feat(editor): re-add In-Place Preview toggle to Markdown toolbar

Re-add the runtime In-Place Preview toggle button (default on, edit-mode only) to MarkdownViewWindow2's toolbar, migrated from the legacy MarkdownViewWindow. The toggle drives MarkdownEditor::setInplacePreviewEnabled and stays in sync via a runtime member re-applied on lazy editor creation.

Refs #2709

Author: tamlok

src/widgets/markdownviewwindow2.cpp

@@ -214,6 +214,20 @@ void MarkdownViewWindow2::addAdditionalRightToolBarActions(QToolBar *p_toolBar)
       setEditViewMode(mode);
     });
   }
+
+  // In-place preview toggle (visible only in Edit mode).
+  {
+    auto *inplacePreviewAction =
+        addAction(p_toolBar, ViewWindowToolBarHelper2::InplacePreview);
+    // setChecked before connect so this does not fire the toggled handler.
+    inplacePreviewAction->setChecked(m_inplacePreviewEnabled);
+    connect(inplacePreviewAction, &QAction::toggled, this, [this](bool p_checked) {
+      m_inplacePreviewEnabled = p_checked;
+      if (m_mode == ViewWindowMode::Edit && m_editor) {
+        m_editor->setInplacePreviewEnabled(p_checked);
+      }
+    });
+  }
 }
 
 void MarkdownViewWindow2::handlePrint() {
@@ -292,6 +306,9 @@ void MarkdownViewWindow2::setupTextEditor() {
   m_previewHelper->setMarkdownEditor(m_editor);
   m_editor->setPreviewHelper(m_previewHelper);
 
+  // Apply the current in-place preview toggle state to the freshly created editor.
+  m_editor->setInplacePreviewEnabled(m_inplacePreviewEnabled);
+
   // Set content path and base path from Buffer2.
   // contentPath: used by MarkdownEditor::getRelativeLink() for generating relative links.
   // basePath: used by vtextedit's PreviewMgr for resolving relative URLs to absolute paths.

src/widgets/markdownviewwindow2.h

@@ -216,6 +216,10 @@ protected slots:
   QString m_pendingAnchor;
   MarkdownEditorConfig::EditViewMode m_editViewMode = MarkdownEditorConfig::EditViewMode::EditOnly;
 
+  // Runtime on/off for in-place preview (toolbar toggle). Not persisted; mirrors
+  // the editor default (VMarkdownEditor::m_inplacePreviewEnabled = true).
+  bool m_inplacePreviewEnabled = true;
+
   QTimer *m_syncPreviewTimer = nullptr;
   QSharedPointer<QPrinter> m_printer;
 

src/widgets/viewwindow2.cpp

@@ -529,6 +529,13 @@ QAction *ViewWindow2::addAction(QToolBar *p_toolBar, ViewWindowToolBarHelper2::A
             [act, this]() { act->setVisible(m_mode == ViewWindowMode::Edit); });
     break;
 
+  case ViewWindowToolBarHelper2::InplacePreview:
+    // Visible only in Edit mode. Subclass wires the toggled signal.
+    act->setVisible(false);
+    connect(this, &ViewWindow2::modeChanged, this,
+            [act, this]() { act->setVisible(m_mode == ViewWindowMode::Edit); });
+    break;
+
   case ViewWindowToolBarHelper2::Tag: {
     auto *toolBtn = dynamic_cast<QToolButton *>(p_toolBar->widgetForAction(act));
     Q_ASSERT(toolBtn);

src/widgets/viewwindowtoolbarhelper2.cpp

@@ -349,6 +349,14 @@ QAction *ViewWindowToolBarHelper2::addAction(QToolBar *p_tb, Action p_action,
     }
     break;
 
+  case Action::InplacePreview:
+    act = p_tb->addAction(
+        generateIcon(p_services, QStringLiteral("inplace_preview_editor.svg")),
+        QObject::tr("Toggle In-Place Preview"));
+    act->setProperty("iconName", QStringLiteral("inplace_preview_editor.svg"));
+    act->setCheckable(true);
+    break;
+
   case Action::Outline: {
     act = p_tb->addAction(generateIcon(p_services, QStringLiteral("outline_editor.svg")),
                           QObject::tr("Outline"));

src/widgets/viewwindowtoolbarhelper2.h

@@ -54,6 +54,9 @@ class ViewWindowToolBarHelper2 {
     // Live preview toggle (Edit mode only).
     ToggleLivePreview,
 
+    // In-place preview toggle (Edit mode only).
+    InplacePreview,
+
     // Outline popup button.
     Outline,