Read correct font hinting config on Gnome/Unity

Fixes regression against Qt 4. This tries to recreate the logic
from 5c46d9a4c85abbcc0b5db2bbbafded3efd784cd9 in Qt 4, where we
on Gnome would override the default hint style specified in
FontConfig with Xft.hintstyle settings. This is the configuration
used for changing the hint style in the Gnome Tweak Tool.

Task-number: QTBUG-29582
Change-Id: I6b9fe2c8ff55ff080d034e5a53fc8cbb49f7651f
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>

src/platformsupport/fontdatabases/fontconfig/qfontconfigdatabase.cpp

@@ -47,11 +47,17 @@
 
 #include <QtCore/QElapsedTimer>
 
+#include <qpa/qplatformnativeinterface.h>
 #include <qpa/qplatformscreen.h>
+#include <qpa/qplatformintegration.h>
+#include <qpa/qplatformservices.h>
 
 #include <QtGui/private/qfontengine_ft_p.h>
 #include <QtGui/private/qfontengine_p.h>
 #include <QtGui/private/qfontengine_qpa_p.h>
+#include <QtGui/private/qguiapplication_p.h>
+
+#include <QtGui/qguiapplication.h>
 
 #include <ft2build.h>
 #include FT_TRUETYPE_TABLES_H
@@ -640,6 +646,19 @@ QFontEngine *QFontconfigDatabase::fontEngine(const QFontDef &f, QChar::Script sc
                 break;
             }
         }
+
+        if (f.hintingPreference == QFont::PreferDefaultHinting) {
+            QByteArray desktopEnvironment = QGuiApplicationPrivate::platformIntegration()->services()->desktopEnvironment();
+            if (desktopEnvironment == "GNOME" || desktopEnvironment == "UNITY") {
+                void *hintStyleResource =
+                        QGuiApplication::platformNativeInterface()->nativeResourceForScreen("hintstyle",
+                                                                                            QGuiApplication::primaryScreen());
+                int hintStyle = int(reinterpret_cast<qintptr>(hintStyleResource));
+                if (hintStyle > 0)
+                    default_hint_style = QFontEngine::HintStyle(hintStyle - 1);
+            }
+        }
+
         engine->setDefaultHintStyle(default_hint_style);
 
         if (antialias) {

src/plugins/platforms/xcb/qxcbnativeinterface.cpp

@@ -77,6 +77,7 @@ public:
         insert("glxcontext",QXcbNativeInterface::GLXContext);
         insert("apptime",QXcbNativeInterface::AppTime);
         insert("appusertime",QXcbNativeInterface::AppUserTime);
+        insert("hintstyle", QXcbNativeInterface::ScreenHintStyle);
     }
 };
 
@@ -139,6 +140,8 @@ void *QXcbNativeInterface::nativeResourceForScreen(const QByteArray &resource, Q
     case AppUserTime:
         result = appUserTime(xcbScreen);
         break;
+    case ScreenHintStyle:
+        result = reinterpret_cast<void *>(xcbScreen->hintStyle() + 1);
     default:
         break;
     }

src/plugins/platforms/xcb/qxcbnativeinterface.h

@@ -64,7 +64,8 @@ public:
         EglContext,
         GLXContext,
         AppTime,
-        AppUserTime
+        AppUserTime,
+        ScreenHintStyle
     };
 
     QXcbNativeInterface();

src/plugins/platforms/xcb/qxcbscreen.cpp

@@ -67,6 +67,7 @@ QXcbScreen::QXcbScreen(QXcbConnection *connection, xcb_screen_t *scr,
     , m_number(number)
     , m_refreshRate(60)
     , m_forcedDpi(-1)
+    , m_hintStyle(QFontEngine::HintStyle(-1))
 {
     if (connection->hasXRandr())
         xcb_randr_select_input(xcb_connection(), screen()->root, true);
@@ -481,6 +482,35 @@ QPixmap QXcbScreen::grabWindow(WId window, int x, int y, int width, int height)
     return result;
 }
 
+bool QXcbScreen::xResource(const QByteArray &identifier,
+                           const QByteArray &expectedIdentifier,
+                           int *value)
+{
+    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;
+        }
+
+        return true;
+    }
+
+    return false;
+}
+
 void QXcbScreen::readXResources()
 {
     int offset = 0;
@@ -508,13 +538,11 @@ void QXcbScreen::readXResources()
     QList<QByteArray> split = resources.split('\n');
     for (int i = 0; i < split.size(); ++i) {
         const QByteArray &r = split.at(i);
-        if (r.startsWith("Xft.dpi:\t")) {
-            bool ok;
-            int dpi = r.mid(sizeof("Xft.dpi:")).toInt(&ok);
-            if (ok)
-                m_forcedDpi = dpi;
-            break;
-        }
+        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);
     }
 }
 

src/plugins/platforms/xcb/qxcbscreen.h

@@ -50,6 +50,8 @@
 
 #include "qxcbobject.h"
 
+#include <private/qfontengine_p.h>
+
 QT_BEGIN_NAMESPACE
 
 class QXcbConnection;
@@ -97,7 +99,13 @@ public:
     void updateRefreshRate();
 
     void readXResources();
+
+    QFontEngine::HintStyle hintStyle() const { return m_hintStyle; }
 private:
+    static bool xResource(const QByteArray &identifier,
+                         const QByteArray &expectedIdentifier,
+                         int *value);
+
     xcb_screen_t *m_screen;
     xcb_randr_crtc_t m_crtc;
     QString m_outputName;
@@ -116,6 +124,7 @@ private:
     QXcbCursor *m_cursor;
     int m_refreshRate;
     int m_forcedDpi;
+    QFontEngine::HintStyle m_hintStyle;
 };
 
 QT_END_NAMESPACE