Fix fontconfig usage in X11 font database

We should do FcConfigSubstitute(0, pattern, FcMatchFont) on a
FcPattern for query because the family list in it will contain
almost all the families after FcConfigSubstitute(0, pattern,
FcMatchPattern), then the test in <match target="font"> will
almost always succeed. In general, FcMatchFont substitute
should only be done on the FcPattern that we got after
FcFontMatch() or FcFontRenderPrepare().

Based on the suggestion of fontconfig author Behdad Esfahbod,
this patch reorganized the tryPatternLoad logic so that it only
does the QFontEngine creation part, FcPattern *match is retrieved
outside of that function. In this way, the match pattern we got
can be either from FcFontMatch() or after FcFontRenderPrepare()
on one of the fonts we got from qt_fontSetForPattern(). Then we
don't need to duplicate the pattern and add all criterias back
with qt_addPatternProps(). It not only simplified the code a lot
but also fix the way we apply FcMatchFont substitution. This
substitution will either be done by FcFontMatch() or
FcFontRenderPrepare, both implicitly.

Task-number: QTBUG-2148, QTBUG-19947
Reviewed-by: Eskil

0 files changed, 0 insertions, 0 deletions