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, that is, the number of dots per inch. Generally, the value is 160 or 480. |
densityPixels | number | Yes | No | Logical density of the display, which is a scaling coefficient independent of the pixel unit. Generally, the value is 1 or 3. |
scaledDensity | number | Yes | No | Scaling factor for fonts displayed on the display. Generally, the value is the same as that of densityPixels. |
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");