Support antialias and rgba Xft settings as used by GNOME and UNITY

We only parsed the hintstyle from the Xft settings. This patch adds
parsing for also subpixel style and disabling antialiasing.

Task-number: QTBUG-27106
Change-Id: Icdb88ccc10e50d76eb30a5b126bee7590e257022
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>

1 files changed, 52 insertions, 17 deletions

diff --git a/src/platformsupport/fontdatabases/fontconfig/qfontconfigdatabase.cpp b/src/platformsupport/fontdatabases/fontconfig/qfontconfigdatabase.cpp
index 7b5f882982..13a4c13099 100644
--- a/src/platformsupport/fontdatabases/fontconfig/qfontconfigdatabase.cpp
+++ b/src/platformsupport/fontdatabases/fontconfig/qfontconfigdatabase.cpp
@@ -516,7 +516,7 @@ QFontEngineMulti *QFontconfigDatabase::fontEngineMulti(QFontEngine *fontEngine,
 }
 
 namespace {
-QFontEngine::HintStyle defaultHintStyleFromMatch(QFont::HintingPreference hintingPreference, FcPattern *match)
+QFontEngine::HintStyle defaultHintStyleFromMatch(QFont::HintingPreference hintingPreference, FcPattern *match, bool useXftConf)
 {
     switch (hintingPreference) {
     case QFont::PreferNoHinting:
@@ -529,8 +529,7 @@ QFontEngine::HintStyle defaultHintStyleFromMatch(QFont::HintingPreference hintin
         break;
     }
 
-    const QPlatformServices *services = QGuiApplicationPrivate::platformIntegration()->services();
-    if (services && (services->desktopEnvironment() == "GNOME" || services->desktopEnvironment() == "UNITY")) {
+    if (useXftConf) {
         void *hintStyleResource =
                 QGuiApplication::platformNativeInterface()->nativeResourceForScreen("hintstyle",
                                                                                     QGuiApplication::primaryScreen());
@@ -558,8 +557,17 @@ QFontEngine::HintStyle defaultHintStyleFromMatch(QFont::HintingPreference hintin
     return QFontEngine::HintFull;
 }
 
-QFontEngine::SubpixelAntialiasingType subpixelTypeFromMatch(FcPattern *match)
+QFontEngine::SubpixelAntialiasingType subpixelTypeFromMatch(FcPattern *match, bool useXftConf)
 {
+    if (useXftConf) {
+        void *subpixelTypeResource =
+                QGuiApplication::platformNativeInterface()->nativeResourceForScreen("subpixeltype",
+                                                                                    QGuiApplication::primaryScreen());
+        int subpixelType = int(reinterpret_cast<qintptr>(subpixelTypeResource));
+        if (subpixelType > 0)
+            return QFontEngine::SubpixelAntialiasingType(subpixelType - 1);
+    }
+
     int subpixel = FC_RGBA_UNKNOWN;
     FcPatternGetInteger(match, FC_RGBA, 0, &subpixel);
 
@@ -596,8 +604,22 @@ QFontEngine *QFontconfigDatabase::fontEngine(const QFontDef &f, void *usrPtr)
     fid.index = fontfile->indexValue;
 
     bool antialias = !(fontDef.styleStrategy & QFont::NoAntialias);
+    bool forcedAntialiasSetting = !antialias;
     engine = new QFontEngineFT(fontDef);
 
+    const QPlatformServices *services = QGuiApplicationPrivate::platformIntegration()->services();
+    bool useXftConf = (services && (services->desktopEnvironment() == "GNOME" || services->desktopEnvironment() == "UNITY"));
+    if (useXftConf) {
+        void *antialiasResource =
+                QGuiApplication::platformNativeInterface()->nativeResourceForScreen("antialiasingEnabled",
+                                                                                    QGuiApplication::primaryScreen());
+        int antialiasingEnabled = int(reinterpret_cast<qintptr>(antialiasResource));
+        if (antialiasingEnabled > 0) {
+            antialias = antialiasingEnabled - 1;
+            forcedAntialiasSetting = true;
+        }
+    }
+
     QFontEngine::GlyphFormat format;
     // try and get the pattern
     FcPattern *pattern = FcPatternCreate();
@@ -622,7 +644,7 @@ QFontEngine *QFontconfigDatabase::fontEngine(const QFontDef &f, void *usrPtr)
 
     FcPattern *match = FcFontMatch(0, pattern, &result);
     if (match) {
-        engine->setDefaultHintStyle(defaultHintStyleFromMatch((QFont::HintingPreference)f.hintingPreference, match));
+        engine->setDefaultHintStyle(defaultHintStyleFromMatch((QFont::HintingPreference)f.hintingPreference, match, useXftConf));
 
         FcBool fc_autohint;
         if (FcPatternGetBool(match, FC_AUTOHINT,0, &fc_autohint) == FcResultMatch)
@@ -634,18 +656,16 @@ QFontEngine *QFontconfigDatabase::fontEngine(const QFontDef &f, void *usrPtr)
             engine->lcdFilterType = lcdFilter;
 #endif
 
-        if (antialias) {
-            // If antialiasing is not fully disabled, fontconfig may still disable it on a font match basis.
+        if (!forcedAntialiasSetting) {
             FcBool fc_antialias;
-            if (FcPatternGetBool(match, FC_ANTIALIAS,0, &fc_antialias) != FcResultMatch)
-                fc_antialias = true;
-            antialias = fc_antialias;
+            if (FcPatternGetBool(match, FC_ANTIALIAS,0, &fc_antialias) == FcResultMatch)
+                antialias = fc_antialias;
         }
 
         if (antialias) {
             QFontEngine::SubpixelAntialiasingType subpixelType = QFontEngine::Subpixel_None;
             if (!(f.styleStrategy & QFont::NoSubpixelAntialias))
-                subpixelType = subpixelTypeFromMatch(match);
+                subpixelType = subpixelTypeFromMatch(match, useXftConf);
             engine->subpixelType = subpixelType;
 
             format = (subpixelType == QFontEngine::Subpixel_None)
@@ -676,6 +696,20 @@ QFontEngine *QFontconfigDatabase::fontEngine(const QByteArray &fontData, qreal p
 
     QFontDef fontDef = engine->fontDef;
 
+    bool forcedAntialiasSetting = false;
+    const QPlatformServices *services = QGuiApplicationPrivate::platformIntegration()->services();
+    bool useXftConf = (services && (services->desktopEnvironment() == "GNOME" || services->desktopEnvironment() == "UNITY"));
+    if (useXftConf) {
+        void *antialiasResource =
+                QGuiApplication::platformNativeInterface()->nativeResourceForScreen("antialiasingEnabled",
+                                                                                    QGuiApplication::primaryScreen());
+        int antialiasingEnabled = int(reinterpret_cast<qintptr>(antialiasResource));
+        if (antialiasingEnabled > 0) {
+            engine->antialias = antialiasingEnabled - 1;
+            forcedAntialiasSetting = true;
+        }
+    }
+
     QFontEngine::GlyphFormat format;
     // try and get the pattern
     FcPattern *pattern = FcPatternCreate();
@@ -693,7 +727,7 @@ QFontEngine *QFontconfigDatabase::fontEngine(const QByteArray &fontData, qreal p
 
     FcPattern *match = FcFontMatch(0, pattern, &result);
     if (match) {
-        engine->setDefaultHintStyle(defaultHintStyleFromMatch(hintingPreference, match));
+        engine->setDefaultHintStyle(defaultHintStyleFromMatch(hintingPreference, match, useXftConf));
 
         FcBool fc_autohint;
         if (FcPatternGetBool(match, FC_AUTOHINT,0, &fc_autohint) == FcResultMatch)
@@ -705,13 +739,14 @@ QFontEngine *QFontconfigDatabase::fontEngine(const QByteArray &fontData, qreal p
             engine->lcdFilterType = lcdFilter;
 #endif
 
-        FcBool fc_antialias;
-        if (FcPatternGetBool(match, FC_ANTIALIAS,0, &fc_antialias) != FcResultMatch)
-            fc_antialias = true;
-        engine->antialias = fc_antialias;
+        if (!forcedAntialiasSetting) {
+            FcBool fc_antialias;
+            if (FcPatternGetBool(match, FC_ANTIALIAS,0, &fc_antialias) == FcResultMatch)
+                engine->antialias = fc_antialias;
+        }
 
         if (engine->antialias) {
-            QFontEngine::SubpixelAntialiasingType subpixelType = subpixelTypeFromMatch(match);
+            QFontEngine::SubpixelAntialiasingType subpixelType = subpixelTypeFromMatch(match, useXftConf);
             engine->subpixelType = subpixelType;
 
             format = subpixelType == QFontEngine::Subpixel_None