Bug 396732. Cache codepoints with no fonts to avoid repeated system-wide font lookup. r+sr=vlad

gfx/thebes/public/gfxFontUtils.h

@@ -143,7 +143,13 @@ public:
         return size;
     }
 
-
+    // clear out all blocks in the array
+    void reset() {
+        PRUint32 i;
+        for (i = 0; i < mBlocks.Length(); i++)
+            mBlocks[i] = nsnull;    
+    }
+    
     nsTArray< nsAutoPtr<Block> > mBlocks;
 };
 

gfx/thebes/src/gfxQuartzFontCache.h

@@ -215,6 +215,9 @@ private:
     // maps list of family names ==> array of family entries, one per lang group
     nsDataHashtable<nsUint32HashKey, nsTArray<nsRefPtr<MacOSFamilyEntry> > > mPrefFonts;
 
+    // when system-wide font lookup fails for a character, cache it to skip future searches
+    gfxSparseBitSet mCodepointsWithNoFonts;
+
 };
 
 #endif /* GFXQUARTZFONTCACHE_H_ */

gfx/thebes/src/gfxQuartzFontCache.mm

@@ -532,6 +532,7 @@ gfxQuartzFontCache::InitFontList()
     mFontFamilies.Clear();
     mLocalizedFamilies.Clear();
     mPrefFonts.Clear();
+    mCodepointsWithNoFonts.reset();
     
     // iterate over available families
     NSFontManager *fontManager = [NSFontManager sharedFontManager];
@@ -618,6 +619,11 @@ gfxQuartzFontCache::InitFontList()
     
     // xxx - need to remove bogus Helvetica/Courier italic faces (Cocoa inanity!)
     
+    // initialize ranges of characters for which system-wide font search should be skipped
+    mCodepointsWithNoFonts.SetRange(0,0x1f);     // C0 controls
+    mCodepointsWithNoFonts.SetRange(0x7f,0x9f);  // C1 controls
+    mCodepointsWithNoFonts.set(0xfffd);          // unknown
+                               
     [localizedNames release];
 }
 
@@ -701,11 +707,21 @@ gfxQuartzFontCache::GetFontList (const nsACString& aLangGroup,
 MacOSFontEntry*  
 gfxQuartzFontCache::FindFontForChar(const PRUint32 aCh, gfxAtsuiFont *aPrevFont)
 {
+    // is codepoint with no matching font? return null immediately
+    if (mCodepointsWithNoFonts.test(aCh)) {
+        return nsnull;
+    }
+
     FontSearch data(aCh, aPrevFont);
 
     // iterate over all font families to find a font that support the character
     mFontFamilies.Enumerate(gfxQuartzFontCache::FindFontForCharProc, &data);
 
+    // no match? add to set of non-matching codepoints
+    if (!data.bestMatch) {
+        mCodepointsWithNoFonts.set(aCh);
+    }
+    
     return data.bestMatch;
 }