MQTT Subscriptions

 // Copyright (C) 2017 The Qt Company Ltd.
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause

 #include "subscriptionwindow.h"
 #include "ui_subscriptionwindow.h"

 using namespace Qt::StringLiterals;

 SubscriptionWindow::SubscriptionWindow(QMqttSubscription *sub, QWidget *parent) :
     QWidget(parent),
     ui(new Ui::SubscriptionWindow),
     m_sub(sub)
 {
     ui->setupUi(this);

     ui->labelSub->setText(m_sub->topic().filter());
     ui->labelQoS->setText(QString::number(m_sub->qos()));
     updateStatus(m_sub->state());
     connect(m_sub, &QMqttSubscription::messageReceived, this, &SubscriptionWindow::updateMessage);
     connect(m_sub, &QMqttSubscription::stateChanged, this, &SubscriptionWindow::updateStatus);
     connect(m_sub, &QMqttSubscription::qosChanged, [this](quint8 qos) {
         ui->labelQoS->setText(QString::number(qos));
     });
     connect(ui->pushButton, &QAbstractButton::clicked, m_sub, &QMqttSubscription::unsubscribe);
 }

 SubscriptionWindow::~SubscriptionWindow()
 {
     m_sub->unsubscribe();
     delete ui;
 }

 void SubscriptionWindow::updateMessage(const QMqttMessage &msg)
 {
     ui->listWidget->addItem(msg.payload());
 }

 void SubscriptionWindow::updateStatus(QMqttSubscription::SubscriptionState state)
 {
     switch (state) {
     case QMqttSubscription::Unsubscribed:
         ui->labelStatus->setText(u"Unsubscribed"_s);
         break;
     case QMqttSubscription::SubscriptionPending:
         ui->labelStatus->setText(u"Pending"_s);
         break;
     case QMqttSubscription::Subscribed:
         ui->labelStatus->setText(u"Subscribed"_s);
         break;
     case QMqttSubscription::Error:
         ui->labelStatus->setText(u"Error"_s);
         break;
     case QMqttSubscription::UnsubscriptionPending:
         ui->labelStatus->setText(u"Pending Unsubscription"_s);
         break;
     default:
         ui->labelStatus->setText(u"--Unknown--"_s);
         break;
     }
 }