Migrate documentviewer example into plugin based architecture

This patch changes the document viewer example to a plugin based
architecture.
It adapts the documentation accordingly.

Change-Id: Ia24028aa27e21fb8ab36f5ef3a9953be60858b19
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

examples/demos/CMakeLists.txt

@@ -23,6 +23,6 @@ endif()
 if(TARGET Qt::Quick AND TARGET Qt::qsb AND TARGET Qt::Pdf)
     qt_internal_add_example(photosurface)
 endif()
-if(TARGET Qt::Widgets AND TARGET Qt::PdfWidgets)
+if(TARGET Qt::Widgets)
     qt_internal_add_example(documentviewer)
 endif()

examples/demos/colorpaletteclient/CMakeLists.txt

@@ -11,7 +11,7 @@ endif()
 set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/demos/${PROJECT_NAME}")
 
 find_package(Qt6 REQUIRED COMPONENTS Core Gui Qml Quick)
-qt_standard_project_setup(REQUIRES 6.5)
+qt_standard_project_setup()
 
 qt_add_executable(colorpaletteclient
     main.cpp

examples/demos/documentviewer/CMakeLists.txt

@@ -1,93 +1,21 @@
+# Copyright (C) 2022 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
 cmake_minimum_required(VERSION 3.16)
 project(documentviewer LANGUAGES CXX)
 
-set(CMAKE_AUTOMOC ON)
+find_package(Qt6 REQUIRED COMPONENTS Core Gui Widgets
+                 OPTIONAL_COMPONENTS PrintSupport PdfWidgets)
 
 if(NOT DEFINED INSTALL_EXAMPLESDIR)
     set(INSTALL_EXAMPLESDIR "examples")
 endif()
 
-set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}")
-
-find_package(Qt6 REQUIRED COMPONENTS Core Gui Widgets PdfWidgets
-                 OPTIONAL_COMPONENTS PrintSupport)
-
-qt_standard_project_setup()
-
-qt_add_executable(documentviewer
-    main.cpp
-    mainwindow.cpp mainwindow.h mainwindow.ui
-    abstractviewer.cpp abstractviewer.h
-    viewerfactory.cpp viewerfactory.h
-    jsonviewer.cpp jsonviewer.h
-    txtviewer.cpp txtviewer.h
-    pdfviewer.cpp pdfviewer.h
-    zoomselector.cpp zoomselector.h
-    hoverwatcher.cpp hoverwatcher.cpp
-)
-
-set_target_properties(documentviewer PROPERTIES
-    WIN32_EXECUTABLE TRUE
-    MACOSX_BUNDLE TRUE
-)
-# Resources:
-set(documentviewer_resource_files
-    "images/copy@2x.png"
-    "images/copy.png"
-    "images/cut@2x.png"
-    "images/cut.png"
-    "images/go-next-view@2x.png"
-    "images/go-next-view-page@2x.png"
-    "images/go-next-view-page.png"
-    "images/go-next-view.png"
-    "images/go-previous-view@2x.png"
-    "images/go-previous-view-page@2x.png"
-    "images/go-previous-view-page.png"
-    "images/go-previous-view.png"
-    "images/magnifier@2x.png"
-    "images/magnifier.png"
-    "images/open@2x.png"
-    "images/open.png"
-    "images/paste@2x.png"
-    "images/paste.png"
-    "images/print2x.png"
-    "images/print.png"
-    "images/qt-logo@2x.png"
-    "images/qt-logo.png"
-    "images/zoom-fit-best@2x.png"
-    "images/zoom-fit-best.png"
-    "images/zoom-fit-width@2x.png"
-    "images/zoom-fit-width.png"
-    "images/zoom-in@2x.png"
-    "images/zoom-in.png"
-    "images/zoom-original@2x.png"
-    "images/zoom-original.png"
-    "images/zoom-out@2x.png"
-    "images/zoom-out.png"
-    "images/zoom-previous@2x.png"
-    "images/zoom-previous.png"
-)
-
-qt6_add_resources(documentviewer "documentviewer"
-    PREFIX
-        "/demos/documentviewer"
-    FILES
-        ${documentviewer_resource_files}
-)
-
-target_link_libraries(documentviewer PUBLIC
-    Qt::Core
-    Qt::Gui
-    Qt::Widgets
-    Qt::PdfWidgets
-)
-
 if(TARGET Qt6::PrintSupport)
-    target_link_libraries(documentviewer PRIVATE Qt6::PrintSupport)
+    add_compile_definitions(QT_DOCUMENTVIEWER_PRINTSUPPORT)
 endif()
 
-install(TARGETS documentviewer
-    RUNTIME DESTINATION "${INSTALL_EXAMPLEDIR}"
-    BUNDLE DESTINATION "${INSTALL_EXAMPLEDIR}"
-    LIBRARY DESTINATION "${INSTALL_EXAMPLEDIR}"
-)
+set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/demos/documentviewer")
+
+add_subdirectory(app)
+add_subdirectory(plugins)

examples/demos/documentviewer/app/CMakeLists.txt

@@ -0,0 +1,96 @@
+cmake_minimum_required(VERSION 3.16)
+project(documentviewer LANGUAGES CXX)
+
+find_package(Qt6 REQUIRED COMPONENTS Core Gui Widgets
+                 OPTIONAL_COMPONENTS PrintSupport PdfWidgets)
+
+qt_standard_project_setup()
+
+set(CMAKE_AUTOMOC ON)
+
+qt_add_executable(documentviewer
+    main.cpp
+    mainwindow.cpp mainwindow.h mainwindow.ui
+    viewerfactory.cpp viewerfactory.h
+    abstractviewer.cpp abstractviewer.h
+    recentfiles.cpp recentfiles.h
+    recentfilemenu.cpp recentfilemenu.h
+    viewerinterfaces.h
+)
+
+set_target_properties(documentviewer PROPERTIES
+    WIN32_EXECUTABLE TRUE
+    MACOSX_BUNDLE TRUE
+)
+
+qt_add_resources(documentviewer "documentviewer"
+    PREFIX
+        "/demos/documentviewer"
+    FILES
+        "images/copy@2x.png"
+        "images/copy.png"
+        "images/cut@2x.png"
+        "images/cut.png"
+        "images/go-next-view@2x.png"
+        "images/go-next-view-page@2x.png"
+        "images/go-next-view-page.png"
+        "images/go-next-view.png"
+        "images/go-previous-view@2x.png"
+        "images/go-previous-view-page@2x.png"
+        "images/go-previous-view-page.png"
+        "images/go-previous-view.png"
+        "images/magnifier@2x.png"
+        "images/magnifier.png"
+        "images/open@2x.png"
+        "images/open.png"
+        "images/paste@2x.png"
+        "images/paste.png"
+        "images/print2x.png"
+        "images/print.png"
+        "images/qt-logo@2x.png"
+        "images/qt-logo.png"
+        "images/zoom-fit-best@2x.png"
+        "images/zoom-fit-best.png"
+        "images/zoom-fit-width@2x.png"
+        "images/zoom-fit-width.png"
+        "images/zoom-in@2x.png"
+        "images/zoom-in.png"
+        "images/zoom-original@2x.png"
+        "images/zoom-original.png"
+        "images/zoom-out@2x.png"
+        "images/zoom-out.png"
+        "images/zoom-previous@2x.png"
+        "images/zoom-previous.png"
+)
+
+target_link_libraries(documentviewer PRIVATE
+    Qt::Core
+    Qt::Gui
+    Qt::Widgets
+)
+
+if(QT6_IS_SHARED_LIBS_BUILD)
+    add_dependencies(documentviewer
+        jsonviewer
+        pdfviewer
+        txtviewer
+    )
+else()
+    target_link_libraries(documentviewer PRIVATE
+        jsonviewer
+        pdfviewer
+        txtviewer
+    )
+endif()
+
+if(TARGET Qt6::PrintSupport)
+    target_link_libraries(documentviewer PRIVATE Qt6::PrintSupport)
+    add_compile_definitions(QT_DOCUMENTVIEWER_PRINTSUPPORT)
+endif()
+
+install(TARGETS documentviewer
+    RUNTIME DESTINATION "${INSTALL_EXAMPLEDIR}"
+    BUNDLE DESTINATION "${INSTALL_EXAMPLEDIR}"
+    LIBRARY DESTINATION "${INSTALL_EXAMPLEDIR}"
+)
+

examples/demos/documentviewer/app/abstractviewer.cpp

@@ -13,14 +13,18 @@
 #include <QSettings>
 #include <QApplication>
 
-#if defined(QT_ABSTRACTVIEWER_PRINTSUPPORT)
+#ifdef QT_DOCUMENTVIEWER_PRINTSUPPORT
 #include <QPrintDialog>
-#endif // QT_ABSTRACTVIEWER_PRINTSUPPORT
+#endif // QT_DOCUMENTVIEWER_PRINTSUPPORT
 
-AbstractViewer::AbstractViewer(QFile *file, QWidget *widget, QMainWindow *mainWindow) :
-    m_file(file),
-    m_widget(widget)
+AbstractViewer::AbstractViewer() : m_file(nullptr), m_widget(nullptr)
 {
+}
+
+void AbstractViewer::init(QFile *file, QWidget *widget, QMainWindow *mainWindow)
+{
+    m_file.reset(file);
+    m_widget = widget;
     Q_ASSERT(widget);
     Q_ASSERT(mainWindow);
     m_uiAssets.mainWindow = mainWindow;
@@ -35,6 +39,96 @@ AbstractViewer::~AbstractViewer()
     qDeleteAll(m_toolBars);
 }
 
+bool AbstractViewer::isEmpty() const
+{
+    return !hasContent();
+}
+
+bool AbstractViewer::isPrintingEnabled() const
+{
+    return m_printingEnabled;
+}
+
+bool AbstractViewer::hasContent() const
+{
+    return false;
+}
+
+bool AbstractViewer::supportsOverview() const
+{
+    return false;
+}
+
+bool AbstractViewer::isModified() const
+{
+    return false;
+}
+
+bool AbstractViewer::saveDocument()
+{
+    return false;
+}
+
+bool AbstractViewer::saveDocumentAs()
+{
+    return false;
+}
+
+QList<QAction *> AbstractViewer::actions() const
+{
+    return m_actions;
+}
+
+QWidget *AbstractViewer::widget() const
+{
+    return m_widget;
+}
+
+QList<QMenu *> AbstractViewer::menus() const
+{
+    return m_menus;
+}
+
+QMainWindow *AbstractViewer::mainWindow() const
+{
+    return m_uiAssets.mainWindow;
+}
+
+QStatusBar *AbstractViewer::statusBar() const
+{
+    return mainWindow()->statusBar();
+}
+
+QMenuBar *AbstractViewer::menuBar() const
+{
+    return mainWindow()->menuBar();
+}
+
+void AbstractViewer::maybeEnablePrinting()
+{
+    maybeSetPrintingEnabled(true);
+}
+
+void AbstractViewer::disablePrinting()
+{
+    maybeSetPrintingEnabled(false);
+}
+
+bool AbstractViewer::isDefaultViewer() const
+{
+    return false;
+}
+
+AbstractViewer *AbstractViewer::viewer()
+{
+    return this;
+}
+
+const AbstractViewer *AbstractViewer::viewer() const
+{
+    return this;
+}
+
 void AbstractViewer::statusMessage(const QString &message, const QString &type, int timeout)
 {
     const QString msg = viewerName() + (type.isEmpty() ? ": " : "/" + type + ": ") + message;
@@ -78,7 +172,7 @@ QMenu *AbstractViewer::fileMenu()
 
 void AbstractViewer::print()
 {
-#ifdef QT_ABSTRACTVIEWER_PRINTSUPPORT
+#ifdef QT_DOCUMENTVIEWER_PRINTSUPPORT
     static const QString type = tr("Printing");
     if (!hasContent()) {
         statusMessage(tr("No content to print."), type);
@@ -126,7 +220,7 @@ void AbstractViewer::print()
  */
 void AbstractViewer::maybeSetPrintingEnabled(bool enabled)
 {
-#ifndef QT_ABSTRACTVIEWER_PRINTSUPPORT
+#ifndef QT_DOCUMENTVIEWER_PRINTSUPPORT
     enabled = false;
 #else
     if (!hasContent())

examples/demos/documentviewer/app/abstractviewer.h

@@ -8,14 +8,9 @@
 #include <QMainWindow>
 #include <QFileInfo>
 
-#if defined(QT_PRINTSUPPORT_LIB)
+#ifdef QT_DOCUMENTVIEWER_PRINTSUPPORT
 #include <QtPrintSupport/qtprintsupportglobal.h>
-#if QT_CONFIG(printer)
-#if QT_CONFIG(printdialog)
-#define QT_ABSTRACTVIEWER_PRINTSUPPORT
 #include <QPrinter>
-#endif // QT_CONFIG(printdialog)
-#endif // QT_CONFIG(printer)
 #endif // QT_PRINTSUPPORT_LIB
 
 class QToolBar;
@@ -27,28 +22,32 @@ class AbstractViewer : public QObject
     Q_OBJECT
 
 protected:
-    explicit AbstractViewer(QFile *file, QWidget *widget, QMainWindow *mainWindow);
+    AbstractViewer();
 
 public:
     virtual ~AbstractViewer();
-
+    virtual void init(QFile *file, QWidget *widget, QMainWindow *mainWindow);
     void initViewer(QAction *back, QAction *forward, QAction *help, QTabWidget *tabs);
-    virtual bool isModified() const { return false; }
-    virtual bool saveDocument() { return false; }
-    virtual bool saveDocumentAs() { return false; }
+    virtual bool isModified() const;
+    virtual bool saveDocument();
+    virtual bool saveDocumentAs();
     virtual QString viewerName() const = 0;
-    virtual bool supportsOverview() const { return false; }
+    virtual bool supportsOverview() const;
     virtual QByteArray saveState() const = 0;
     virtual bool restoreState(QByteArray &) = 0;
-    virtual bool hasContent() const { return false; }
-    bool isEmpty() const { return !hasContent(); }
-    bool isPrintingEnabled() const { return m_printingEnabled; }
+    virtual bool hasContent() const;
+    virtual QStringList supportedMimeTypes() const = 0;
+    virtual bool isDefaultViewer() const;
+    bool isEmpty() const;
+    bool isPrintingEnabled() const;
+    AbstractViewer *viewer();
+    const AbstractViewer *viewer() const;
 
-    QList<QAction *> actions() const { return m_actions; }
-    QWidget *widget() const { return m_widget; }
-    QList<QMenu *> menus() const { return m_menus; }
+    QList<QAction *> actions() const;
+    QWidget *widget() const;
+    QList<QMenu *> menus() const;
 
-#ifdef QT_ABSTRACTVIEWER_PRINTSUPPORT
+#ifdef QT_DOCUMENTVIEWER_PRINTSUPPORT
 protected:
     virtual void printDocument(QPrinter *) const {};
 #endif
@@ -76,18 +75,18 @@ protected:
     QToolBar *addToolBar(const QString &);
     QMenu *addMenu(const QString &);
     QMenu *fileMenu();
-    QMainWindow *mainWindow() const { return m_uiAssets.mainWindow; }
-    QStatusBar *statusBar() const { return mainWindow()->statusBar(); }
-    QMenuBar *menuBar() const { return mainWindow()->menuBar(); }
+    QMainWindow *mainWindow() const;
+    QStatusBar *statusBar() const;
+    QMenuBar *menuBar() const;
 
     std::unique_ptr<QFile> m_file;
     QList<QAction *> m_actions;
-    QWidget *m_widget;
+    QWidget *m_widget = nullptr;
 
 protected slots:
     void maybeSetPrintingEnabled(bool enabled);
-    inline void maybeEnablePrinting() { return maybeSetPrintingEnabled(true); }
-    inline void disablePrinting() { return maybeSetPrintingEnabled(false); }
+    void maybeEnablePrinting();
+    void disablePrinting();
 
 private:
     QList<QMenu *> m_menus;

examples/demos/documentviewer/app/mainwindow.cpp

@@ -1,9 +1,12 @@
 // Copyright (C) 2023 The Qt Company Ltd.
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
 #include "mainwindow.h"
 #include "ui_mainwindow.h"
-#include "abstractviewer.h"
 #include "viewerfactory.h"
+#include "abstractviewer.h"
+#include "recentfiles.h"
+#include "recentfilemenu.h"
 #include <QFileDialog>
 #include <QSettings>
 #include <QToolButton>
@@ -15,7 +18,25 @@ MainWindow::MainWindow(QWidget *parent) :
     ui(new Ui::MainWindow)
 {
     ui->setupUi(this);
+
+    m_recentFiles.reset(new RecentFiles(ui->actionRecent));
+    connect(m_recentFiles.get(), &RecentFiles::countChanged, this, [&](int count){
+        ui->actionRecent->setText(QString("%1 recent files").arg(count));
+    });
+
     readSettings();
+    m_factory.reset(new ViewerFactory(ui->viewArea, this));
+    const QStringList &viewers = m_factory->viewerNames();
+    const QString msg = tr("Available viewers: ") + viewers.join(", ");
+    statusBar()->showMessage(msg);
+
+    auto *menu = new RecentFileMenu(this, m_recentFiles.get());
+    ui->actionRecent->setMenu(menu);
+    connect(menu, &RecentFileMenu::fileOpened, this, &MainWindow::openFile);
+    QWidget *w = ui->mainToolBar->widgetForAction(ui->actionRecent);
+    auto *button = qobject_cast<QToolButton *>(w);
+    if (button)
+        connect(ui->actionRecent, &QAction::triggered, button, &QToolButton::showMenu);
 }
 
 MainWindow::~MainWindow()
@@ -46,24 +67,48 @@ void MainWindow::openFile(const QString &fileName)
 
     QFileInfo fileInfo(*file);
     m_currentDir = fileInfo.dir();
+    m_recentFiles->addFile(fileInfo.absoluteFilePath());
 
     // If a viewer is already open, save its state first
     saveViewerSettings();
-    m_viewer.reset(ViewerFactory::makeViewer(file, ui->viewArea, this));
-    restoreViewerSettings();
+    m_viewer = m_factory->viewer(file);
+    if (!m_viewer) {
+        statusBar()->showMessage(tr("File %1 can't be opened.").arg(fileName));
+        return;
+    }
 
     ui->actionPrint->setEnabled(m_viewer->hasContent());
-    connect(m_viewer.get(), &AbstractViewer::printingEnabledChanged, ui->actionPrint, &QAction::setEnabled);
-    connect(ui->actionPrint, &QAction::triggered, m_viewer.get(), &AbstractViewer::print);
-    connect(m_viewer.get(), &AbstractViewer::showMessage, statusBar(), &QStatusBar::showMessage);
+    connect(m_viewer, &AbstractViewer::printingEnabledChanged, ui->actionPrint, &QAction::setEnabled);
+    connect(ui->actionPrint, &QAction::triggered, m_viewer, &AbstractViewer::print);
+    connect(m_viewer, &AbstractViewer::showMessage, statusBar(), &QStatusBar::showMessage);
 
     m_viewer->initViewer(ui->actionBack, ui->actionForward, ui->menuHelp->menuAction(), ui->tabWidget);
+    restoreViewerSettings();
     ui->scrollArea->setWidget(m_viewer->widget());
 }
 
 void MainWindow::on_actionAbout_triggered()
 {
-    QMessageBox::aboutQt(this);
+    static const QString &text = [&]{
+        QString text = tr("A Widgets application to display and print JSON, "
+                          "text and PDF files. Demonstrates various features to use "
+                          "in widget applications: Using QSettings, query and save "
+                          "user preferences, manage file histories and control cursor "
+                          "behavior when hovering over widgets.\n\n"
+                          "This version has loaded the following plugins:\n") +
+                          m_factory->viewerNames().join(", ") +
+                          tr("\n\nIt supports thow following mime types:\n") +
+                          m_factory->supportedMimeTypes().join("\n");
+
+        AbstractViewer *def = m_factory->defaultViewer();
+        if (def) {
+            text += tr("\n\nOther mime types will be displayed with ") + def->viewerName() + ".";
+        }
+
+        return text;
+    }();
+
+    QMessageBox::about(this, tr("About Document Viewer Demo"), text);
 }
 
 void MainWindow::on_actionAboutQt_triggered()
@@ -86,6 +131,9 @@ void MainWindow::readSettings()
         QByteArray mainWindowState = settings.value(settingsMainWindow).toByteArray();
         restoreState(mainWindowState);
     }
+
+    // Restore recent files
+    m_recentFiles->restoreFromSettings(settings, settingsFiles);
 }
 
 void MainWindow::saveSettings() const
@@ -98,6 +146,9 @@ void MainWindow::saveSettings() const
     // Save QMainWindow state
     settings.setValue(settingsMainWindow, saveState());
 
+    // Save recent files
+    m_recentFiles->saveSettings(settings, settingsFiles);
+
     settings.sync();
 }
 

examples/demos/documentviewer/app/mainwindow.h

@@ -10,6 +10,8 @@
 #include <QStringLiteral>
 
 class AbstractViewer;
+class RecentFiles;
+class ViewerFactory;
 namespace Ui {
 class MainWindow;
 }
@@ -37,14 +39,17 @@ private:
     void saveViewerSettings() const;
 
     QDir m_currentDir;
+    AbstractViewer *m_viewer = nullptr;
     std::unique_ptr<Ui::MainWindow> ui;
-    std::unique_ptr<AbstractViewer> m_viewer;
+    std::unique_ptr<RecentFiles> m_recentFiles;
     int m_classId = -1;
+    std::unique_ptr<ViewerFactory> m_factory;
 
     static constexpr QLatin1StringView settingsName = QLatin1StringView("DocumentViewerExample");
     static constexpr QLatin1StringView settingsDir = QLatin1StringView("WorkingDir");
     static constexpr QLatin1StringView settingsMainWindow = QLatin1StringView("MainWindow");
     static constexpr QLatin1StringView settingsViewers = QLatin1StringView("Viewers");
+    static constexpr QLatin1StringView settingsFiles = QLatin1StringView("RecentFiles");
 };
 
 #endif // MAINWINDOW_H

examples/demos/documentviewer/app/mainwindow.ui

@@ -14,7 +14,7 @@
    <string>Document Viewer Demo</string>
   </property>
   <property name="windowIcon">
-   <iconset resource="../../../../../build/dev/qtdoc/examples/demos/documentviewer/.rcc/documentviewer.qrc">
+   <iconset resource="../../../../../../build/dev/qtdoc/examples/demos/documentviewer/app/.rcc/documentviewer.qrc">
     <normaloff>:/demos/documentviewer/images/qt-logo.png</normaloff>:/demos/documentviewer/images/qt-logo.png</iconset>
   </property>
   <widget class="QWidget" name="centralwidget">
@@ -96,6 +96,7 @@
      <string>File</string>
     </property>
     <addaction name="actionOpen"/>
+    <addaction name="actionRecent"/>
     <addaction name="actionPrint"/>
     <addaction name="actionQuit"/>
    </widget>
@@ -121,6 +122,7 @@
     <bool>false</bool>
    </attribute>
    <addaction name="actionOpen"/>
+   <addaction name="actionRecent"/>
    <addaction name="actionPrint"/>
    <addaction name="separator"/>
    <addaction name="actionBack"/>
@@ -141,8 +143,8 @@
   </action>
   <action name="actionAbout">
    <property name="icon">
-    <iconset theme="help-about">
-     <normaloff>.</normaloff>.</iconset>
+    <iconset theme="help-about" resource="../../../../../../build/dev/qtdoc/examples/demos/documentviewer/app/.rcc/documentviewer.qrc">
+     <normaloff>:/demos/documentviewer/images/qt-logo.png</normaloff>:/demos/documentviewer/images/qt-logo.png</iconset>
    </property>
    <property name="text">
     <string>about documentviewer</string>
@@ -189,8 +191,8 @@
     <bool>false</bool>
    </property>
    <property name="icon">
-    <iconset theme="document-print">
-    <normaloff>:/demos/documentviewer/images/print.png</normaloff>:/demos/documentviewer/images/print.png</iconset>
+    <iconset theme="document-print" resource="../../../../../../build/dev/qtdoc/examples/demos/documentviewer/app/.rcc/documentviewer.qrc">
+     <normaloff>:/demos/documentviewer/images/print.png</normaloff>:/demos/documentviewer/images/print.png</iconset>
    </property>
    <property name="text">
     <string>Print</string>
@@ -204,9 +206,9 @@
   </action>
   <action name="actionAboutQt">
    <property name="icon">
-    <iconset resource="../../../../../build/dev/qthttpserver/examples/httpserver/simple/.rcc/assets.qrc">
-    <normaloff>:/demos/documentviewer/images/qt-logo.png</normaloff>
-    <normalon>:/demos/documentviewer/images/qt-logo.png</normalon>:/demos/documentviewer/images/qt-logo.png</iconset>
+    <iconset resource="../../../../../../build/dev/qtdoc/examples/demos/documentviewer/app/.rcc/documentviewer.qrc">
+     <normaloff>:/demos/documentviewer/images/qt-logo.png</normaloff>
+     <normalon>:/demos/documentviewer/images/qt-logo.png</normalon>:/demos/documentviewer/images/qt-logo.png</iconset>
    </property>
    <property name="text">
     <string>About Qt</string>
@@ -224,7 +226,7 @@
      <normaloff>.</normaloff>.</iconset>
    </property>
    <property name="text">
-    <string>Open</string>
+    <string>Recently opened...</string>
    </property>
    <property name="shortcut">
     <string>Meta+R</string>
@@ -232,7 +234,8 @@
   </action>
   <action name="actionQuit">
    <property name="icon">
-    <iconset theme="application-exit"/>
+    <iconset theme="application-exit">
+     <normaloff>.</normaloff>.</iconset>
    </property>
    <property name="text">
     <string>Quit</string>
@@ -246,8 +249,7 @@
   </action>
  </widget>
  <resources>
-  <include location="../../../../../build/dev/qtdoc/examples/demos/documentviewer/.rcc/documentviewer.qrc"/>
-  <include location="../../../../../build/dev/qthttpserver/examples/httpserver/simple/.rcc/assets.qrc"/>
+  <include location="../../../../../../build/dev/qtdoc/examples/demos/documentviewer/app/.rcc/documentviewer.qrc"/>
  </resources>
  <connections>
   <connection>

examples/demos/documentviewer/app/recentfilemenu.cpp

@@ -0,0 +1,38 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include "recentfilemenu.h"
+#include "recentfiles.h"
+
+#include <QAction>
+#include <QObject>
+#include <QWidget>
+
+RecentFileMenu::RecentFileMenu(QWidget *parent, RecentFiles *recent) :
+    QMenu(parent), m_recentFiles(recent)
+{
+    Q_ASSERT(recent);
+    connect(m_recentFiles, &RecentFiles::changed, this, &RecentFileMenu::updateList);
+    connect(m_recentFiles, &QObject::destroyed, this, &QObject::deleteLater);
+    updateList();
+}
+
+void RecentFileMenu::updateList()
+{
+    QList<QAction *> acts = actions();
+    qDeleteAll(acts);
+
+    if (m_recentFiles->isEmpty()) {
+        addAction(tr("<no recent files>"));
+        return;
+    }
+
+    for (const QString &fileName : m_recentFiles->recentFiles()) {
+        QAction *action = addAction(fileName);
+        connect(action, &QAction::triggered, this, [&](){
+            QAction *action = qobject_cast<QAction *>(sender());
+            Q_ASSERT(action);
+            emit fileOpened(action->text());
+        });
+    }
+}

examples/demos/documentviewer/app/recentfilemenu.h

@@ -0,0 +1,28 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#ifndef RECENTFILEMENU_H
+#define RECENTFILEMENU_H
+
+#include <QMenu>
+
+class RecentFiles;
+class QAction;
+class RecentFileMenu : public QMenu
+{
+    Q_OBJECT
+
+public:
+    explicit RecentFileMenu(QWidget *parent, RecentFiles *recent);
+
+signals:
+    void fileOpened(const QString &fileName);
+
+private slots:
+    void updateList();
+
+private:
+    RecentFiles *m_recentFiles;
+};
+
+#endif // RECENTFILEMENU_H

examples/demos/documentviewer/app/recentfiles.cpp

@@ -0,0 +1,169 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include "recentfiles.h"
+#include <QFileInfo>
+#include <QSettings>
+
+RecentFiles::RecentFiles(QObject *parent) : QObject(parent)
+{
+}
+
+void RecentFiles::clear()
+{
+    if (isEmpty())
+        return;
+
+    QStringList::clear();
+    emit countChanged(0);
+    emit listCleared();
+}
+
+void RecentFiles::addFile(const QString &fileName, EmitPolicy policy)
+{
+    if (!testFileAccess(fileName))
+        return;
+
+    // Remember size, as cleanup can result in a change without size change
+    const qsizetype c = count();
+
+    // Clean dangling and duplicate files
+    bool duplicateFound = false;
+    for (const QString &file : *this) {
+        if (!testFileAccess(file)) {
+            removeFile(file, RemoveReason::Dangling);
+        } else if (file == fileName) {
+            removeFile(file, RemoveReason::Duplicate);
+            duplicateFound = true;
+        }
+    }
+
+    // Cut tail
+    while (count() > m_maxFiles)
+        removeFile((count() - 1), RemoveReason::TailCut);
+
+    prepend(fileName);
+
+    switch (policy) {
+    case EmitPolicy::NeverEmit:
+        return;
+
+    case EmitPolicy::AllwaysEmit:
+        emit changed();
+        emit fileAdded(fileName);
+        emit countChanged(count());
+        return;
+
+    case EmitPolicy::EmitWhenChanged:
+        emit changed();
+        if (!duplicateFound)
+            emit fileAdded(fileName);
+
+        if (c != count())
+            emit countChanged(count());
+
+        return;
+    }
+}
+
+void RecentFiles::addFiles(const QStringList &files)
+{
+    if (files.isEmpty())
+        return;
+
+    if (files.count() == 1) {
+        addFile(files.at(0));
+        return;
+    }
+
+    const auto &c = count();
+
+    for (const auto &file : files)
+        addFile(file, EmitPolicy::NeverEmit);
+
+    emit filesAdded(files);
+    emit changed();
+    if (count() != c)
+        emit countChanged(count());
+}
+
+// Test if file exists and can be opened
+bool RecentFiles::testFileAccess(const QString &fileName) const
+{
+    QFileInfo info(fileName);
+    if (!info.isFile())
+        return false;
+
+    switch (m_openMode) {
+    case QIODevice::ReadOnly:
+        if (!info.isReadable())
+            return false;
+        break;
+    case QIODevice::ReadWrite:
+        if (!(info.isReadable() && info.isWritable()))
+            return false;
+        break;
+    case QIODevice::WriteOnly:
+        if (!info.isWritable())
+            return false;
+        break;
+    }
+    return true;
+}
+
+void RecentFiles::removeFile(qsizetype index, RemoveReason reason)
+{
+    if (index < 0 || index >= count())
+        return;
+
+    const QString &fileName = at(index);
+    remove(index);
+
+    // No emit for duplicate removal, add emits changed later.
+    if (reason == RemoveReason::Duplicate)
+        return;
+
+    emit fileRemoved(fileName, reason);
+    emit changed();
+}
+
+void RecentFiles::saveSettings(QSettings &settings, const QString &key) const
+{
+    settings.beginGroup(key);
+    settings.setValue(s_maxFiles, maxFiles());
+    settings.setValue(s_openMode, static_cast<int>(openMode()));
+    if (!isEmpty()) {
+        settings.beginWriteArray(s_fileNames, count());
+        for (int index = 0; index < count(); ++index) {
+            settings.setArrayIndex(index);
+            settings.setValue(s_file, at(index));
+        }
+        settings.endArray();
+    }
+    settings.endGroup();
+}
+
+bool RecentFiles::restoreFromSettings(QSettings &settings, const QString &key)
+{
+    settings.beginGroup(key);
+    const qsizetype mxFiles = settings.value(s_maxFiles, maxFiles()).toLongLong();
+    const auto mode = qvariant_cast<QIODevice::OpenMode>(settings.value(s_openMode,
+                                             static_cast<int>(openMode())).toInt());
+    setMaxFiles(mxFiles);
+    setOpenMode(mode);
+    QStringList::clear(); // clear list without emitting
+    const int numberFiles = settings.beginReadArray(s_fileNames);
+    for (int index = 0; index < numberFiles; ++index) {
+        settings.setArrayIndex(index);
+        const QString absoluteFilePath = settings.value(s_file).toString();
+        addFile(absoluteFilePath, EmitPolicy::NeverEmit);
+    }
+    settings.endArray();
+    settings.endGroup();
+    if (count() > 0) {
+        emit settingsRestored(count());
+        emit changed();
+    }
+
+    return true;
+}

examples/demos/documentviewer/app/recentfiles.h

@@ -0,0 +1,81 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#ifndef RECENTFILES_H
+#define RECENTFILES_H
+
+#include <QMenu>
+#include <QFile>
+
+class QSettings;
+class RecentFiles : public QObject, private QStringList
+{
+    Q_OBJECT
+public:
+    enum class RemoveReason {
+        Reset,
+        Dangling,
+        TailCut,
+        RemovedManually,
+        Duplicate
+    };
+    Q_ENUM(RemoveReason)
+
+    explicit RecentFiles(QObject *parent);
+
+    // Access to QStringList member functions
+    qsizetype count() const {return QStringList::count(); };
+    const QStringList recentFiles() const {return *this; }
+    bool isEmpty() const { return QStringList::isEmpty(); }
+
+    // Properties
+    qsizetype maxFiles() const { return m_maxFiles; }
+    void setMaxFiles(qsizetype maxFiles) { m_maxFiles = maxFiles; }
+    QIODevice::OpenMode openMode() const { return m_openMode; }
+    void setOpenMode(QIODevice::OpenMode mode) { m_openMode = mode; }
+
+public slots:
+    void addFile(const QString &fileName) {addFile(fileName, EmitPolicy::EmitWhenChanged); }
+    void addFiles(const QStringList &fileNames);
+    void removeFile(const QString &fileName) {removeFile(indexOf(fileName)); }
+    void removeFile(qsizetype index) {removeFile(index, RemoveReason::RemovedManually); }
+    void saveSettings(QSettings &settings, const QString &key) const;
+    bool restoreFromSettings(QSettings &settings, const QString &key);
+    void clear();
+
+signals:
+    void fileAdded(const QString &fileName);
+    void filesAdded(const QStringList &files);
+    void fileRemoved(const QString &fileName, RecentFiles::RemoveReason reason);
+    void countChanged(int count);
+    void listCleared();
+    void settingsRestored(qsizetype count);
+    void changed();
+
+private:
+    bool testFileAccess(const QString &fileName) const;
+
+    // Private removers with reason
+    void removeFile(qsizetype index, RemoveReason reason);
+    void removeFile(const QString &fileName, RemoveReason reason) {removeFile(indexOf(fileName), reason); }
+
+    // Private adder with emit policy
+    enum class EmitPolicy {
+        AllwaysEmit,
+        EmitWhenChanged,
+        NeverEmit
+    };
+
+    void addFile(const QString &fileName, EmitPolicy policy);
+
+    qsizetype m_maxFiles = 10;
+    QIODevice::OpenMode m_openMode = QIODevice::ReadOnly;
+
+    // Constexprs for settings
+    static constexpr QLatin1StringView s_maxFiles = QLatin1StringView("maxFiles");
+    static constexpr QLatin1StringView s_openMode = QLatin1StringView("openMode");
+    static constexpr QLatin1StringView s_fileNames = QLatin1StringView("fileNames");
+    static constexpr QLatin1StringView s_file = QLatin1StringView("file");
+};
+
+#endif // RECENTFILES_H

examples/demos/documentviewer/app/viewerfactory.cpp

@@ -0,0 +1,173 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include <QWidget>
+#include <QMimeDatabase>
+#include <QMimeType>
+#include <QApplication>
+#include <QPluginLoader>
+#include <QDir>
+#include "abstractviewer.h"
+#include "viewerfactory.h"
+#include "viewerinterfaces.h"
+#include <concepts>
+
+ViewerFactory::ViewerFactory(QWidget *displayWidget, QMainWindow *mainWindow, DefaultPolicy policy)
+    : m_defaultPolicy(policy),
+      m_displayWidget(displayWidget),
+      m_mainWindow(mainWindow)
+{
+    Q_ASSERT(m_displayWidget);
+    Q_ASSERT(m_mainWindow);
+    loadViewerPlugins();
+}
+
+ViewerFactory::~ViewerFactory()
+{
+    unload();
+}
+
+AbstractViewer *ViewerFactory::viewer(QFile *file) const
+{
+    Q_ASSERT(file);
+
+    const QFileInfo info(*file);
+    QMimeDatabase db;
+    const auto mimeType = db.mimeTypeForFile(info);
+
+    AbstractViewer *viewer = ViewerFactory::viewer(mimeType);
+    if (!viewer) {
+        qWarning() << "Mime type" << mimeType.name() << "not supported.";
+        return nullptr;
+    }
+
+    viewer->init(file, m_displayWidget, m_mainWindow);
+    return viewer;
+}
+
+void ViewerFactory::loadViewerPlugins()
+{
+    if (!m_viewers.isEmpty())
+        return;
+
+    // Load static plugins
+    const QObjectList &staticPlugins = QPluginLoader::staticInstances();
+    for (auto *plugin : staticPlugins)
+        addViewer(plugin);
+
+    // Load shared plugins
+    QDir pluginsDir = QDir(QApplication::applicationDirPath());
+
+#if defined(Q_OS_WIN)
+    if (pluginsDir.dirName().toLower() == "debug" || pluginsDir.dirName().toLower() == "release")
+        pluginsDir.cdUp();
+#elif defined(Q_OS_DARWIN)
+    if (pluginsDir.dirName() == "macOS") {
+        pluginsDir.cdUp();
+        pluginsDir.cdUp();
+        pluginsDir.cdUp();
+    }
+#endif
+    const auto entryList = pluginsDir.entryList(QDir::Files);
+    for (const QString &fileName : entryList) {
+        QPluginLoader loader(pluginsDir.absoluteFilePath(fileName));
+        QObject *plugin = loader.instance();
+        if (plugin)
+            addViewer(plugin);
+#if 0
+        else
+            qDebug() << loader.errorString();
+#endif
+    }
+}
+
+void ViewerFactory::unload()
+{
+    qDeleteAll(viewers());
+    m_viewers.clear();
+}
+
+void ViewerFactory::addViewer(QObject *viewerObject)
+{
+    auto *interface = qobject_cast<ViewerInterface *>(viewerObject);
+    if (!interface)
+        return;
+
+    // Set custom default viewer
+    if (interface->viewer()->isDefaultViewer())
+        m_defaultViewer = interface->viewer();
+
+    m_viewers.insert(interface->viewerName(), interface->viewer());
+}
+
+QStringList ViewerFactory::viewerNames(bool showDefault) const
+{
+    if (!showDefault)
+        return m_viewers.keys();
+
+    QStringList list;
+    for (auto it = m_viewers.constBegin(); it != m_viewers.constEnd(); ++it) {
+        QString name = it.key();
+        if ((m_defaultViewer && it.value()->isDefaultViewer())
+             || (!m_defaultViewer && it.key() == "TxtViewer")) {
+            name += "(default)";
+        }
+        list.append(name);
+    }
+    return list;
+}
+
+ViewerFactory::ViewerList ViewerFactory::viewers() const
+{
+    return m_viewers.values();
+}
+
+AbstractViewer *ViewerFactory::findViewer(const QString &viewerName) const
+{
+    const ViewerList &viewerList = viewers();
+    for (auto *viewer : viewerList) {
+        if (viewer->viewerName() == viewerName)
+            return viewer;
+    }
+    qWarning() << "Plugin" << viewerName << "not loaded.";
+    return nullptr;
+}
+
+AbstractViewer *ViewerFactory::viewer(const QMimeType &mimeType) const
+{
+    const ViewerList &viewerList = viewers();
+
+    for (AbstractViewer *viewer : viewerList) {
+        for (const QString &type : viewer->supportedMimeTypes()) {
+            if (mimeType.inherits(type))
+                return viewer;
+        }
+    }
+
+    return defaultViewer();
+}
+
+AbstractViewer *ViewerFactory::defaultViewer() const
+{
+    switch (m_defaultPolicy) {
+    case DefaultPolicy::NeverDefault:
+        return nullptr;
+    case DefaultPolicy::DefaultToCustomViewer:
+        return m_defaultViewer ? m_defaultViewer : findViewer("TxtViewer");
+    case DefaultPolicy::DefaultToTxtViewer:
+        return findViewer("TxtViewer");
+    }
+    Q_UNREACHABLE();
+}
+
+QStringList ViewerFactory::supportedMimeTypes() const
+{
+    static QStringList mimeTypes;
+    if (!mimeTypes.isEmpty())
+        return mimeTypes;
+
+    const ViewerList &viewerList = viewers();
+    for (auto viewer : viewerList)
+        mimeTypes.append(viewer->supportedMimeTypes());
+    return mimeTypes;
+}

examples/demos/documentviewer/app/viewerfactory.h

@@ -0,0 +1,57 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#ifndef VIEWERFACTORY_H
+#define VIEWERFACTORY_H
+
+#include <QString>
+#include <QMimeType>
+#include <QObject>
+#include <QMap>
+
+class AbstractViewer;
+class QWidget;
+class QMainWindow;
+class Questions;
+class QFile;
+class ViewerFactory
+{
+public:
+    enum class DefaultPolicy {
+        NeverDefault,
+        DefaultToTxtViewer,
+        DefaultToCustomViewer
+    };
+
+    explicit ViewerFactory(QWidget *displayWidget, QMainWindow *mainWindow,
+                           DefaultPolicy policy = DefaultPolicy::DefaultToTxtViewer);
+    ~ViewerFactory();
+
+    DefaultPolicy defaultPolicy() const { return m_defaultPolicy; }
+    void setDefaultPolicy(DefaultPolicy policy) { m_defaultPolicy = policy; }
+
+    AbstractViewer *viewer(QFile *file) const;
+
+
+    typedef QMap<QString, AbstractViewer *> ViewerMap;
+    typedef QList<AbstractViewer *> ViewerList;
+    QStringList viewerNames(bool showDefault = false) const;
+    ViewerList viewers() const;
+    AbstractViewer *findViewer(const QString &viewerName) const;
+    AbstractViewer *defaultViewer() const;
+    QStringList supportedMimeTypes() const;
+
+private:
+    DefaultPolicy m_defaultPolicy;
+    QWidget *m_displayWidget;
+    QMainWindow *m_mainWindow;
+    ViewerMap m_viewers;
+    AbstractViewer *m_defaultViewer = nullptr;
+
+    void loadViewerPlugins();
+    void addViewer(QObject *viewerObject);
+    AbstractViewer *viewer(const QMimeType &type) const;
+    void unload();
+};
+
+#endif // VIEWERFACTORY_H

examples/demos/documentviewer/app/viewerinterfaces.h

@@ -0,0 +1,39 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#ifndef VIEWERINTERFACES_H
+#define VIEWERINTERFACES_H
+
+#include "abstractviewer.h"
+#include <QtPlugin>
+#include <QWidget>
+
+QT_BEGIN_NAMESPACE
+class QFile;
+class QMainWindow;
+class QWidget;
+class QTabWidget;
+class QPrinter;
+QT_END_NAMESPACE
+
+class ViewerInterface : public AbstractViewer
+{
+public:
+    virtual ~ViewerInterface() = default;
+    virtual QString viewerName() const override = 0;
+    virtual QByteArray saveState() const override = 0;
+    virtual bool restoreState(QByteArray &) override = 0;
+    virtual bool supportsOverview() const override = 0;
+    virtual bool hasContent() const override = 0;
+#ifdef QT_DOCUMENTVIEWER_PRINTSUPPORT
+    virtual void printDocument(QPrinter *) const override = 0;
+    virtual QStringList supportedMimeTypes() const override = 0;
+#endif
+};
+
+QT_BEGIN_NAMESPACE
+#define ViewerInterface_iid "org.qt-project.Qt.Examples.DocumentViewer.ViewerInterface/1.0"
+Q_DECLARE_INTERFACE(ViewerInterface, ViewerInterface_iid)
+QT_END_NAMESPACE
+
+#endif //VIEWERINTERFACES_H

examples/demos/documentviewer/doc/src/documentviewer.qdoc

@@ -27,14 +27,14 @@
     To create an executable, we use a standard main.cpp file.
     First, we set the application's organization name:
 
-    \quotefromfile demos/documentviewer/main.cpp
+    \quotefromfile demos/documentviewer/app/main.cpp
     \skipto int main
     \printuntil QApplication::set
     \endsection1
 
     \section1 Creating an application and showing the main window
 
-    \quotefromfile demos/documentviewer/main.cpp
+    \quotefromfile demos/documentviewer/app/main.cpp
     \skipto QApplication app
     \printuntil }
     \endsection1
@@ -44,13 +44,17 @@
     The class constructor initializes the user interface created in Qt Designer.
     It links the actions for opening a file and the about dialog to their implementation.
 
-    \quotefromfile demos/documentviewer/mainwindow.cpp
+    \quotefromfile demos/documentviewer/app/mainwindow.cpp
     \skipto ui->setupUi
     \printuntil triggered
 
     The \c mainwindow.ui file provides a QTabWidget on the left, where bookmarks and thumbnails
     can be displayed. It provides a QScrollArea on the right, where the viewed file contents are
-    displayed.
+    \printuntil showMenu);
+
+    If a file is opened, the {File} class (inheriting from {QFile}) automatically determines
+    the FileType used in this application. If no valid file type could be established, the user
+    is asked, if it should be opened as plain text.
 
     The ViewerFactory class provides a static method to create a file type specific viewer.
 
@@ -62,7 +66,7 @@
     virtual restoreState method. Afterwards, the standard UI assets are passed to the viewer
     and it's display widget is displayed in the main scroll area.
 
-    \quotefromfile demos/documentviewer/mainwindow.cpp
+    \quotefromfile demos/documentviewer/app/mainwindow.cpp
     \skipuntil void MainWindow::openFile
     \skipto m_viewer->initViewer
     \printuntil }
@@ -74,7 +78,7 @@
     displayed, the main window and the user questions.
     Depending on the file's mime type, it creates an appropriate document viewer.
 
-    \quotefromfile demos/documentviewer/mainwindow.cpp
+    \quotefromfile demos/documentviewer/app/mainwindow.cpp
     \skipto AbstractViewer
     \printuntil }
     \endsection1
@@ -159,40 +163,40 @@
     HoverWatcher inherits from QObject and the QWidget watched becomes the instance's parent.
     An event filter is used to intercept the hover events without consuming them.
 
-    \quotefromfile demos/documentviewer/hoverwatcher.cpp
+    \quotefromfile demos/documentviewer/plugins/pdfviewer/hoverwatcher.cpp
     \skipto HoverWatcher::HoverWatcher
     \printuntil }
 
     The actions watched are represented in an enum.
 
-    \quotefromfile demos/documentviewer/hoverwatcher.h
+    \quotefromfile demos/documentviewer/plugins/pdfviewer/hoverwatcher.h
     \skipto enum HoverAction
     \printuntil };
 
     Static methods create watchers, check their existence for a specific QWidget or dismiss
     a watcher.
 
-    \quotefromfile demos/documentviewer/hoverwatcher.h
+    \quotefromfile demos/documentviewer/plugins/pdfviewer/hoverwatcher.h
     \skipto static HoverWatcher
     \printuntil static void dismiss
 
     A cursor shape can be specified or unset for each HoverAction. If no cursor shape is
     specified for an action, the application's override cursor will be restored when it occurs.
 
-    \quotefromfile demos/documentviewer/hoverwatcher.h
+    \quotefromfile demos/documentviewer/plugins/pdfviewer/hoverwatcher.h
     \skipto public slots
     \printuntil void unSetCursorShape
 
     The mouseButtons property specifies, which mouse buttons to consider for the MousePress action.
 
-    \quotefromfile demos/documentviewer/hoverwatcher.h
+    \quotefromfile demos/documentviewer/plugins/pdfviewer/hoverwatcher.h
     \skipuntil public slots
     \skipto setMouseButtons
     \printuntil setMouseButton(
 
     Action specific signals are emitted when an action has been processed.
 
-    \quotefromfile demos/documentviewer/hoverwatcher.h
+    \quotefromfile demos/documentviewer/plugins/pdfviewer/hoverwatcher.h
     \skipto signals
     \printuntil left();
 
@@ -201,6 +205,72 @@
     \code
     void hoverAction(HoverAction action);
     \endcode
+    \endsection2
+
+    \section2 The {RecentFiles} class
+
+    The class is a QStringList, specialized to manage a list of recently opened files.
+
+    \quotefromfile demos/documentviewer/recentfiles.cpp
+    \skipto RecentFiles::RecentFiles
+    \printuntil }
+
+    It provides slots to add a single or multiple files, by passing their path or a list
+    of paths as an argument. A file is added, if the path leads to a valid file.
+    If a file already exists in the list of recent files, it is removed from its original position
+    and added on the top.
+
+    \quotefromfile demos/documentviewer/recentfiles.h
+    \skipto public slots
+    \printuntil addFiles
+
+    Files can be removed by name or by index.
+
+    \quotefromfile demos/documentviewer/recentfiles.h
+    \skipuntil public slots
+    \skipto removeFile
+    \printuntil addFiles
+
+    Slots are available to save and restore from {QSettings}.
+    Files restored from settings are ignored, if they no longer exist.
+
+    \quotefromfile demos/documentviewer/recentfiles.h
+    \skipuntil public slots
+    \skipto saveSettings
+    \printuntil restoreFromSettings
+
+    The maxFiles property manages the maximum amount of recent files to be remebered (default: 10).
+
+    \code
+    qsizetype maxFiles();
+    void setMaxFiles(qsizetype maxFiles);
+    \endcode
+
+    {RecentFiles} verifies a file can be opened in {openMode}, before adding it.
+
+    \code
+    void setOpenMode(QIODevice::OpenMode mode);
+    QIODevice::OpenMode openMode() const;
+    \endcode
+    \endsection2
+
+    \section2 The {RecentFileMenu} class
+
+    The {RecentFileMenu} class is a QMenu, specialized as a submenu to display a \l{RecentFiles}
+    object as a submenu.
+
+    Its constructor takes a parent widget, usually and QAction or a QMenu.
+    Its fileOpened signal passes a QString argument with the absolute file name, when the
+    application user has selected a recent file from the list.
+
+    \note
+    A {RecentFileMenu} is deleted either with its parent widget, or with the RecentFiles object
+    passed to its constructor.
+
+    \quotefromfile demos/documentviewer/recentfilemenu.h
+    \skipuntil class RecentFileMenu
+    \printuntil void fileOpened
+
     \endsection2
     \endsection1
 

examples/demos/documentviewer/plugins/CMakeLists.txt

@@ -0,0 +1,6 @@
+# Copyright (C) 2023 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+add_subdirectory(jsonviewer)
+add_subdirectory(pdfviewer)
+add_subdirectory(txtviewer)

examples/demos/documentviewer/plugins/jsonviewer/CMakeLists.txt

@@ -0,0 +1,35 @@
+# Copyright (C) 2023 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+qt_add_plugin(jsonviewer
+    CLASS_NAME JsonViewer
+    jsonviewer.cpp jsonviewer.h
+    ../../app/abstractviewer.h ../../app/abstractviewer.cpp
+)
+
+find_package(Qt6 REQUIRED COMPONENTS Core Gui Widgets
+                 OPTIONAL_COMPONENTS PrintSupport)
+
+set_target_properties(jsonviewer PROPERTIES
+    LIBRARY_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/app"
+)
+
+target_include_directories(jsonviewer PRIVATE
+    ../../app
+)
+
+target_link_libraries(jsonviewer PRIVATE
+    Qt6::Core
+    Qt6::Gui
+    Qt6::Widgets
+)
+
+if(TARGET Qt6::PrintSupport)
+    target_link_libraries(jsonviewer PRIVATE Qt6::PrintSupport)
+endif()
+
+install(TARGETS jsonviewer
+    BUNDLE DESTINATION "${INSTALL_EXAMPLEDIR}/plugins"
+    LIBRARY DESTINATION "${INSTALL_EXAMPLEDIR}/plugins"
+)
+

examples/demos/documentviewer/plugins/jsonviewer/jsonviewer.cpp

@@ -18,14 +18,14 @@
 #include <QLineEdit>
 #include <QLabel>
 #include <QApplication>
-#ifdef QT_ABSTRACTVIEWER_PRINTSUPPORT
+#ifdef QT_DOCUMENTVIEWER_PRINTSUPPORT
 #include <QPrinter>
 #include <QPainter>
 #endif
 
-JsonViewer::JsonViewer(QFile *file, QWidget *parent, QMainWindow *mainWindow) :
-    AbstractViewer(file, new QTreeView(parent), mainWindow)
+void JsonViewer::init(QFile *file, QWidget *parent, QMainWindow *mainWindow)
 {
+    AbstractViewer::init(file, new QTreeView(parent), mainWindow);
     m_tree = qobject_cast<QTreeView *>(widget());
     connect(this, &AbstractViewer::uiInitialized, this, &JsonViewer::setupJsonUi);
 }
@@ -35,6 +35,11 @@ JsonViewer::~JsonViewer()
     delete m_toplevel;
 }
 
+QStringList JsonViewer::supportedMimeTypes() const
+{
+    return {"application/json"};
+}
+
 void JsonViewer::setupJsonUi()
 {
     // Build Menus and toolbars
@@ -268,7 +273,7 @@ bool JsonViewer::hasContent() const
     return !m_root.isEmpty();
 }
 
-#if defined(QT_ABSTRACTVIEWER_PRINTSUPPORT)
+#ifdef QT_DOCUMENTVIEWER_PRINTSUPPORT
 void JsonViewer::printDocument(QPrinter *printer) const
 {
     if (!hasContent())
@@ -278,7 +283,7 @@ void JsonViewer::printDocument(QPrinter *printer) const
     doc.print(printer);
 }
 
-#endif // QT_ABSTRACTVIEWER_PRINTSUPPORT
+#endif // QT_DOCUMENTVIEWER_PRINTSUPPORT
 
 QByteArray JsonViewer::saveState() const
 {

examples/demos/documentviewer/plugins/jsonviewer/jsonviewer.h

@@ -4,7 +4,7 @@
 #ifndef JSONVIEWER_H
 #define JSONVIEWER_H
 
-#include "abstractviewer.h"
+#include "viewerinterfaces.h"
 #include <QJsonValue>
 #include <QJsonDocument>
 #include <QAbstractItemModel>
@@ -15,21 +15,25 @@ class QTreeView;
 class QListWidget;
 class QListWidgetItem;
 class QLineEdit;
+class QPrinter;
 
-class JsonViewer : public AbstractViewer
+class JsonViewer : public ViewerInterface
 {
-    Q_GADGET
+    Q_OBJECT
+    Q_PLUGIN_METADATA(IID "org.qt-project.Qt.Examples.DocumentViewer.ViewerInterface/1.0" FILE "jsonviewer.json")
+    Q_INTERFACES(ViewerInterface)
 public:
-    JsonViewer(QFile *file, QWidget *parent, QMainWindow *mainWindow);
     ~JsonViewer() override;
 
+    void init(QFile *file, QWidget *parent, QMainWindow *mainWindow) override;
     QString viewerName() const override { return staticMetaObject.className(); };
+    QStringList supportedMimeTypes() const override;
     QByteArray saveState() const override;
     bool restoreState(QByteArray &) override;
     bool supportsOverview() const override { return true; }
     bool hasContent() const override;
 
-#if defined(QT_ABSTRACTVIEWER_PRINTSUPPORT)
+#ifdef QT_DOCUMENTVIEWER_PRINTSUPPORT
 protected:
     void printDocument(QPrinter *printer) const override;
 #endif // QT_ABSTRACTVIEWER_PRINTSUPPORT

examples/demos/documentviewer/plugins/jsonviewer/jsonviewer.json

@@ -0,0 +1 @@
+{ "Keys": [ "jsonviewer" ] }

examples/demos/documentviewer/plugins/pdfviewer/CMakeLists.txt

@@ -0,0 +1,39 @@
+# Copyright (C) 2023 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+find_package(Qt6 REQUIRED COMPONENTS Core Gui Widgets PdfWidgets
+                 OPTIONAL_COMPONENTS PrintSupport)
+
+qt_add_plugin(pdfviewer
+    CLASS_NAME PdfViewer
+    pdfviewer.cpp pdfviewer.h
+    zoomselector.cpp zoomselector.h
+    hoverwatcher.cpp hoverwatcher.h
+    ../../app/abstractviewer.h ../../app/abstractviewer.cpp
+)
+
+set_target_properties(pdfviewer PROPERTIES
+    LIBRARY_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/app"
+)
+
+target_include_directories(pdfviewer PRIVATE
+    ../../app
+    ..
+)
+
+target_link_libraries(pdfviewer PRIVATE
+    Qt6::Core
+    Qt6::Gui
+    Qt6::Widgets
+    Qt6::PdfWidgets
+)
+
+if(TARGET Qt6::PrintSupport)
+    target_link_libraries(pdfviewer PRIVATE Qt6::PrintSupport)
+endif()
+
+install(TARGETS pdfviewer
+    BUNDLE DESTINATION "${INSTALL_EXAMPLEDIR}/plugins"
+    LIBRARY DESTINATION "${INSTALL_EXAMPLEDIR}/plugins"
+)
+

examples/demos/documentviewer/plugins/pdfviewer/pdfviewer.cpp

@@ -25,20 +25,21 @@
 #include <QEvent>
 #include <QMouseEvent>
 #include <QScroller>
-#ifdef QT_ABSTRACTVIEWER_PRINTSUPPORT
+#ifdef QT_DOCUMENTVIEWER_PRINTSUPPORT
 #include <QPrinter>
 #include <QPainter>
 #endif
 
 Q_LOGGING_CATEGORY(lcExample, "qt.examples.pdfviewer")
 
-PdfViewer::PdfViewer(QFile *file, QWidget *parent, QMainWindow *mainWindow) :
-    AbstractViewer(file, new QPdfView(parent), mainWindow), m_document(new QPdfDocument(this))
-
+void PdfViewer::init(QFile *file, QWidget *parent, QMainWindow *mainWindow)
 {
+    AbstractViewer::init(file, new QPdfView(parent), mainWindow);
+    m_document = new QPdfDocument(this);
     m_pdfView = qobject_cast<QPdfView *>(widget());
     connect(this, &AbstractViewer::uiInitialized, this, &PdfViewer::initPdfViewer);
 }
+
 PdfViewer::~PdfViewer()
 {
     delete m_pages;
@@ -46,6 +47,11 @@ PdfViewer::~PdfViewer()
     delete m_document;
 }
 
+QStringList PdfViewer::supportedMimeTypes() const
+{
+    return {"application/pdf"};
+}
+
 void PdfViewer::initPdfViewer()
 {
     m_toolBar = addToolBar("PDF");
@@ -154,7 +160,7 @@ bool PdfViewer::hasContent() const
     return m_document ? m_document->pageCount() > 0 : false;
 }
 
-#if defined(QT_ABSTRACTVIEWER_PRINTSUPPORT)
+#ifdef QT_DOCUMENTVIEWER_PRINTSUPPORT
 void PdfViewer::printDocument(QPrinter *printer) const
 {
     if (!hasContent())
@@ -172,7 +178,7 @@ void PdfViewer::printDocument(QPrinter *printer) const
     }
     painter.end();
 }
-#endif // QT_ABSTRACTVIEWER_PRINTSUPPORT
+#endif // QT_DOCUMENTVIEWER_PRINTSUPPORT
 
 void PdfViewer::bookmarkSelected(const QModelIndex &index)
 {

examples/demos/documentviewer/plugins/pdfviewer/pdfviewer.h

@@ -4,7 +4,7 @@
 #ifndef PDFVIEWER_H
 #define PDFVIEWER_H
 
-#include "abstractviewer.h"
+#include "viewerinterfaces.h"
 #include <QLoggingCategory>
 
 Q_DECLARE_LOGGING_CATEGORY(lcExample)
@@ -17,22 +17,25 @@ class QListView;
 class QTabWidget;
 class QTreeView;
 class ZoomSelector;
-class PdfViewer : public AbstractViewer
+class PdfViewer : public ViewerInterface
 {
+    Q_OBJECT
+    Q_PLUGIN_METADATA(IID "org.qt-project.Qt.Examples.DocumentViewer.ViewerInterface" FILE "pdfviewer.json")
+    Q_INTERFACES(ViewerInterface)
 public:
-    PdfViewer(QFile *file, QWidget *parent, QMainWindow *mainWindow);
-
     ~PdfViewer() override;
+    void init(QFile *file, QWidget *parent, QMainWindow *mainWindow) override;
     QString viewerName() const override { return staticMetaObject.className(); };
+    QStringList supportedMimeTypes() const override;
     bool supportsOverview() const override { return true; }
     bool hasContent() const override;
     QByteArray saveState() const override { return QByteArray(); }
     bool restoreState(QByteArray &) override { return true; }
 
-#if defined(QT_ABSTRACTVIEWER_PRINTSUPPORT)
+#ifdef QT_DOCUMENTVIEWER_PRINTSUPPORT
 protected:
     void printDocument(QPrinter *printer) const override;
-#endif // QT_ABSTRACTVIEWER_PRINTSUPPORT
+#endif // QT_DOCUMENTVIEWER_PRINTSUPPORT
 
 public slots:
     void openPdfFile();
@@ -58,10 +61,10 @@ private:
     const qreal zoomMultiplier = qSqrt(2.0);
     static constexpr int maxIconWidth = 200;
     QToolBar *m_toolBar = nullptr;
-    ZoomSelector *m_zoomSelector;
-    QPdfPageSelector *m_pageSelector;
-    QPdfDocument *m_document;
-    QPdfView *m_pdfView;
+    ZoomSelector *m_zoomSelector = nullptr;
+    QPdfPageSelector *m_pageSelector = nullptr;
+    QPdfDocument *m_document = nullptr;
+    QPdfView *m_pdfView = nullptr;
     QAction *m_actionForward = nullptr;
     QAction *m_actionBack = nullptr;
     QTreeView *m_bookmarks = nullptr;

examples/demos/documentviewer/plugins/pdfviewer/pdfviewer.json

@@ -0,0 +1 @@
+{ "Keys": [ "pdfviewer" ] }

examples/demos/documentviewer/plugins/txtviewer/CMakeLists.txt

@@ -0,0 +1,35 @@
+# Copyright (C) 2023 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+find_package(Qt6 REQUIRED COMPONENTS Core Gui Widgets
+                 OPTIONAL_COMPONENTS PrintSupport)
+
+qt_add_plugin(txtviewer
+    CLASS_NAME TxtViewer
+    txtviewer.cpp txtviewer.h
+    ../../app/abstractviewer.h ../../app/abstractviewer.cpp
+)
+
+set_target_properties(txtviewer PROPERTIES
+    LIBRARY_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/app"
+)
+
+target_include_directories(txtviewer PRIVATE
+    ../../app
+)
+
+target_link_libraries(txtviewer PRIVATE
+    Qt6::Core
+    Qt6::Gui
+    Qt6::Widgets
+)
+
+if(TARGET Qt6::PrintSupport)
+    target_link_libraries(txtviewer PRIVATE Qt6::PrintSupport)
+endif()
+
+install(TARGETS jsonviewer
+    BUNDLE DESTINATION "${INSTALL_EXAMPLEDIR}/plugins"
+    LIBRARY DESTINATION "${INSTALL_EXAMPLEDIR}/plugins"
+)
+

examples/demos/documentviewer/plugins/txtviewer/txtviewer.cpp

@@ -13,14 +13,14 @@
 #include <QMetaObject>
 #include <QScrollBar>
 #include <QPainter>
-#ifdef QT_ABSTRACTVIEWER_PRINTSUPPORT
+#ifdef QT_DOCUMENTVIEWER_PRINTSUPPORT
 #include <QPrinter>
 #include <QPrintDialog>
 #endif
 
-TxtViewer::TxtViewer(QFile *file, QWidget *parent, QMainWindow *mainWindow) :
-        AbstractViewer(file, new QPlainTextEdit(parent), mainWindow)
+void TxtViewer::init(QFile *file, QWidget *parent, QMainWindow *mainWindow)
 {
+    AbstractViewer::init(file, new QPlainTextEdit(parent), mainWindow);
     m_textEdit = qobject_cast<QPlainTextEdit *>(widget());
     connect(this, &AbstractViewer::uiInitialized, this, &TxtViewer::setupTxtUi);
 }
@@ -29,6 +29,11 @@ TxtViewer::~TxtViewer()
 {
 }
 
+QStringList TxtViewer::supportedMimeTypes() const
+{
+    return {"text/plain"};
+}
+
 void TxtViewer::setupTxtUi()
 {
     QMenu *editMenu = addMenu(tr("&Edit"));
@@ -119,7 +124,7 @@ bool TxtViewer::hasContent() const
     return (!m_textEdit->toPlainText().isEmpty());
 }
 
-#if defined(QT_ABSTRACTVIEWER_PRINTSUPPORT)
+#ifdef QT_DOCUMENTVIEWER_PRINTSUPPORT
 void TxtViewer::printDocument(QPrinter *printer) const
 {
     if (!hasContent())
@@ -127,8 +132,7 @@ void TxtViewer::printDocument(QPrinter *printer) const
 
     m_textEdit->print(printer);
 }
-
-#endif // QT_ABSTRACTVIEWER_PRINTSUPPORT
+#endif // QT_DOCUMENTVIEWER_PRINTSUPPORT
 
 bool TxtViewer::saveFile(QFile *file)
 {

examples/demos/documentviewer/plugins/txtviewer/txtviewer.h

@@ -4,28 +4,34 @@
 #ifndef TXTVIEWER_H
 #define TXTVIEWER_H
 
+#include "viewerinterfaces.h"
 #include "abstractviewer.h"
 #include <QPointer>
 
 class QMainWindow;
 class QPlainTextEdit;
 class QLabel;
-class TxtViewer : public AbstractViewer
+class TxtViewer : public ViewerInterface
 {
+    Q_OBJECT
+    Q_PLUGIN_METADATA(IID "org.qt-project.Qt.Examples.DocumentViewer.ViewerInterface" FILE "txtviewer.json")
+    Q_INTERFACES(ViewerInterface)
 public:
-    TxtViewer(QFile *file, QWidget *parent, QMainWindow *mainWindow);
     ~TxtViewer() override;
+    void init(QFile *file, QWidget *parent, QMainWindow *mainWindow) override;
     QString viewerName() const override { return staticMetaObject.className(); };
+    QStringList supportedMimeTypes() const override;
     bool saveDocument() override { return saveFile(m_file.get()); };
     bool saveDocumentAs() override;
     bool hasContent() const override;
     QByteArray saveState() const override { return QByteArray(); }
     bool restoreState(QByteArray &) override { return true; }
+    bool supportsOverview() const override { return false; }
 
-#if defined(QT_ABSTRACTVIEWER_PRINTSUPPORT)
+#ifdef QT_DOCUMENTVIEWER_PRINTSUPPORT
 protected:
     void printDocument(QPrinter *printer) const override;
-#endif // QT_ABSTRACTVIEWER_PRINTSUPPORT
+#endif // QT_DOCUMENTVIEWER_PRINTSUPPORT
 
 private slots:
     void setupTxtUi();

examples/demos/documentviewer/plugins/txtviewer/txtviewer.json

@@ -0,0 +1 @@
+{ "Keys": [ "txtviewer" ] }

examples/demos/documentviewer/viewerfactory.cpp

@@ -1,32 +0,0 @@
-// Copyright (C) 2023 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
-
-#include <QWidget>
-#include <QMimeDatabase>
-#include <QMimeType>
-#include "viewerfactory.h"
-
-#include "abstractviewer.h"
-#include "pdfviewer.h"
-#include "txtviewer.h"
-#include "jsonviewer.h"
-
-AbstractViewer *ViewerFactory::makeViewer(QFile *file, QWidget *displayWidget,
-                                          QMainWindow *mainWindow)
-{
-    Q_ASSERT(file);
-
-    const QFileInfo info(*file);
-    QMimeDatabase db;
-    const auto mimeType = db.mimeTypeForFile(info);
-
-    if (mimeType.inherits("application/json"))
-        return  new JsonViewer(file, displayWidget, mainWindow);
-    if (mimeType.inherits("text/plain"))
-        return  new TxtViewer(file, displayWidget, mainWindow);
-    if (mimeType.inherits("application/pdf"))
-        return new PdfViewer(file, displayWidget, mainWindow);
-
-    // Default to text viewer
-    return new TxtViewer(file, displayWidget, mainWindow);
-}

examples/demos/documentviewer/viewerfactory.h

@@ -1,19 +0,0 @@
-// Copyright (C) 2023 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
-
-#ifndef VIEWERFACTORY_H
-#define VIEWERFACTORY_H
-
-class AbstractViewer;
-class QWidget;
-class QMainWindow;
-class Questions;
-class QFile;
-class ViewerFactory
-{
-public:
-    ViewerFactory() = delete;
-    static AbstractViewer *makeViewer(QFile *file, QWidget *displayWidget, QMainWindow *mainWindow);
-};
-
-#endif // VIEWERFACTORY_H

examples/demos/photosurface/CMakeLists.txt

@@ -14,7 +14,7 @@ set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/demos/photosurface")
 
 find_package(Qt6 REQUIRED COMPONENTS Core Gui Qml Quick ShaderTools)
 
-qt_standard_project_setup(REQUIRES 6.5)
+qt_standard_project_setup()
 
 if (WIN32)
 #! [appicon_windows]
@@ -48,6 +48,7 @@ target_link_libraries(photosurfaceexample PRIVATE
 
 qt_add_qml_module(photosurfaceexample
     URI photosurface
+    VERSION 1.0
     QML_FILES
       "photosurface.qml"
       "resources/MomentumAnimation.qml"