Support transient enablement in QSubtreeEnabler

Change-Id: I422cf0fb0991319b0f54e5a26b9b3694cb093454
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

8 files changed, 240 insertions, 6 deletions

diff --git a/src/render/framegraph/framegraph.pri b/src/render/framegraph/framegraph.pri
index e833d4590..bb833422f 100644
--- a/src/render/framegraph/framegraph.pri
+++ b/src/render/framegraph/framegraph.pri
@@ -68,6 +68,7 @@ HEADERS += \
     $$PWD/qnopicking.h \
     $$PWD/nopicking_p.h \
     $$PWD/qsubtreeenabler.h \
+    $$PWD/qsubtreeenabler_p.h \
     $$PWD/subtreeenabler_p.h
 
 SOURCES += \
diff --git a/src/render/framegraph/framegraphvisitor.cpp b/src/render/framegraph/framegraphvisitor.cpp
index 5ccad87e1..9af0297a0 100644
--- a/src/render/framegraph/framegraphvisitor.cpp
+++ b/src/render/framegraph/framegraphvisitor.cpp
@@ -41,6 +41,7 @@
 #include "framegraphvisitor_p.h"
 
 #include "framegraphnode_p.h"
+#include "subtreeenabler_p.h"
 #include <Qt3DRender/private/renderer_p.h>
 #include <Qt3DRender/private/managers_p.h>
 #include <QThreadPool>
@@ -61,6 +62,7 @@ FrameGraphVisitor::FrameGraphVisitor(const FrameGraphManager *manager)
 QVector<FrameGraphNode *> FrameGraphVisitor::traverse(FrameGraphNode *root)
 {
     m_leaves.clear();
+    m_enablersToDisable.clear();
 
     Q_ASSERT_X(root, Q_FUNC_INFO, "The FrameGraphRoot is null");
 
@@ -72,10 +74,23 @@ QVector<FrameGraphNode *> FrameGraphVisitor::traverse(FrameGraphNode *root)
     return m_leaves;
 }
 
+// intended to be called after traverse
+// (returns data that is captured during the traverse)
+QVector<FrameGraphNode *> &&FrameGraphVisitor::takeEnablersToDisable()
+{
+    return std::move(m_enablersToDisable);
+}
+
 void FrameGraphVisitor::visit(Render::FrameGraphNode *node)
 {
-    if (node->nodeType() == Render::FrameGraphNode::SubtreeEnabler && !node->isEnabled())
-        return;
+    if (node->nodeType() == Render::FrameGraphNode::SubtreeEnabler) {
+        if (!node->isEnabled())
+            return;
+        if (static_cast<SubtreeEnabler*>(node)->enablement() == QSubtreeEnabler::SingleShot) {
+            node->setEnabled(false);
+            m_enablersToDisable.push_back(node);
+        }
+    }
 
     // Recurse to children (if we have any), otherwise if this is a leaf node,
     // initiate a rendering from the current camera
diff --git a/src/render/framegraph/framegraphvisitor_p.h b/src/render/framegraph/framegraphvisitor_p.h
index f4c0d7796..5706a169d 100644
--- a/src/render/framegraph/framegraphvisitor_p.h
+++ b/src/render/framegraph/framegraphvisitor_p.h
@@ -72,12 +72,14 @@ public:
     explicit FrameGraphVisitor(const FrameGraphManager *nodeManager);
 
     QVector<FrameGraphNode *> traverse(FrameGraphNode *root);
+    QVector<FrameGraphNode *> &&takeEnablersToDisable();
 
 private:
     void visit(Render::FrameGraphNode *node);
 
     const FrameGraphManager *m_manager;
     QVector<FrameGraphNode *> m_leaves;
+    QVector<FrameGraphNode *> m_enablersToDisable;
 };
 
 } // namespace Render
diff --git a/src/render/framegraph/qsubtreeenabler.cpp b/src/render/framegraph/qsubtreeenabler.cpp
index 5355b6fbd..d2c25852b 100644
--- a/src/render/framegraph/qsubtreeenabler.cpp
+++ b/src/render/framegraph/qsubtreeenabler.cpp
@@ -37,8 +37,8 @@
 **
 ****************************************************************************/
 
-#include <Qt3DRender/qsubtreeenabler.h>
-#include <Qt3DRender/private/qframegraphnode_p.h>
+#include "qsubtreeenabler_p.h"
+#include <Qt3DRender/qframegraphnodecreatedchange.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -100,7 +100,7 @@ namespace Qt3DRender
  */
 
 QSubtreeEnabler::QSubtreeEnabler(Qt3DCore::QNode *parent)
-    : QFrameGraphNode(*new QFrameGraphNodePrivate, parent)
+    : QFrameGraphNode(*new QSubtreeEnablerPrivate, parent)
 {
 }
 
@@ -108,6 +108,78 @@ QSubtreeEnabler::~QSubtreeEnabler()
 {
 }
 
+/*!
+    \enum QSubtreeEnabler::Enablement
+
+    Specifies whether subtree enablement is persistent or transient.
+
+    \value Persistent
+    The value of enabled is persistent. This is the default.
+
+    \value SingleShot
+    The value of enabled will last for a single frame and then be reset to false.
+    This might be used for a subtree drawing to an FBO, for example, to only update
+    the FBO when the relevant portions of the scene changed.
+*/
+
+/*!
+    \qmlproperty enumeration Qt3D.Render::SubtreeEnabler::enablement
+    Controls whether subtree enablement is persistent or transient.
+
+    \value Persistent
+    The value of enabled is persistent. This is the default.
+
+    \value SingleShot
+    The value of enabled will last for a single frame and then be reset to false.
+    This might be used for a subtree drawing to an FBO, for example, to only update
+    the FBO when the relevant portions of the scene changed.
+*/
+
+/*!
+    \property Qt3DRender::QSubtreeEnabler::enablement
+    Controls whether subtree enablement is persistent or transient.
+*/
+QSubtreeEnabler::Enablement QSubtreeEnabler::enablement() const
+{
+    Q_D(const QSubtreeEnabler);
+    return d->m_enablement;
+}
+
+void QSubtreeEnabler::setEnablement(QSubtreeEnabler::Enablement enablement)
+{
+    Q_D(QSubtreeEnabler);
+    if (d->m_enablement == enablement)
+        return;
+    d->m_enablement = enablement;
+    emit enablementChanged(d->m_enablement);
+}
+
+/*!
+    \qmlmethod void Qt3D.Render::SubtreeEnabler::requestUpdate()
+    Requests that the subtree be enabled.
+
+    A conveninence method intended to be used with \c SingleShot enablement.
+ */
+
+/*!
+    Requests that the subtree be enabled.
+
+    A conveninence method intended to be used with \c SingleShot enablement.
+ */
+void QSubtreeEnabler::requestUpdate()
+{
+    setEnabled(true);
+}
+
+Qt3DCore::QNodeCreatedChangeBasePtr QSubtreeEnabler::createNodeCreationChange() const
+{
+    auto creationChange = QFrameGraphNodeCreatedChangePtr<QSubtreeEnablerData>::create(this);
+    auto &data = creationChange->data;
+    Q_D(const QSubtreeEnabler);
+    data.enablement = d->m_enablement;
+    return creationChange;
+}
+
 } //Qt3DRender
 
 QT_END_NAMESPACE
diff --git a/src/render/framegraph/qsubtreeenabler.h b/src/render/framegraph/qsubtreeenabler.h
index 82334b3da..558e3b8b7 100644
--- a/src/render/framegraph/qsubtreeenabler.h
+++ b/src/render/framegraph/qsubtreeenabler.h
@@ -47,12 +47,33 @@ QT_BEGIN_NAMESPACE
 namespace Qt3DRender
 {
 
+class QSubtreeEnablerPrivate;
+
 class Q_3DRENDERSHARED_EXPORT QSubtreeEnabler : public QFrameGraphNode
 {
     Q_OBJECT
+    Q_PROPERTY(Enablement enablement READ enablement WRITE setEnablement NOTIFY enablementChanged)
 public:
     explicit QSubtreeEnabler(Qt3DCore::QNode *parent = nullptr);
     ~QSubtreeEnabler();
+
+    enum Enablement {
+        Persistent,
+        SingleShot
+    };
+    Q_ENUM(Enablement)
+
+    Enablement enablement() const;
+    void setEnablement(Enablement enablement);
+
+    Q_INVOKABLE void requestUpdate();
+
+Q_SIGNALS:
+    void enablementChanged(Qt3DRender::QSubtreeEnabler::Enablement enablement);
+
+private:
+    Q_DECLARE_PRIVATE(QSubtreeEnabler)
+    Qt3DCore::QNodeCreatedChangeBasePtr createNodeCreationChange() const override;
 };
 
 } //Qt3DRender
diff --git a/src/render/framegraph/qsubtreeenabler_p.h b/src/render/framegraph/qsubtreeenabler_p.h
new file mode 100644
index 000000000..72354fe89
--- /dev/null
+++ b/src/render/framegraph/qsubtreeenabler_p.h
@@ -0,0 +1,80 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 Ford Motor Company
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the Qt3D module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://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.LGPL3 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-3.0.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 (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QT3DRENDER_QSUBTREEENABLER_P_H
+#define QT3DRENDER_QSUBTREEENABLER_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists for the convenience
+// of other Qt classes.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include "qsubtreeenabler.h"
+#include <private/qframegraphnode_p.h>
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3DRender {
+
+class QSubtreeEnablerPrivate : public QFrameGraphNodePrivate
+{
+public:
+    QSubtreeEnablerPrivate() = default;
+
+    QSubtreeEnabler::Enablement m_enablement = QSubtreeEnabler::Persistent;
+
+    Q_DECLARE_PUBLIC(QSubtreeEnabler)
+};
+
+struct QSubtreeEnablerData
+{
+    QSubtreeEnabler::Enablement enablement;
+};
+
+} // namespace Qt3DRender
+
+QT_END_NAMESPACE
+
+#endif // QT3DRENDER_QSUBTREEENABLER_P_H
diff --git a/src/render/framegraph/subtreeenabler.cpp b/src/render/framegraph/subtreeenabler.cpp
index e4b4e4ba7..160e1a5b5 100644
--- a/src/render/framegraph/subtreeenabler.cpp
+++ b/src/render/framegraph/subtreeenabler.cpp
@@ -38,6 +38,8 @@
 ****************************************************************************/
 
 #include "subtreeenabler_p.h"
+#include <Qt3DRender/private/qsubtreeenabler_p.h>
+#include <Qt3DCore/qpropertyupdatedchange.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -46,10 +48,43 @@ namespace Qt3DRender {
 namespace Render {
 
 SubtreeEnabler::SubtreeEnabler()
-    : FrameGraphNode(FrameGraphNode::SubtreeEnabler)
+    : FrameGraphNode(FrameGraphNode::SubtreeEnabler, FrameGraphNode::ReadWrite)
 {
 }
 
+void SubtreeEnabler::sendDisableToFrontend()
+{
+    if (m_enablement != QSubtreeEnabler::SingleShot)
+        return;
+
+    if (isEnabled())
+        return;
+
+    auto e = Qt3DCore::QPropertyUpdatedChangePtr::create(peerId());
+    e->setDeliveryFlags(Qt3DCore::QSceneChange::DeliverToAll);
+    e->setPropertyName("enabled");
+    e->setValue(false);
+    notifyObservers(e);
+}
+
+void SubtreeEnabler::syncFromFrontEnd(const Qt3DCore::QNode *frontEnd, bool firstTime)
+{
+    const QSubtreeEnabler *node = qobject_cast<const QSubtreeEnabler *>(frontEnd);
+    if (!node)
+        return;
+
+    if (node->isEnabled() != isEnabled())
+        markDirty(AbstractRenderer::AllDirty);
+
+    FrameGraphNode::syncFromFrontEnd(frontEnd, firstTime);
+
+    const auto enablement = node->enablement();
+    if (enablement != m_enablement) {
+        m_enablement = enablement;
+        markDirty(AbstractRenderer::FrameGraphDirty);
+    }
+}
+
 } //Render
 
 } //Qt3DRender
diff --git a/src/render/framegraph/subtreeenabler_p.h b/src/render/framegraph/subtreeenabler_p.h
index 22782da12..2de8dfabf 100644
--- a/src/render/framegraph/subtreeenabler_p.h
+++ b/src/render/framegraph/subtreeenabler_p.h
@@ -51,6 +51,7 @@
 // We mean it.
 //
 
+#include <Qt3DRender/qsubtreeenabler.h>
 #include <Qt3DRender/private/framegraphnode_p.h>
 
 QT_BEGIN_NAMESPACE
@@ -63,6 +64,13 @@ class Q_AUTOTEST_EXPORT SubtreeEnabler : public FrameGraphNode
 {
 public:
     SubtreeEnabler();
+    QSubtreeEnabler::Enablement enablement() const { return m_enablement; }
+    void sendDisableToFrontend();
+
+    void syncFromFrontEnd(const Qt3DCore::QNode *frontEnd, bool firstTime) override;
+
+private:
+    QSubtreeEnabler::Enablement m_enablement = QSubtreeEnabler::Persistent;
 };
 
 } //Render