Help viewer: Add option for scroll wheel zooming

Fixes: QTCREATORBUG-14154
Change-Id: Ia6c4aedb78954614477f0228ba82c4dc476a2525
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/help/generalsettingspage.cpp

@@ -119,6 +119,9 @@ QWidget *GeneralSettingsPage::widget()
 
         m_returnOnClose = LocalHelpManager::returnOnClose();
         m_ui->m_returnOnClose->setChecked(m_returnOnClose);
+
+        m_scrollWheelZoomingEnabled = LocalHelpManager::isScrollWheelZoomingEnabled();
+        m_ui->scrollWheelZooming->setChecked(m_scrollWheelZoomingEnabled);
     }
     return m_widget;
 }
@@ -159,6 +162,12 @@ void GeneralSettingsPage::apply()
         m_returnOnClose = close;
         LocalHelpManager::setReturnOnClose(m_returnOnClose);
     }
+
+    const bool zoom = m_ui->scrollWheelZooming->isChecked();
+    if (m_scrollWheelZoomingEnabled != zoom) {
+        m_scrollWheelZoomingEnabled = zoom;
+        LocalHelpManager::setScrollWheelZoomingEnabled(m_scrollWheelZoomingEnabled);
+    }
 }
 
 void GeneralSettingsPage::setCurrentPage()

src/plugins/help/generalsettingspage.h

@@ -69,6 +69,7 @@ private:
 
     int m_startOption;
     bool m_returnOnClose;
+    bool m_scrollWheelZoomingEnabled;
 
     QPointer<QWidget> m_widget;
     Ui::GeneralSettingsPage *m_ui = nullptr;

src/plugins/help/generalsettingspage.ui

@@ -288,6 +288,13 @@
       <string>Behaviour</string>
      </property>
      <layout class="QVBoxLayout" name="verticalLayout_4">
+      <item>
+       <widget class="QCheckBox" name="scrollWheelZooming">
+        <property name="text">
+         <string>Enable scroll wheel zooming</string>
+        </property>
+       </widget>
+      </item>
       <item>
        <widget class="QCheckBox" name="m_returnOnClose">
         <property name="toolTip">

src/plugins/help/helpplugin.cpp

@@ -495,6 +495,9 @@ HelpViewer *HelpPlugin::createHelpViewer(qreal zoom)
 
     // initialize zoom
     viewer->setScale(zoom);
+    viewer->setScrollWheelZoomingEnabled(LocalHelpManager::isScrollWheelZoomingEnabled());
+    connect(LocalHelpManager::instance(), &LocalHelpManager::scrollWheelZoomingEnabledChanged,
+            viewer, &HelpViewer::setScrollWheelZoomingEnabled);
 
     // add find support
     auto agg = new Aggregation::Aggregate;

src/plugins/help/helpviewer.cpp

@@ -91,6 +91,16 @@ HelpViewer::~HelpViewer()
     restoreOverrideCursor();
 }
 
+void HelpViewer::setScrollWheelZoomingEnabled(bool enabled)
+{
+    m_scrollWheelZoomingEnabled = enabled;
+}
+
+bool HelpViewer::isScrollWheelZoomingEnabled() const
+{
+    return m_scrollWheelZoomingEnabled;
+}
+
 void HelpViewer::setActionVisible(Action action, bool visible)
 {
     if (visible)
@@ -162,6 +172,16 @@ void HelpViewer::home()
     setSource(LocalHelpManager::homePage());
 }
 
+void HelpViewer::wheelEvent(QWheelEvent *event)
+{
+    if (m_scrollWheelZoomingEnabled && event->modifiers() == Qt::ControlModifier) {
+        event->accept();
+        event->delta() > 0 ? scaleUp() : scaleDown();
+    } else {
+        QWidget::wheelEvent(event);
+    }
+}
+
 void HelpViewer::slotLoadStarted()
 {
     ++m_loadOverrideStack;

src/plugins/help/helpviewer.h

@@ -57,6 +57,9 @@ public:
     virtual qreal scale() const = 0;
     virtual void setScale(qreal scale) = 0;
 
+    void setScrollWheelZoomingEnabled(bool enabled);
+    bool isScrollWheelZoomingEnabled() const;
+
     virtual QString title() const = 0;
 
     virtual QUrl source() const = 0;
@@ -105,12 +108,15 @@ signals:
     void externalPageRequested(const QUrl &url);
 
 protected:
+    void wheelEvent(QWheelEvent *event) override;
+
     void slotLoadStarted();
     void slotLoadFinished();
 
     void restoreOverrideCursor();
 
     Actions m_visibleActions;
+    bool m_scrollWheelZoomingEnabled = true;
     int m_loadOverrideStack = 0;
 };
 

src/plugins/help/localhelpmanager.cpp

@@ -65,6 +65,7 @@ static const char kFontSizeKey[] = "Help/FallbackFontSize";
 static const char kStartOptionKey[] = "Help/StartOption";
 static const char kContextHelpOptionKey[] = "Help/ContextHelpOption";
 static const char kReturnOnCloseKey[] = "Help/ReturnOnClose";
+static const char kUseScrollWheelZooming[] = "Help/UseScrollWheelZooming";
 static const char kLastShownPagesKey[] = "Help/LastShownPages";
 static const char kLastShownPagesZoomKey[] = "Help/LastShownPagesZoom";
 static const char kLastSelectedTabKey[] = "Help/LastSelectedTab";
@@ -225,6 +226,17 @@ void LocalHelpManager::setReturnOnClose(bool returnOnClose)
     emit m_instance->returnOnCloseChanged();
 }
 
+bool LocalHelpManager::isScrollWheelZoomingEnabled()
+{
+    return Core::ICore::settings()->value(kUseScrollWheelZooming, true).toBool();
+}
+
+void LocalHelpManager::setScrollWheelZoomingEnabled(bool enabled)
+{
+    Core::ICore::settings()->setValue(kUseScrollWheelZooming, enabled);
+    emit m_instance->scrollWheelZoomingEnabledChanged(enabled);
+}
+
 QStringList LocalHelpManager::lastShownPages()
 {
     const QVariant value = Core::ICore::settings()->value(kLastShownPagesKey, QVariant());

src/plugins/help/localhelpmanager.h

@@ -78,6 +78,9 @@ public:
     static bool returnOnClose();
     static void setReturnOnClose(bool returnOnClose);
 
+    static bool isScrollWheelZoomingEnabled();
+    static void setScrollWheelZoomingEnabled(bool enabled);
+
     static QStringList lastShownPages();
     static void setLastShownPages(const QStringList &pages);
 
@@ -106,6 +109,7 @@ signals:
     void filterIndexChanged(int index);
     void fallbackFontChanged(const QFont &font);
     void returnOnCloseChanged();
+    void scrollWheelZoomingEnabledChanged(bool enabled);
 
 private:
     static bool m_guiNeedsSetup;

src/plugins/help/textbrowserhelpviewer.cpp

@@ -406,16 +406,6 @@ bool TextBrowserHelpWidget::eventFilter(QObject *obj, QEvent *event)
     return QTextBrowser::eventFilter(obj, event);
 }
 
-void TextBrowserHelpWidget::wheelEvent(QWheelEvent *e)
-{
-    if (e->modifiers() == Qt::ControlModifier) {
-        e->accept();
-        e->delta() > 0 ? scaleUp() : scaleDown();
-    } else {
-        QTextBrowser::wheelEvent(e);
-    }
-}
-
 void TextBrowserHelpWidget::mousePressEvent(QMouseEvent *e)
 {
     if (Utils::HostOsInfo::isLinuxHost() && m_parent->handleForwardBackwardMouseButtons(e))

src/plugins/help/textbrowserhelpviewer.h

@@ -98,7 +98,6 @@ public:
 protected:
     void contextMenuEvent(QContextMenuEvent *event) override;
     bool eventFilter(QObject *obj, QEvent *event) override;
-    void wheelEvent(QWheelEvent *e) override;
     void mousePressEvent(QMouseEvent *e) override;
     void mouseReleaseEvent(QMouseEvent *e) override;
 

src/plugins/help/webenginehelpviewer.cpp

@@ -292,6 +292,31 @@ WebView::WebView(WebEngineHelpViewer *viewer)
 {
 }
 
+bool WebView::event(QEvent *ev)
+{
+    // work around QTBUG-43602
+    if (ev->type() == QEvent::ChildAdded) {
+        auto ce = static_cast<QChildEvent *>(ev);
+        ce->child()->installEventFilter(this);
+    } else if (ev->type() == QEvent::ChildRemoved) {
+        auto ce = static_cast<QChildEvent *>(ev);
+        ce->child()->removeEventFilter(this);
+    }
+    return QWebEngineView::event(ev);
+}
+
+bool WebView::eventFilter(QObject *src, QEvent *e)
+{
+    Q_UNUSED(src)
+    // work around QTBUG-43602
+    if (m_viewer->isScrollWheelZoomingEnabled() && e->type() == QEvent::Wheel) {
+        auto we = static_cast<QWheelEvent *>(e);
+        if (we->modifiers() == Qt::ControlModifier)
+            return true;
+    }
+    return false;
+}
+
 void WebView::contextMenuEvent(QContextMenuEvent *event)
 {
     QMenu *menu = page()->createStandardContextMenu();

src/plugins/help/webenginehelpviewer.h

@@ -53,6 +53,9 @@ class WebView : public QWebEngineView
 public:
     explicit WebView(WebEngineHelpViewer *viewer);
 
+    bool event(QEvent *ev) override;
+    bool eventFilter(QObject *src, QEvent *e) override;
+
 protected:
     void contextMenuEvent(QContextMenuEvent *event) override;