Allow DelegateModel-based views to support multiple delegate types

This patch adds a specific abstract QQmlComponent subclass,
QQmlAbstractDelegateComponent, and a default implementation,
DelegateChooser, that, together with the type DelegateChoice
allows determining the delegate type by role and/or index.

The patch also adds QQmlAbstractDelegateComponent support
to QQmlTableInstanceModel, that is a simplified version of
the delegate model, currently only used in the new table view.

DelegateChoosers are intended to behave just like Components
in the context of the view. This means that they can be declared
outside of the view, and also in separate files, and the same
delegate component can be used at the same time in multiple views.

[ChangeLog][QtQuick][Item Views] Added a DelegateChooser Component
to host DelegateChoice instances to choose different delegates in
an Item View (e.g. TableView) depending on model roles.

Done-with: Michael Brasser <michael.brasser@live.com>
Task-number: QTBUG-26681
Change-Id: Ibe24a31daf9142c8a9ff45ef6c65da0aec8a14dc
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

3 files changed, 97 insertions, 0 deletions

diff --git a/src/imports/labsmodels/labsmodels.pro b/src/imports/labsmodels/labsmodels.pro
new file mode 100644
index 0000000000..1795ae5e43
--- /dev/null
+++ b/src/imports/labsmodels/labsmodels.pro
@@ -0,0 +1,11 @@
+CXX_MODULE = qml
+TARGET  = labsmodelsplugin
+TARGETPATH = Qt/labs/qmlmodels
+IMPORT_VERSION = 1.0
+
+SOURCES += \
+    plugin.cpp
+
+QT = qml-private
+
+load(qml_plugin)
diff --git a/src/imports/labsmodels/plugin.cpp b/src/imports/labsmodels/plugin.cpp
new file mode 100644
index 0000000000..e18f08b70b
--- /dev/null
+++ b/src/imports/labsmodels/plugin.cpp
@@ -0,0 +1,83 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the plugins 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 <QtQml/qqmlextensionplugin.h>
+#include <QtQml/qqml.h>
+
+#include <private/qqmlmodelsmodule_p.h>
+
+QT_BEGIN_NAMESPACE
+
+/*!
+    \qmlmodule Qt.labs.qmlmodels 1.0
+    \title Qt QML Models experimental QML Types
+    \ingroup qmlmodules
+    \brief Provides QML experimental types for data models
+    \since 5.12
+
+    This QML module contains experimental QML types related to data models.
+
+    To use the types in this module, import the module with the following line:
+
+    \code
+    import Qt.labs.qmlmodels 1.0
+    \endcode
+*/
+
+//![class decl]
+class QtQmlLabsModelsPlugin : public QQmlExtensionPlugin
+{
+    Q_OBJECT
+    Q_PLUGIN_METADATA(IID QQmlExtensionInterface_iid)
+public:
+    QtQmlLabsModelsPlugin(QObject *parent = nullptr) : QQmlExtensionPlugin(parent) { }
+    void registerTypes(const char *uri) override
+    {
+        Q_ASSERT(QLatin1String(uri) == QLatin1String("Qt.labs.qmlmodels"));
+        Q_UNUSED(uri);
+        QQmlModelsModule::defineLabsModule();
+
+        qmlRegisterModule(uri, 1, 0);
+    }
+};
+//![class decl]
+
+QT_END_NAMESPACE
+
+#include "plugin.moc"
diff --git a/src/imports/labsmodels/qmldir b/src/imports/labsmodels/qmldir
new file mode 100644
index 0000000000..9c735711c4
--- /dev/null
+++ b/src/imports/labsmodels/qmldir
@@ -0,0 +1,3 @@
+module Qt.labs.qmlmodels
+plugin labsmodelsplugin
+classname QtQmlLabsModelsPlugin