android GPS HAL 回调函数实现
/** Represents the standard GPS interface. */
typedef struct {
size_t size;
int (*init)( GpsCallbacks* callbacks );
int (*start)( void );
int (*stop)( void );
void (*cleanup)( void );
int (*inject_time)(GpsUtcTime time, int64_t timeReference, int uncertainty);
int (*inject_location)(double latitude, double longitude, float accuracy);
void (*delete_aiding_data)(GpsAidingData flags);
int (*set_position_mode)(GpsPositionMode mode, GpsPositionRecurrence recurrence,
uint32_t min_interval, uint32_t preferred_accuracy, uint32_t preferred_time);
const void* (*get_extension)(const char* name);
} GpsInterface;
/** GPS callback structure. */ typedef struct { /** set to sizeof(GpsCallbacks) */ size_t size; gps_location_callback location_cb; gps_status_callback status_cb; gps_sv_status_callback sv_status_cb; gps_nmea_callback nmea_cb; gps_set_capabilities set_capabilities_cb; gps_acquire_wakelock acquire_wakelock_cb; gps_release_wakelock release_wakelock_cb; gps_create_thread create_thread_cb; } GpsCallbacks;
static jboolean android_location_GpsLocationProvider_init(JNIEnv* env, jobject obj) { const GpsInterface* interface = GetGpsInterface(env, obj); if (!interface) return false; if (!sGpsDebugInterface) sGpsDebugInterface = (const GpsDebugInterface*)interface->get_extension(GPS_DEBUG_INTERFACE); return true; }
调用了GetGpsInterface去获取接口并初始化GPS
static const GpsInterface* GetGpsInterface(JNIEnv* env, jobject obj) { // this must be set before calling into the HAL library if (!mCallbacksObj) mCallbacksObj = env->NewGlobalRef(obj); if (!sGpsInterface) { sGpsInterface = get_gps_interface(); if (!sGpsInterface || sGpsInterface->init(&sGpsCallbacks) != 0) { sGpsInterface = NULL; return NULL; } } return sGpsInterface; }