 - whitelist font families to avoid space lookup check for default features. r=jfkthame

gfx/thebes/gfxFT2FontList.cpp

@@ -1020,6 +1020,9 @@ gfxFT2FontList::AddFaceToList(const nsCString& aEntryName, uint32_t aIndex,
         if (!family) {
             family = new FT2FontFamily(name);
             mFontFamilies.Put(name, family);
+            if (mSkipSpaceLookupCheckFamilies.Contains(name)) {
+                family->SetSkipSpaceFeatureCheck(true);
+            }
             if (mBadUnderlineFamilyNames.Contains(name)) {
                 family->SetBadUnderlineFamily();
             }
@@ -1318,6 +1321,9 @@ gfxFT2FontList::AppendFaceFromFontListEntry(const FontListEntry& aFLE,
         if (!family) {
             family = new FT2FontFamily(name);
             mFontFamilies.Put(name, family);
+            if (mSkipSpaceLookupCheckFamilies.Contains(name)) {
+                family->SetSkipSpaceFeatureCheck(true);
+            }
             if (mBadUnderlineFamilyNames.Contains(name)) {
                 family->SetBadUnderlineFamily();
             }
@@ -1348,12 +1354,27 @@ gfxFT2FontList::GetFontList(InfallibleTArray<FontListEntry>* retValue)
     mFontFamilies.Enumerate(AddFamilyToFontList, retValue);
 }
 
+static void
+LoadSkipSpaceLookupCheck(nsTHashtable<nsStringHashKey>& aSkipSpaceLookupCheck)
+{
+    nsAutoTArray<nsString, 5> skiplist;
+    gfxFontUtils::GetPrefsFontList("font.whitelist.skip_space_lookup_check",
+                                   skiplist);
+    uint32_t numFonts = skiplist.Length();
+    for (uint32_t i = 0; i < numFonts; i++) {
+        ToLowerCase(skiplist[i]);
+        aSkipSpaceLookupCheck.PutEntry(skiplist[i]);
+    }
+}
+
 nsresult
 gfxFT2FontList::InitFontList()
 {
     // reset font lists
     gfxPlatformFontList::InitFontList();
     
+    LoadSkipSpaceLookupCheck(mSkipSpaceLookupCheckFamilies);
+
     FindFonts();
 
     return NS_OK;

gfx/thebes/gfxFT2FontList.h

@@ -156,6 +156,8 @@ protected:
 #ifdef ANDROID
     void FindFontsInDir(const nsCString& aDir, FontNameCache* aFNC);
 #endif
+
+    nsTHashtable<nsStringHashKey> mSkipSpaceLookupCheckFamilies;
 };
 
 #endif /* GFX_FT2FONTLIST_H */

gfx/thebes/gfxFont.cpp

@@ -79,6 +79,14 @@ static uint32_t gGlyphExtentsSetupLazyTight = 0;
 static uint32_t gGlyphExtentsSetupFallBackToTight = 0;
 #endif
 
+#ifdef PR_LOGGING
+#define LOG_FONTINIT(args) PR_LOG(gfxPlatform::GetLog(eGfxLog_fontinit), \
+                                  PR_LOG_DEBUG, args)
+#define LOG_FONTINIT_ENABLED() PR_LOG_TEST( \
+                                        gfxPlatform::GetLog(eGfxLog_fontinit), \
+                                        PR_LOG_DEBUG)
+#endif // PR_LOGGING
+
 void
 gfxCharacterMap::NotifyReleased()
 {
@@ -104,6 +112,7 @@ gfxFontEntry::gfxFontEntry() :
     mHasSpaceFeatures(false),
     mHasSpaceFeaturesKerning(false),
     mHasSpaceFeaturesNonKerning(false),
+    mSkipDefaultFeatureSpaceCheck(false),
     mCheckedForGraphiteTables(false),
     mHasCmapTable(false),
     mGrFaceInitialized(false),
@@ -132,6 +141,7 @@ gfxFontEntry::gfxFontEntry(const nsAString& aName, bool aIsStandardFace) :
     mHasSpaceFeatures(false),
     mHasSpaceFeaturesKerning(false),
     mHasSpaceFeaturesNonKerning(false),
+    mSkipDefaultFeatureSpaceCheck(false),
     mCheckedForGraphiteTables(false),
     mHasCmapTable(false),
     mGrFaceInitialized(false),
@@ -2196,6 +2206,14 @@ gfxFont::CheckForFeaturesInvolvingSpace()
 {
     mFontEntry->mHasSpaceFeaturesInitialized = true;
 
+#ifdef PR_LOGGING
+    bool log = LOG_FONTINIT_ENABLED();
+    TimeStamp start;
+    if (MOZ_UNLIKELY(log)) {
+        start = TimeStamp::Now();
+    }
+#endif
+
     bool result = false;
 
     uint32_t spaceGlyph = GetSpaceGlyph();
@@ -2291,10 +2309,14 @@ gfxFont::CheckForFeaturesInvolvingSpace()
     hb_face_destroy(face);
     mFontEntry->mHasSpaceFeatures = result;
 
-#ifdef DEBUG_SPACE_LOOKUPS
-    printf("font: %s - subst default: %8.8x %8.8x %8.8x %8.8x "
+#ifdef PR_LOGGING
+    if (MOZ_UNLIKELY(log)) {
+        TimeDuration elapsed = TimeStamp::Now() - start;
+        LOG_FONTINIT((
+            "(fontinit-spacelookups) font: %s - "
+            "subst default: %8.8x %8.8x %8.8x %8.8x "
             "subst non-default: %8.8x %8.8x %8.8x %8.8x "
-           "kerning: %s non-kerning: %s\n",
+            "kerning: %s non-kerning: %s time: %6.3f\n",
             NS_ConvertUTF16toUTF8(mFontEntry->Name()).get(),
             mFontEntry->mDefaultSubSpaceFeatures[3],
             mFontEntry->mDefaultSubSpaceFeatures[2],
@@ -2305,8 +2327,10 @@ gfxFont::CheckForFeaturesInvolvingSpace()
             mFontEntry->mNonDefaultSubSpaceFeatures[1],
             mFontEntry->mNonDefaultSubSpaceFeatures[0],
             (mFontEntry->mHasSpaceFeaturesKerning ? "true" : "false"),
-           (mFontEntry->mHasSpaceFeaturesNonKerning ? "true" : "false")
-    );
+            (mFontEntry->mHasSpaceFeaturesNonKerning ? "true" : "false"),
+            elapsed.ToMilliseconds()
+        ));
+    }
 #endif
 }
 
@@ -2348,6 +2372,14 @@ gfxFont::HasSubstitutionRulesWithSpaceLookups(int32_t aRunScript)
 bool
 gfxFont::SpaceMayParticipateInShaping(int32_t aRunScript)
 {
+    // avoid checking fonts known not to include default space-dependent features
+    if (MOZ_UNLIKELY(mFontEntry->mSkipDefaultFeatureSpaceCheck)) {
+        if (!mKerningSet && mStyle.featureSettings.IsEmpty() &&
+            mFontEntry->mFeatureSettings.IsEmpty()) {
+            return false;
+        }
+    }
+
     // We record the presence of space-dependent features in the font entry
     // so that subsequent instantiations for the same font face won't
     // require us to re-check the tables; however, the actual check is done

gfx/thebes/gfxFont.h

@@ -438,6 +438,7 @@ public:
     bool             mHasSpaceFeatures : 1;
     bool             mHasSpaceFeaturesKerning : 1;
     bool             mHasSpaceFeaturesNonKerning : 1;
+    bool             mSkipDefaultFeatureSpaceCheck : 1;
     bool             mHasGraphiteTables : 1;
     bool             mCheckedForGraphiteTables : 1;
     bool             mHasCmapTable : 1;
@@ -676,7 +677,8 @@ public:
         mHasStyles(false),
         mIsSimpleFamily(false),
         mIsBadUnderlineFamily(false),
-        mFamilyCharacterMapInitialized(false)
+        mFamilyCharacterMapInitialized(false),
+        mSkipDefaultFeatureSpaceCheck(false)
         { }
 
     virtual ~gfxFontFamily() { }
@@ -697,6 +699,7 @@ public:
             aFontEntry->mIgnoreGDEF = true;
         }
         aFontEntry->mFamilyName = Name();
+        aFontEntry->mSkipDefaultFeatureSpaceCheck = mSkipDefaultFeatureSpaceCheck;
         mAvailableFonts.AppendElement(aFontEntry);
     }
 
@@ -798,6 +801,10 @@ public:
         return false;
     }
 
+    void SetSkipSpaceFeatureCheck(bool aSkipCheck) {
+        mSkipDefaultFeatureSpaceCheck = aSkipCheck;
+    }
+
 protected:
     // fills in an array with weights of faces that match style,
     // returns whether any matching entries found
@@ -828,6 +835,7 @@ protected:
     bool mIsSimpleFamily : 1;
     bool mIsBadUnderlineFamily : 1;
     bool mFamilyCharacterMapInitialized : 1;
+    bool mSkipDefaultFeatureSpaceCheck : 1;
 
     enum {
         // for "simple" families, the faces are stored in mAvailableFonts

modules/libpref/src/init/all.js

@@ -1512,6 +1512,14 @@ pref("font.mathfont-family", "MathJax_Main, STIXNonUnicode, STIXSizeOneSym, STIX
 // These fonts are ignored the underline offset, instead of it, the underline is lowered to bottom of its em descent.
 pref("font.blacklist.underline_offset", "FangSong,Gulim,GulimChe,MingLiU,MingLiU-ExtB,MingLiU_HKSCS,MingLiU-HKSCS-ExtB,MS Gothic,MS Mincho,MS PGothic,MS PMincho,MS UI Gothic,PMingLiU,PMingLiU-ExtB,SimHei,SimSun,SimSun-ExtB,Hei,Kai,Apple LiGothic,Apple LiSung,Osaka");
 
+#ifdef MOZ_WIDGET_GONK
+// Whitelist of fonts that ship with B2G that do not include space lookups in
+// default features. This allows us to skip analyzing the GSUB/GPOS tables
+// unless features are explicitly enabled.
+// Use NSPR_LOG_MODULES=fontinit:5 to dump out details of space lookups
+pref("font.whitelist.skip_default_features_space_check", "Fira Sans OT,Fira Mono OT");
+#endif
+
 pref("images.dither", "auto");
 pref("security.directory",              "");