Fix fontconfig pattern merging

When merging fontconfig patterns, we need to clean up existing object
first, otherwise the added object will be appended instead of replacing
the existing object. When multiple font engines are using shaping, if
fontconfig patterns are not correctly merged, it will result using the
old font. For instance, in "<b>Fake Bold</b> Normal", "Normal" text will
continue using the font for "Fake Bold" (that only happen with fallback
fonts).

Task-number: QTBUG-14455
Reviewed-by: Eskil

1 files changed, 7 insertions, 0 deletions

diff --git a/src/gui/text/qfontdatabase_x11.cpp b/src/gui/text/qfontdatabase_x11.cpp
index 2fa16bb..67bcc7a 100644
--- a/src/gui/text/qfontdatabase_x11.cpp
+++ b/src/gui/text/qfontdatabase_x11.cpp
@@ -1462,6 +1462,7 @@ void qt_addPatternProps(FcPattern *pattern, int screen, int script, const QFontD
         weight_value = FC_WEIGHT_DEMIBOLD;
     else if (request.weight < (QFont::Bold + QFont::Black) / 2)
         weight_value = FC_WEIGHT_BOLD;
+    FcPatternDel(pattern, FC_WEIGHT);
     FcPatternAddInteger(pattern, FC_WEIGHT, weight_value);
 
     int slant_value = FC_SLANT_ROMAN;
@@ -1469,20 +1470,25 @@ void qt_addPatternProps(FcPattern *pattern, int screen, int script, const QFontD
         slant_value = FC_SLANT_ITALIC;
     else if (request.style == QFont::StyleOblique)
         slant_value = FC_SLANT_OBLIQUE;
+    FcPatternDel(pattern, FC_SLANT);
     FcPatternAddInteger(pattern, FC_SLANT, slant_value);
 
     double size_value = qMax(qreal(1.), request.pixelSize);
+    FcPatternDel(pattern, FC_PIXEL_SIZE);
     FcPatternAddDouble(pattern, FC_PIXEL_SIZE, size_value);
 
     int stretch = request.stretch;
     if (!stretch)
         stretch = 100;
+    FcPatternDel(pattern, FC_WIDTH);
     FcPatternAddInteger(pattern, FC_WIDTH, stretch);
 
     if (X11->display && QX11Info::appDepth(screen) <= 8) {
+        FcPatternDel(pattern, FC_ANTIALIAS);
         // can't do antialiasing on 8bpp
         FcPatternAddBool(pattern, FC_ANTIALIAS, false);
     } else if (request.styleStrategy & (QFont::PreferAntialias|QFont::NoAntialias)) {
+        FcPatternDel(pattern, FC_ANTIALIAS);
         FcPatternAddBool(pattern, FC_ANTIALIAS,
                          !(request.styleStrategy & QFont::NoAntialias));
     }
@@ -1491,6 +1497,7 @@ void qt_addPatternProps(FcPattern *pattern, int screen, int script, const QFontD
         Q_ASSERT(script < QUnicodeTables::ScriptCount);
         FcLangSet *ls = FcLangSetCreate();
         FcLangSetAdd(ls, (const FcChar8*)specialLanguages[script]);
+        FcPatternDel(pattern, FC_LANG);
         FcPatternAddLangSet(pattern, FC_LANG, ls);
         FcLangSetDestroy(ls);
     }