Add internal QQuickStylePlugin

This is a common base class for QtQuickMaterialStylePlugin and
QtQuickUniversalStylePlugin that takes care of the proxy theme
installation and manages its life time by using a scoped pointer.

Change-Id: I2cbe38287565d284b18fab4265456a41a2dbd8d4
Reviewed-by: Mitch Curtis <mitch.curtis@theqtcompany.com>

3 files changed, 162 insertions, 0 deletions

diff --git a/src/controls/controls.pri b/src/controls/controls.pri
index dc1920fb..5424c5c7 100644
--- a/src/controls/controls.pri
+++ b/src/controls/controls.pri
@@ -4,6 +4,7 @@ HEADERS += \
     $$PWD/qquickproxytheme_p.h \
     $$PWD/qquickstyle.h \
     $$PWD/qquickstyleattached_p.h \
+    $$PWD/qquickstyleplugin_p.h \
     $$PWD/qquickstyleselector_p.h \
     $$PWD/qquickstyleselector_p_p.h \
     $$PWD/qquickpaddedrectangle_p.h
@@ -14,5 +15,6 @@ SOURCES += \
     $$PWD/qquickproxytheme.cpp \
     $$PWD/qquickstyle.cpp \
     $$PWD/qquickstyleattached.cpp \
+    $$PWD/qquickstyleplugin.cpp \
     $$PWD/qquickstyleselector.cpp \
     $$PWD/qquickpaddedrectangle.cpp
diff --git a/src/controls/qquickstyleplugin.cpp b/src/controls/qquickstyleplugin.cpp
new file mode 100644
index 00000000..ceb6531e
--- /dev/null
+++ b/src/controls/qquickstyleplugin.cpp
@@ -0,0 +1,81 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the Qt Labs Controls module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL3$
+** 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 The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/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 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPLv3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or later as published by the Free
+** Software Foundation and appearing in the file LICENSE.GPL included in
+** the packaging of this file. Please review the following information to
+** ensure the GNU General Public License version 2.0 requirements will be
+** met: http://www.gnu.org/licenses/gpl-2.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qquickstyleplugin_p.h"
+#include "qquickproxytheme_p.h"
+#include "qquickstyle.h"
+
+#include <QtGui/private/qguiapplication_p.h>
+
+QT_BEGIN_NAMESPACE
+
+QQuickStylePlugin::QQuickStylePlugin(QObject *parent) : QQmlExtensionPlugin(parent)
+{
+}
+
+QQuickStylePlugin::~QQuickStylePlugin()
+{
+}
+
+void QQuickStylePlugin::registerTypes(const char *uri)
+{
+    Q_UNUSED(uri);
+}
+
+void QQuickStylePlugin::initializeEngine(QQmlEngine *engine, const char *uri)
+{
+    Q_UNUSED(engine);
+    Q_UNUSED(uri);
+
+    const QString style = name();
+    if (!style.isEmpty() && style.compare(QQuickStyle::name(), Qt::CaseInsensitive) == 0) {
+        m_theme.reset(createTheme());
+        if (m_theme)
+            QGuiApplicationPrivate::platform_theme = m_theme.data();
+    }
+}
+
+QString QQuickStylePlugin::name() const
+{
+    return QString();
+}
+
+QQuickProxyTheme *QQuickStylePlugin::createTheme() const
+{
+    return nullptr;
+}
+
+QT_END_NAMESPACE
diff --git a/src/controls/qquickstyleplugin_p.h b/src/controls/qquickstyleplugin_p.h
new file mode 100644
index 00000000..93be0aa8
--- /dev/null
+++ b/src/controls/qquickstyleplugin_p.h
@@ -0,0 +1,79 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the Qt Labs Controls module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL3$
+** 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 The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/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 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPLv3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or later as published by the Free
+** Software Foundation and appearing in the file LICENSE.GPL included in
+** the packaging of this file. Please review the following information to
+** ensure the GNU General Public License version 2.0 requirements will be
+** met: http://www.gnu.org/licenses/gpl-2.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QQUICKSTYLEPLUGIN_P_H
+#define QQUICKSTYLEPLUGIN_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtCore/qscopedpointer.h>
+#include <QtQml/qqmlextensionplugin.h>
+#include <QtQuickControls/private/qtquickcontrolsglobal_p.h>
+
+QT_BEGIN_NAMESPACE
+
+class QQuickProxyTheme;
+
+class Q_QUICKCONTROLS_PRIVATE_EXPORT QQuickStylePlugin : public QQmlExtensionPlugin
+{
+    Q_OBJECT
+
+public:
+    explicit QQuickStylePlugin(QObject *parent = nullptr);
+    ~QQuickStylePlugin();
+
+    void registerTypes(const char *uri) override;
+    void initializeEngine(QQmlEngine *engine, const char *uri) override;
+
+    virtual QString name() const;
+    virtual QQuickProxyTheme *createTheme() const;
+
+private:
+    QScopedPointer<QQuickProxyTheme> m_theme;
+};
+
+QT_END_NAMESPACE
+
+#endif // QQUICKSTYLEPLUGIN_P_H