Time for action – stepping the event loop

Let's extend the previous example to step our application when events are processed.

1. Open jni/Types.hpp and define a new type status to represent return codes:

   #ifndef _PACKT_TYPES_HPP_
   #define _PACKT_TYPES_HPP_
   
   #include <cstdlib>
   
   typedef int32_t status;
   
   const status STATUS_OK   = 0;
   const status STATUS_KO   = -1;
   const status STATUS_EXIT = -2;
   
   #endif

2. Create the jni/ActivityHandler.hpp header and define an "interface" to observe native activity events. Each possible event has its own handler method: onStart(), onResume(), onPause(), onStop(), onDestroy(), and so on. However, we are generally interested in three specific moments in the activity life cycle:

   • onActivate(), invoked when the activity is resumed and its window is available and focused

   • onDeactivate(), invoked when the activity is paused or the display window loses its focus or is destroyed

   • onStep(), invoked when no event has to be processed and computations can take place

     #ifndef _PACKT_ACTIVITYHANDLER_HPP_...