Display

The Display module provides APIs for managing displays, such as obtaining information about the default display, obtaining information about all displays, and listening for the addition and removal of displays.

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';

DisplayState

Enumerates the display states.

System capability: SystemCapability.WindowManager.WindowManager.Core

Name	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.

System capability: SystemCapability.WindowManager.WindowManager.Core

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<Display>): void

Obtains the default display object. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.WindowManager.WindowManager.Core

Parameters

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

Example

var displayClass = null;
display.getDefaultDisplay((err, data) => {
    if (err.code) {
        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.getDefaultDisplay

getDefaultDisplay(): Promise<Display>

Obtains the default display object. This API uses a promise to return the result.

System capability: SystemCapability.WindowManager.WindowManager.Core

Return value

Type	Description
Promise<Display>	Promise used to return the default display object.

Example

var displayClass = null;
let promise = display.getDefaultDisplay();
promise.then((data) => {
    displayClass = data;
    console.info('Succeeded in obtaining the default display object. Data:' + JSON.stringify(data));
}).catch((err) => {
    console.error('Failed to obtain the default display object. Code:  ' + JSON.stringify(err));
});

display.getAllDisplay

getAllDisplay(callback: AsyncCallback<Array<Display>>): void

Obtains all display objects. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.WindowManager.WindowManager.Core

Parameters

Name	Type	Mandatory	Description
callback	AsyncCallback<Array<Display>>	Yes	Callback used to return all the display objects.

Example

display.getAllDisplay((err, data) => {
    if (err.code) {
        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.getAllDisplay

getAllDisplay(): Promise<Array<Display>>

Obtains all display objects. This API uses a promise to return the result.

System capability: SystemCapability.WindowManager.WindowManager.Core

Return value

Type	Description
Promise<Array<Display>>	Promise used to return all the display objects.

Example

let promise = display.getAllDisplay();
promise.then((data) => {
    console.info('Succeeded in obtaining all the display objects. Data: ' + JSON.stringify(data));
}).catch((err) => {
    console.error('Failed to obtain all the display objects. Code: ' + JSON.stringify(err));
});

display.on('add'|'remove'|'change')

on(type: 'add'|'remove'|'change', callback: Callback<number>): void

Subscribes to display changes.

System capability: SystemCapability.WindowManager.WindowManager.Core

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type. - add, indicating the display addition event. - remove, indicating the display removal event. - change, indicating the display change event.
callback	Callback<number>	Yes	Callback used to return the ID of the display.

Example

var callback = (data) => {
    console.info('Listening enabled. Data: ' + JSON.stringify(data))
}
display.on("add", callback);

display.off('add'|'remove'|'change')

off(type: 'add'|'remove'|'change', callback?: Callback<number>): void

Unsubscribes from display changes.

System capability: SystemCapability.WindowManager.WindowManager.Core

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type. - add, indicating the display addition event. - remove, indicating the display removal event. - change, indicating the display change event.
callback	Callback<number>	No	Callback used to return the ID of the display.

Example

display.off("remove");