Media key: Managing Callbacks from Media Key Events

This tutorial demonstrates how you can manage callbacks for media key events.

Warm-up

Become familiar with the Media key API basics by learning about:

• Monitoring Media Key Events

  Register and unregister a callback for a media key event.

Monitoring Media Key Events

To monitor media key events:

1. To use the media key-related features of the Media key API (in mobile and wearable applications), include the <media_key.h> header file in your application:

   #include <media_key.h>
   

2. Implement the callback to handle media key events:

   void event_cb(media_key_e key, media_key_event_e status, void* user_data)
   {
      switch (key) 
      {
         case MEDIA_KEY_PLAY:
            dlog_print(DLOG_INFO, LOG_TAG, "Key : MEDIA_KEY_PLAY");
            break;
         case MEDIA_KEY_STOP:
            dlog_print(DLOG_INFO, LOG_TAG, "Key : MEDIA_KEY_STOP");
            break;
         case MEDIA_KEY_PAUSE:
            dlog_print(DLOG_INFO, LOG_TAG, "Key : MEDIA_KEY_PAUSE");
            break;
         case MEDIA_KEY_PREVIOUS:
            dlog_print(DLOG_INFO, LOG_TAG, "Key : MEDIA_KEY_PREVIOUS");
            break;
         case MEDIA_KEY_NEXT:
            dlog_print(DLOG_INFO, LOG_TAG, "Key : MEDIA_KEY_NEXT");
            break;
         case MEDIA_KEY_FASTFORWARD:
            dlog_print(DLOG_INFO, LOG_TAG, "Key : MEDIA_KEY_FASTFORWARD");
            break;
         case MEDIA_KEY_REWIND:
            dlog_print(DLOG_INFO, LOG_TAG, "Key : MEDIA_KEY_REWIND");
            break;
         case MEDIA_KEY_PLAYPAUSE:
            dlog_print(DLOG_INFO, LOG_TAG, "Key : MEDIA_KEY_PLAYPAUSE");
            break;
         case MEDIA_KEY_UNKNOWN:
            dlog_print(DLOG_INFO, LOG_TAG, "Key : MEDIA_KEY_UNKNOWN");
            break;
         default:
            dlog_print(DLOG_INFO, LOG_TAG, "Key : Unknown");
            break;
      }
      switch (status) 
      {
         case MEDIA_KEY_STATUS_PRESSED:
            dlog_print(DLOG_INFO, LOG_TAG, "Event : MEDIA_KEY_STATUS_PRESSED");
            break;
         case MEDIA_KEY_STATUS_RELEASED:
            dlog_print(DLOG_INFO, LOG_TAG, "Event : MEDIA_KEY_STATUS_RELEASED");
            break;
         case MEDIA_KEY_STATUS_UNKNOWN:
            dlog_print(DLOG_INFO, LOG_TAG, "Event : MEDIA_KEY_STATUS_UNKNOWN");
            break;
         default:
            dlog_print(DLOG_INFO, LOG_TAG, "Event : Unknown");
            break;
      }
   }
   

3. Register the defined callback with the media_key_reserve() function:

   void media_key_api_func()
   {
      int r = 0;
   
      r = media_key_reserve(event_cb, NULL);
   
      if (r == MEDIA_KEY_ERROR_NONE)
      {
         dlog_print(DLOG_INFO, LOG_TAG, "Reserve media key success.");
      }
      else
      {
         dlog_print(DLOG_ERROR, LOG_TAG, "Reserve media key fail.");
      }
   

4. When you no longer need to track media key events, unregister the callback with the media_key_release() function:

      r = media_key_release(event_cb, NULL);
   
      if (r == MEDIA_KEY_ERROR_NONE)
      {
         dlog_print(DLOG_INFO, LOG_TAG, "Release media key success.");
      }
      else if (r == MEDIA_KEY_ERROR_INVALID_PARAMETER)
      {
         dlog_print(DLOG_ERROR, LOG_TAG, "Invalid parameter.");
      }
      else if (r == MEDIA_KEY_ERROR_OPERATION_FAILED)
      {
         dlog_print(DLOG_ERROR, LOG_TAG, "Operation failed.");
      }
      else
      {
         dlog_print(DLOG_ERROR, LOG_TAG, "Fail. Unknown reason.");
      }
   }