Gingerbread中 GPS 主要流程分析

amuhong

1. GPS enable process

1.1. onPreferenceTreeClick() in SecureSetting.java.

            Settings.Secure.setLocationProviderEnabled(getContentResolver(),

                    LocationManager.GPS_PROVIDER, enabled);

if user selects GPS, configuration value in secure settings database will be updated accordingly.

1.2. initialize() in LocationManagerService.java.

        mSettings = new ContentQueryMap(settingsCursor, Settings.System.NAME, true, mLocationHandler);

        SettingsObserver settingsObserver = new SettingsObserver();

        mSettings.addObserver(settingsObserver);

it will observe the value in secure settings database.

and then call updateProvidersLocked() as below.

    private final class SettingsObserver implements Observer {

        public void update(Observable o, Object arg) {

            synchronized (mLock) {

                updateProvidersLocked();

            }

        }

    }

1.3. do GPS / AGPS initial process.

 

updateProvidersLocked() -> updateProviderListenersLocked() -> enable() in GpsLocationProvider.java -> send message - ENABLE -> handleEnable() -> native_init() / native_supports_xtra() / native_set_agps_server().

2. GPS disable process

2.1. onPreferenceTreeClick() in SecureSetting.java.

            Settings.Secure.setLocationProviderEnabled(getContentResolver(),

                    LocationManager.GPS_PROVIDER, enabled);

if user selects GPS, configuration value in secure settings database will be updated accordingly.

2.2. initialize() in LocationManagerService.java.

        mSettings = new ContentQueryMap(settingsCursor, Settings.System.NAME, true, mLocationHandler);

        SettingsObserver settingsObserver = new SettingsObserver();

        mSettings.addObserver(settingsObserver);

it will observe the value in secure settings database.

and then call updateProvidersLocked() as below.

    private final class SettingsObserver implements Observer {

        public void update(Observable o, Object arg) {

            synchronized (mLock) {

                updateProvidersLocked();

            }

        }

    }

2.3. do GPS / AGPS de-initial process.

updateProvidersLocked() -> updateProviderListenersLocked() -> disable() in GpsLocationProvider.java -> send message - ENABLE -> handleDisable() -> stopNavigating() / native_cleanup().

3. GPS start navigation process

3.1. Application calls requestLocationUpdates() in SDK API layer, requestLocationUpdates() is in LocationManager.java.

_requestLocationUpdates() 

-> requestLocationUpdates() 

-> requestLocationUpdatesLocked() in LocationManagerService.java 

-> enableLocationTracking() in GpsLocationProvider.java 

-> send message - ENABLE_TRACKING 

-> handleEnableLocationTracking() 

-> startNavigating() 

-> native_set_position_mode() / native_start().

4. GPS stop navigation process

4.1. Application calls removeUpdates() in SDK API layer, removeUpdates() is in LocationManager.java.

removeUpdates() 

removeUpdates() in LocationManagerService.java 

-> removeUpdatesLocked()

-> enableLocationTracking() in GpsLocationProvider.java 

-> send message - ENABLE_TRACKING 

-> handleEnableLocationTracking() 

-> stopNavigating() 

-> native_stop().