AOD provides an alternatative 'screen-off' experience. Instead, of completely turning the display off, it provides a distraction-free, glanceable experience for the phone in a low-powered mode. In this low-powered mode, the display will have a lower refresh rate and the UI should frequently shift its displayed contents in order to prevent burn-in.
The default doze component is specified by `config_dozeComponent` in the [framework config][1]. SystemUI provides a default Doze Component: [DozeService][2]. [DozeService][2] builds a [DozeMachine][3] with dependencies specified in [DozeModule][4] and configurations in [AmbientDisplayConfiguration][13] and [DozeParameters][14].
[DozeMachine][3] handles the following main states:
* AOD - persistently showing UI when the device is in a low-powered state
* Pulsing - waking up the screen to show notifications (from AOD and screen off)
* Docked UI - UI to show when the device is docked
* Wake-up gestures - including lift to wake and tap to wake (from AOD and screen off)
## Doze States ([see DozeMachine.State][3])
### DOZE
Device is asleep and listening for enabled pulsing and wake-up gesture triggers. In this state, no UI shows.
### DOZE_AOD
Device is asleep, showing UI, and listening for enabled pulsing and wake-up triggers. In this state, screen brightness is handled by [DozeScreenBrightness][5] which uses the brightness sensor specified by `doze_brightness_sensor_type` in the [SystemUI config][6]. To save power, this should be a low-powered sensor that shouldn't trigger as often as the light sensor used for on-screen adaptive brightness.
### DOZE_AOD_PAUSED
Device is asleep and would normally be in state `DOZE_AOD`; however, instead the display is temporarily off since the proximity sensor reported near for a minimum abount of time. [DozePauser][7] handles transitioning from `DOZE_AOD_PAUSING` after the minimum timeout after the NEAR is reported by the proximity sensor from [DozeTriggers][8]).
### DOZE_PULSING
Device is awake and showing UI. This is state typically occurs in response to incoming notification, but may also be from other pulse triggers specified in [DozeTriggers][8].
### DOZE_AOD_DOCKED
Device is awake, showing docking UI and listening for enabled pulsing and wake-up triggers. The default DockManager is provided by an empty interface at [DockManagerImpl][9]. SystemUI should override the DockManager for the DozeService to handle docking events.
[DozeDockHandler][11] listens for Dock state changes from [DockManager][10] and updates the doze docking state.
## Wake-up gestures
Doze sensors are registered in [DozeTriggers][8] via [DozeSensors][12]. Sensors can be configured per posture for foldable devices.
Relevant sensors include:
* Proximity sensor
* Brightness sensor
* Wake-up gestures
* tap to wake
* double tap to wake
* lift to wake
* significant motion
And are configured in the [AmbientDisplayConfiguration][13] with some related configurations specified in [DozeParameters][14].
## Debugging Tips
Enable DozeLog to print directly to logcat:
```
adb shell settings put global systemui/buffer/DozeLog v
```
Enable all DozeService logs to print directly to logcat:
```
adb shell setprop log.tag.DozeService DEBUG
```
Other helpful dumpsys commands (`adb shell dumpsys <service>`):
* activity service com.android.systemui/.doze.DozeService
* activity service com.android.systemui/.SystemUIService
