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, 54 insertions, 24 deletions

diff --git a/src/plugins/platforms/xcb/qxcbscreen.cpp b/src/plugins/platforms/xcb/qxcbscreen.cpp
index 85f4dfbd43..952f32d806 100644
--- a/src/plugins/platforms/xcb/qxcbscreen.cpp
+++ b/src/plugins/platforms/xcb/qxcbscreen.cpp
@@ -69,6 +69,8 @@ QXcbScreen::QXcbScreen(QXcbConnection *connection, xcb_screen_t *scr,
     , m_refreshRate(60)
     , m_forcedDpi(-1)
     , m_hintStyle(QFontEngine::HintStyle(-1))
+    , m_subpixelType(QFontEngine::SubpixelAntialiasingType(-1))
+    , m_antialiasingEnabled(-1)
     , m_xSettings(0)
 {
     if (connection->hasXRandr())
@@ -547,32 +549,52 @@ QPixmap QXcbScreen::grabWindow(WId window, int x, int y, int width, int height)
     return result;
 }
 
+static bool parseXftInt(const QByteArray& stringValue, int *value)
+{
+    Q_ASSERT(value != 0);
+    bool ok;
+    *value = stringValue.toInt(&ok);
+    return ok;
+}
+
+static QFontEngine::HintStyle parseXftHintStyle(const QByteArray& stringValue)
+{
+    if (stringValue == "hintfull")
+        return QFontEngine::HintFull;
+    else if (stringValue == "hintnone")
+        return QFontEngine::HintNone;
+    else if (stringValue == "hintmedium")
+        return QFontEngine::HintMedium;
+    else if (stringValue == "hintslight")
+        return QFontEngine::HintLight;
+
+    return QFontEngine::HintStyle(-1);
+}
+
+static QFontEngine::SubpixelAntialiasingType parseXftRgba(const QByteArray& stringValue)
+{
+    if (stringValue == "none")
+        return QFontEngine::Subpixel_None;
+    else if (stringValue == "rgb")
+        return QFontEngine::Subpixel_RGB;
+    else if (stringValue == "bgr")
+        return QFontEngine::Subpixel_BGR;
+    else if (stringValue == "vrgb")
+        return QFontEngine::Subpixel_VRGB;
+    else if (stringValue == "vbgr")
+        return QFontEngine::Subpixel_VBGR;
+
+    return QFontEngine::SubpixelAntialiasingType(-1);
+}
+
 bool QXcbScreen::xResource(const QByteArray &identifier,
                            const QByteArray &expectedIdentifier,
-                           int *value)
+                           QByteArray& stringValue)
 {
-    Q_ASSERT(value != 0);
     if (identifier.startsWith(expectedIdentifier)) {
-        QByteArray stringValue = identifier.mid(expectedIdentifier.size());
-
-        bool ok;
-        *value = stringValue.toInt(&ok);
-        if (!ok) {
-            if (stringValue == "hintfull")
-                *value = QFontEngine::HintFull;
-            else if (stringValue == "hintnone")
-                *value = QFontEngine::HintNone;
-            else if (stringValue == "hintmedium")
-                *value = QFontEngine::HintMedium;
-            else if (stringValue == "hintslight")
-                *value = QFontEngine::HintLight;
-
-            return *value != 0;
-        }
-
+        stringValue = identifier.mid(expectedIdentifier.size());
         return true;
     }
-
     return false;
 }
 
@@ -604,10 +626,18 @@ void QXcbScreen::readXResources()
     for (int i = 0; i < split.size(); ++i) {
         const QByteArray &r = split.at(i);
         int value;
-        if (xResource(r, "Xft.dpi:\t", &value))
-            m_forcedDpi = value;
-        else if (xResource(r, "Xft.hintstyle:\t", &value))
-            m_hintStyle = QFontEngine::HintStyle(value);
+        QByteArray stringValue;
+        if (xResource(r, "Xft.dpi:\t", stringValue)) {
+            if (parseXftInt(stringValue, &value))
+                m_forcedDpi = value;
+        } else if (xResource(r, "Xft.hintstyle:\t", stringValue)) {
+            m_hintStyle = parseXftHintStyle(stringValue);
+        } else if (xResource(r, "Xft.antialias:\t", stringValue)) {
+            if (parseXftInt(stringValue, &value))
+                m_antialiasingEnabled = value;
+        } else if (xResource(r, "Xft.rgba:\t", stringValue)) {
+            m_subpixelType = parseXftRgba(stringValue);
+        }
     }
 }