Power States
PUBLISHED
You can access a device's power resources. Currently, the screen and CPU power resources are supported, allowing you to request a specific power state and control the brightness of the screen.
This feature is supported in mobile and wearable applications only.
The main features of the Power API include:
- Managing power resources
- Managing the screen brightness
You can get and set the screen brightness.
- Managing the screen state
You can switch the screen on and off, and check whether the screen is on.
Prerequisites
To use the Power API (in mobile [1] and wearable [2] applications), the application has to request permission by adding the following privilege to the config.xml
file:
<tizen:privilege name="http://tizen.org/privilege/power"/>
Managing Power Resources
You can request and release a minimum power state for the screen and CPU. The request locks the screen to a minimum state and keeps the device bright and awake. For example, if you set the minimum power state to SCREEN_NORMAL
, the device display always remains in the SCREEN_NORMAL
level and never goes down to the SCREEN_DIM
level.
The following table lists the levels you can request.
Table: Power state levels
Level | Description |
---|---|
SCREEN_OFF |
In this state, the screen is off. You cannot request this state, but it can be used in event handlers. |
SCREEN_DIM |
In this state, the screen is dimmed. When this state is requested, the device does not go to the SCREEN_OFF state automatically. |
SCREEN_NORMAL |
In this state, the screen uses the default brightness the user has configured for the device. When this state is requested, the device does not go to the SCREEN_DIM state automatically. |
CPU_AWAKE |
In this state, the CPU is awake. When this state is requested, the device does not go to SLEEP state automatically. |
To request and release the power state:
-
To set the power state, call the
request()
method of thePowerManager
interface (in mobile [3] and wearable [4] applications) with the intended power resource and its state. In this example, theSCREEN_NORMAL
state is requested for the screen resource:tizen.power.request('SCREEN', 'SCREEN_NORMAL');
-
To release a power state, call the
release()
method with the intended resource:tizen.power.release('SCREEN');
-
To listen for the screen state changes, use the
setScreenStateChangeListener()
method:function onScreenStateChanged(previousState, changedState) { console.log('Screen state changed from' + previousState + 'to' + changedState); } tizen.power.setScreenStateChangeListener(onScreenStateChanged);
-
To unset the screen state change callback and stop monitoring it, use the
unsetScreenStateChangeListener()
method:tizen.power.unsetScreenStateChangeListener();
Managing the Screen Brightness
To get, set, and restore the screen brightness:
-
To get the screen brightness, call the
getScreenBrightness()
method of thePowerManager
interface (in mobile [3] and wearable [4] applications):var screenBrightness = tizen.power.getScreenBrightness();
-
To set the screen brightness, call the
setScreenBrightness()
method of thePowerManager
interface with the value from 0 to 1.In this example, the screen brightness is set to
1
(the brightest setting).tizen.power.setScreenBrightness(1);
-
To restore the default screen brightness, use the
restoreScreenBrightness()
method of thePowerManager
interface:tizen.power.restoreScreenBrightness();
Managing the Screen State
To check whether the screen is on, call the isScreenOn()
method of the PowerManager
interface (in mobile [3] and wearable [4] applications):
var isScreenOn = tizen.power.isScreenOn();