Add new QML example to publish topics/messages

New QML-based example that allows to send topic/message (along with QoS
and retain properties) based mainly on existing QML subscription
example, in order to provide a way for showing the whole
publish/subscription model in MQTT via QML applications.

Change-Id: I1673177371297969098adf635e7a582c25e4d0c7
Reviewed-by: Maurice Kalinowski <maurice.kalinowski@qt.io>

7 files changed, 461 insertions, 0 deletions

diff --git a/examples/mqtt/mqtt.pro b/examples/mqtt/mqtt.pro
index 767ed5e..c734248 100644
--- a/examples/mqtt/mqtt.pro
+++ b/examples/mqtt/mqtt.pro
@@ -4,4 +4,5 @@ SUBDIRS += \
            subscriptions
 
 qtHaveModule(quick): SUBDIRS += quicksubscription
+qtHaveModule(quick): SUBDIRS += quickpublication
 qtHaveModule(websockets): SUBDIRS += websocketsubscription
diff --git a/examples/mqtt/quickpublication/main.cpp b/examples/mqtt/quickpublication/main.cpp
new file mode 100644
index 0000000..a1bd557
--- /dev/null
+++ b/examples/mqtt/quickpublication/main.cpp
@@ -0,0 +1,70 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** 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.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qmlmqttclient.h"
+
+#include <QGuiApplication>
+#include <QQmlApplicationEngine>
+#include <QLoggingCategory>
+
+int main(int argc, char *argv[])
+{
+    QGuiApplication app(argc, argv);
+
+    QQmlApplicationEngine engine;
+
+    qmlRegisterType<QmlMqttClient>("MqttClient", 1, 0, "MqttClient");
+
+    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
+    if (engine.rootObjects().isEmpty())
+        return -1;
+
+    return app.exec();
+}
diff --git a/examples/mqtt/quickpublication/main.qml b/examples/mqtt/quickpublication/main.qml
new file mode 100644
index 0000000..b018e68
--- /dev/null
+++ b/examples/mqtt/quickpublication/main.qml
@@ -0,0 +1,221 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** 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.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+import QtQuick 2.8
+import QtQuick.Window 2.2
+import QtQuick.Controls 2.1
+import QtQuick.Layouts 1.1
+import MqttClient 1.0
+
+Window {
+    visible: true
+    width: 640
+    height: 480
+    title: qsTr("Qt Quick MQTT Publish Example")
+    id: root
+
+    MqttClient {
+        id: client
+        hostname: hostnameField.text
+        port: portField.text
+    }
+
+    ListModel {
+        id: messageModel
+    }
+
+    function addMessage(payload)
+    {
+        messageModel.insert(0, {"payload" : payload})
+
+        if (messageModel.count >= 100)
+            messageModel.remove(99)
+    }
+
+    GridLayout {
+        anchors.fill: parent
+        columns: 2
+
+        Label {
+            text: "Hostname:"
+            enabled: client.state === MqttClient.Disconnected
+        }
+
+        TextField {
+            id: hostnameField
+            Layout.fillWidth: true
+            text: "test.mosquitto.org"
+            placeholderText: "<Enter host running MQTT broker>"
+            enabled: client.state === MqttClient.Disconnected
+        }
+
+        Label {
+            text: "Port:"
+            enabled: client.state === MqttClient.Disconnected
+        }
+
+        TextField {
+            id: portField
+            Layout.fillWidth: true
+            text: "1883"
+            placeholderText: "<Port>"
+            inputMethodHints: Qt.ImhDigitsOnly
+            enabled: client.state === MqttClient.Disconnected
+        }
+
+        Button {
+            id: connectButton
+            Layout.columnSpan: 2
+            text: client.state === MqttClient.Connected ? "Disconnect" : "Connect"
+            onClicked: {
+                if (client.state === MqttClient.Connected)
+                    client.disconnectFromHost()
+                else
+                    client.connectToHost()
+            }
+        }
+
+        RowLayout {
+            enabled: client.state === MqttClient.Connected
+            Layout.columnSpan: 2
+            Layout.fillWidth: true
+
+            Label {
+                text: "Topic:"
+            }
+
+            TextField {
+                id: pubField
+                placeholderText: "<Publication topic>"
+            }
+
+            Label {
+                text: "Message:"
+            }
+
+            TextField {
+                id: msgField
+                placeholderText: "<Publication message>"
+            }
+        }
+
+        RowLayout {
+            enabled: client.state === MqttClient.Connected
+            Layout.columnSpan: 2
+            Layout.fillWidth: true
+
+            Label {
+                text: "QoS:"
+            }
+
+            ComboBox {
+                id: qosItems
+                editable: false
+                model: [0, 1, 2]
+            }
+
+            CheckBox {
+                id: retain
+                checked: false
+                text: "Retain"
+            }
+
+            Button {
+                id: pubButton
+                text: "Publish"
+                onClicked: {
+                    if (pubField.text.length === 0) {
+                        console.log("No payload to send. Skipping publish...")
+                        return
+                    }
+                    client.publish(pubField.text, msgField.text, qosItems.currentText, retain.checked)
+                    addMessage(msgField.text)
+                }
+            }
+        }
+
+        ListView {
+            id: messageView
+            model: messageModel
+            height: 300
+            width: 200
+            Layout.fillHeight: true
+            delegate: Rectangle {
+                width: 150
+                height: 30
+                color: index % 2 ? "#DDDDDD" : "#888888"
+                radius: 5
+                Text {
+                    text: payload
+                    anchors.centerIn: parent
+                }
+            }
+        }
+
+        Label {
+            function stateToString(value) {
+                if (value === 0)
+                    return "Disconnected"
+                else if (value === 1)
+                    return "Connecting"
+                else if (value === 2)
+                    return "Connected"
+                else
+                    return "Unknown"
+            }
+
+            Layout.columnSpan: 2
+            Layout.fillWidth: true
+            color: "#333333"
+            text: "Status:" + stateToString(client.state) + "(" + client.state + ")"
+            enabled: client.state === MqttClient.Connected
+        }
+    }
+}
diff --git a/examples/mqtt/quickpublication/qml.qrc b/examples/mqtt/quickpublication/qml.qrc
new file mode 100644
index 0000000..5f6483a
--- /dev/null
+++ b/examples/mqtt/quickpublication/qml.qrc
@@ -0,0 +1,5 @@
+<RCC>
+    <qresource prefix="/">
+        <file>main.qml</file>
+    </qresource>
+</RCC>
diff --git a/examples/mqtt/quickpublication/qmlmqttclient.cpp b/examples/mqtt/quickpublication/qmlmqttclient.cpp
new file mode 100644
index 0000000..28f69fc
--- /dev/null
+++ b/examples/mqtt/quickpublication/qmlmqttclient.cpp
@@ -0,0 +1,64 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** 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.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qmlmqttclient.h"
+#include <QDebug>
+#include <QMqttTopicName>
+
+QmlMqttClient::QmlMqttClient(QObject *parent)
+    : QMqttClient(parent)
+{
+}
+
+int QmlMqttClient::publish(const QString &topic, const QString &message, int qos, bool retain)
+{
+    auto result = QMqttClient::publish(QMqttTopicName(topic), message.toUtf8(), qos, retain);
+    return result;
+}
diff --git a/examples/mqtt/quickpublication/qmlmqttclient.h b/examples/mqtt/quickpublication/qmlmqttclient.h
new file mode 100644
index 0000000..85b6532
--- /dev/null
+++ b/examples/mqtt/quickpublication/qmlmqttclient.h
@@ -0,0 +1,68 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** 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.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QMLMQTTCLIENT_H
+#define QMLMQTTCLIENT_H
+
+#include <QtCore/QMap>
+#include <QtMqtt/QMqttClient>
+
+class QmlMqttClient : public QMqttClient
+{
+    Q_OBJECT
+public:
+    QmlMqttClient(QObject *parent = nullptr);
+
+    Q_INVOKABLE int publish(const QString &topic, const QString &message, int qos = 0, bool retain = false);
+private:
+    Q_DISABLE_COPY(QmlMqttClient)
+};
+
+#endif // QMLMQTTCLIENT_H
diff --git a/examples/mqtt/quickpublication/quickpublication.pro b/examples/mqtt/quickpublication/quickpublication.pro
new file mode 100644
index 0000000..20bdcc7
--- /dev/null
+++ b/examples/mqtt/quickpublication/quickpublication.pro
@@ -0,0 +1,32 @@
+TEMPLATE = app
+
+QT += qml quick mqtt
+CONFIG += c++11
+
+SOURCES += main.cpp \
+    qmlmqttclient.cpp
+
+HEADERS += \
+    qmlmqttclient.h
+
+RESOURCES += qml.qrc
+
+# Additional import path used to resolve QML modules in Qt Creator's code model
+QML_IMPORT_PATH =
+
+# Additional import path used to resolve QML modules just for Qt Quick Designer
+QML_DESIGNER_IMPORT_PATH =
+
+# The following define makes your compiler emit warnings if you use
+# any feature of Qt which as been marked deprecated (the exact warnings
+# depend on your compiler). Please consult the documentation of the
+# deprecated API in order to know how to port your code away from it.
+DEFINES += QT_DEPRECATED_WARNINGS
+
+# You can also make your code fail to compile if you use deprecated APIs.
+# In order to do so, uncomment the following line.
+# You can also select to disable deprecated APIs only up to a certain version of Qt.
+#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
+
+target.path = $$[QT_INSTALL_EXAMPLES]/mqtt/quickpublication
+INSTALLS += target