QSystemTrayIcon uses D-Bus StatusNotifier on Linux when possible

Implementing org.kde.StatusNotifier DBus interface
http://www.freedesktop.org/wiki/Specifications/StatusNotifierItem/
as well as org.canonical.dbusmenu for the limited purpose of showing
the tray icon's context menu.  If a desktop environment (such as
KDE or Unity) has a StatusNotifierWatcher listening, then tray icon
information is sent to be displayed by the tray implementation
instead of being rendered directly in an XEmbed window.  This is
necessary because some modern tray implementations no longer provide
XEmbed "hosting".

[ChangeLog][QPA][Xcb] QSystemTrayIcon uses StatusNotifier D-Bus
protocol when the desktop environment supports it

Task-number: QTBUG-31762
Done-with: Marco Martin <mart@kde.org>
Change-Id: I3b1f744d621eefc7e9c61d1469460ebfcc77fc54
Reviewed-by: Jørgen Lind <jorgen.lind@theqtcompany.com>
Reviewed-by: Dmitry Shachnev <mitya57@gmail.com>

1 files changed, 127 insertions, 0 deletions

diff --git a/src/platformsupport/dbusmenu/qdbusmenuconnection.cpp b/src/platformsupport/dbusmenu/qdbusmenuconnection.cpp
new file mode 100644
index 0000000000..83ba6054fc
--- /dev/null
+++ b/src/platformsupport/dbusmenu/qdbusmenuconnection.cpp
@@ -0,0 +1,127 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL21$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia. For licensing terms and
+** conditions see http://qt.digia.com/licensing. For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights. These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QT_NO_SYSTEMTRAYICON
+#include "qdbustrayicon_p.h"
+#endif
+#include "qdbusmenuconnection_p.h"
+#include "qdbusmenuadaptor_p.h"
+#include "qdbusplatformmenu_p.h"
+
+#include <QtDBus/QDBusMessage>
+#include <QtDBus/QDBusServiceWatcher>
+#include <QtDBus/QDBusConnectionInterface>
+#include <qdebug.h>
+#include <qcoreapplication.h>
+
+QT_BEGIN_NAMESPACE
+
+Q_DECLARE_LOGGING_CATEGORY(qLcMenu)
+
+const QString StatusNotifierWatcherService = QLatin1String("org.kde.StatusNotifierWatcher");
+const QString StatusNotifierWatcherPath = QLatin1String("/StatusNotifierWatcher");
+const QString StatusNotifierItemPath = QLatin1String("/StatusNotifierItem");
+const QString MenuBarPath = QLatin1String("/MenuBar");
+
+/*!
+    \class QDBusMenuConnection
+    \internal
+    A D-Bus connection which is used for both menu and tray icon services.
+    Connects to the session bus and registers with the respective watcher services.
+*/
+QDBusMenuConnection::QDBusMenuConnection(QObject *parent)
+    : QObject(parent)
+    , m_connection(QDBusConnection::sessionBus())
+    , m_dbusWatcher(new QDBusServiceWatcher(StatusNotifierWatcherService, m_connection, QDBusServiceWatcher::WatchForRegistration, this))
+    , m_watcherRegistered(false)
+{
+#ifndef QT_NO_SYSTEMTRAYICON
+    // Start monitoring if any known tray-related services are registered.
+    if (m_connection.interface()->isServiceRegistered(StatusNotifierWatcherService))
+        m_watcherRegistered = true;
+    else
+        qCDebug(qLcMenu) << "failed to find service" << StatusNotifierWatcherService;
+#endif
+}
+
+void QDBusMenuConnection::dbusError(const QDBusError &error)
+{
+    qWarning() << "QDBusTrayIcon encountered a D-Bus error:" << error;
+}
+
+#ifndef QT_NO_SYSTEMTRAYICON
+bool QDBusMenuConnection::registerTrayIcon(QDBusTrayIcon *item)
+{
+    bool success = connection().registerService(item->instanceId());
+    if (!success) {
+        qWarning() << "failed to register service" << item->instanceId();
+        return false;
+    }
+
+    success = connection().registerObject(StatusNotifierItemPath, item);
+    if (!success) {
+        unregisterTrayIcon(item);
+        qWarning() << "failed to register" << item->instanceId() << StatusNotifierItemPath;
+        return false;
+    }
+
+    if (item->menu()) {
+        success = connection().registerObject(MenuBarPath, item->menu());
+        if (!success) {
+            unregisterTrayIcon(item);
+            qWarning() << "failed to register" << item->instanceId() << MenuBarPath;
+            return false;
+        }
+    }
+
+    QDBusMessage registerMethod = QDBusMessage::createMethodCall(
+                StatusNotifierWatcherService, StatusNotifierWatcherPath, StatusNotifierWatcherService,
+                QLatin1String("RegisterStatusNotifierItem"));
+    registerMethod.setArguments(QVariantList() << item->instanceId());
+    success = m_connection.callWithCallback(registerMethod, this, SIGNAL(trayIconRegistered()), SLOT(dbusError(QDBusError)));
+
+    return success;
+}
+
+bool QDBusMenuConnection::unregisterTrayIcon(QDBusTrayIcon *item)
+{
+    connection().unregisterObject(MenuBarPath);
+    connection().unregisterObject(StatusNotifierItemPath);
+    bool success = connection().unregisterService(item->instanceId());
+    if (!success)
+        qWarning() << "failed to unregister service" << item->instanceId();
+    return success;
+}
+#endif // QT_NO_SYSTEMTRAYICON
+
+QT_END_NAMESPACE