bug 668813 pt 2 - maintain a character coverage map for gfxFontFamily. r=jdaggett

gfx/thebes/gfxFont.cpp

@@ -692,12 +692,15 @@ void gfxFontFamily::LocalizedName(nsAString& aLocalizedName)
 void
 gfxFontFamily::FindFontForChar(FontSearch *aMatchData)
 {
-    if (!mHasStyles)
+    if (!mHasStyles) {
         FindStyleVariations();
+    }
 
-    // xxx - optimization point - keep a bit vector with the union of supported unicode ranges
-    // by all fonts for this family and bail immediately if the character is not in any of
-    // this family's cmaps
+    if (!TestCharacterMap(aMatchData->mCh)) {
+        // none of the faces in the family support the required char,
+        // so bail out immediately
+        return;
+    }
 
     // iterate over fonts
     PRUint32 numFonts = mAvailableFonts.Length();
@@ -3366,11 +3369,8 @@ gfxFontGroup::FindFontForChar(PRUint32 aCh, PRUint32 aPrevCh,
             return font.forget();
         }
         // check other faces of the family
-        // XXX optimization point: give the family a charmap that is the union
-        // of the char maps of all its faces, so we can quickly test whether
-        // it's worth doing this search
         gfxFontFamily *family = font->GetFontEntry()->Family();
-        if (family) {
+        if (family && family->TestCharacterMap(aCh)) {
             FontSearch matchData(aCh, font);
             family->FindFontForChar(&matchData);
             gfxFontEntry *fe = matchData.mBestMatch;

gfx/thebes/gfxFont.h

@@ -510,7 +510,8 @@ public:
         mFaceNamesInitialized(false),
         mHasStyles(false),
         mIsSimpleFamily(false),
-        mIsBadUnderlineFamily(false)
+        mIsBadUnderlineFamily(false),
+        mCharacterMapInitialized(false)
         { }
 
     virtual ~gfxFontFamily() {
@@ -583,10 +584,28 @@ public:
     // read in cmaps for all the faces
     void ReadCMAP() {
         PRUint32 i, numFonts = mAvailableFonts.Length();
-        // called from RunLoader BEFORE CheckForSimpleFamily so that there cannot
-        // be any NULL entries in mAvailableFonts
-        for (i = 0; i < numFonts; i++)
-            mAvailableFonts[i]->ReadCMAP();
+        for (i = 0; i < numFonts; i++) {
+            gfxFontEntry *fe = mAvailableFonts[i];
+            if (!fe) {
+                continue;
+            }
+            fe->ReadCMAP();
+            mCharacterMap.Union(fe->mCharacterMap);
+        }
+        mCharacterMap.Compact();
+        mCharacterMapInitialized = true;
+    }
+
+    bool TestCharacterMap(PRUint32 aCh) {
+        if (!mCharacterMapInitialized) {
+            ReadCMAP();
+        }
+        return mCharacterMap.test(aCh);
+    }
+
+    void ResetCharacterMap() {
+        mCharacterMap.reset();
+        mCharacterMapInitialized = false;
     }
 
     // mark this family as being in the "bad" underline offset blacklist
@@ -629,12 +648,14 @@ protected:
 
     nsString mName;
     nsTArray<nsRefPtr<gfxFontEntry> >  mAvailableFonts;
+    gfxSparseBitSet mCharacterMap;
     bool mOtherFamilyNamesInitialized;
     bool mHasOtherFamilyNames;
     bool mFaceNamesInitialized;
     bool mHasStyles;
     bool mIsSimpleFamily;
     bool mIsBadUnderlineFamily;
+    bool mCharacterMapInitialized;
 
     enum {
         // for "simple" families, the faces are stored in mAvailableFonts

gfx/thebes/gfxFontUtils.cpp

@@ -315,7 +315,7 @@ gfxFontUtils::ReadCMAPTableFormat12(const PRUint8 *aBuf, PRUint32 aLength,
         prevEndCharCode = endCharCode;
     }
 
-    aCharacterMap.mBlocks.Compact();
+    aCharacterMap.Compact();
 
     return NS_OK;
 }
@@ -395,7 +395,7 @@ gfxFontUtils::ReadCMAPTableFormat4(const PRUint8 *aBuf, PRUint32 aLength,
         }
     }
 
-    aCharacterMap.mBlocks.Compact();
+    aCharacterMap.Compact();
 
     return NS_OK;
 }

gfx/thebes/gfxFontUtils.h

@@ -165,8 +165,6 @@ public:
         Block *block = mBlocks[blockIndex];
         if (!block) {
             block = new Block;
-            if (NS_UNLIKELY(!block)) // OOM
-                return;
             mBlocks[blockIndex] = block;
         }
         block->mBits[(aIndex>>3) & (BLOCK_SIZE - 1)] |= 1 << (aIndex & 0x7);
@@ -201,9 +199,6 @@ public:
                     fullBlock = true;
 
                 block = new Block(fullBlock ? 0xFF : 0);
-
-                if (NS_UNLIKELY(!block)) // OOM
-                    return;
                 mBlocks[i] = block;
 
                 if (fullBlock)
@@ -279,7 +274,44 @@ public:
         for (i = 0; i < mBlocks.Length(); i++)
             mBlocks[i] = nsnull;    
     }
-    
+
+    // set this bitset to the union of its current contents and another
+    void Union(const gfxSparseBitSet& aBitset) {
+        // ensure mBlocks is large enough
+        PRUint32 blockCount = aBitset.mBlocks.Length();
+        if (blockCount > mBlocks.Length()) {
+            PRUint32 needed = blockCount - mBlocks.Length();
+            nsAutoPtr<Block> *blocks = mBlocks.AppendElements(needed);
+            if (NS_UNLIKELY(!blocks)) { // OOM
+                return;
+            }
+        }
+        // for each block that may be present in aBitset...
+        for (PRUint32 i = 0; i < blockCount; ++i) {
+            // if it is missing (implicitly empty), just skip
+            if (!aBitset.mBlocks[i]) {
+                continue;
+            }
+            // if the block is missing in this set, just copy the other
+            if (!mBlocks[i]) {
+                mBlocks[i] = new Block(*aBitset.mBlocks[i]);
+                continue;
+            }
+            // else set existing block to the union of both
+            PRUint32 *dst = reinterpret_cast<PRUint32*>(mBlocks[i]->mBits);
+            const PRUint32 *src =
+                reinterpret_cast<const PRUint32*>(aBitset.mBlocks[i]->mBits);
+            for (PRUint32 j = 0; j < BLOCK_SIZE / 4; ++j) {
+                dst[j] |= src[j];
+            }
+        }
+    }
+
+    void Compact() {
+        mBlocks.Compact();
+    }
+
+private:
     nsTArray< nsAutoPtr<Block> > mBlocks;
 };
 

gfx/thebes/gfxUserFontSet.h

@@ -110,10 +110,11 @@ public:
         nsRefPtr<gfxFontEntry> fe = aFontEntry;
         mAvailableFonts.AppendElement(fe);
         aFontEntry->SetFamily(this);
+        ResetCharacterMap();
     }
 
-    void ReplaceFontEntry(gfxFontEntry *aOldFontEntry, gfxFontEntry *aNewFontEntry) 
-    {
+    void ReplaceFontEntry(gfxFontEntry *aOldFontEntry,
+                          gfxFontEntry *aNewFontEntry) {
         PRUint32 numFonts = mAvailableFonts.Length();
         for (PRUint32 i = 0; i < numFonts; i++) {
             gfxFontEntry *fe = mAvailableFonts[i];
@@ -123,22 +124,23 @@ public:
                 // other reference to it except from its family
                 mAvailableFonts[i] = aNewFontEntry;
                 aNewFontEntry->SetFamily(this);
-                return;
+                break;
             }
         }
+        ResetCharacterMap();
     }
 
-    void RemoveFontEntry(gfxFontEntry *aFontEntry) 
-    {
+    void RemoveFontEntry(gfxFontEntry *aFontEntry) {
         PRUint32 numFonts = mAvailableFonts.Length();
         for (PRUint32 i = 0; i < numFonts; i++) {
             gfxFontEntry *fe = mAvailableFonts[i];
             if (fe == aFontEntry) {
                 aFontEntry->SetFamily(nsnull);
                 mAvailableFonts.RemoveElementAt(i);
-                return;
+                break;
             }
         }
+        ResetCharacterMap();
     }
 
     // clear family pointer for all entries and remove them from the family;