xcb: Fix getting the primary screen from QXcbConnection::screens()

Currently getting QXcbScreen* for primary screen is too messy and it
wrongly uses QXcbConnection::primaryScreen() as an index in
QXcbConnection::screens() although QXcbConnection::screens() returns
the primary screen as the first item in the list since
3c8eb404877df9c967d81fa9df7d718c538fb407.

So to clear the API rename primaryScreen() to primaryScreenNumber(),
add QXcbConnection::primaryScreen() that returns correct QXcbScreen*
and use it directly.

Change-Id: Icb7391aa3e82b32ca48f2bda764dcf7ffd89cc47
Reviewed-by: Uli Schlachter <psychon@znc.in>
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>

8 files changed, 26 insertions, 20 deletions

diff --git a/src/plugins/platforms/xcb/qxcbclipboard.cpp b/src/plugins/platforms/xcb/qxcbclipboard.cpp
index 45856f3e6c..8b3893ec2f 100644
--- a/src/plugins/platforms/xcb/qxcbclipboard.cpp
+++ b/src/plugins/platforms/xcb/qxcbclipboard.cpp
@@ -276,7 +276,7 @@ QXcbClipboard::QXcbClipboard(QXcbConnection *c)
     m_timestamp[QClipboard::Clipboard] = XCB_CURRENT_TIME;
     m_timestamp[QClipboard::Selection] = XCB_CURRENT_TIME;
 
-    m_screen = connection()->screens().at(connection()->primaryScreen());
+    m_screen = connection()->primaryScreen();
 
     int x = 0, y = 0, w = 3, h = 3;
 
diff --git a/src/plugins/platforms/xcb/qxcbconnection.cpp b/src/plugins/platforms/xcb/qxcbconnection.cpp
index 835c414d85..5510c3b1b4 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection.cpp
@@ -244,7 +244,7 @@ void QXcbConnection::updateScreens()
                         // the first or an exact match.  An exact match isn't
                         // always available if primary->output is XCB_NONE
                         // or currently disconnected output.
-                        if (m_primaryScreen == xcbScreenNumber) {
+                        if (m_primaryScreenNumber == xcbScreenNumber) {
                             if (!primaryScreen || (primary && outputs[i] == primary->output)) {
                                 primaryScreen = screen;
                                 siblings.prepend(siblings.takeLast());
@@ -306,7 +306,7 @@ void QXcbConnection::updateScreens()
 QXcbConnection::QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGrabServer, const char *displayName)
     : m_connection(0)
     , m_canGrabServer(canGrabServer)
-    , m_primaryScreen(0)
+    , m_primaryScreenNumber(0)
     , m_displayName(displayName ? QByteArray(displayName) : qgetenv("DISPLAY"))
     , m_nativeInterface(nativeInterface)
     , xfixes_first_event(0)
@@ -331,7 +331,7 @@ QXcbConnection::QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGra
 #ifdef XCB_USE_XLIB
     dpy = XOpenDisplay(m_displayName.constData());
     if (dpy) {
-        m_primaryScreen = DefaultScreen(dpy);
+        m_primaryScreenNumber = DefaultScreen(dpy);
         m_connection = XGetXCBConnection(dpy);
         XSetEventQueueOwner(dpy, XCBOwnsEventQueue);
         XSetErrorHandler(nullErrorHandler);
@@ -339,7 +339,7 @@ QXcbConnection::QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGra
         m_xlib_display = dpy;
     }
 #else
-    m_connection = xcb_connect(m_displayName.constData(), &m_primaryScreen);
+    m_connection = xcb_connect(m_displayName.constData(), &m_primaryScreenNumber);
 #endif //XCB_USE_XLIB
 
     if (!m_connection || xcb_connection_has_error(m_connection))
@@ -449,6 +449,16 @@ QXcbConnection::~QXcbConnection()
     delete m_keyboard;
 }
 
+QXcbScreen *QXcbConnection::primaryScreen() const
+{
+    if (!m_screens.isEmpty()) {
+        Q_ASSERT(m_screens.first()->screenNumber() == primaryScreenNumber());
+        return m_screens.first();
+    }
+
+    return Q_NULLPTR;
+}
+
 void QXcbConnection::addWindowEventListener(xcb_window_t id, QXcbWindowEventListener *eventListener)
 {
     m_mapper.insert(id, eventListener);
@@ -1219,7 +1229,7 @@ xcb_timestamp_t QXcbConnection::getTimestamp()
 
 xcb_window_t QXcbConnection::rootWindow()
 {
-    return screens().at(primaryScreen())->root();
+    return primaryScreen()->root();
 }
 
 void QXcbConnection::processXcbEvents()
diff --git a/src/plugins/platforms/xcb/qxcbconnection.h b/src/plugins/platforms/xcb/qxcbconnection.h
index 4a16e116c6..51c7c91bf6 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.h
+++ b/src/plugins/platforms/xcb/qxcbconnection.h
@@ -369,7 +369,8 @@ public:
     QXcbConnection *connection() const { return const_cast<QXcbConnection *>(this); }
 
     const QList<QXcbScreen *> &screens() const { return m_screens; }
-    int primaryScreen() const { return m_primaryScreen; }
+    int primaryScreenNumber() const { return m_primaryScreenNumber; }
+    QXcbScreen *primaryScreen() const;
 
     inline xcb_atom_t atom(QXcbAtom::Atom atom) const { return m_allAtoms[atom]; }
     QXcbAtom::Atom qatom(xcb_atom_t atom) const;
@@ -550,7 +551,7 @@ private:
     bool m_canGrabServer;
 
     QList<QXcbScreen *> m_screens;
-    int m_primaryScreen;
+    int m_primaryScreenNumber;
 
     xcb_atom_t m_allAtoms[QXcbAtom::NAtoms];
 
diff --git a/src/plugins/platforms/xcb/qxcbdrag.cpp b/src/plugins/platforms/xcb/qxcbdrag.cpp
index 53437f24ae..7037e102e2 100644
--- a/src/plugins/platforms/xcb/qxcbdrag.cpp
+++ b/src/plugins/platforms/xcb/qxcbdrag.cpp
@@ -311,7 +311,7 @@ void QXcbDrag::move(const QMouseEvent *me)
         return;
 
     const QList<QXcbScreen *> &screens = connection()->screens();
-    QXcbScreen *screen = screens.at(connection()->primaryScreen());
+    QXcbScreen *screen = connection()->primaryScreen();
     for (int i = 0; i < screens.size(); ++i) {
         if (screens.at(i)->geometry().contains(globalPos)) {
             screen = screens.at(i);
diff --git a/src/plugins/platforms/xcb/qxcbintegration.cpp b/src/plugins/platforms/xcb/qxcbintegration.cpp
index d3533b8e44..52269bafea 100644
--- a/src/plugins/platforms/xcb/qxcbintegration.cpp
+++ b/src/plugins/platforms/xcb/qxcbintegration.cpp
@@ -417,10 +417,8 @@ QVariant QXcbIntegration::styleHint(QPlatformIntegration::StyleHint hint) const
     case QPlatformIntegration::StartDragDistance: {
         // The default (in QPlatformTheme::defaultThemeHint) is 10 pixels, but
         // on a high-resolution screen it makes sense to increase it.
-        const QList<QXcbScreen *> &screens = defaultConnection()->screens();
         qreal dpi = 100.0;
-        if (screens.length() > 0) {
-            const QXcbScreen *screen = screens.at(defaultConnection()->primaryScreen());
+        if (const QXcbScreen *screen = defaultConnection()->primaryScreen()) {
             if (screen->logicalDpi().first > dpi)
                 dpi = screen->logicalDpi().first;
             if (screen->logicalDpi().second > dpi)
diff --git a/src/plugins/platforms/xcb/qxcbnativeinterface.cpp b/src/plugins/platforms/xcb/qxcbnativeinterface.cpp
index 0d75a7f032..3058b29f2d 100644
--- a/src/plugins/platforms/xcb/qxcbnativeinterface.cpp
+++ b/src/plugins/platforms/xcb/qxcbnativeinterface.cpp
@@ -367,7 +367,7 @@ void *QXcbNativeInterface::x11Screen()
     QXcbIntegration *integration = static_cast<QXcbIntegration *>(QGuiApplicationPrivate::platformIntegration());
     QXcbConnection *defaultConnection = integration->defaultConnection();
     if (defaultConnection)
-        return reinterpret_cast<void *>(defaultConnection->primaryScreen());
+        return reinterpret_cast<void *>(defaultConnection->primaryScreenNumber());
     return 0;
 }
 
diff --git a/src/plugins/platforms/xcb/qxcbsystemtraytracker.cpp b/src/plugins/platforms/xcb/qxcbsystemtraytracker.cpp
index 9ec4ea80ec..40a50f61ab 100644
--- a/src/plugins/platforms/xcb/qxcbsystemtraytracker.cpp
+++ b/src/plugins/platforms/xcb/qxcbsystemtraytracker.cpp
@@ -59,7 +59,7 @@ QXcbSystemTrayTracker *QXcbSystemTrayTracker::create(QXcbConnection *connection)
     const xcb_atom_t trayAtom = connection->atom(QXcbAtom::_NET_SYSTEM_TRAY_OPCODE);
     if (!trayAtom)
         return 0;
-    const QByteArray netSysTray = QByteArrayLiteral("_NET_SYSTEM_TRAY_S") + QByteArray::number(connection->primaryScreen());
+    const QByteArray netSysTray = QByteArrayLiteral("_NET_SYSTEM_TRAY_S") + QByteArray::number(connection->primaryScreenNumber());
     const xcb_atom_t selection = connection->internAtom(netSysTray.constData());
     if (!selection)
         return 0;
@@ -145,11 +145,8 @@ QRect QXcbSystemTrayTracker::systemTrayWindowGlobalGeometry(xcb_window_t window)
 
 inline void QXcbSystemTrayTracker::emitSystemTrayWindowChanged()
 {
-    const int screen = m_connection->primaryScreen();
-    if (screen >= 0 && screen < m_connection->screens().size()) {
-        const QPlatformScreen *ps = m_connection->screens().at(screen);
+    if (const QPlatformScreen *ps = m_connection->primaryScreen())
         emit systemTrayWindowChanged(ps->screen());
-    }
 }
 
 // Client messages with the "MANAGER" atom on the root window indicate creation of a new tray.
diff --git a/src/plugins/platforms/xcb/qxcbwmsupport.cpp b/src/plugins/platforms/xcb/qxcbwmsupport.cpp
index 0458be32f6..1be9ab3e05 100644
--- a/src/plugins/platforms/xcb/qxcbwmsupport.cpp
+++ b/src/plugins/platforms/xcb/qxcbwmsupport.cpp
@@ -56,7 +56,7 @@ void QXcbWMSupport::updateNetWMAtoms()
 {
     net_wm_atoms.clear();
 
-    xcb_window_t root = connection()->screens().at(connection()->primaryScreen())->root();
+    xcb_window_t root = connection()->primaryScreen()->root();
     int offset = 0;
     int remaining = 0;
     do {
@@ -90,7 +90,7 @@ void QXcbWMSupport::updateVirtualRoots()
     if (!isSupportedByWM(atom(QXcbAtom::_NET_VIRTUAL_ROOTS)))
         return;
 
-    xcb_window_t root = connection()->screens().at(connection()->primaryScreen())->root();
+    xcb_window_t root = connection()->primaryScreen()->root();
     int offset = 0;
     int remaining = 0;
     do {