Help: De-duplicate management of help viewer pages

For the help mode, the help viewer pages were managed both by the
OpenPagesModel and the HelpWidget, and needed manual keeping in sync.

Instead make the model just an aspect of the HelpWidget, manage
creation/deletion of pages via the HelpWidget, and use the model only
for the pure MVC API purposes.

Task-number: QTCREATORBUG-20558
Change-Id: Ib7d6f2561239b0d5f3328dfd30c84718f81af0a1
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/help/helpwidget.cpp

@@ -55,8 +55,8 @@
 #include <QCoreApplication>
 #include <QHBoxLayout>
 #include <QMenu>
-#include <QPrinter>
 #include <QPrintDialog>
+#include <QPrinter>
 #include <QStackedWidget>
 #include <QStatusBar>
 #include <QToolButton>
@@ -67,6 +67,39 @@ static const char kModeSideBarSettingsKey[] = "Help/ModeSideBar";
 namespace Help {
 namespace Internal {
 
+OpenPagesModel::OpenPagesModel(HelpWidget *parent)
+    : m_parent(parent)
+{}
+
+int OpenPagesModel::rowCount(const QModelIndex &parent) const
+{
+    return parent.isValid() ? 0 : m_parent->viewerCount();
+}
+
+int OpenPagesModel::columnCount(const QModelIndex &parent) const
+{
+    // page title + funky close button
+    return parent.isValid() ? 0 : 2;
+}
+
+QVariant OpenPagesModel::data(const QModelIndex &index, int role) const
+{
+    if (!index.isValid() || index.row() >= rowCount() || index.column() >= columnCount() - 1)
+        return QVariant();
+
+    switch (role) {
+    case Qt::ToolTipRole:
+        return m_parent->viewerAt(index.row())->source().toString();
+    case Qt::DisplayRole: {
+        const QString title = m_parent->viewerAt(index.row())->title();
+        return title.isEmpty() ? HelpWidget::tr("(Untitled)") : title;
+    }
+    default:
+        break;
+    }
+    return QVariant();
+}
+
 static void openUrlInWindow(const QUrl &url)
 {
     HelpPlugin::showHelpUrl(url, Core::HelpManager::ExternalHelpAlways);
@@ -77,12 +110,16 @@ static bool isBookmarkable(const QUrl &url)
     return !url.isEmpty() && url != QUrl(Help::Constants::AboutBlank);
 }
 
-HelpWidget::HelpWidget(const Core::Context &context, WidgetStyle style, QWidget *parent) :
-    QWidget(parent),
-    m_style(style)
+HelpWidget::HelpWidget(const Core::Context &context, WidgetStyle style, QWidget *parent)
+    : QWidget(parent)
+    , m_model(this)
+    , m_style(style)
 {
     m_viewerStack = new QStackedWidget;
 
+    if (style == ModeWidget)
+        m_openPagesManager = new OpenPagesManager(this);
+
     auto topLayout = new QVBoxLayout;
     topLayout->setContentsMargins(0, 0, 0, 0);
     topLayout->setSpacing(0);
@@ -299,9 +336,8 @@ HelpWidget::HelpWidget(const Core::Context &context, WidgetStyle style, QWidget
     }
 
     if (style != ModeWidget) {
-        HelpViewer *viewer = HelpPlugin::createHelpViewer(qreal(0.0));
-        addViewer(viewer);
-        setCurrentViewer(viewer);
+        addViewer({});
+        setCurrentIndex(0);
     }
 }
 
@@ -333,6 +369,12 @@ HelpWidget::~HelpWidget()
         Core::ActionManager::unregisterAction(m_scaleDown, TextEditor::Constants::DECREASE_FONT_SIZE);
     if (m_resetScale)
         Core::ActionManager::unregisterAction(m_resetScale, TextEditor::Constants::RESET_FONT_SIZE);
+    delete m_openPagesManager;
+}
+
+QAbstractItemModel *HelpWidget::model()
+{
+    return &m_model;
 }
 
 void HelpWidget::addSideBar()
@@ -469,8 +511,15 @@ int HelpWidget::currentIndex() const
     return m_viewerStack->currentIndex();
 }
 
-void HelpWidget::addViewer(HelpViewer *viewer)
+void HelpWidget::setCurrentIndex(int index)
 {
+    setCurrentViewer(viewerAt(index));
+}
+
+HelpViewer *HelpWidget::addViewer(const QUrl &url, qreal zoom)
+{
+    m_model.beginInsertRows(QModelIndex(), viewerCount(), viewerCount());
+    HelpViewer *viewer = HelpPlugin::createHelpViewer(zoom);
     m_viewerStack->addWidget(viewer);
     viewer->setFocus(Qt::OtherFocusReason);
     viewer->setActionVisible(HelpViewer::Action::NewPage, m_style == ModeWidget);
@@ -490,28 +539,36 @@ void HelpWidget::addViewer(HelpViewer *viewer)
         if (currentViewer() == viewer)
             m_backAction->setEnabled(available);
     });
-    connect(viewer, &HelpViewer::printRequested, this, [viewer, this]() {
-        print(viewer);
-    });
+    connect(viewer, &HelpViewer::printRequested, this, [viewer, this]() { print(viewer); });
     if (m_style == ExternalWindow)
         connect(viewer, &HelpViewer::titleChanged, this, &HelpWidget::updateWindowTitle);
+    connect(viewer, &HelpViewer::titleChanged, &m_model, [this, viewer] {
+        const int i = indexOf(viewer);
+        QTC_ASSERT(i >= 0, return );
+        m_model.dataChanged(m_model.index(i, 0), m_model.index(i, 0));
+    });
 
     connect(viewer, &HelpViewer::loadFinished, this, &HelpWidget::highlightSearchTerms);
     connect(viewer, &HelpViewer::newPageRequested, [](const QUrl &url) {
         OpenPagesManager::instance().createPage(url);
     });
     connect(viewer, &HelpViewer::externalPageRequested, this, &openUrlInWindow);
-
     updateCloseButton();
+    m_model.endInsertRows();
+    if (url.isValid())
+        viewer->setSource(url);
+    return viewer;
 }
 
 void HelpWidget::removeViewerAt(int index)
 {
-    QWidget *viewerWidget = m_viewerStack->widget(index);
+    HelpViewer *viewerWidget = viewerAt(index);
     QTC_ASSERT(viewerWidget, return);
+    m_model.beginRemoveRows(QModelIndex(), index, index);
+    viewerWidget->stop();
     m_viewerStack->removeWidget(viewerWidget);
-    // do not delete, that is done in the model
-    // delete viewerWidget;
+    m_model.endRemoveRows();
+    delete viewerWidget;
     if (m_viewerStack->currentWidget())
         setCurrentViewer(qobject_cast<HelpViewer *>(m_viewerStack->currentWidget()));
     updateCloseButton();
@@ -581,6 +638,14 @@ void HelpWidget::closeEvent(QCloseEvent *)
     emit aboutToClose();
 }
 
+int HelpWidget::indexOf(HelpViewer *viewer) const
+{
+    for (int i = 0; i < viewerCount(); ++i)
+        if (viewerAt(i) == viewer)
+            return i;
+    return -1;
+}
+
 void HelpWidget::updateBackMenu()
 {
     m_backMenu->clear();