ObjectProxy.cc

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/*

Copyright (C) 2011-2018 Michael Goffioul

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 <QCoreApplication>
#include <QString>
#include <QThread>

#include "oct-mutex.h"
#include "utils.h"

#include "Object.h"
#include "ObjectProxy.h"

namespace QtHandles
{

  ObjectProxy::ObjectProxy (Object *obj)
    : QObject (), m_object (nullptr)
  {
    init (obj);
  }

  void
  ObjectProxy::init (Object *obj)
  {
    if (obj != m_object)
      {
        if (m_object)
          {
            disconnect (this, SIGNAL (sendUpdate (int)),
                        m_object, SLOT (slotUpdate (int)));
            disconnect (this, SIGNAL (sendFinalize (void)),
                        m_object, SLOT (slotFinalize (void)));
            disconnect (this, SIGNAL (sendRedraw (void)),
                        m_object, SLOT (slotRedraw (void)));
            disconnect (this, SIGNAL (sendPrint (const QString&, const QString&)),
                        m_object, SLOT (slotPrint (const QString&, const QString&)));
          }

        m_object = obj;

        if (m_object)
          {
            connect (this, SIGNAL (sendUpdate (int)),
                     m_object, SLOT (slotUpdate (int)));
            connect (this, SIGNAL (sendFinalize (void)),
                     m_object, SLOT (slotFinalize (void)));
            connect (this, SIGNAL (sendRedraw (void)),
                     m_object, SLOT (slotRedraw (void)));
            connect (this, SIGNAL (sendPrint (const QString&, const QString&)),
                     m_object, SLOT (slotPrint (const QString&, const QString&)),
                     Qt::BlockingQueuedConnection);
          }
      }
  }

  void
  ObjectProxy::setObject (Object *obj)
  {
    emit sendFinalize ();
    init (obj);
  }

  void
  ObjectProxy::update (int pId)
  {
    if (octave::thread::is_thread ())
      emit sendUpdate (pId);
    else if (m_object)
      m_object->slotUpdate (pId);
  }

  void
  ObjectProxy::finalize (void)
  {
    emit sendFinalize ();
    init (nullptr);
  }

  void
  ObjectProxy::redraw (void)
  {
    emit sendRedraw ();
  }

  void
  ObjectProxy::print (const QString& file_cmd, const QString& term)
  {
    emit sendPrint (file_cmd, term);
  }

  uint8NDArray
  ObjectProxy::get_pixels (void)
  {
    uint8NDArray retval;

    // The ObjectProxy is generally ran from the interpreter thread
    // while the actual Figure (Object) lives in the gui thread. The
    // following ensures synchronous execution of the Figure method and
    // allows retrieving a return value.

    Qt::ConnectionType t = Qt::BlockingQueuedConnection;

    if (QThread::currentThread () == QCoreApplication::instance ()->thread ())
      t = Qt::DirectConnection;

    QMetaObject::invokeMethod (m_object, "slotGetPixels", t,
                               Q_RETURN_ARG (uint8NDArray, retval));

    // FIXME: The following may fail for obscure reasons, see bug #53328.
    //        In absence of a solution, we retry twice before calling error().
    if (! QMetaObject::invokeMethod (m_object, "slotGetPixels", t,
                                     Q_RETURN_ARG (uint8NDArray, retval)))
      {
        octave_sleep (0.1);
        if (! QMetaObject::invokeMethod (m_object, "slotGetPixels", t,
                                         Q_RETURN_ARG (uint8NDArray, retval)))
          {
            octave_sleep (0.2);
            if (! QMetaObject::invokeMethod (m_object, "slotGetPixels", t,
                                             Q_RETURN_ARG (uint8NDArray, retval)))
              error ("getframe: unable to retrieve figure pixels");
          }
      }

    return retval;
  }

};