What streams are and how to create your own

Streams describe the connection between two items. For example, the main stream of the roviz framework is the image stream. It transports objects of type Image from one item to another. If you would like to transport your own type with a stream, all you have to do is the following:

1. Create a class for your transport type
2. Make it publically inherit from StreamObject (streams/stream_object.h)
3. Add a static QWidget *initWidget(OutputPrivate *out); function
   This function should return a pointer to a QWidget that will be displayed in the shared window for this stream. If you do not want do display anything, just return nullptr. Make sure you enclose it with a #ifndef ROVIZ_BACKEND == ROVIZ_BACKEND_Dev ... #endif block, because that part only works with the ‘Dev’ backend. The out parameter refers to the output that will be associated with this stream. You should should use it to call OutputPrivate::connect to get notified when new data should be displayed (see OutputPrivate::connect).
4. Add your class to usercore/include/streams/template_decl.h
   There are some functions in the core that accept stream types as template parameters. We have to ensure that those functions are instantiated with every stream type. This is done by macros, all you have to do is to add your class to the DO_FOR_ALL_STREAMS macro in usercore/include/core/template_decl.h. Also make sure that you declare your class in that file (class YourClass;), just like the existing streams do.
5. Choose a color
   Every stream is identified by a connection color. You can set that color by adding your class to the color table in the usercore/src/backend_dev/startup_init.cpp file. The color is a QColor, see the Qt documentation for that.
6. Include your class in usercore/include/streams/all_streams.h
   If a file needs to include all stream object it will include streams/all_streams.h. Just add a line where you include the header of your class.

Now you’re ready to go! Rebuild roviz with qmake and make.