NaviTrack Tutorial:Integrating:Passing image data
You can pass image data from one application to another through NaviTrack in almost same way as passing coordinate data.
Contents
Sending side
Modify MyTutorialModule
To send data through NaviTrack, it is necessary to generate a new event, which contains the data. The following code is implemented into MyTutorialModule to be called from your application.
void MyTutorialModule::setImage(Image& img, int w, int h) { if(source!=NULL) { Event event; event.setAttribute("image", img); event.setAttribute("xsize", w); event.setAttribute("ysize", h); event.timeStamp(); source->updateObservers( event ); } }
pushpos.cxx
Receiving side
Modify MyTutorialSink and MyTutorialModule
MyTutorialSink.h: Add member variables to hold the coordinate data:
private: Image image; int width; int height;
MyTutorialSink.cxx:
void MyTutorialSink::onEventGenerated( Event& event, Node& generator) { if (event.hasAttribute("image") && event.hasAttribute("xsize") && event.hasAttribute("ysize")) { image = event.getAttribute((Image*)NULL, "image"); width = event.getAttribute(std::string("xsize"),0); height = event.getAttribute(std::string("ysize"),0); } else { width = 0; height = 0; } }
MyTutorialModule.cxx (and .h): add the follwing function:
void MyTutorialModule::getImage(Image& img, int& w, int& h) { std::cout << "MyTutorialModule::getImage() is called." << std::endl; if(sink != NULL) { sink->getImage(img, w, h); } }
pullpos.cxx
Testing
In terminal 1 (sending side: pushimage)
$ ./pushimage tutorial_source.xml
In terminal 2 (receiving side: pullimage)
$ ./pullimage tutorial_source.xml
!!NOTE!! You may encounter application errors, while passing image data through a network using NaviTrack NetworkModule.
This is because NaviTrack NetworkModule uses UDP for a communication between Sink and Source.
Each data has header information in this communication including entire size of the data,
and packet loss causes inconsistency between data size information in header and actual data size.
NaviTrack has no capability to recover this kind of error in the current version.
Back to Integrating into your application.