Bug 1454598 - part 4 - Disable font variations on macOS Sierra due to Core Text unreliability. r=jwatt

gfx/thebes/gfxFcPlatformFontList.cpp

@@ -1066,6 +1066,10 @@ gfxFontconfigFontEntry::HasVariations()
     mHasVariationsInitialized = true;
     mHasVariations = false;
 
+    if (!gfxPlatform::GetPlatform()->HasVariationFontSupport()) {
+        return mHasVariations;
+    }
+
     // For installed fonts, query the fontconfig pattern rather than paying
     // the cost of loading a FT_Face that we otherwise might never need.
     if (!IsUserFont() || IsLocalUserFont()) {
@@ -1208,7 +1212,10 @@ gfxFontconfigFontFamily::FindStyleVariations(FontInfoData *aFontInfoData)
 
         gfxFontconfigFontEntry *fontEntry =
             new gfxFontconfigFontEntry(faceName, face, mContainsAppFonts);
-        fontEntry->SetupVariationRanges();
+
+        if (gfxPlatform::GetPlatform()->HasVariationFontSupport()) {
+            fontEntry->SetupVariationRanges();
+        }
 
         AddFontEntry(fontEntry);
 

gfx/thebes/gfxFontEntry.cpp

@@ -1035,7 +1035,8 @@ gfxFontEntry::GetColorLayersInfo(uint32_t aGlyphId,
 void
 gfxFontEntry::SetupVariationRanges()
 {
-    if (!HasVariations() || IsUserFont()) {
+    if (!gfxPlatform::GetPlatform()->HasVariationFontSupport() ||
+        !HasVariations() || IsUserFont()) {
         return;
     }
     AutoTArray<gfxFontVariationAxis,4> axes;
@@ -1097,6 +1098,10 @@ void
 gfxFontEntry::GetVariationsForStyle(nsTArray<gfxFontVariation>& aResult,
                                     const gfxFontStyle& aStyle)
 {
+    if (!gfxPlatform::GetPlatform()->HasVariationFontSupport()) {
+        return;
+    }
+
     // Resolve high-level CSS properties from the requested style
     // (font-{style,weight,stretch}) to the appropriate variations.
     float clampedWeight = Weight().Clamp(aStyle.weight).ToFloat();

gfx/thebes/gfxMacPlatformFontList.mm

@@ -288,7 +288,9 @@ MacOSFontEntry::HasVariations()
 {
     if (!mHasVariationsInitialized) {
         mHasVariationsInitialized = true;
-        mHasVariations = HasFontTable(TRUETYPE_TAG('f','v','a','r'));
+        mHasVariations =
+            gfxPlatform::GetPlatform()->HasVariationFontSupport() &&
+            HasFontTable(TRUETYPE_TAG('f','v','a','r'));
     }
 
     return mHasVariations;
@@ -929,7 +931,9 @@ gfxMacFontFamily::FindStyleVariations(FontInfoData *aFontInfoData)
             fontEntry->mFixedPitch = true;
         }
 
-        fontEntry->SetupVariationRanges();
+        if (gfxPlatform::GetPlatform()->HasVariationFontSupport()) {
+            fontEntry->SetupVariationRanges();
+        }
 
         if (LOG_FONTLIST_ENABLED()) {
             nsAutoCString weightString;

gfx/thebes/gfxPlatform.cpp

@@ -778,6 +778,9 @@ gfxPlatform::Init()
     Factory::SetFTLibrary(gPlatform->GetFTLibrary());
 #endif
 
+    gPlatform->mHasVariationFontSupport =
+        gPlatform->CheckVariationFontSupport();
+
     nsresult rv;
     rv = gfxPlatformFontList::Init();
     if (NS_FAILED(rv)) {
@@ -851,7 +854,7 @@ gfxPlatform::Init()
     if (XRE_IsParentProcess()) {
       gfxVars::SetDXInterop2Blocked(IsDXInterop2Blocked());
       Preferences::Unlock(FONT_VARIATIONS_PREF);
-      if (!gPlatform->CheckVariationFontSupport()) {
+      if (!gPlatform->HasVariationFontSupport()) {
         // Ensure variation fonts are disabled and the pref is locked.
         Preferences::SetBool(FONT_VARIATIONS_PREF, false,
                              PrefValueKind::Default);

gfx/thebes/gfxPlatform.h

@@ -724,6 +724,10 @@ public:
       return nullptr;
     }
 
+    bool HasVariationFontSupport() const {
+      return mHasVariationFontSupport;
+    }
+
     // you probably want to use gfxVars::UseWebRender() instead of this
     static bool WebRenderPrefEnabled();
     // you probably want to use gfxVars::UseWebRender() instead of this
@@ -814,6 +818,9 @@ protected:
     // when doing system font fallback
     int8_t  mFallbackUsesCmaps;
 
+    // Whether the platform supports rendering OpenType font variations
+    bool    mHasVariationFontSupport;
+
     // max character limit for words in word cache
     int32_t mWordCacheCharLimit;
 

gfx/thebes/gfxPlatformMac.cpp

@@ -639,8 +639,9 @@ gfxPlatformMac::GetPlatformCMSOutputProfile(void* &mem, size_t &size)
 bool
 gfxPlatformMac::CheckVariationFontSupport()
 {
-    // We don't allow variation fonts to be enabled before 10.12,
+    // We don't allow variation fonts to be enabled before 10.13,
     // as although the Core Text APIs existed, they are known to be
     // fairly buggy.
-    return nsCocoaFeatures::OnSierraOrLater();
+    // (Note that Safari also requires 10.13 for variation-font support.)
+    return nsCocoaFeatures::OnHighSierraOrLater();
 }