octave-qobject.cc

Go to the documentation of this file.

////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2011-2022 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Octave is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////
 
#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif
 
#include <utility>
 
#include <QApplication>
#include <QClipboard>
#include <QFile>
#include <QTextCodec>
#include <QThread>
#include <QTimer>
#include <QTranslator>
 
// QTerminal includes
#include "QTerminal.h"
 
#include "command-widget.h"
#include "community-news.h"
#include "documentation-dock-widget.h"
#include "files-dock-widget.h"
#include "history-dock-widget.h"
#include "interpreter-qobject.h"
#include "main-window.h"
#include "octave-qobject.h"
#include "qt-application.h"
#include "qt-interpreter-events.h"
#include "release-notes.h"
#include "resource-manager.h"
#include "shortcut-manager.h"
#include "terminal-dock-widget.h"
#include "variable-editor.h"
#include "workspace-model.h"
#include "workspace-view.h"
 
// Bug #55940 (Disable App Nap on Mac)
#if defined (Q_OS_MAC)
#  include <objc/runtime.h>
#  include <objc/message.h>
#endif
 
#include "interpreter.h"
#include "oct-env.h"
#include "version.h"
 
#include "ovl.h"
 
 
// Bug #55940 (Disable App Nap on Mac)
#if defined (Q_OS_MAC)
static void disable_app_nap (void)
{
  Class process_info_class;
  SEL process_info_selector;
  SEL begin_activity_with_options_selector;
  id process_info;
  id reason_string;
  id osx_latencycritical_activity;
 
  // Option codes found at https://stackoverflow.com/questions/22784886/what-can-make-nanosleep-drift-with-exactly-10-sec-on-mac-os-x-10-9/32729281#32729281
  unsigned long long NSActivityUserInitiatedAllowingIdleSystemSleep = 0x00FFFFFFULL;
  unsigned long long NSActivityLatencyCritical = 0xFF00000000ULL;
 
  // Avoid errors on older versions of OS X
  process_info_class = reinterpret_cast<Class> (objc_getClass ("NSProcessInfo"));
  if (process_info_class == nil)
    return;
 
  process_info_selector = sel_getUid ("processInfo");
  if (class_getClassMethod (process_info_class, process_info_selector)
      == nullptr)
    return;
 
  begin_activity_with_options_selector = sel_getUid ("beginActivityWithOptions:reason:");
  if (class_getInstanceMethod (process_info_class,
                               begin_activity_with_options_selector)
      == nullptr)
    return;
 
  process_info = reinterpret_cast<id (*) (id, SEL)> (objc_msgSend)
                   (reinterpret_cast<id> (process_info_class),
                    process_info_selector);
  if (process_info == nil)
    return;
 
  reason_string = reinterpret_cast<id (*) (id, SEL)> (objc_msgSend)
                    (reinterpret_cast<id> (objc_getClass ("NSString")),
                     sel_getUid ("alloc"));
  reason_string = reinterpret_cast<id (*) (id, SEL, const char *)> (objc_msgSend)
                    (reason_string, sel_getUid ("initWithUTF8String:"),
                     "App Nap causes pause() malfunction");
 
  // Start an Activity that suppresses App Nap.  This Activity will run for
  // the entire duration of the Octave process.  This is intentional,
  // not a leak.
  osx_latencycritical_activity =
    reinterpret_cast<id (*) (id, SEL, unsigned long long, id)> (objc_msgSend)
      (process_info,
       begin_activity_with_options_selector,
       NSActivityUserInitiatedAllowingIdleSystemSleep
       | NSActivityLatencyCritical,
       reason_string);
}
#endif
 
namespace octave
{
  // Disable all Qt messages by default.
 
  static void
  message_handler (QtMsgType, const QMessageLogContext&, const QString&)
  { }
 
  //! Reimplement QApplication::notify.  Octave's own exceptions are
  //! caught and rethrown in the interpreter thread.
 
  bool octave_qapplication::notify (QObject *receiver, QEvent *ev)
  {
    try
      {
        return QApplication::notify (receiver, ev);
      }
    catch (execution_exception& ee)
      {
        emit interpreter_event
          ([=] (void)
           {
             // INTERPRETER THREAD
             throw ee;
           });
      }
 
    return false;
  }
 
  // We will create a QApplication object, even if START_GUI is false,
  // so that we can use Qt widgets for plot windows when running in
  // command-line mode.  Note that we are creating an
  // octave_qapplication object but handling it as a QApplication object
  // because the octave_qapplication should behave identically to a
  // QApplication object except that it overrides the notify method so
  // we can handle forward Octave interpreter exceptions from the GUI
  // thread to the interpreter thread.
 
  base_qobject::base_qobject (qt_application& app_context, bool gui_app)
    : QObject (),
      m_app_context (app_context),
      m_argc (m_app_context.sys_argc ()),
      m_argv (m_app_context.sys_argv ()),
      m_qapplication (new octave_qapplication (m_argc, m_argv)),
      m_resource_manager (),
      m_shortcut_manager (*this),
      m_qt_tr (new QTranslator ()),
      m_gui_tr (new QTranslator ()),
      m_qsci_tr (new QTranslator ()),
      m_translators_installed (false),
      m_qt_interpreter_events (new qt_interpreter_events (*this)),
      m_interpreter_qobj (new interpreter_qobject (*this)),
      m_main_thread (new QThread ()),
      m_gui_app (gui_app),
      m_interpreter_ready (false),
      m_workspace_model (new workspace_model ()),
      m_documentation_widget (),
      m_file_browser_widget (),
      m_history_widget (),
      m_workspace_widget (),
      m_editor_widget (),
      m_variable_editor_widget (),
      m_main_window (nullptr)
  {
    std::string show_gui_msgs =
      sys::env::getenv ("OCTAVE_SHOW_GUI_MESSAGES");
 
    // Installing our handler suppresses the messages.
 
    if (show_gui_msgs.empty ())
      qInstallMessageHandler (message_handler);
 
    // Set the codec for all strings (before wizard or any GUI object)
#if ! defined (Q_OS_WIN32)
    QTextCodec::setCodecForLocale (QTextCodec::codecForName ("UTF-8"));
#endif
 
    // Initialize global Qt application metadata.
 
    QCoreApplication::setApplicationName ("GNU Octave");
    QCoreApplication::setApplicationVersion (OCTAVE_VERSION);
 
    // Register octave_value_list for connecting thread crossing signals.
 
    qRegisterMetaType<octave_value_list> ("octave_value_list");
 
// Bug #55940 (Disable App Nap on Mac)
#if defined (Q_OS_MAC)
    // Mac App Nap feature causes pause() and sleep() to misbehave.
    // Disable it for the entire program run.
    disable_app_nap ();
#endif
 
    // Force left-to-right alignment (see bug #46204)
    m_qapplication->setLayoutDirection (Qt::LeftToRight);
 
    // Qt docs recommend using Qt::QueuedConnection when connecting to
    // the QCoreApplication::exit slot.
    connect (m_interpreter_qobj, &interpreter_qobject::shutdown_finished,
             m_qapplication, &octave_qapplication::exit,
             Qt::QueuedConnection);
 
    connect (m_interpreter_qobj, &interpreter_qobject::ready,
             this, &base_qobject::interpreter_ready);
 
    connect (m_main_thread, &QThread::finished,
             m_main_thread, &QThread::deleteLater);
 
    // Handle any interpreter_event signal from the octave_qapplication
    // object here.
 
    connect (m_qapplication, QOverload<const fcn_callback&>::of (&octave_qapplication::interpreter_event),
             this, QOverload<const fcn_callback&>::of (&base_qobject::interpreter_event));
 
    connect (m_qapplication, QOverload<const meth_callback&>::of (&octave_qapplication::interpreter_event),
             this, QOverload<const meth_callback&>::of (&base_qobject::interpreter_event));
 
    if (m_app_context.experimental_terminal_widget ())
      {
        connect (qt_link (), &qt_interpreter_events::start_gui_signal,
                 this, &base_qobject::start_gui);
 
        connect (qt_link (), &qt_interpreter_events::show_terminal_window_signal,
                 this, &base_qobject::show_terminal_window);
      }
 
    connect (qt_link (), &qt_interpreter_events::copy_image_to_clipboard_signal,
             this, &base_qobject::copy_image_to_clipboard);
 
    connect (qt_link (), &qt_interpreter_events::show_documentation_signal,
             this, &base_qobject::show_documentation_window);
 
    connect (qt_link (), &qt_interpreter_events::show_file_browser_signal,
             this, &base_qobject::show_file_browser_window);
 
    connect (qt_link (), &qt_interpreter_events::show_command_history_signal,
             this, &base_qobject::show_command_history_window);
 
    connect (qt_link (), &qt_interpreter_events::show_workspace_signal,
             this, &base_qobject::show_workspace_window);
 
    connect (qt_link (), &qt_interpreter_events::edit_variable_signal,
             this, &base_qobject::show_variable_editor_window);
 
    connect (qt_link (), &qt_interpreter_events::show_community_news_signal,
             this, &base_qobject::show_community_news);
 
    connect (qt_link (), &qt_interpreter_events::show_release_notes_signal,
             this, &base_qobject::show_release_notes);
 
    if (m_app_context.experimental_terminal_widget ())
      {
        m_qapplication->setQuitOnLastWindowClosed (false);
      }
    else
      {
        if (gui_app)
          {
            m_main_window = new main_window (*this);
 
            connect (m_main_window, &main_window::show_community_news_signal,
                     this, &base_qobject::show_community_news);
 
            connect (m_main_window, &main_window::show_release_notes_signal,
                     this, &base_qobject::show_release_notes);
 
            if (m_interpreter_ready)
              m_main_window->handle_octave_ready ();
            else
              connect (m_interpreter_qobj, &interpreter_qobject::ready,
                       m_main_window, &main_window::handle_octave_ready);
 
            connect (qt_link (), &qt_interpreter_events::focus_window_signal,
                     m_main_window, &main_window::focus_window);
 
            m_app_context.gui_running (true);
          }
        else
          {
            // Get settings file.
            m_resource_manager.reload_settings ();
 
            // After settings.
            config_translators ();
 
            // Initilize the shortcut-manager
            m_shortcut_manager.init_data ();
 
            m_qapplication->setQuitOnLastWindowClosed (false);
          }
      }
 
    start_main_thread ();
  }
 
  base_qobject::~base_qobject (void)
  {
    // Note that we don't delete m_main_thread here.  That is handled by
    // deleteLater slot that is called when the m_main_thread issues a
    // finished signal.
 
    // FIXME: Why are dock widget settings and/or the main window
    // configuration not saved correctly if the main window is deleted
    // after the dock widgets?
 
 
    // Calling close will cause settings to be saved.
    // If m_main_window exists, the widgets are closed by the main window
 
    if (! m_main_window)
      {
        if (m_terminal_widget)
          m_terminal_widget->close ();
 
        if (m_documentation_widget)
          m_documentation_widget->close ();
 
        if (m_file_browser_widget)
          m_file_browser_widget->close ();
 
        if (m_history_widget)
          m_history_widget->close ();
 
        if (m_workspace_widget)
          m_workspace_widget->close ();
 
        if (m_editor_widget)
          m_editor_widget->close ();
 
        if (m_variable_editor_widget)
          m_variable_editor_widget->close ();
 
        if (m_community_news)
          m_community_news->close ();
      }
    else
      {
        delete m_main_window;
      }
 
    delete m_terminal_widget;
    delete m_documentation_widget;
    delete m_file_browser_widget;
    delete m_history_widget;
    delete m_workspace_widget;
    delete m_editor_widget;
    delete m_variable_editor_widget;
    delete m_community_news;
 
    delete m_interpreter_qobj;
    delete m_qsci_tr;
    delete m_gui_tr;
    delete m_qt_tr;
    delete m_qapplication;
    delete m_workspace_model;
 
    string_vector::delete_c_str_vec (m_argv);
  }
 
  void base_qobject::config_translators (void)
  {
    if (m_translators_installed)
      return;
 
    m_resource_manager.config_translators (m_qt_tr, m_qsci_tr, m_gui_tr);
 
    m_qapplication->installTranslator (m_qt_tr);
    m_qapplication->installTranslator (m_gui_tr);
    m_qapplication->installTranslator (m_qsci_tr);
 
    m_translators_installed = true;
  }
 
  void base_qobject::start_main_thread (void)
  {
    // Note: if using the new experimental terminal widget, we defer
    // initializing and executing the interpreter until the main event
    // loop begins executing.
 
    // With the old terminal widget, we defer initializing and executing
    // the interpreter until after the main window and QApplication are
    // running to prevent race conditions.
 
    QTimer::singleShot (0, m_interpreter_qobj, SLOT (execute (void)));
 
    m_interpreter_qobj->moveToThread (m_main_thread);
 
    m_main_thread->start ();
  }
 
  int base_qobject::exec (void)
  {
    int status = m_qapplication->exec ();
 
#if defined (Q_OS_MAC)
    // fprintf to stderr is needed by macOS, for poorly-understood reasons.
    fprintf (stderr, "\n");
#endif
 
    m_main_thread->quit ();
    m_main_thread->wait ();
 
    return status;
  }
 
  // Provided for convenience.  Will be removed once we eliminate the
  // old terminal widget.
  bool base_qobject::experimental_terminal_widget (void) const
  {
    return m_app_context.experimental_terminal_widget ();
  }
 
  bool base_qobject::gui_running (void) const
  {
    return m_app_context.gui_running ();
  }
 
  QPointer<terminal_dock_widget>
  base_qobject::terminal_widget (main_window *mw)
  {
    if (m_terminal_widget && mw)
      {
        m_terminal_widget->set_main_window (mw);
        m_terminal_widget->set_adopted (true);
      }
    else if (! m_terminal_widget)
      {
        m_terminal_widget
          = QPointer<terminal_dock_widget> (new terminal_dock_widget (mw, *this));
        if (experimental_terminal_widget ())
          {
            command_widget *cmd_widget
              = m_terminal_widget->get_command_widget ();
 
            connect (cmd_widget, &command_widget::interpreter_pause,
                     this, &base_qobject::interpreter_pause);
 
            connect (cmd_widget, &command_widget::interpreter_resume,
                     this, &base_qobject::interpreter_resume);
 
            connect (cmd_widget, &command_widget::interpreter_stop,
                     this, &base_qobject::interpreter_stop);
 
            connect (qt_link (), &qt_interpreter_events::interpreter_output_signal,
                     m_terminal_widget, &terminal_dock_widget::interpreter_output);
 
            connect (qt_link (), &qt_interpreter_events::update_prompt_signal,
                     m_terminal_widget, &terminal_dock_widget::update_prompt);
 
            connect_interpreter_events (cmd_widget);
          }
        else
          {
            QTerminal *cmd_widget = m_terminal_widget->get_qterminal ();
 
            // Connect the interrupt signal (emitted by Ctrl-C)
            connect (cmd_widget, &QTerminal::interrupt_signal,
                     this, &base_qobject::interpreter_interrupt);
          }
      }
 
    return m_terminal_widget;
  }
 
  QPointer<documentation_dock_widget>
  base_qobject::documentation_widget (main_window *mw)
  {
    if (m_documentation_widget && mw)
      {
        m_documentation_widget->set_main_window (mw);
        m_documentation_widget->set_adopted (true);
      }
    else if (! m_documentation_widget)
      {
        m_documentation_widget
          = QPointer<documentation_dock_widget> (new documentation_dock_widget (mw, *this));
 
        connect (qt_link (),
                 &qt_interpreter_events::register_documentation_signal,
                 m_documentation_widget,
                 &documentation_dock_widget::registerDoc);
 
        connect (qt_link (),
                 &qt_interpreter_events::unregister_documentation_signal,
                 m_documentation_widget,
                 &documentation_dock_widget::unregisterDoc);
      }
 
    return m_documentation_widget;
  }
 
  QPointer<files_dock_widget>
  base_qobject::file_browser_widget (main_window *mw)
  {
    if (m_file_browser_widget)
      {
        m_file_browser_widget->set_main_window (mw);
        m_file_browser_widget->set_adopted (true);
      }
    else if (! m_file_browser_widget)
      m_file_browser_widget
        = QPointer<files_dock_widget> (new files_dock_widget (mw, *this));
 
    connect (qt_link (), &qt_interpreter_events::directory_changed_signal,
             m_file_browser_widget, &files_dock_widget::update_octave_directory);
 
    return m_file_browser_widget;
  }
 
  QPointer<history_dock_widget>
  base_qobject::history_widget (main_window *mw)
  {
    if (m_history_widget)
      {
        m_history_widget->set_main_window (mw);
        m_history_widget->set_adopted (true);
      }
    else if (! m_history_widget)
      {
        m_history_widget
          = QPointer<history_dock_widget> (new history_dock_widget (mw, *this));
 
        connect (qt_link (), &qt_interpreter_events::set_history_signal,
                 m_history_widget, &history_dock_widget::set_history);
 
        connect (qt_link (), &qt_interpreter_events::append_history_signal,
                 m_history_widget, &history_dock_widget::append_history);
 
        connect (qt_link (), &qt_interpreter_events::clear_history_signal,
                 m_history_widget, &history_dock_widget::clear_history);
 
        emit interpreter_event
          ([=] (interpreter& interp) {
            // INTERPRETER THREAD
 
            event_manager& xevmgr = interp.get_event_manager ();
 
            xevmgr.set_history ();
          });
      }
 
    return m_history_widget;
  }
 
  QPointer<workspace_view>
  base_qobject::workspace_widget (main_window *mw)
  {
    if (m_workspace_widget)
      {
        m_workspace_widget->set_main_window (mw);
        m_workspace_widget->set_adopted (true);
      }
    else if (! m_workspace_widget)
      {
        m_workspace_widget
          = QPointer<workspace_view> (new workspace_view (mw, *this));
 
        m_workspace_widget->setModel (m_workspace_model);
 
        connect (m_workspace_model, &workspace_model::model_changed,
                 m_workspace_widget, &workspace_view::handle_model_changed);
 
        connect (qt_link (), &qt_interpreter_events::set_workspace_signal,
                 m_workspace_model, &workspace_model::set_workspace);
 
        connect (qt_link (), &qt_interpreter_events::clear_workspace_signal,
                 m_workspace_model, &workspace_model::clear_workspace);
 
        connect (m_workspace_widget,
                 &workspace_view::copy_variable_value_to_clipboard,
                 [=] (const QString& var_name) {
                   emit interpreter_event
                     ([=] (interpreter& interp)
                      {
                        // INTERPRETER THREAD
 
                        octave_value val = interp.varval (var_name.toStdString ());
 
                        if (val.is_undefined ())
                          val = 0;
 
                        std::ostringstream buf;
                        val.print_raw (buf, true);
 
                        // FIXME: is the following operation thread safe or should
                        // it be done with a signal/slot connection?
 
                        QClipboard *clipboard = QApplication::clipboard ();
                        clipboard->setText (QString::fromStdString (buf.str ()));
                      });
                 });
 
        connect (m_workspace_widget, &workspace_view::rename_variable_signal,
                 [=] (const QString& old_name, const QString& new_name) {
                   emit interpreter_event
                     ([=] (interpreter& interp) {
                       // INTERPRETER THREAD
 
                       symbol_scope scope = interp.get_current_scope ();
 
                       if (scope)
                         {
                           scope.rename (old_name.toStdString (),
                                         new_name.toStdString ());
 
                           tree_evaluator& tw = interp.get_evaluator ();
 
                           event_manager& xevmgr = interp.get_event_manager ();
 
                           xevmgr.set_workspace (true, tw.get_symbol_info ());
                         }
 
                       // FIXME: if this action fails, do we need a way to
                       // display that info in the GUI?
                     });
                 });
 
        connect (m_workspace_widget, &workspace_view::edit_variable_signal,
                 [=] (const QString& var_name) {
                   emit interpreter_event
                     ([=] (interpreter& interp) {
                       // INTERPRETER THREAD
 
                       std::string name = var_name.toStdString ();
                       octave_value val = interp.varval (name);
 
                       event_manager& xevmgr = interp.get_event_manager ();
 
                       xevmgr.edit_variable (name, val);
                     });
                 });
 
        emit interpreter_event
          ([=] (interpreter& interp) {
            // INTERPRETER THREAD
 
            event_manager& xevmgr = interp.get_event_manager ();
 
            xevmgr.set_workspace ();
          });
      }
 
    return m_workspace_widget;
  }
 
  QPointer<file_editor_interface>
  base_qobject::editor_widget (main_window */*mw*/)
  {
#if 0
    if (m_editor_widget && mw)
      {
        m_editor_widget->set_main_window (mw);
        m_editor_widget->set_adopted (true);
      }
    else if (! m_editor_widget)
      m_editor_widget = new file_editor (mw, *this);
#endif
 
    return m_editor_widget;
  }
 
  QPointer<variable_editor>
  base_qobject::variable_editor_widget (main_window *mw)
  {
    if (m_variable_editor_widget && mw)
      {
        m_variable_editor_widget->set_main_window (mw);
        m_variable_editor_widget->set_adopted (true);
      }
    else if (! m_variable_editor_widget)
      {
        m_variable_editor_widget
          = QPointer<variable_editor> (new variable_editor (mw, *this));
 
        connect (m_variable_editor_widget, &variable_editor::updated,
                 this, &base_qobject::handle_variable_editor_update);
 
        connect (m_variable_editor_widget, &variable_editor::command_signal,
                 this, &base_qobject::execute_command);
 
        connect (qt_link (),
                 &qt_interpreter_events::refresh_variable_editor_signal,
                 m_variable_editor_widget, &variable_editor::refresh);
 
        connect_interpreter_events<variable_editor> (m_variable_editor_widget);
      }
 
    return m_variable_editor_widget;
  }
 
  QPointer<community_news> base_qobject::community_news_widget (int serial)
  {
    if (! m_community_news)
      m_community_news
        = QPointer<community_news> (new community_news (*this, serial));
 
    return m_community_news;
  }
 
  QPointer<release_notes> base_qobject::release_notes_widget (void)
  {
    if (! m_release_notes)
      m_release_notes = QPointer<release_notes> (new release_notes ());
 
    return m_release_notes;
  }
 
  bool base_qobject::confirm_shutdown (void)
  {
    // Currently, we forward to main_window::confirm_shutdown instead of
    // just displaying a dialog box here because the main_window also
    // knows about and is responsible for notifying the editor.
 
    return m_main_window ? m_main_window->confirm_shutdown () : true;
  }
 
  void base_qobject::start_gui (bool gui_app)
  {
    if (m_app_context.experimental_terminal_widget ())
      {
        if (m_main_window)
          return;
 
        m_gui_app = gui_app;
 
        m_main_window = new main_window (*this);
 
        connect (qt_link (), &qt_interpreter_events::focus_window_signal,
                 m_main_window, &main_window::focus_window);
 
        connect (qt_link (), &qt_interpreter_events::close_gui_signal,
                 this, &base_qobject::close_gui);
 
        connect (m_main_window, &main_window::close_gui_signal,
                 this, &base_qobject::close_gui);
 
        connect (m_main_window, &main_window::show_community_news_signal,
                 this, &base_qobject::show_community_news);
 
        connect (m_main_window, &main_window::show_release_notes_signal,
                 this, &base_qobject::show_release_notes);
 
        if (m_interpreter_ready)
          m_main_window->handle_octave_ready ();
        else
          connect (m_interpreter_qobj, &interpreter_qobject::ready,
                   m_main_window, &main_window::handle_octave_ready);
 
        if (m_gui_app)
          m_qapplication->setQuitOnLastWindowClosed (true);
        else
          {
            // FIXME: Save current values of PS1 and PS2 so they can be
            // restored when we return to the command line?
          }
 
        m_app_context.gui_running (true);
      }
  }
 
  void base_qobject::show_terminal_window (void)
  {
    terminal_dock_widget *widget
      = (m_terminal_widget
         ? m_terminal_widget : terminal_widget ());
 
    if (! widget->isVisible ())
      {
        widget->show ();
        widget->raise ();
      }
  }
 
  void base_qobject::show_documentation_window (const QString& file)
  {
    documentation_dock_widget *widget
      = (m_documentation_widget
         ? m_documentation_widget : documentation_widget ());
 
    widget->showDoc (file);
 
    if (! widget->isVisible ())
      {
        widget->show ();
        widget->raise ();
      }
  }
 
  void base_qobject::show_file_browser_window (void)
  {
    files_dock_widget *widget
      = m_file_browser_widget ? m_file_browser_widget : file_browser_widget ();
 
    if (! widget->isVisible ())
      {
        widget->show ();
        widget->raise ();
      }
  }
 
  void base_qobject::show_command_history_window (void)
  {
    history_dock_widget *widget
      = m_history_widget ? m_history_widget : history_widget ();
 
    if (! widget->isVisible ())
      {
        widget->show ();
        widget->raise ();
      }
  }
 
  void base_qobject::show_workspace_window (void)
  {
    workspace_view *widget
      = m_workspace_widget ? m_workspace_widget : workspace_widget ();
 
    if (! widget->isVisible ())
      {
        widget->show ();
        widget->raise ();
      }
  }
 
  void base_qobject::show_variable_editor_window (const QString& name,
                                                  const octave_value& value)
  {
    variable_editor *widget
      = (m_variable_editor_widget
         ? m_variable_editor_widget : variable_editor_widget ());
 
    if (! widget->isVisible ())
      {
        widget->show ();
        widget->raise ();
      }
 
    // FIXME: Should this be done with a signal/slot connection?
    widget->edit_variable (name, value);
  }
 
  void base_qobject::handle_variable_editor_update (void)
  {
    // Called when the variable editor emits the updated signal.  The size
    // of a variable may have changed, so we refresh the workspace in the
    // interpreter.  That will eventually cause the workspace view in the
    // GUI to be updated.
 
    interpreter_event
      ([] (interpreter& interp)
       {
         // INTERPRETER THREAD
 
         tree_evaluator& tw = interp.get_evaluator ();
 
         event_manager& xevmgr = interp.get_event_manager ();
 
         xevmgr.set_workspace (true, tw.get_symbol_info (), false);
       });
  }
 
  void base_qobject::show_community_news (int serial)
  {
    // Ensure widget exists.
    community_news_widget (serial);
 
    m_community_news->display ();
  }
 
  void base_qobject::show_release_notes (void)
  {
    // Ensure widget exists.
    release_notes_widget ();
 
    m_release_notes->display ();
  }
 
  void base_qobject::execute_command (const QString& command)
  {
    emit interpreter_event
      ([=] (interpreter& interp)
      {
        // INTERPRETER THREAD
 
        // FIXME: Do we need to do anything special about errors here?
        // Currently the eval function will just call error() in the
        // interpreter event loop and throw an execution error.  It will
        // be caught, so shouldn't crash the interpreter, but the
        // message may not go anywhere useful depending on how the GUI
        // is being used or if Octave running server mode.
 
        interp.eval (command.toStdString (), 0);
      });
  }
 
  void base_qobject::close_gui (void)
  {
    if (m_app_context.experimental_terminal_widget ())
      {
        if (! m_main_window)
          return;
 
        // FIXME: Restore previous values of PS1 and PS2 if we are
        // returning to the command line?
 
        interpreter_event
          ([=] (interpreter& interp)
          {
            // INTERPRETER THREAD
 
            application *app = interp.get_app_context ();
 
            cmdline_options opts = app->options ();
 
            if (opts.gui ())
              interp.quit (0, false, false);
          });
 
        m_app_context.gui_running (false);
 
        if (m_main_window)
          {
            m_main_window->deleteLater ();
 
            m_main_window = nullptr;
          }
      }
  }
 
  void base_qobject::interpreter_ready (void)
  {
    m_interpreter_ready = true;
  }
 
  void base_qobject::interpreter_event (const fcn_callback& fcn)
  {
    // The following is a direct function call across threads.  It works
    // because it is accessing a thread-safe queue of events that
    // are later executed by the Octave interpreter in the other thread.
 
    // See also the comments in interpreter-qobject.h about
    // interpreter_qobject slots.
 
    m_interpreter_qobj->interpreter_event (fcn);
  }
 
  void base_qobject::interpreter_event (const meth_callback& meth)
  {
    // The following is a direct function call across threads.  It works
    // because it is accessing a thread-safe queue of events that
    // are later executed by the Octave interpreter in the other thread.
 
    // See also the comments in interpreter-qobject.h about
    // interpreter_qobject slots.
 
    m_interpreter_qobj->interpreter_event (meth);
  }
 
  void base_qobject::interpreter_interrupt (void)
  {
    m_interpreter_qobj->interrupt ();
  }
 
  // FIXME: Should we try to make the pause, stop, and resume actions
  // work for both the old and new terminal widget?
 
  void base_qobject::interpreter_pause (void)
  {
    if (m_app_context.experimental_terminal_widget ())
      m_interpreter_qobj->pause ();
  }
 
  void base_qobject::interpreter_stop (void)
  {
    if (m_app_context.experimental_terminal_widget ())
      m_interpreter_qobj->stop ();
  }
 
  void base_qobject::interpreter_resume (void)
  {
    if (m_app_context.experimental_terminal_widget ())
      m_interpreter_qobj->resume ();
  }
 
  void base_qobject::copy_image_to_clipboard (const QString& file,
                                              bool remove_file)
  {
    QClipboard *clipboard = QApplication::clipboard ();
 
    QImage img (file);
 
    if (img.isNull ())
      {
        // Report error?
        return;
      }
 
    clipboard->setImage (img);
 
    if (remove_file)
      QFile::remove (file);
  }
}