[welcome] Show progress during requirements checking

src/modules/welcome/WelcomePage.cpp

@@ -48,6 +48,7 @@ WelcomePage::WelcomePage( QWidget* parent )
 {
     connect( Calamares::ModuleManager::instance(), &Calamares::ModuleManager::requirementsResult, m_checkingWidget, &CheckerContainer::requirementsChecked );
     connect( Calamares::ModuleManager::instance(), &Calamares::ModuleManager::requirementsComplete, m_checkingWidget, &CheckerContainer::requirementsComplete );
+    connect( Calamares::ModuleManager::instance(), &Calamares::ModuleManager::requirementsProgress, m_checkingWidget, &CheckerContainer::requirementsProgress );
     ui->setupUi( this );
 
     ui->verticalLayout->insertSpacing( 1, CalamaresUtils::defaultFontHeight() * 2 );

src/modules/welcome/checker/CheckerContainer.cpp

@@ -54,7 +54,7 @@ void CheckerContainer::requirementsComplete( bool ok )
     m_checkerWidget->init( m_requirements );
     layout()->removeWidget( m_waitingWidget );
     m_waitingWidget->deleteLater();
-    m_waitingWidget = nullptr;  // Don't delete in constructor
+    m_waitingWidget = nullptr;  // Don't delete in destructor
     m_checkerWidget->setParent( this );
     layout()->addWidget( m_checkerWidget );
 
@@ -66,6 +66,12 @@ void CheckerContainer::requirementsChecked(const Calamares::RequirementsList& l)
     m_requirements.append( l );
 }
 
+void CheckerContainer::requirementsProgress(const QString& message)
+{
+    if ( m_waitingWidget )
+        m_waitingWidget->setText( message );
+}
+
 bool CheckerContainer::verdict() const
 {
     return m_verdict;

src/modules/welcome/checker/CheckerContainer.h

@@ -51,6 +51,8 @@ public slots:
     /** @brief All the requirements are complete, switch to list view */
     void requirementsComplete( bool );
 
+    void requirementsProgress( const QString& message );
+
 protected:
     WaitingWidget *m_waitingWidget;
     CheckerWidget *m_checkerWidget;