# Display >![](../../public_sys-resources/icon-note.gif) **NOTE:** >The initial APIs of this module are supported since API version 7. Newly added APIs will be marked with a superscript to indicate their earliest API version. ## Modules to Import ``` import display from '@ohos.display'; ``` ## Required Permissions None ## DisplayState Provides the state of a display.

Name	Default Value	Description
STATE_UNKNOWN	0	Unknown.
STATE_OFF	1	The display is shut down.
STATE_ON	2	The display is powered on.
STATE_DOZE	3	The display is in sleep mode.
STATE_DOZE_SUSPEND	4	The display is in sleep mode, and the CPU is suspended.
STATE_VR	5	The display is in VR mode.
STATE_ON_SUSPEND	6	The display is powered on, and the CPU is suspended.

## Display Describes the attributes of a display. ### Attributes

Name	Type	Readable	Writable	Description
id	number	Yes	No	ID of the display.
name	string	Yes	No	Name of the display.
alive	boolean	Yes	No	Whether the display is alive.
state	DisplayState	Yes	No	State of the display.
refreshRate	number	Yes	No	Refresh rate of the display.
rotation	number	Yes	No	Screen rotation angle of the display.
width	number	Yes	No	Width of the display, in pixels.
height	number	Yes	No	Height of the display, in pixels.
densityDPI	number	Yes	No	Screen density of the display, in DPI.
densityPixels	number	Yes	No	Screen density of the display, in pixels.
scaledDensity	number	Yes	No	Scaling factor for fonts displayed on the display.
xDPI	number	Yes	No	Exact physical dots per inch of the screen in the horizontal direction.
yDPI	number	Yes	No	Exact physical dots per inch of the screen in the vertical direction.

## display.getDefaultDisplay getDefaultDisplay\(callback: AsyncCallback\): void; Obtains the default display object. - Parameters

Name	Type	Mandatory	Description
callback	AsyncCallback<Display>	Yes	Callback used to return the attributes of the default display.

- Example ``` var displayClass = null; display.getDefaultDisplay((err, data) => { if (err) { console.error('Failed to obtain the default display object. Code: ' + JSON.stringify(err)); return; } console.info('Succeeded in obtaining the default display object. Data:' + JSON.stringify(data)); displayClass = data; }); ``` ## display.getAllDisplay getAllDisplay\(callback: AsyncCallback\>\): void; Obtains all the display objects. - Parameters

Name	Type	Mandatory	Description
callback	AsyncCallback<Array<Display>>	Yes	Callback used to return the attributes of all displays.

- Example ``` display.getAllDisplay((err, data) => { if (err) { console.error('Failed to obtain all the display objects. Code: ' + JSON.stringify(err)); return; } console.info('Succeeded in obtaining all the display objects. Data: ' + JSON.stringify(data)) }); ``` ## display.on\('add'|'remove'|'change'\) on\(type: 'add'|'remove'|'change', callback: Callback\): void; Enables listening. - Parameters

Name	Type	Mandatory	Description
type	string	Yes	Listening type. add: listening for whether a display is added remove: listening for whether a display is removed change: listening for whether a display is changed
callback	Callback<number>	Yes	Callback used to return the ID of the display.

Name

Type

Mandatory

Description

type

string

Yes

Listening type.

add: listening for whether a display is added
remove: listening for whether a display is removed
change: listening for whether a display is changed

callback

Callback<number>

Yes

Callback used to return the ID of the display.

- Example ``` var type = "add"; var callback = (data) => { console.info('Listening enabled. Data: ' + JSON.stringify(data)) } display.on(type, callback); ``` ## display.off\('add'|'remove'|'change'\) off\(type: 'add'|'remove'|'change', callback?: Callback\): void; Disables listening. - Parameters

Name	Type	Mandatory	Description
type	string	Yes	Listening type. add: listening for whether a display is added remove: listening for whether a display is removed change: listening for whether a display is changed
callback	Callback<number>	No	Callback used to return the ID of the display.