[Paraview] Plugin with own thread

[Stephan Rogge]

Hello,

 

after reading the tutorials and How-to's for writing ParaView Plugins I've
started with the Autostart-Example project. My goal was to create a plugin
which is executed in an external thread. It might happens that I need this
in the near future. 

 

Well, it works quit well, I guess. But to avoid some errors and
miss-behaviors I need a confirmation that I am on the right way.

 

My approach is to use the signal-slot-pattern to communicate between the
main thread of ParaView and my own plugin-thread. The class
pqMyApplicationStarter represents the ParaView-plugin (which is running in
the main thread of ParaView?). There is an object in this class which
executes a loop within an external thread ( class Thread ), which extends
QThread. 

 

As I read somewhere that vtk isn't implemented threaded-safe at all (at
least the rendering stuff) I decided to do all render calls in
pqMyApplicationStarter. When the UpdatedData()signal is fired the active
view needs to re-rendered. 

 

The question I want to ask is very simple: Is this the right / best way to
create a thread and communicate with it via signals?

 

 

/////////////// Thread.h ////////////////////////////

class Thread : public QThread

{

Q_OBJECT

public:

Thread(QObject* parent = 0);

virtual ~Thread();

virtual void run();

signals:

      void UpdatedData();

};

 

 

 

void Thread::run()

{

      running = true;

 

      while( running )

      {

// Sleep awhile

            msleep( 800 );

            // Fire the signal

            emit UpdatedData();                      

      }                 

}

/////////////////////////////////////////////////////

 

 

/////////////// pqMyApplicationStarter //////////////

class pqMyApplicationStarter : public QObject

{

      Q_OBJECT

      typedef QObject Superclass;

 

public:

      pqMyApplicationStarter(QObject* p=0);

      ~pqMyApplicationStarter();

 

      // Callback for startup.

      void onStartup();

 

public slots:

      void Trigger();

};

 

 

 

void pqMyApplicationStarter::onStartup()

{

      myThread = new Thread();

      myThread->start();

 

      pqActiveObjects::instance().connect( myThread, SIGNAL(UpdatedData()),
this, SLOT(Trigger()) );            

}

 

void pqMyApplicationStarter::Trigger()

{     

      pqActiveObjects* object = &(pqActiveObjects::instance());

      pqView* view            = object->activeView();

 

      if (view)

      {

            view->render();

      }

 

      view  = NULL;

}

 

 

Thanks a lot.

 

Cheers,

Stephan

 

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