xcb: Get some style hints from xsettings

According to
https://www.freedesktop.org/wiki/Specifications/XSettingsRegistry/.
Added support for Net/CursorBlinkTime Net/DoubleClickTime
Net/DoubleClickDistance Net/DndDragThreshold.

Change-Id: Ief208736ed2938792d935bfd730fefdd745394b6
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

4 files changed, 28 insertions, 4 deletions

diff --git a/src/gui/kernel/qplatformintegration.cpp b/src/gui/kernel/qplatformintegration.cpp
index 66513a86e6..4d4f501ae4 100644
--- a/src/gui/kernel/qplatformintegration.cpp
+++ b/src/gui/kernel/qplatformintegration.cpp
@@ -408,6 +408,8 @@ QVariant QPlatformIntegration::styleHint(StyleHint hint) const
         return QPlatformTheme::defaultThemeHint(QPlatformTheme::WheelScrollLines);
     case MouseQuickSelectionThreshold:
         return QPlatformTheme::defaultThemeHint(QPlatformTheme::MouseQuickSelectionThreshold);
+    case MouseDoubleClickDistance:
+        return QPlatformTheme::defaultThemeHint(QPlatformTheme::MouseDoubleClickDistance);
     }
 
     return 0;
diff --git a/src/gui/kernel/qplatformintegration.h b/src/gui/kernel/qplatformintegration.h
index 46f1d74309..cc617faca9 100644
--- a/src/gui/kernel/qplatformintegration.h
+++ b/src/gui/kernel/qplatformintegration.h
@@ -160,7 +160,8 @@ public:
         UiEffects,
         WheelScrollLines,
         ShowShortcutsInContextMenus,
-        MouseQuickSelectionThreshold
+        MouseQuickSelectionThreshold,
+        MouseDoubleClickDistance
     };
 
     virtual QVariant styleHint(StyleHint hint) const;
diff --git a/src/gui/kernel/qstylehints.cpp b/src/gui/kernel/qstylehints.cpp
index 64c3a88be2..042f793a27 100644
--- a/src/gui/kernel/qstylehints.cpp
+++ b/src/gui/kernel/qstylehints.cpp
@@ -122,7 +122,7 @@ int QStyleHints::mouseDoubleClickDistance() const
     Q_D(const QStyleHints);
     return d->m_mouseDoubleClickDistance >= 0 ?
                 d->m_mouseDoubleClickDistance :
-                themeableHint(QPlatformTheme::MouseDoubleClickDistance).toInt();
+                themeableHint(QPlatformTheme::MouseDoubleClickDistance, QPlatformIntegration::MouseDoubleClickDistance).toInt();
 }
 
 /*!
diff --git a/src/plugins/platforms/xcb/qxcbintegration.cpp b/src/plugins/platforms/xcb/qxcbintegration.cpp
index c60269f9a0..8b49fb73ca 100644
--- a/src/plugins/platforms/xcb/qxcbintegration.cpp
+++ b/src/plugins/platforms/xcb/qxcbintegration.cpp
@@ -20,6 +20,7 @@
 #ifndef QT_NO_SESSIONMANAGER
 #include "qxcbsessionmanager.h"
 #endif
+#include "qxcbxsettings.h"
 
 #include <xcb/xcb.h>
 
@@ -423,12 +424,30 @@ QPlatformTheme *QXcbIntegration::createPlatformTheme(const QString &name) const
     return QGenericUnixTheme::createUnixTheme(name);
 }
 
+#define RETURN_VALID_XSETTINGS(key) { \
+    auto value = connection()->primaryScreen()->xSettings()->setting(key); \
+    if (value.isValid()) return value; \
+}
+
 QVariant QXcbIntegration::styleHint(QPlatformIntegration::StyleHint hint) const
 {
     switch (hint) {
-    case QPlatformIntegration::CursorFlashTime:
-    case QPlatformIntegration::KeyboardInputInterval:
+    case QPlatformIntegration::CursorFlashTime: {
+        bool ok = false;
+        // If cursor blinking is off, returns 0 to keep the cursor awlays display.
+        if (connection()->primaryScreen()->xSettings()->setting(QByteArrayLiteral("Net/CursorBlink")).toInt(&ok) == 0 && ok)
+            return 0;
+
+        RETURN_VALID_XSETTINGS(QByteArrayLiteral("Net/CursorBlinkTime"));
+        break;
+    }
     case QPlatformIntegration::MouseDoubleClickInterval:
+        RETURN_VALID_XSETTINGS(QByteArrayLiteral("Net/DoubleClickTime"));
+        break;
+    case QPlatformIntegration::MouseDoubleClickDistance:
+        RETURN_VALID_XSETTINGS(QByteArrayLiteral("Net/DoubleClickDistance"));
+        break;
+    case QPlatformIntegration::KeyboardInputInterval:
     case QPlatformIntegration::StartDragTime:
     case QPlatformIntegration::KeyboardAutoRepeatRate:
     case QPlatformIntegration::PasswordMaskDelay:
@@ -438,6 +457,8 @@ QVariant QXcbIntegration::styleHint(QPlatformIntegration::StyleHint hint) const
         // TODO using various xcb, gnome or KDE settings
         break; // Not implemented, use defaults
     case QPlatformIntegration::StartDragDistance: {
+        RETURN_VALID_XSETTINGS(QByteArrayLiteral("Net/DndDragThreshold"));
+
         // The default (in QPlatformTheme::defaultThemeHint) is 10 pixels, but
         // on a high-resolution screen it makes sense to increase it.
         qreal dpi = 100.0;