System Settings: Getting Miscellaneous System Settings and Preferences

This tutorial demonstrates how you can manage and monitor system settings.

Warm-up

Become familiar with the System Settings API basics by learning about:

• Managing System Settings

  Obtain, set, and track system settings.

Managing System Settings

To manage system settings, which provide access to system variables:

1. To use the system settings-related features of the System Settings API (in mobile and wearable applications), include the <system_settings.h> header file in your application:

   #include <system_settings.h>
   

2. Define auxiliary structures:

   struct _ret_type_define
   {
      system_settings_key_e key;
      int returns;
   };
   
   typedef enum
   {
      _RET_BOO = 0,
      _RET_INT,
      _RET_STRING
   } _SYSTEM_SETTINGS_TYPES;
   
   struct _ret_type_define _ret_type[] =
   {
      {
         SYSTEM_SETTINGS_KEY_INCOMING_CALL_RINGTONE, _RET_STRING
      },
      {
         SYSTEM_SETTINGS_KEY_WALLPAPER_HOME_SCREEN, _RET_STRING
      },
      {
         SYSTEM_SETTINGS_KEY_WALLPAPER_LOCK_SCREEN, _RET_STRING
      },
      {
         SYSTEM_SETTINGS_KEY_FONT_SIZE, _RET_INT
      },
      {
         SYSTEM_SETTINGS_KEY_FONT_TYPE, _RET_STRING
      },
      {
         SYSTEM_SETTINGS_KEY_MOTION_ACTIVATION, _RET_BOOL
      },
      {
         // Others
      }
   };
   

   static const char *_info_key[SYS_INFO_COUNT]=
   {
      "SYSTEM_SETTINGS_KEY_INCOMING_CALL_RINGTONE",
      "SYSTEM_SETTINGS_KEY_WALLPAPER_HOME_SCREEN",
      "SYSTEM_SETTINGS_KEY_WALLPAPER_LOCK_SCREEN",
      "SYSTEM_SETTINGS_KEY_FONT_SIZE",
      "SYSTEM_SETTINGS_KEY_FONT_TYPE",
      "SYSTEM_SETTINGS_KEY_MOTION_ACTIVATION",
      // Others
   };
   

3. Get the setting data.

   The available settings are defined in the system_settings_key_e enumerator (in mobile and wearable applications).

   Read the data using the following functions, according to the data type of the value you want to read:

   • int system_settings_get_value_int (system_settings_key_e key, int *value)
   • int system_settings_get_value_bool (system_settings_key_e key, bool *value)
   • int system_settings_get_value_double (system_settings_key_e key, double *value)
   • int system_settings_get_value_string (system_settings_key_e key, char **value)

   #define  SYS_INFO_COUNT 6
   
   int i;
   for (i = 0; i<SYS_INFO_COUNT; i++)
   {
      dlog_print(DLOG_ERROR,LOG_TAG,"%d- System_settings: %s : ", i, _info_key[_ret_type[i].key]);
   
      if (_ret_type[i].returns==_RET_BOOL)
      {
         system_settings_get_value_bool(_ret_type[i].key, &_bool_ret);
         dlog_print(DLOG_ERROR, LOG_TAG, "%d", _bool_ret);
      }
      else if (_ret_type[i].returns==_RET_INT)
      {
         system_settings_get_value_int (_ret_type[i].key, &_int_ret);
         dlog_print(DLOG_ERROR, LOG_TAG, "%d", _int_ret);
      }
      else if (_ret_type[i].returns==_RET_STRING)
      {
         system_settings_get_value_string(_ret_type[i].key, &_string_ret);
         dlog_print(DLOG_ERROR, LOG_TAG, "%s", _string_ret);
         free(_string_ret);
      }
      else if (_ret_type[i].returns==_RET_DOUBLE)
      {
         system_settings_get_value_double(_ret_type[i].key, &_double_ret);
         dlog_print(DLOG_ERROR, LOG_TAG, "%f", _double_ret);
      }
      else dlog_print(DLOG_ERROR, LOG_TAG, "Undefined return type");
   }
   

4. Track changes in the settings.

   1. To track changes in the value of any system setting, set a callback function with the proper key.

      The SYSTEM_SETTINGS_KEY_DEFAULT_FONT_TYPE setting does not support the callback function, so you must iterate through the SYS_INFO_COUNT-1 records.

      for (i = 0; i<SYS_INFO_COUNT-1; i++)
      {
         system_settings_set_changed_cb(_ret_type[i].key, _system_settings_changed_cb, 0);
      }
      

   2. Define the callback which is invoked after each change. The system_settings_key_e key refers to the key which has changed.

      static void _system_settings_changed_cb(system_settings_key_e key, void *user_data)
      {
         dlog_print(DLOG_ERROR, LOG_TAG, "Runtime Info changed: %s", _info_key[key]);
      }
      

   3. When they are no longer needed, unregister the callbacks:

      for (i = 0; i<SYS_INFO_COUNT-1; i++)
      {
         system_settings_unset_changed_cb(_ret_type[i].key, _system_settings_changed_cb, 0);
      }