Help: Add option for help viewer backend

Add "Reload" menu item, which re-creates the help viewer with the
current backend.

Change-Id: I979cb9cdf5ae5635f4d028dc41d71ab71ce80248
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/help/generalsettingspage.cpp

@@ -37,6 +37,7 @@
 #include <coreplugin/helpmanager.h>
 #include <coreplugin/icore.h>
 
+#include <utils/algorithm.h>
 #include <utils/fileutils.h>
 
 #include <QCoreApplication>
@@ -122,6 +123,21 @@ QWidget *GeneralSettingsPage::widget()
 
         m_scrollWheelZoomingEnabled = LocalHelpManager::isScrollWheelZoomingEnabled();
         m_ui->scrollWheelZooming->setChecked(m_scrollWheelZoomingEnabled);
+
+        const QString tooltip = tr("Change takes effect after reloading help pages.");
+        m_ui->viewerBackendLabel->setToolTip(tooltip);
+        m_ui->viewerBackend->setToolTip(tooltip);
+        m_ui->viewerBackend->addItem(tr("Default (%1)", "Default viewer backend")
+                                         .arg(LocalHelpManager::defaultViewerBackend().displayName));
+        const QByteArray currentBackend = LocalHelpManager::viewerBackendId();
+        const QVector<HelpViewerFactory> backends = LocalHelpManager::viewerBackends();
+        for (const HelpViewerFactory &f : backends) {
+            m_ui->viewerBackend->addItem(f.displayName, f.id);
+            if (f.id == currentBackend)
+                m_ui->viewerBackend->setCurrentIndex(m_ui->viewerBackend->count() - 1);
+        }
+        if (backends.size() == 1)
+            m_ui->viewerBackend->setEnabled(false);
     }
     return m_widget;
 }
@@ -168,6 +184,9 @@ void GeneralSettingsPage::apply()
         m_scrollWheelZoomingEnabled = zoom;
         LocalHelpManager::setScrollWheelZoomingEnabled(m_scrollWheelZoomingEnabled);
     }
+
+    const QByteArray viewerBackendId = m_ui->viewerBackend->currentData().toByteArray();
+    LocalHelpManager::setViewerBackendId(viewerBackendId);
 }
 
 void GeneralSettingsPage::setCurrentPage()

src/plugins/help/generalsettingspage.ui

@@ -305,6 +305,33 @@
         </property>
        </widget>
       </item>
+      <item>
+       <layout class="QHBoxLayout" name="horizontalLayout_5">
+        <item>
+         <widget class="QLabel" name="viewerBackendLabel">
+          <property name="text">
+           <string>Viewer backend:</string>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QComboBox" name="viewerBackend"/>
+        </item>
+        <item>
+         <spacer name="horizontalSpacer">
+          <property name="orientation">
+           <enum>Qt::Horizontal</enum>
+          </property>
+          <property name="sizeHint" stdset="0">
+           <size>
+            <width>40</width>
+            <height>20</height>
+           </size>
+          </property>
+         </spacer>
+        </item>
+       </layout>
+      </item>
      </layout>
     </widget>
    </item>
@@ -337,6 +364,15 @@
             </color>
            </brush>
           </colorrole>
+          <colorrole role="PlaceholderText">
+           <brush brushstyle="NoBrush">
+            <color alpha="128">
+             <red>255</red>
+             <green>0</green>
+             <blue>0</blue>
+            </color>
+           </brush>
+          </colorrole>
          </active>
          <inactive>
           <colorrole role="Text">
@@ -348,6 +384,15 @@
             </color>
            </brush>
           </colorrole>
+          <colorrole role="PlaceholderText">
+           <brush brushstyle="NoBrush">
+            <color alpha="128">
+             <red>255</red>
+             <green>0</green>
+             <blue>0</blue>
+            </color>
+           </brush>
+          </colorrole>
          </inactive>
          <disabled>
           <colorrole role="Text">
@@ -359,6 +404,15 @@
             </color>
            </brush>
           </colorrole>
+          <colorrole role="PlaceholderText">
+           <brush brushstyle="NoBrush">
+            <color alpha="128">
+             <red>255</red>
+             <green>0</green>
+             <blue>0</blue>
+            </color>
+           </brush>
+          </colorrole>
          </disabled>
         </palette>
        </property>

src/plugins/help/helpwidget.cpp

@@ -300,13 +300,15 @@ HelpWidget::HelpWidget(const Core::Context &context, WidgetStyle style, QWidget
         advancedMenu->addAction(cmd, Core::Constants::G_EDIT_FONT);
     }
 
+    auto openButton = new QToolButton;
+    openButton->setIcon(Utils::Icons::SPLIT_HORIZONTAL_TOOLBAR.icon());
+    openButton->setPopupMode(QToolButton::InstantPopup);
+    openButton->setProperty("noArrow", true);
+    layout->addWidget(openButton);
+    auto openMenu = new QMenu(openButton);
+    openButton->setMenu(openMenu);
+
     if (style != ExternalWindow) {
-        auto openButton = new QToolButton;
-        openButton->setIcon(Utils::Icons::SPLIT_HORIZONTAL_TOOLBAR.icon());
-        openButton->setPopupMode(QToolButton::InstantPopup);
-        openButton->setProperty("noArrow", true);
-        layout->addWidget(openButton);
-        auto openMenu = new QMenu(openButton);
         if (m_switchToHelp)
             openMenu->addAction(m_switchToHelp);
         if (style == ModeWidget) {
@@ -324,7 +326,7 @@ HelpWidget::HelpWidget(const Core::Context &context, WidgetStyle style, QWidget
                     emit closeButtonClicked();
             }
         });
-        openButton->setMenu(openMenu);
+        openMenu->addSeparator();
 
         const Utils::Icon &icon = style == ModeWidget ? Utils::Icons::CLOSE_TOOLBAR
                                                       : Utils::Icons::CLOSE_SPLIT_RIGHT;
@@ -335,6 +337,15 @@ HelpWidget::HelpWidget(const Core::Context &context, WidgetStyle style, QWidget
         layout->addWidget(button);
     }
 
+    QAction *reload = openMenu->addAction(tr("Reload"));
+    connect(reload, &QAction::triggered, this, [this]() {
+        const int index = m_viewerStack->currentIndex();
+        HelpViewer *previous = currentViewer();
+        insertViewer(index, previous->source(), previous->scale());
+        removeViewerAt(index + 1);
+        setCurrentIndex(index);
+    });
+
     if (style != ModeWidget) {
         addViewer({});
         setCurrentIndex(0);
@@ -516,9 +527,14 @@ void HelpWidget::setCurrentIndex(int index)
 
 HelpViewer *HelpWidget::addViewer(const QUrl &url, qreal zoom)
 {
-    m_model.beginInsertRows(QModelIndex(), viewerCount(), viewerCount());
+    return insertViewer(m_viewerStack->count(), url, zoom);
+}
+
+HelpViewer *HelpWidget::insertViewer(int index, const QUrl &url, qreal zoom)
+{
+    m_model.beginInsertRows({}, index, index);
     HelpViewer *viewer = HelpPlugin::createHelpViewer(zoom);
-    m_viewerStack->addWidget(viewer);
+    m_viewerStack->insertWidget(index, viewer);
     viewer->setFocus(Qt::OtherFocusReason);
     viewer->setActionVisible(HelpViewer::Action::NewPage, m_style == ModeWidget);
     viewer->setActionVisible(HelpViewer::Action::ExternalWindow, m_style != ExternalWindow);

src/plugins/help/helpwidget.h

@@ -114,7 +114,7 @@ signals:
 
 private:
     int indexOf(HelpViewer *viewer) const;
-
+    HelpViewer *insertViewer(int index, const QUrl &url, qreal zoom);
     void updateBackMenu();
     void updateForwardMenu();
     void updateWindowTitle();

src/plugins/help/localhelpmanager.cpp

@@ -45,6 +45,7 @@
 #include <coreplugin/icore.h>
 #include <utils/algorithm.h>
 #include <utils/hostosinfo.h>
+#include <utils/optional.h>
 #include <utils/qtcassert.h>
 
 #include <QDesktopServices>
@@ -81,6 +82,10 @@ static const char kUseScrollWheelZooming[] = "Help/UseScrollWheelZooming";
 static const char kLastShownPagesKey[] = "Help/LastShownPages";
 static const char kLastShownPagesZoomKey[] = "Help/LastShownPagesZoom";
 static const char kLastSelectedTabKey[] = "Help/LastSelectedTab";
+static const char kViewerBackend[] = "Help/ViewerBackend";
+
+static const char kQtWebEngineBackend[] = "qtwebengine";
+static const char kTextBrowserBackend[] = "textbrowser";
 
 static const int kDefaultFallbackFontSize = 14;
 
@@ -287,25 +292,39 @@ void LocalHelpManager::setLastSelectedTab(int index)
     Core::ICore::settings()->setValue(kLastSelectedTabKey, index);
 }
 
-QByteArray LocalHelpManager::defaultViewerBackend()
+static Utils::optional<HelpViewerFactory> backendForId(const QByteArray &id)
+{
+    const QVector<HelpViewerFactory> factories = LocalHelpManager::viewerBackends();
+    const auto backend = std::find_if(std::begin(factories),
+                                      std::end(factories),
+                                      Utils::equal(&HelpViewerFactory::id, id));
+    if (backend != std::end(factories))
+        return *backend;
+    return {};
+}
+
+HelpViewerFactory LocalHelpManager::defaultViewerBackend()
 {
     const QByteArray backend = qgetenv("QTC_HELPVIEWER_BACKEND");
-    if (Utils::contains(viewerBackends(), Utils::equal(&HelpViewerFactory::id, backend)))
+    if (!backend.isEmpty()) {
-        return backend;
+        const Utils::optional<HelpViewerFactory> factory = backendForId(backend);
-    else if (!backend.isEmpty())
+        if (factory)
+            return *factory;
+    }
+    if (!backend.isEmpty())
         qWarning("Help viewer backend \"%s\" not found, using default.", backend.constData());
-#ifdef QTC_WEBENGINE_HELPVIEWER
+    const Utils::optional<HelpViewerFactory> factory = backendForId(kQtWebEngineBackend);
-    return "qtwebengine";
+    if (factory)
-#else
+        return *factory;
-    return "textbrowser";
+    return backendForId(kTextBrowserBackend).value_or(HelpViewerFactory());
-#endif
 }
 
 QVector<HelpViewerFactory> LocalHelpManager::viewerBackends()
 {
     QVector<HelpViewerFactory> result;
 #ifdef QTC_WEBENGINE_HELPVIEWER
-    result.append({"qtwebengine", tr("QtWebEngine"), []() { return new WebEngineHelpViewer; }});
+    result.append(
+        {kQtWebEngineBackend, tr("QtWebEngine"), []() { return new WebEngineHelpViewer; }});
 #endif
 #ifdef QTC_LITEHTML_HELPVIEWER
     result.append({"litehtml", tr("litehtml"), []() { return new LiteHtmlHelpViewer; }});
@@ -313,18 +332,30 @@ QVector<HelpViewerFactory> LocalHelpManager::viewerBackends()
 #ifdef QTC_MAC_NATIVE_HELPVIEWER
     result.append({"native", tr("WebKit"), []() { return new MacWebKitHelpViewer; }});
 #endif
-    result.append({"textbrowser", tr("QTextBrowser"), []() { return new TextBrowserHelpViewer; }});
+    result.append(
+        {kTextBrowserBackend, tr("QTextBrowser"), []() { return new TextBrowserHelpViewer; }});
     return result;
 }
 
 HelpViewerFactory LocalHelpManager::viewerBackend()
 {
-    const QVector<HelpViewerFactory> factories = viewerBackends();
+    const QByteArray id = Core::ICore::settings()->value(kViewerBackend).toByteArray();
-    const auto backend = std::find_if(std::begin(factories),
+    if (!id.isEmpty())
-                                      std::end(factories),
+        return backendForId(id).value_or(defaultViewerBackend());
-                                      Utils::equal(&HelpViewerFactory::id, defaultViewerBackend()));
+    return defaultViewerBackend();
-    QTC_ASSERT(backend != std::end(factories), return {});
+}
-    return *backend;
+
+void LocalHelpManager::setViewerBackendId(const QByteArray &id)
+{
+    if (id.isEmpty())
+        Core::ICore::settings()->remove(kViewerBackend);
+    else
+        Core::ICore::settings()->setValue(kViewerBackend, id);
+}
+
+QByteArray LocalHelpManager::viewerBackendId()
+{
+    return Core::ICore::settings()->value(kViewerBackend).toByteArray();
 }
 
 void LocalHelpManager::setupGuiHelpEngine()

src/plugins/help/localhelpmanager.h

@@ -26,7 +26,6 @@
 #pragma once
 
 #include <coreplugin/helpmanager.h>
-#include <utils/optional.h>
 
 #include <QMetaType>
 #include <QMutex>
@@ -102,9 +101,11 @@ public:
     static int lastSelectedTab();
     static void setLastSelectedTab(int index);
 
-    static QByteArray defaultViewerBackend();
+    static HelpViewerFactory defaultViewerBackend();
     static QVector<HelpViewerFactory> viewerBackends();
     static HelpViewerFactory viewerBackend();
+    static void setViewerBackendId(const QByteArray &id);
+    static QByteArray viewerBackendId();
 
     static void setupGuiHelpEngine();
     static void setEngineNeedsUpdate();