Bug: https://bugs.openjdk.java.net/browse/JDK-7162125 Fix: http://cr.openjdk.java.net/~prr/7162125/
The problem is that complex text layout and accompanying typographic support is largely limping along on OS X and then only thanks to some canonical tables that the ICU library has. The bug is that the internal font "peer" that passes the font tables containing the necessary information for OpenType (and AAT) layout does not implement the necessary functions. So there is no way to get the information that the font itself contains, resulting in incorrect rendering. The fix needs to be to add to the osx "CFont" class the necessary code to pass that information. That is not so hard. But there is an additional complication that the OS X code uses "fallback" or "substitution" or "cascading" fonts and so a font like "Lucida Grande" might report that it supports code points from Indic scripts when it does not. It does this by reporting negative glyph codes for such cases and fixes it up in the final rendering step. The problem with that is that layout needs to use the font-specific tables and this subverts that. We need to know for sure which code points are supported and split into runs of text that the font supports. So we need to find the real fonts that the CFont uses. In core text this is obtainable as the cascading font list. We can get this and construct a CompositeFont and make its glyph mapper check that there are no *negative* glyph codes not just no zero ones. Now we can give layout proper runs and tables. The final bit is that rendering needs to also know that if it is passed a font that might implement FontSubstition that it needs to expect that layout returned glyph codes that are intended to be used with the Composite. A reliable regression test is tricky. I have looked for a simple code point sequence that an installed OS X font provides that I can "measure" to see that the ligature forms but have not found one. I have however tested using the font provided in https://bugs.openjdk.java.net/browse/JDK-8139741 but I cannot check that in. -phil.
