bug 721719 - ignore the GSUB table in Roboto on Android because of bad ligature rule. r=jdaggett

gfx/thebes/gfxFT2FontList.cpp

@@ -766,6 +766,14 @@ gfxFT2FontList::AppendFacesFromFontFile(nsCString& aFileName,
                 if (family->IsBadUnderlineFamily()) {
                     fe->mIsBadUnderlineFont = true;
                 }
+
+                // bug 721719 - set the IgnoreGSUB flag on entries for Roboto
+                // because of unwanted on-by-default "ae" ligature.
+                // (See also AppendFaceFromFontListEntry.)
+                if (name.EqualsLiteral("roboto")) {
+                    fe->mIgnoreGSUB = true;
+                }
+
                 AppendToFaceList(faceList, name, fe);
 #ifdef PR_LOGGING
                 if (LOG_ENABLED()) {
@@ -975,6 +983,17 @@ gfxFT2FontList::AppendFaceFromFontListEntry(const FontListEntry& aFLE,
         if (family->IsBadUnderlineFamily()) {
             fe->mIsBadUnderlineFont = true;
         }
+
+        // bug 721719 - set the IgnoreGSUB flag on entries for Roboto
+        // because of unwanted on-by-default "ae" ligature.
+        // This totally sucks, but if we don't hack around these broken fonts
+        // we get really bad text rendering, which we can't inflict on users. :(
+        // If we accumulate a few more examples of this stuff, it'll be time
+        // to create some prefs for the list of fonts where we need to ignore
+        // layout tables. Sigh.
+        if (name.EqualsLiteral("roboto")) {
+            fe->mIgnoreGSUB = true;
+        }
     }
 }
 

gfx/thebes/gfxFont.h

@@ -207,6 +207,7 @@ public:
         mIsLocalUserFont(false), mStandardFace(aIsStandardFace),
         mSymbolFont(false),
         mIgnoreGDEF(false),
+        mIgnoreGSUB(false),
         mWeight(500), mStretch(NS_FONT_STRETCH_NORMAL),
 #ifdef MOZ_GRAPHITE
         mCheckedForGraphiteTables(false),
@@ -240,6 +241,7 @@ public:
     bool IsItalic() const { return mItalic; }
     bool IsBold() const { return mWeight >= 600; } // bold == weights 600 and above
     bool IgnoreGDEF() const { return mIgnoreGDEF; }
+    bool IgnoreGSUB() const { return mIgnoreGSUB; }
 
     virtual bool IsSymbolFont();
 
@@ -323,6 +325,7 @@ public:
     bool             mStandardFace : 1;
     bool             mSymbolFont  : 1;
     bool             mIgnoreGDEF  : 1;
+    bool             mIgnoreGSUB  : 1;
 
     PRUint16         mWeight;
     PRInt16          mStretch;
@@ -357,6 +360,7 @@ protected:
         mStandardFace(false),
         mSymbolFont(false),
         mIgnoreGDEF(false),
+        mIgnoreGSUB(false),
         mWeight(500), mStretch(NS_FONT_STRETCH_NORMAL),
 #ifdef MOZ_GRAPHITE
         mCheckedForGraphiteTables(false),

gfx/thebes/gfxHarfBuzzShaper.cpp

@@ -117,8 +117,14 @@ HBGetTable(hb_face_t *face, hb_tag_t aTag, void *aUserData)
     // bug 589682 - ignore the GDEF table in buggy fonts (applies to
     // Italic and BoldItalic faces of Times New Roman)
     if (aTag == TRUETYPE_TAG('G','D','E','F') &&
-        font->GetFontEntry()->IgnoreGDEF())
-    {
+        font->GetFontEntry()->IgnoreGDEF()) {
+        return nsnull;
+    }
+
+    // bug 721719 - ignore the GSUB table in buggy fonts (applies to Roboto,
+    // at least on some Android ICS devices; set in gfxFT2FontList.cpp)
+    if (aTag == TRUETYPE_TAG('G','S','U','B') &&
+        font->GetFontEntry()->IgnoreGSUB()) {
         return nsnull;
     }