Merge branch 'fix-slideshow'

CHANGES

@@ -9,7 +9,9 @@ This release contains contributions from (alphabetically by first name):
  - No external contributors yet
 
 ## Core ##
- - No core changes yet
+ - The slideshow in `branding.desc` can be configured with QML (recommended,
+   as it has been for the past umpteen releases) or with a list of
+   images (new).
 
 ## Modules ##
  - No module changes yet

src/branding/default/branding.desc

@@ -141,8 +141,23 @@ images:
 
 # The slideshow is displayed during execution steps (e.g. when the
 # installer is actually writing to disk and doing other slow things).
+#
+# The slideshow can be a QML file (recommended) which can display
+# arbitrary things -- text, images, animations, or even play a game --
+# during the execution step. The QML **is** abruptly stopped when the
+# execution step is done, though, so maybe a game isn't a great idea.
+#
+# The slideshow can also be a sequence of images (not recommended unless
+# you don't want QML at all in your Calamares). The images are displayed
+# at a rate of 1 every 2 seconds during the execution step.
+#
+# To configure a QML file, list a single filename:
+#   slideshow:               "show.qml"
+# To configure images, like the filenames (here, as an inline list):
+#   slideshow: [ "/etc/calamares/slideshow/0.png", "/etc/logo.png" ]
 slideshow:               "show.qml"
-# There are two available APIs for the slideshow:
+
+# There are two available APIs for a QML slideshow:
 #  - 1 (the default) loads the entire slideshow when the installation-
 #      slideshow page is shown and starts the QML then. The QML
 #      is never stopped (after installation is done, times etc.
@@ -151,6 +166,8 @@ slideshow:               "show.qml"
 #      onLeave() in the root object. After the installation is done,
 #      the show is stopped (first by calling onLeave(), then destroying
 #      the QML components).
+#
+# An image slideshow does not need to have the API defined.
 slideshowAPI: 2
 
 

src/libcalamaresui/Branding.cpp

@@ -41,6 +41,13 @@
 #include <KOSRelease>
 #endif
 
+[[noreturn]] static void
+bail( const QString& descriptorPath, const QString& message )
+{
+    cError() << "FATAL in" << descriptorPath << Logger::Continuation << Logger::NoQuote {} << message;
+    ::exit( EXIT_FAILURE );
+}
+
 namespace Calamares
 {
 
@@ -153,7 +160,7 @@ Branding::Branding( const QString& brandingFilePath, QObject* parent )
     QDir componentDir( componentDirectory() );
     if ( !componentDir.exists() )
     {
-        bail( "Bad component directory path." );
+        bail( m_descriptorPath, "Bad component directory path." );
     }
 
     QFile file( brandingFilePath );
@@ -168,7 +175,8 @@ Branding::Branding( const QString& brandingFilePath, QObject* parent )
 
             m_componentName = QString::fromStdString( doc[ "componentName" ].as< std::string >() );
             if ( m_componentName != componentDir.dirName() )
-                bail( "The branding component name should match the name of the "
+                bail( m_descriptorPath,
+                      "The branding component name should match the name of the "
                       "component directory." );
 
             initSimpleSettings( doc );
@@ -214,7 +222,8 @@ Branding::Branding( const QString& brandingFilePath, QObject* parent )
                     // Not found, bail out with the filename used
                     if ( icon.isNull() )
                     {
-                        bail( QString( "Image file %1 does not exist." ).arg( imageFi.absoluteFilePath() ) );
+                        bail( m_descriptorPath,
+                              QString( "Image file %1 does not exist." ).arg( imageFi.absoluteFilePath() ) );
                     }
                     return imageName;  // Not turned into a path
                 }
@@ -232,40 +241,44 @@ Branding::Branding( const QString& brandingFilePath, QObject* parent )
                     QFileInfo imageFi( componentDir.absoluteFilePath( pathString ) );
                     if ( !imageFi.exists() )
                     {
-                        bail( QString( "Slideshow file %1 does not exist." ).arg( imageFi.absoluteFilePath() ) );
+                        bail( m_descriptorPath,
+                              QString( "Slideshow file %1 does not exist." ).arg( imageFi.absoluteFilePath() ) );
                     }
 
                     slideShowPictures[ i ] = imageFi.absoluteFilePath();
                 }
 
-                //FIXME: implement a GenericSlideShow.qml that uses these slideShowPictures
+                m_slideshowFilenames = slideShowPictures;
+                m_slideshowAPI = -1;
             }
             else if ( doc[ "slideshow" ].IsScalar() )
             {
                 QString slideshowPath = QString::fromStdString( doc[ "slideshow" ].as< std::string >() );
                 QFileInfo slideshowFi( componentDir.absoluteFilePath( slideshowPath ) );
                 if ( !slideshowFi.exists() || !slideshowFi.fileName().toLower().endsWith( ".qml" ) )
-                    bail( QString( "Slideshow file %1 does not exist or is not a valid QML file." )
+                    bail( m_descriptorPath,
+                          QString( "Slideshow file %1 does not exist or is not a valid QML file." )
                               .arg( slideshowFi.absoluteFilePath() ) );
                 m_slideshowPath = slideshowFi.absoluteFilePath();
+
+                // API choice is relevant for QML slideshow
+                int api = doc[ "slideshowAPI" ].IsScalar() ? doc[ "slideshowAPI" ].as< int >() : -1;
+                if ( ( api < 1 ) || ( api > 2 ) )
+                {
+                    cWarning() << "Invalid or missing *slideshowAPI* in branding file.";
+                    api = 1;
+                }
+                m_slideshowAPI = api;
             }
             else
             {
-                bail( "Syntax error in slideshow sequence." );
+                bail( m_descriptorPath, "Syntax error in slideshow sequence." );
             }
-
-            int api = doc[ "slideshowAPI" ].IsScalar() ? doc[ "slideshowAPI" ].as< int >() : -1;
-            if ( ( api < 1 ) || ( api > 2 ) )
-            {
-                cWarning() << "Invalid or missing *slideshowAPI* in branding file.";
-                api = 1;
-            }
-            m_slideshowAPI = api;
         }
         catch ( YAML::Exception& e )
         {
             CalamaresUtils::explainYamlException( e, ba, file.fileName() );
-            bail( e.what() );
+            bail( m_descriptorPath, e.what() );
         }
 
         QDir translationsDir( componentDir.filePath( "lang" ) );
@@ -540,12 +553,4 @@ Branding::initSimpleSettings( const YAML::Node& doc )
     }
 }
 
-
-[[noreturn]] void
-Branding::bail( const QString& message )
-{
-    cError() << "FATAL in" << m_descriptorPath << Logger::Continuation << Logger::NoQuote {} << message;
-    ::exit( EXIT_FAILURE );
-}
-
 }  // namespace Calamares

src/libcalamaresui/Branding.h

@@ -165,8 +165,16 @@ public:
      */
     QString translationsDirectory() const { return m_translationsPathPrefix; }
 
-    /** @brief Path to the slideshow QML file, if any. */
+    /** @brief Path to the slideshow QML file, if any. (API == 1 or 2)*/
     QString slideshowPath() const { return m_slideshowPath; }
+    /// @brief List of pathnames of slideshow images, if any. (API == -1)
+    QStringList slideshowImages() const { return m_slideshowFilenames; }
+    /** @brief Which slideshow API to use for the slideshow?
+     *
+     *  -  2    For QML-based slideshows loaded asynchronously (current)
+     *  -  1    For QML-based slideshows, loaded when shown (legacy)
+     *  - -1    For oldschool image-slideshows.
+     */
     int slideshowAPI() const { return m_slideshowAPI; }
 
     QPixmap image( Branding::ImageEntry imageEntry, const QSize& size ) const;
@@ -230,13 +238,21 @@ private:
     static const QStringList s_imageEntryStrings;
     static const QStringList s_styleEntryStrings;
 
-    [[noreturn]] void bail( const QString& message );
-
     QString m_descriptorPath;  // Path to descriptor (e.g. "/etc/calamares/default/branding.desc")
     QString m_componentName;  // Matches last part of full path to containing directory
     QMap< QString, QString > m_strings;
     QMap< QString, QString > m_images;
     QMap< QString, QString > m_style;
+
+    /* The slideshow can be done in one of two ways:
+     *  - as a sequence of images
+     *  - as a QML file
+     * The slideshow: setting selects which one is used. If it is
+     * a list (of filenames) then it is a sequence of images, and otherwise
+     * it is a QML file which is run. (For QML, the slideshow API is
+     * important).
+     */
+    QStringList m_slideshowFilenames;
     QString m_slideshowPath;
     int m_slideshowAPI;
     QString m_translationsPathPrefix;

src/libcalamaresui/CMakeLists.txt

@@ -19,6 +19,7 @@ set( calamaresui_SOURCES
     viewpages/BlankViewStep.cpp
     viewpages/ExecutionViewStep.cpp
     viewpages/QmlViewStep.cpp
+    viewpages/Slideshow.cpp
     viewpages/ViewStep.cpp
 
     widgets/ClickableLabel.cpp

src/libcalamaresui/viewpages/ExecutionViewStep.cpp

@@ -20,6 +20,8 @@
 
 #include "ExecutionViewStep.h"
 
+#include "Slideshow.h"
+
 #include "Branding.h"
 #include "Job.h"
 #include "JobQueue.h"
@@ -37,12 +39,26 @@
 #include <QDir>
 #include <QLabel>
 #include <QProgressBar>
-#include <QQmlComponent>
-#include <QQmlEngine>
-#include <QQuickItem>
-#include <QQuickWidget>
 #include <QVBoxLayout>
 
+static Calamares::Slideshow*
+makeSlideshow( QWidget* parent )
+{
+    const int api = Calamares::Branding::instance()->slideshowAPI();
+    switch ( api )
+    {
+    case -1:
+        return new Calamares::SlideshowPictures( parent );
+    case 1:
+        FALLTHRU;
+    case 2:
+        return new Calamares::SlideshowQML( parent );
+    default:
+        cWarning() << "Unknown Branding slideshow API" << api;
+        return new Calamares::SlideshowPictures( parent );
+    }
+}
+
 namespace Calamares
 {
 
@@ -51,20 +67,14 @@ ExecutionViewStep::ExecutionViewStep( QObject* parent )
     , m_widget( new QWidget )
     , m_progressBar( new QProgressBar )
     , m_label( new QLabel )
-    , m_qmlShow( new QQuickWidget )
+    , m_slideshow( makeSlideshow( m_widget ) )
-    , m_qmlComponent( nullptr )
-    , m_qmlObject( nullptr )
 {
     QVBoxLayout* layout = new QVBoxLayout( m_widget );
     QVBoxLayout* innerLayout = new QVBoxLayout;
 
     m_progressBar->setMaximum( 10000 );
 
-    m_qmlShow->setSizePolicy( QSizePolicy::Expanding, QSizePolicy::Expanding );
+    layout->addWidget( m_slideshow->widget() );
-    m_qmlShow->setResizeMode( QQuickWidget::SizeRootObjectToView );
-    m_qmlShow->engine()->addImportPath( CalamaresUtils::qmlModulesDir().absolutePath() );
-
-    layout->addWidget( m_qmlShow );
     CalamaresUtils::unmarginLayout( layout );
     layout->addLayout( innerLayout );
 
@@ -72,17 +82,7 @@ ExecutionViewStep::ExecutionViewStep( QObject* parent )
     innerLayout->addWidget( m_progressBar );
     innerLayout->addWidget( m_label );
 
-    cDebug() << "QML import paths:" << Logger::DebugList( m_qmlShow->engine()->importPathList() );
-    if ( Branding::instance()->slideshowAPI() == 2 )
-    {
-        cDebug() << "QML load on startup, API 2.";
-        loadQmlV2();
-    }
-
     connect( JobQueue::instance(), &JobQueue::progress, this, &ExecutionViewStep::updateFromJobQueue );
-#if QT_VERSION >= QT_VERSION_CHECK( 5, 10, 0 )
-    CALAMARES_RETRANSLATE( m_qmlShow->engine()->retranslate(); )
-#endif
 }
 
 
@@ -139,108 +139,10 @@ ExecutionViewStep::isAtEnd() const
     return !JobQueue::instance()->isRunning();
 }
 
-void
-ExecutionViewStep::loadQmlV2()
-{
-    if ( !m_qmlComponent && !Calamares::Branding::instance()->slideshowPath().isEmpty() )
-    {
-        m_qmlComponent = new QQmlComponent( m_qmlShow->engine(),
-                                            QUrl::fromLocalFile( Calamares::Branding::instance()->slideshowPath() ),
-                                            QQmlComponent::CompilationMode::Asynchronous );
-        connect( m_qmlComponent, &QQmlComponent::statusChanged, this, &ExecutionViewStep::loadQmlV2Complete );
-    }
-}
-
-/// @brief State-change of the slideshow, for changeSlideShowState()
-enum class Slideshow
-{
-    Start,
-    Stop
-};
-
-/** @brief Tells the slideshow we activated or left the show.
- *
- * If @p state is @c Slideshow::Start, calls suitable activation procedures.
- * If @p state is @c Slideshow::Stop, calls deactivation procedures.
- *
- * Applies V1 and V2 QML activation / deactivation:
- *  - V1 loads the QML in @p widget on activation. Sets root object property
- *    *activatedInCalamares* as appropriate.
- *  - V2 calls onActivate() or onLeave() in the QML as appropriate. Also
- *    sets the *activatedInCalamares* property.
- */
-static void
-changeSlideShowState( Slideshow state, QQuickItem* slideshow, QQuickWidget* widget )
-{
-    bool activate = state == Slideshow::Start;
-
-    if ( Branding::instance()->slideshowAPI() == 2 )
-    {
-        // The QML was already loaded in the constructor, need to start it
-        CalamaresUtils::callQMLFunction( slideshow, activate ? "onActivate" : "onLeave" );
-    }
-    else if ( !Calamares::Branding::instance()->slideshowPath().isEmpty() )
-    {
-        // API version 1 assumes onCompleted is the trigger
-        if ( activate )
-        {
-            widget->setSource( QUrl::fromLocalFile( Calamares::Branding::instance()->slideshowPath() ) );
-        }
-        // needs the root object for property setting, below
-        slideshow = widget->rootObject();
-    }
-
-    // V1 API has picked up the root object for use, V2 passed it in.
-    if ( slideshow )
-    {
-        static const char propertyName[] = "activatedInCalamares";
-        auto property = slideshow->property( propertyName );
-        if ( property.isValid() && ( property.type() == QVariant::Bool ) && ( property.toBool() != activate ) )
-        {
-            slideshow->setProperty( propertyName, activate );
-        }
-    }
-}
-
-void
-ExecutionViewStep::loadQmlV2Complete()
-{
-    if ( m_qmlComponent && m_qmlComponent->isReady() && !m_qmlObject )
-    {
-        cDebug() << "QML component complete, API 2";
-        // Don't do this again
-        disconnect( m_qmlComponent, &QQmlComponent::statusChanged, this, &ExecutionViewStep::loadQmlV2Complete );
-
-        QObject* o = m_qmlComponent->create();
-        m_qmlObject = qobject_cast< QQuickItem* >( o );
-        if ( !m_qmlObject )
-        {
-            delete o;
-        }
-        else
-        {
-            cDebug() << Logger::SubEntry << "Loading" << Calamares::Branding::instance()->slideshowPath();
-
-            // setContent() is public API, but not documented publicly.
-            // It is marked \internal in the Qt sources, but does exactly
-            // what is needed: sets up visual parent by replacing the root
-            // item, and handling resizes.
-            m_qmlShow->setContent(
-                QUrl::fromLocalFile( Calamares::Branding::instance()->slideshowPath() ), m_qmlComponent, m_qmlObject );
-            if ( ViewManager::instance()->currentStep() == this )
-            {
-                // We're alreay visible! Must have been slow QML loading, and we
-                // passed onActivate already.
-                changeSlideShowState( Slideshow::Start, m_qmlObject, m_qmlShow );
-            }
-        }
-    }
-}
-
 void
 ExecutionViewStep::onActivate()
 {
-    changeSlideShowState( Slideshow::Start, m_qmlObject, m_qmlShow );
+    m_slideshow->changeSlideShowState( Slideshow::Start );
 
     JobQueue* queue = JobQueue::instance();
     foreach ( const QString& instanceKey, m_jobInstanceKeys )
@@ -288,13 +190,7 @@ ExecutionViewStep::updateFromJobQueue( qreal percent, const QString& message )
 void
 ExecutionViewStep::onLeave()
 {
-    changeSlideShowState( Slideshow::Stop, m_qmlObject, m_qmlShow );
+    m_slideshow->changeSlideShowState( Slideshow::Stop );
-    // API version 2 is explicitly stopped; version 1 keeps running
-    if ( Branding::instance()->slideshowAPI() == 2 )
-    {
-        delete m_qmlObject;
-        m_qmlObject = nullptr;
-    }
 }
 
 }  // namespace Calamares

src/libcalamaresui/viewpages/ExecutionViewStep.h

@@ -27,13 +27,12 @@
 class QLabel;
 class QObject;
 class QProgressBar;
-class QQmlComponent;
-class QQuickItem;
-class QQuickWidget;
 
 namespace Calamares
 {
 
+class Slideshow;
+
 class ExecutionViewStep : public ViewStep
 {
     Q_OBJECT
@@ -60,20 +59,14 @@ public:
 
     void appendJobModuleInstanceKey( const QString& instanceKey );
 
-public slots:
-    void loadQmlV2Complete();
-
 private:
     QWidget* m_widget;
     QProgressBar* m_progressBar;
     QLabel* m_label;
-    QQuickWidget* m_qmlShow;
+    Slideshow* m_slideshow;
-    QQmlComponent* m_qmlComponent;
-    QQuickItem* m_qmlObject;  ///< The actual show
 
     QStringList m_jobInstanceKeys;
 
-    void loadQmlV2();  ///< Loads the slideshow QML (from branding) for API version 2
     void updateFromJobQueue( qreal percent, const QString& message );
 };
 

src/libcalamaresui/viewpages/Slideshow.cpp

@@ -0,0 +1,258 @@
+/* === This file is part of Calamares - <https://github.com/calamares> ===
+ *
+ *   Copyright 2014, Aurélien Gâteau <agateau@kde.org>
+ *   Copyright 2014-2015, Teo Mrnjavac <teo@kde.org>
+ *   Copyright 2018, Adriaan de Groot <groot@kde.org>
+ *
+ *   Calamares is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   Calamares is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with Calamares. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "Slideshow.h"
+
+#include "Branding.h"
+#include "utils/Dirs.h"
+#include "utils/Logger.h"
+#include "utils/Qml.h"
+#include "utils/Retranslator.h"
+
+#include <QLabel>
+#include <QMutexLocker>
+#include <QQmlComponent>
+#include <QQmlEngine>
+#include <QQuickItem>
+#include <QQuickWidget>
+#include <QTimer>
+
+#include <chrono>
+
+namespace Calamares
+{
+
+Slideshow::~Slideshow() {}
+
+SlideshowQML::SlideshowQML( QWidget* parent )
+    : Slideshow( parent )
+    , m_qmlShow( new QQuickWidget )
+    , m_qmlComponent( nullptr )
+    , m_qmlObject( nullptr )
+{
+    m_qmlShow->setSizePolicy( QSizePolicy::Expanding, QSizePolicy::Expanding );
+    m_qmlShow->setResizeMode( QQuickWidget::SizeRootObjectToView );
+    m_qmlShow->engine()->addImportPath( CalamaresUtils::qmlModulesDir().absolutePath() );
+
+    cDebug() << "QML import paths:" << Logger::DebugList( m_qmlShow->engine()->importPathList() );
+#if QT_VERSION >= QT_VERSION_CHECK( 5, 10, 0 )
+    CALAMARES_RETRANSLATE( if ( m_qmlShow ) { m_qmlShow->engine()->retranslate(); } )
+#endif
+
+    if ( Branding::instance()->slideshowAPI() == 2 )
+    {
+        cDebug() << "QML load on startup, API 2.";
+        loadQmlV2();
+    }
+}
+
+SlideshowQML::~SlideshowQML()
+{
+    delete m_qmlObject;
+    delete m_qmlComponent;
+    delete m_qmlShow;
+}
+
+QWidget*
+SlideshowQML::widget()
+{
+    return m_qmlShow;
+}
+
+void
+SlideshowQML::loadQmlV2()
+{
+    QMutexLocker l( &m_mutex );
+    if ( !m_qmlComponent && !Calamares::Branding::instance()->slideshowPath().isEmpty() )
+    {
+        m_qmlComponent = new QQmlComponent( m_qmlShow->engine(),
+                                            QUrl::fromLocalFile( Calamares::Branding::instance()->slideshowPath() ),
+                                            QQmlComponent::CompilationMode::Asynchronous );
+        connect( m_qmlComponent, &QQmlComponent::statusChanged, this, &SlideshowQML::loadQmlV2Complete );
+    }
+}
+
+void
+SlideshowQML::loadQmlV2Complete()
+{
+    QMutexLocker l( &m_mutex );
+    if ( m_qmlComponent && m_qmlComponent->isReady() && !m_qmlObject )
+    {
+        cDebug() << "QML component complete, API 2";
+        // Don't do this again
+        disconnect( m_qmlComponent, &QQmlComponent::statusChanged, this, &SlideshowQML::loadQmlV2Complete );
+
+        QObject* o = m_qmlComponent->create();
+        m_qmlObject = qobject_cast< QQuickItem* >( o );
+        if ( !m_qmlObject )
+        {
+            delete o;
+        }
+        else
+        {
+            cDebug() << Logger::SubEntry << "Loading" << Calamares::Branding::instance()->slideshowPath();
+
+            // setContent() is public API, but not documented publicly.
+            // It is marked \internal in the Qt sources, but does exactly
+            // what is needed: sets up visual parent by replacing the root
+            // item, and handling resizes.
+            m_qmlShow->setContent(
+                QUrl::fromLocalFile( Calamares::Branding::instance()->slideshowPath() ), m_qmlComponent, m_qmlObject );
+            if ( isActive() )
+            {
+                // We're alreay visible! Must have been slow QML loading, and we
+                // passed onActivate already.
+                changeSlideShowState( Slideshow::Start );
+            }
+        }
+    }
+}
+
+/*
+ * Applies V1 and V2 QML activation / deactivation:
+ *  - V1 loads the QML in @p widget on activation. Sets root object property
+ *    *activatedInCalamares* as appropriate.
+ *  - V2 calls onActivate() or onLeave() in the QML as appropriate. Also
+ *    sets the *activatedInCalamares* property.
+ */
+void
+SlideshowQML::changeSlideShowState( Action state )
+{
+    QMutexLocker l( &m_mutex );
+    bool activate = state == Slideshow::Start;
+
+    if ( Branding::instance()->slideshowAPI() == 2 )
+    {
+        // The QML was already loaded in the constructor, need to start it
+        CalamaresUtils::callQMLFunction( m_qmlObject, activate ? "onActivate" : "onLeave" );
+    }
+    else if ( !Calamares::Branding::instance()->slideshowPath().isEmpty() )
+    {
+        // API version 1 assumes onCompleted is the trigger
+        if ( activate )
+        {
+            m_qmlShow->setSource( QUrl::fromLocalFile( Calamares::Branding::instance()->slideshowPath() ) );
+        }
+        // needs the root object for property setting, below
+        m_qmlObject = m_qmlShow->rootObject();
+    }
+
+    // V1 API has picked up the root object for use, V2 passed it in.
+    if ( m_qmlObject )
+    {
+        static const char propertyName[] = "activatedInCalamares";
+        auto property = m_qmlObject->property( propertyName );
+        if ( property.isValid() && ( property.type() == QVariant::Bool ) && ( property.toBool() != activate ) )
+        {
+            m_qmlObject->setProperty( propertyName, activate );
+        }
+    }
+
+    if ( ( Branding::instance()->slideshowAPI() == 2 ) && ( state == Slideshow::Stop ) )
+    {
+        delete m_qmlObject;
+        m_qmlObject = nullptr;
+    }
+
+    m_state = state;
+}
+
+SlideshowPictures::SlideshowPictures( QWidget* parent )
+    : Slideshow( parent )
+    , m_label( new QLabel( parent ) )
+    , m_timer( new QTimer( this ) )
+    , m_imageIndex( 0 )
+    , m_images( Branding::instance()->slideshowImages() )
+{
+    m_label->setSizePolicy( QSizePolicy::Expanding, QSizePolicy::Expanding );
+    m_label->setAlignment( Qt::AlignCenter );
+    m_timer->setInterval( std::chrono::milliseconds( 2000 ) );
+    connect( m_timer, &QTimer::timeout, this, &SlideshowPictures::next );
+}
+
+SlideshowPictures::~SlideshowPictures()
+{
+    delete m_timer;
+    delete m_label;
+}
+
+QWidget*
+SlideshowPictures::widget()
+{
+    return m_label;
+}
+
+void
+SlideshowPictures::changeSlideShowState( Calamares::Slideshow::Action a )
+{
+    QMutexLocker l( &m_mutex );
+    m_state = a;
+    if ( a == Slideshow::Start )
+    {
+        m_imageIndex = -1;
+        if ( m_images.count() < 1 )
+        {
+            m_label->setPixmap( QPixmap( ":/data/images/squid.svg" ) );
+        }
+        else
+        {
+
+            m_timer->start();
+            QTimer::singleShot( 0, this, &SlideshowPictures::next );
+        }
+    }
+    else
+    {
+        m_timer->stop();
+    }
+}
+
+void
+SlideshowPictures::next()
+{
+    QMutexLocker l( &m_mutex );
+
+    if ( m_imageIndex < 0 )
+    {
+        // Initialization, don't do the advance-by-one
+        m_imageIndex = 0;
+    }
+    else
+    {
+        m_imageIndex++;
+        if ( m_imageIndex >= m_images.count() )
+        {
+            m_imageIndex = 0;
+        }
+    }
+
+    if ( m_imageIndex >= m_images.count() )
+    {
+        // Unusual case: timer is running, but we have 0 images to display.
+        // .. this would have been caught in changeSlideShowState(), which
+        // .. special-cases 0 images.
+        return;
+    }
+
+    m_label->setPixmap( QPixmap( m_images.at( m_imageIndex ) ) );
+}
+
+
+}  // namespace Calamares

src/libcalamaresui/viewpages/Slideshow.h

@@ -0,0 +1,142 @@
+/* === This file is part of Calamares - <https://github.com/calamares> ===
+ *
+ *   Copyright 2014, Aurélien Gâteau <agateau@kde.org>
+ *   Copyright 2014-2015, Teo Mrnjavac <teo@kde.org>
+ *   Copyright 2018, Adriaan de Groot <groot@kde.org>
+ *
+ *   Calamares is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   Calamares is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with Calamares. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LIBCALAMARESUI_SLIDESHOW_H
+#define LIBCALAMARESUI_SLIDESHOW_H
+
+#include <QMutex>
+#include <QStringList>
+#include <QWidget>
+
+class QLabel;
+class QTimer;
+class QQmlComponent;
+class QQuickItem;
+class QQuickWidget;
+
+namespace Calamares
+{
+
+/** @brief API for Slideshow objects
+ *
+ * A Slideshow (subclass) object is created by the ExecutionViewStep
+ * and needs to manage its own configuration (e.g. from Branding).
+ * The slideshow is started and stopped when it becomes visible
+ * and when installation is over, by calling changeSlideShowState()
+ * as appropriate.
+ */
+class Slideshow : public QObject
+{
+    Q_OBJECT
+public:
+    /// @brief State-change of the slideshow, for changeSlideShowState()
+    enum Action
+    {
+        Start,
+        Stop
+    };
+
+    Slideshow( QWidget* parent = nullptr )
+        : QObject( parent )
+    {
+    }
+    virtual ~Slideshow();
+
+    /// @brief Is the slideshow being shown **right now**?
+    bool isActive() const { return m_state == Start; }
+
+    /** @brief The actual widget to show the user.
+     *
+     * Depending on the style of slideshow, this might be a QQuickWidget,
+     * or a QLabel, or something else entirely.
+     */
+    virtual QWidget* widget() = 0;
+
+    /** @brief Tells the slideshow we activated or left the show.
+     *
+     * If @p state is @c Slideshow::Start, calls suitable activation procedures.
+     * If @p state is @c Slideshow::Stop, calls deactivation procedures.
+     */
+    virtual void changeSlideShowState( Action a ) = 0;
+
+protected:
+    QMutex m_mutex;
+    Action m_state = Stop;
+};
+
+/** @brief Slideshow using a QML file
+ *
+ * This is the "classic" slideshow in Calamares, which runs some QML
+ * while the installation is in progress. It is configured through
+ * Branding settings *slideshow* and *slideshowAPI*, showing the QML
+ * file from *slideshow*. The API version influences when and how the
+ * QML is loaded; version 1 does so only when the slideshow is activated,
+ * while version 2 does so asynchronously.
+ */
+class SlideshowQML : public Slideshow
+{
+    Q_OBJECT
+public:
+    SlideshowQML( QWidget* parent );
+    virtual ~SlideshowQML() override;
+
+    QWidget* widget() override;
+    void changeSlideShowState( Action a ) override;
+
+public slots:
+    void loadQmlV2Complete();
+    void loadQmlV2();  ///< Loads the slideshow QML (from branding) for API version 2
+
+private:
+    QQuickWidget* m_qmlShow;
+    QQmlComponent* m_qmlComponent;
+    QQuickItem* m_qmlObject;  ///< The actual show
+};
+
+/** @brief Slideshow using images
+ *
+ * This is an "oldschool" slideshow, but new in Calamares, which
+ * displays static image files one-by-one. It is for systems that
+ * do not use QML at all. It is configured through the Branding
+ * setting *slideshow*. When using this widget, the setting must
+ * be a list of filenames; the API is set to -1.
+ */
+class SlideshowPictures : public Slideshow
+{
+    Q_OBJECT
+public:
+    SlideshowPictures( QWidget* parent );
+    virtual ~SlideshowPictures() override;
+
+    QWidget* widget() override;
+    virtual void changeSlideShowState( Action a ) override;
+
+public slots:
+    void next();
+
+private:
+    QLabel* m_label;
+    QTimer* m_timer;
+    int m_imageIndex;
+    QStringList m_images;
+};
+
+}  // namespace Calamares
+#endif