Introduce QAbstractFrameAdvanceService and QTickClockService

This is a first step toward having aspects such as the Renderer aspect provide
a service to drive the QChangeArbiter. This is a step toward having the
QChangeArbiter synched with the vertical refresh rate

Change-Id: Ie4a98e3591e1a9ebb392e1ac4fd3dd1d213538c7
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

10 files changed, 381 insertions, 18 deletions

diff --git a/src/core/aspects/qaspectmanager.cpp b/src/core/aspects/qaspectmanager.cpp
index 510ea1777..d13e9c2d4 100644
--- a/src/core/aspects/qaspectmanager.cpp
+++ b/src/core/aspects/qaspectmanager.cpp
@@ -44,10 +44,12 @@
 #include "qentity.h"
 
 #include <Qt3DCore/qservicelocator.h>
+#include <Qt3DCore/qtickclockservice.h>
 
 #include <Qt3DCore/private/corelogging_p.h>
 #include <Qt3DCore/private/qscheduler_p.h>
 #include <Qt3DCore/private/qtickclock_p.h>
+#include <Qt3DCore/qabstractframeadvanceservice.h>
 #include <QEventLoop>
 #include <QThread>
 #include <QWaitCondition>
@@ -162,11 +164,7 @@ void QAspectManager::exec()
     // Gentlemen, start your engines
     QEventLoop eventLoop;
 
-    //    QElapsedTimer timer;
-    //    timer.start();
-    //    qint64 t(0);
-    QTickClock tickClock;
-    tickClock.start();
+    QAbstractFrameAdvanceService *frameAdvanceService = Q_NULLPTR;
 
     // Enter the main loop
     while (!m_terminated.load())
@@ -177,14 +175,18 @@ void QAspectManager::exec()
         // Only enter main render loop once the renderer and other aspects are initialized
         while (m_runMainLoop.load())
         {
-            // Update the clocks (just main clock for now).
-            // TODO: Add additional clocks
-            qint64 t = tickClock.waitForNextTick();
-            //        qDebug() << "t =" << t / 1000000;
-            //            const qint64 t1 = timer.nsecsElapsed();
-            //            const qint64 dt = t1 - t;
-            //            t = t1;
-            //            qDebug() << "dt =" << dt;
+            // Retrieve the timer service that may have been overridden by one of the
+            // aspects
+            if (!frameAdvanceService) {
+                // Aspects such as the renderer aspect may override the tickService (vsync)
+                // if no aspect did register a tick service, we create a default one
+                if ((frameAdvanceService = m_serviceLocator->service<QAbstractFrameAdvanceService>(QServiceLocator::FrameAdvanceService)) == Q_NULLPTR) {
+                    m_serviceLocator->registerServiceProvider(QServiceLocator::FrameAdvanceService, new QTickClockService());
+                    frameAdvanceService = m_serviceLocator->service<QAbstractFrameAdvanceService>(QServiceLocator::FrameAdvanceService);
+                }
+            }
+
+            qint64 t = frameAdvanceService->waitForNextFrame();
 
             // For each Aspect
             // Ask them to launch set of jobs for the current frame
diff --git a/src/core/aspects/qaspectmanager_p.h b/src/core/aspects/qaspectmanager_p.h
index 0e04ade93..4d072aff0 100644
--- a/src/core/aspects/qaspectmanager_p.h
+++ b/src/core/aspects/qaspectmanager_p.h
@@ -45,7 +45,6 @@
 
 QT_BEGIN_NAMESPACE
 
-class QWaitCondition;
 class QSurface;
 
 namespace Qt3D {
diff --git a/src/core/services/qabstractframeadvanceservice.cpp b/src/core/services/qabstractframeadvanceservice.cpp
new file mode 100644
index 000000000..6f438b55b
--- /dev/null
+++ b/src/core/services/qabstractframeadvanceservice.cpp
@@ -0,0 +1,82 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 Paul Lemire
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the Qt3D 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 "qabstractframeadvanceservice.h"
+#include "qabstractframeadvanceservice_p.h"
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3D {
+
+/*!
+    \class Qt3D::QAbstractFrameAdvanceServicePrivate
+    \internal
+*/
+
+/*!
+    \class Qt3D::QAbstractFrameAdvanceService
+    \inmodule Qt3DCore
+    \brief Interface for a Qt3D frame advance service
+
+    This is an interface class that should be subclassed by providers of the
+    frame advance service. When used with the Renderer aspect, the aspect needs to
+    be the one providing the ticks depending on the vertical refresh rate. When
+    used with no Renderer aspect, a default tick clock implementation can be
+    used.
+*/
+
+
+QAbstractFrameAdvanceService::QAbstractFrameAdvanceService(const QString &description)
+    : QAbstractServiceProvider(QServiceLocator::FrameAdvanceService, description)
+{
+
+}
+
+QAbstractFrameAdvanceService::QAbstractFrameAdvanceService(QAbstractFrameAdvanceServicePrivate &dd)
+    : QAbstractServiceProvider(dd)
+{
+
+}
+
+/*!
+    \fn qint64 Qt3D::QAbstractTickClockService::waitForNextTick()
+
+    Returns the current time, the call may be blocking if waiting for a tick.
+*/
+
+} // Qt3D
+
+QT_END_NAMESPACE
diff --git a/src/core/services/qabstractframeadvanceservice.h b/src/core/services/qabstractframeadvanceservice.h
new file mode 100644
index 000000000..9bb1d6e73
--- /dev/null
+++ b/src/core/services/qabstractframeadvanceservice.h
@@ -0,0 +1,65 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 Paul Lemire
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the Qt3D 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 QT3D_QABSTRACTFRAMEADVANCESERVICE
+#define QT3D_QABSTRACTFRAMEADVANCESERVICE
+
+#include <Qt3DCore/qt3dcore_global.h>
+#include <Qt3DCore/qservicelocator.h>
+#include <QString>
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3D {
+
+class QAbstractFrameAdvanceServicePrivate;
+
+class QT3DCORESHARED_EXPORT QAbstractFrameAdvanceService : public QAbstractServiceProvider
+{
+public:
+    virtual qint64 waitForNextFrame() = 0;
+
+protected:
+    QAbstractFrameAdvanceService(const QString &description = QString());
+    QAbstractFrameAdvanceService(QAbstractFrameAdvanceServicePrivate &dd);
+};
+
+} // Qt3D
+
+QT_END_NAMESPACE
+
+#endif // QT3D_QABSTRACTFRAMEADVANCESERVICE
+
diff --git a/src/core/services/qabstractframeadvanceservice_p.h b/src/core/services/qabstractframeadvanceservice_p.h
new file mode 100644
index 000000000..67bdd97d2
--- /dev/null
+++ b/src/core/services/qabstractframeadvanceservice_p.h
@@ -0,0 +1,61 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 Paul Lemire
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the Qt3D 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 QT3D_QABSTRACTFRAMEADVANCESERVICE_P_H
+#define QT3D_QABSTRACTFRAMEADVANCESERVICE_P_H
+
+#include <Qt3DCore/qt3dcore_global.h>
+#include <Qt3DCore/private/qabstractserviceprovider_p.h>
+#include <Qt3DCore/qservicelocator.h>
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3D {
+
+class QAbstractFrameAdvanceServicePrivate : public QAbstractServiceProviderPrivate
+{
+public:
+    QAbstractFrameAdvanceServicePrivate(const QString &description)
+        : QAbstractServiceProviderPrivate(QServiceLocator::FrameAdvanceService, description)
+    {}
+};
+
+}
+
+QT_END_NAMESPACE
+
+#endif // QT3D_QABSTRACTFRAMEADVANCESERVICE_P_H
+
diff --git a/src/core/services/qservicelocator.cpp b/src/core/services/qservicelocator.cpp
index 706114378..8ceb3879e 100644
--- a/src/core/services/qservicelocator.cpp
+++ b/src/core/services/qservicelocator.cpp
@@ -205,7 +205,6 @@ QAbstractServiceProvider *QServiceLocator::_q_getServiceHelper(int type)
         return systemInformation();
     case OpenGLInformation:
         return openGLInformation();
-
     default:
         return d->m_services.value(type, Q_NULLPTR);
     }
diff --git a/src/core/services/qservicelocator.h b/src/core/services/qservicelocator.h
index ab8ddb413..4f234892f 100644
--- a/src/core/services/qservicelocator.h
+++ b/src/core/services/qservicelocator.h
@@ -80,7 +80,8 @@ public:
 #if !defined(Q_QDOC)
         DefaultServiceCount, // Add additional default services before here
 #endif
-        UserService = 256
+        FrameAdvanceService,
+        UserService = 256,
     };
 
     void registerServiceProvider(int serviceType, QAbstractServiceProvider *provider);
diff --git a/src/core/services/qtickclockservice.cpp b/src/core/services/qtickclockservice.cpp
new file mode 100644
index 000000000..c23c33cb5
--- /dev/null
+++ b/src/core/services/qtickclockservice.cpp
@@ -0,0 +1,86 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 Paul Lemire
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the Qt3D 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 "qtickclockservice.h"
+#include "qtickclock_p.h"
+#include "qabstractframeadvanceservice_p.h"
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3D {
+/*!
+    \class Qt3D::QTickClockServicePrivate
+    \internal
+*/
+
+class QTickClockServicePrivate : public QAbstractFrameAdvanceServicePrivate
+{
+public:
+    QTickClockServicePrivate()
+        : QAbstractFrameAdvanceServicePrivate(QStringLiteral("Default Frame Advance Service implementation"))
+    {
+        m_clock.setTickFrequency(60);
+        m_clock.start();
+    }
+
+    QTickClock m_clock;
+};
+
+/*!
+    \class Qt3D::QTickClockService
+    \inmodule Qt3DCore
+    \brief Default Qt3D::QAbstractFrameAdvanceService implementation.
+
+    This default Qt3D::QAbstractFrameAdvanceService implementation has a frequency of 60 Hz.
+*/
+QTickClockService::QTickClockService()
+    : QAbstractFrameAdvanceService(*new QTickClockServicePrivate())
+{
+}
+
+QTickClockService::~QTickClockService()
+{
+}
+
+qint64 QTickClockService::waitForNextFrame()
+{
+    Q_D(QTickClockService);
+    return d->m_clock.waitForNextTick();
+}
+
+} // Qt3D
+
+QT_END_NAMESPACE
diff --git a/src/core/services/qtickclockservice.h b/src/core/services/qtickclockservice.h
new file mode 100644
index 000000000..59adee9a1
--- /dev/null
+++ b/src/core/services/qtickclockservice.h
@@ -0,0 +1,63 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 Paul Lemire
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the Qt3D 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 QT3D_QTICKCLOCKSERVICE_H
+#define QT3D_QTICKCLOCKSERVICE_H
+
+#include "qabstractframeadvanceservice.h"
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3D {
+
+class QTickClockServicePrivate;
+
+class QTickClockService : public QAbstractFrameAdvanceService
+{
+public:
+    QTickClockService();
+    ~QTickClockService();
+
+    qint64 waitForNextFrame() Q_DECL_FINAL;
+
+    Q_DECLARE_PRIVATE(QTickClockService)
+};
+
+} // Qt3D
+
+QT_END_NAMESPACE
+
+#endif // QT3D_QTICKCLOCKSERVICE_H
diff --git a/src/core/services/services.pri b/src/core/services/services.pri
index 547ec6d32..370f3c2d6 100644
--- a/src/core/services/services.pri
+++ b/src/core/services/services.pri
@@ -2,7 +2,9 @@
 SOURCES += \
     $$PWD/qservicelocator.cpp \
     $$PWD/qsysteminformationservice.cpp \
-    $$PWD/qopenglinformationservice.cpp
+    $$PWD/qopenglinformationservice.cpp \
+    $$PWD/qtickclockservice.cpp \
+    $$PWD/qabstractframeadvanceservice.cpp
 
 HEADERS += \
     $$PWD/qservicelocator.h \
@@ -11,6 +13,9 @@ HEADERS += \
     $$PWD/qopenglinformationservice.h \
     $$PWD/qabstractserviceprovider_p.h \
     $$PWD/qsysteminformationservice_p.h \
-    $$PWD/qopenglinformationservice_p.h
+    $$PWD/qopenglinformationservice_p.h \
+    $$PWD/qtickclockservice.h \
+    $$PWD/qabstractframeadvanceservice.h \
+    $$PWD/qabstractframeadvanceservice_p.h
 
 INCLUDEPATH += $$PWD