[Shader Graph Gen.] Introduce QShaderGraphLoader

This class allows to load a shader graph from its JSON representation.
To avoid duplicating the shader snippets inside of the JSON which would
be a maintenance nightmare, we instead allow to register a set of node
prototypes by their name and only refer to said names inside the JSON.

Change-Id: I3e7b39e8b3c25f51f331a0a59dda883ac8e2bc57
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

3 files changed, 305 insertions, 0 deletions

diff --git a/src/gui/util/qshadergraphloader.cpp b/src/gui/util/qshadergraphloader.cpp
new file mode 100644
index 0000000000..d246654b9c
--- /dev/null
+++ b/src/gui/util/qshadergraphloader.cpp
@@ -0,0 +1,204 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 Klaralvdalens Datakonsult AB (KDAB).
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtGui 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.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qshadergraphloader_p.h"
+
+#include <QtCore/qdebug.h>
+#include <QtCore/qiodevice.h>
+#include <QtCore/qjsonarray.h>
+#include <QtCore/qjsondocument.h>
+#include <QtCore/qjsonobject.h>
+
+QT_BEGIN_NAMESPACE
+
+QShaderGraphLoader::QShaderGraphLoader() Q_DECL_NOTHROW
+    : m_status(Null),
+      m_device(nullptr)
+{
+}
+
+QShaderGraphLoader::Status QShaderGraphLoader::status() const Q_DECL_NOTHROW
+{
+    return m_status;
+}
+
+QShaderGraph QShaderGraphLoader::graph() const Q_DECL_NOTHROW
+{
+    return m_graph;
+}
+
+QIODevice *QShaderGraphLoader::device() const Q_DECL_NOTHROW
+{
+    return m_device;
+}
+
+void QShaderGraphLoader::setDevice(QIODevice *device) Q_DECL_NOTHROW
+{
+    m_device = device;
+    m_graph = QShaderGraph();
+    m_status = !m_device ? Null
+             : (m_device->openMode() & QIODevice::ReadOnly) ? Waiting
+             : Error;
+}
+
+QHash<QString, QShaderNode> QShaderGraphLoader::prototypes() const Q_DECL_NOTHROW
+{
+    return m_prototypes;
+}
+
+void QShaderGraphLoader::setPrototypes(const QHash<QString, QShaderNode> &prototypes) Q_DECL_NOTHROW
+{
+    m_prototypes = prototypes;
+}
+
+void QShaderGraphLoader::load()
+{
+    if (m_status == Error)
+        return;
+
+    auto error = QJsonParseError();
+    const auto document = QJsonDocument::fromJson(m_device->readAll(), &error);
+
+    if (error.error != QJsonParseError::NoError) {
+        qWarning() << "Invalid JSON document:" << error.errorString();
+        m_status = Error;
+        return;
+    }
+
+    if (document.isEmpty() || !document.isObject()) {
+        qWarning() << "Invalid JSON document, root should be an object";
+        m_status = Error;
+        return;
+    }
+
+    const auto root = document.object();
+
+    const auto nodesValue = root.value(QStringLiteral("nodes"));
+    if (!nodesValue.isArray()) {
+        qWarning() << "Invalid nodes property, should be an array";
+        m_status = Error;
+        return;
+    }
+
+    const auto edgesValue = root.value(QStringLiteral("edges"));
+    if (!edgesValue.isArray()) {
+        qWarning() << "Invalid edges property, should be an array";
+        m_status = Error;
+        return;
+    }
+
+    bool hasError = false;
+
+    const auto nodes = nodesValue.toArray();
+    for (const auto &nodeValue : nodes) {
+        if (!nodeValue.isObject()) {
+            qWarning() << "Invalid node found";
+            hasError = true;
+            continue;
+        }
+
+        const auto nodeObject = nodeValue.toObject();
+
+        const auto uuidString = nodeObject.value(QStringLiteral("uuid")).toString();
+        const auto uuid = QUuid(uuidString);
+        if (uuid.isNull()) {
+            qWarning() << "Invalid UUID found in node:" << uuidString;
+            hasError = true;
+            continue;
+        }
+
+        const auto type = nodeObject.value(QStringLiteral("type")).toString();
+        if (!m_prototypes.contains(type)) {
+            qWarning() << "Unsupported node type found:" << type;
+            hasError = true;
+            continue;
+        }
+
+        auto node = m_prototypes.value(type);
+        node.setUuid(uuid);
+        m_graph.addNode(node);
+    }
+
+    const auto edges = edgesValue.toArray();
+    for (const auto &edgeValue : edges) {
+        if (!edgeValue.isObject()) {
+            qWarning() << "Invalid edge found";
+            hasError = true;
+            continue;
+        }
+
+        const auto edgeObject = edgeValue.toObject();
+
+        const auto sourceUuidString = edgeObject.value(QStringLiteral("sourceUuid")).toString();
+        const auto sourceUuid = QUuid(sourceUuidString);
+        if (sourceUuid.isNull()) {
+            qWarning() << "Invalid source UUID found in edge:" << sourceUuidString;
+            hasError = true;
+            continue;
+        }
+
+        const auto sourcePort = edgeObject.value(QStringLiteral("sourcePort")).toString();
+
+        const auto targetUuidString = edgeObject.value(QStringLiteral("targetUuid")).toString();
+        const auto targetUuid = QUuid(targetUuidString);
+        if (targetUuid.isNull()) {
+            qWarning() << "Invalid target UUID found in edge:" << targetUuidString;
+            hasError = true;
+            continue;
+        }
+
+        const auto targetPort = edgeObject.value(QStringLiteral("targetPort")).toString();
+
+        auto edge = QShaderGraph::Edge();
+        edge.sourceNodeUuid = sourceUuid;
+        edge.sourcePortName = sourcePort;
+        edge.targetNodeUuid = targetUuid;
+        edge.targetPortName = targetPort;
+        m_graph.addEdge(edge);
+    }
+
+    if (hasError) {
+        m_status = Error;
+        m_graph = QShaderGraph();
+    } else {
+        m_status = Ready;
+    }
+}
+
+QT_END_NAMESPACE
diff --git a/src/gui/util/qshadergraphloader_p.h b/src/gui/util/qshadergraphloader_p.h
new file mode 100644
index 0000000000..97cbd8d18c
--- /dev/null
+++ b/src/gui/util/qshadergraphloader_p.h
@@ -0,0 +1,99 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 Klaralvdalens Datakonsult AB (KDAB).
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtGui 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 QSHADERGRAPHLOADER_P_H
+#define QSHADERGRAPHLOADER_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 <QtGui/private/qtguiglobal_p.h>
+
+#include <QtGui/private/qshadergraph_p.h>
+
+QT_BEGIN_NAMESPACE
+
+class QIODevice;
+
+class QShaderGraphLoader
+{
+public:
+    enum Status : char {
+        Null,
+        Waiting,
+        Ready,
+        Error
+    };
+
+    Q_GUI_EXPORT QShaderGraphLoader() Q_DECL_NOTHROW;
+
+    Q_GUI_EXPORT Status status() const Q_DECL_NOTHROW;
+    Q_GUI_EXPORT QShaderGraph graph() const Q_DECL_NOTHROW;
+
+    Q_GUI_EXPORT QIODevice *device() const Q_DECL_NOTHROW;
+    Q_GUI_EXPORT void setDevice(QIODevice *device) Q_DECL_NOTHROW;
+
+    Q_GUI_EXPORT QHash<QString, QShaderNode> prototypes() const Q_DECL_NOTHROW;
+    Q_GUI_EXPORT void setPrototypes(const QHash<QString, QShaderNode> &prototypes) Q_DECL_NOTHROW;
+
+    Q_GUI_EXPORT void load();
+
+private:
+    Status m_status;
+    QIODevice *m_device;
+    QHash<QString, QShaderNode> m_prototypes;
+    QShaderGraph m_graph;
+};
+
+Q_DECLARE_TYPEINFO(QShaderGraphLoader, Q_MOVABLE_TYPE);
+
+QT_END_NAMESPACE
+
+Q_DECLARE_METATYPE(QShaderGraphLoader)
+Q_DECLARE_METATYPE(QShaderGraphLoader::Status)
+
+#endif // QSHADERGRAPHLOADER_P_H
diff --git a/src/gui/util/util.pri b/src/gui/util/util.pri
index e7feda9a4a..bb7a802fd8 100644
--- a/src/gui/util/util.pri
+++ b/src/gui/util/util.pri
@@ -10,6 +10,7 @@ HEADERS += \
         util/qshaderformat_p.h \
         util/qshadergenerator_p.h \
         util/qshadergraph_p.h \
+        util/qshadergraphloader_p.h \
         util/qshadernode_p.h \
         util/qshadernodeport_p.h
 
@@ -22,5 +23,6 @@ SOURCES += \
         util/qshaderformat.cpp \
         util/qshadergenerator.cpp \
         util/qshadergraph.cpp \
+        util/qshadergraphloader.cpp \
         util/qshadernode.cpp \
         util/qshadernodeport.cpp