Bug 705594. Use CoreText for system font fallback on OSX. r=jfkthame

gfx/thebes/gfxMacPlatformFontList.h

@@ -166,6 +166,7 @@ private:
     friend class gfxPlatformMac;
 
     gfxMacPlatformFontList();
+    virtual ~gfxMacPlatformFontList();
 
     // initialize font lists
     virtual nsresult InitFontList();
@@ -181,12 +182,23 @@ private:
 
     static void ATSNotification(ATSFontNotificationInfoRef aInfo, void* aUserArg);
 
+    // search fonts system-wide for a given character, null otherwise
+    virtual gfxFontEntry* GlobalFontFallback(const PRUint32 aCh,
+                                             PRInt32 aRunScript,
+                                             const gfxFontStyle* aMatchStyle,
+                                             PRUint32& aCmapCount);
+
+    virtual bool UsesSystemFallback() { return true; }
+
     // keep track of ATS generation to prevent unneeded updates when loading downloaded fonts
     PRUint32 mATSGeneration;
 
     enum {
         kATSGenerationInitial = -1
     };
+
+    // default font for use with system-wide font fallback
+    CTFontRef mDefaultFont;
 };
 
 #endif /* gfxMacPlatformFontList_H_ */

gfx/thebes/gfxMacPlatformFontList.mm

@@ -58,6 +58,7 @@
 #include "nsDirectoryServiceUtils.h"
 #include "nsDirectoryServiceDefs.h"
 #include "nsISimpleEnumerator.h"
+#include "nsCharTraits.h"
 
 #include "mozilla/Telemetry.h"
 
@@ -704,7 +705,8 @@ gfxSingleFaceMacFontFamily::ReadOtherFamilyNames(gfxPlatformFontList *aPlatformF
 #pragma mark-
 
 gfxMacPlatformFontList::gfxMacPlatformFontList() :
-    gfxPlatformFontList(false), mATSGeneration(PRUint32(kATSGenerationInitial))
+    gfxPlatformFontList(false), mATSGeneration(PRUint32(kATSGenerationInitial)),
+    mDefaultFont(nsnull)
 {
     ::ATSFontNotificationSubscribe(ATSNotification,
                                    kATSFontNotifyOptionDefault,
@@ -719,6 +721,13 @@ gfxMacPlatformFontList::gfxMacPlatformFontList() :
     sFontManager = [NSFontManager sharedFontManager];
 }
 
+gfxMacPlatformFontList::~gfxMacPlatformFontList()
+{
+    if (mDefaultFont) {
+        ::CFRelease(mDefaultFont);
+    }
+}
+
 nsresult
 gfxMacPlatformFontList::InitFontList()
 {
@@ -875,6 +884,93 @@ gfxMacPlatformFontList::ATSNotification(ATSFontNotificationInfoRef aInfo,
     qfc->UpdateFontList();
 }
 
+gfxFontEntry*
+gfxMacPlatformFontList::GlobalFontFallback(const PRUint32 aCh,
+                                           PRInt32 aRunScript,
+                                           const gfxFontStyle* aMatchStyle,
+                                           PRUint32& aCmapCount)
+{
+    bool useCmaps = gfxPlatform::GetPlatform()->UseCmapsDuringSystemFallback();
+
+    if (useCmaps) {
+        return gfxPlatformFontList::GlobalFontFallback(aCh,
+                                                       aRunScript,
+                                                       aMatchStyle,
+                                                       aCmapCount);
+    }
+
+    CFStringRef str;
+    UniChar ch[2];
+    CFIndex len = 1;
+
+    if (IS_IN_BMP(aCh)) {
+        ch[0] = aCh;
+        str = ::CFStringCreateWithCharactersNoCopy(kCFAllocatorDefault, ch, 1,
+                                                   kCFAllocatorNull);
+    } else {
+        ch[0] = H_SURROGATE(aCh);
+        ch[1] = L_SURROGATE(aCh);
+        str = ::CFStringCreateWithCharactersNoCopy(kCFAllocatorDefault, ch, 2,
+                                                   kCFAllocatorNull);
+        if (!str) {
+            return nsnull;
+        }
+        len = 2;
+    }
+
+    // use CoreText to find the fallback family
+
+    gfxFontEntry *fontEntry = nsnull;
+    CTFontRef fallback;
+    bool cantUseFallbackFont = false;
+
+    if (!mDefaultFont) {
+        mDefaultFont = ::CTFontCreateWithName(CFSTR("Lucida Grande"), 12.f,
+                                              NULL);
+    }
+
+    fallback = ::CTFontCreateForString(mDefaultFont, str,
+                                       ::CFRangeMake(0, len));
+
+    if (fallback) {
+        CFStringRef familyName = ::CTFontCopyFamilyName(fallback);
+        ::CFRelease(fallback);
+
+        if (familyName &&
+            ::CFStringCompare(familyName, CFSTR("LastResort"),
+                              kCFCompareCaseInsensitive) != kCFCompareEqualTo)
+        {
+            nsAutoTArray<UniChar, 1024> buffer;
+            CFIndex len = ::CFStringGetLength(familyName);
+            buffer.SetLength(len+1);
+            ::CFStringGetCharacters(familyName, ::CFRangeMake(0, len),
+                                    buffer.Elements());
+            buffer[len] = 0;
+            nsDependentString family(buffer.Elements(), len);
+
+            bool needsBold;  // ignored in the system fallback case
+
+            fontEntry = FindFontForFamily(family, aMatchStyle, needsBold);
+            if (fontEntry && !fontEntry->TestCharacterMap(aCh)) {
+                fontEntry = nsnull;
+                cantUseFallbackFont = true;
+            }
+        }
+
+        if (familyName) {
+            ::CFRelease(familyName);
+        }
+    }
+
+    if (cantUseFallbackFont) {
+        Telemetry::Accumulate(Telemetry::BAD_FALLBACK_FONT, cantUseFallbackFont);
+    }
+
+    ::CFRelease(str);
+
+    return fontEntry;
+}
+
 gfxFontEntry*
 gfxMacPlatformFontList::GetDefaultFont(const gfxFontStyle* aStyle, bool& aNeedsBold)
 {

toolkit/components/telemetry/TelemetryHistograms.h

@@ -147,6 +147,7 @@ HISTOGRAM(WORD_CACHE_LOOKUP_SCRIPT, 1, 110, 111, LINEAR, "Word cache lookup (scr
 HISTOGRAM(WORD_CACHE_HIT_SCRIPT, 1, 110, 111, LINEAR, "Word cache hit (script)")
 
 HISTOGRAM_BOOLEAN(FONT_CACHE_HIT, "font cache hit")
+HISTOGRAM_BOOLEAN(BAD_FALLBACK_FONT, "system fallback font can't be used")
 
 HISTOGRAM_BOOLEAN(SHUTDOWN_OK, "Did the browser start after a successful shutdown")