@ohos.application.AccessibilityExtensionAbility (AccessibilityExtensionAbility) (System API)

AccessibilityExtensionAbility provides accessibility service capabilities based on the ExtensionAbility framework, including connecting to and disconnecting from accessibility services, and processing accessibility service events and accessibility key events.

NOTE

The initial APIs of this module are supported since API version 20. Newly added APIs will be marked with a superscript to indicate their earliest API version.

This topic describes only the system APIs provided by the module. For details about other public APIs, see @ohos.application.AccessibilityExtensionAbility.

Modules to Import

import { AccessibilityExtensionAbility } from '@kit.AccessibilityKit';

AccessibilityEventInfo

Describes the accessibility event information.

System capability: SystemCapability.BarrierFree.Accessibility.Core

Properties

Name	Type	Read-Only	Optional	Description
eventType	AccessibilityEventType	No	No	Event type.
target	AccessibilityElement	No	Yes	Target component where the event occurs.
timeStamp	number	No	Yes	Timestamp of the event, in milliseconds. The default value is 0.
extraInfo	string	No	Yes	Added or deleted text content carried by the TextArea, TextInput, SearchField, or RichEdit component.

AccessibilityExtensionAbility.onAccessibilityConnect

onAccessibilityConnect(): void;

Called when the AccessibilityExtensionAbility is enabled and connected to the system service. In this API, you can have the service logic initialized. This API can be overridden as required. It returns the result to notify that the ability is successfully connected.

System API: This is a system API.

Required permissions: ohos.permission.ACCESSIBILITY_EXTENSION_ABILITY

System capability: SystemCapability.BarrierFree.Accessibility.Core

Error codes

For details about the error codes, see Universal Error Codes.

ID	Error Message
201	Permission verification failed. The application does not have the permission required to call the API.
202	Permission verification failed. A non-system application calls a system API.

Example

import { AccessibilityExtensionAbility } from '@kit.AccessibilityKit';

class MyAccessibilityExtensionAbility extends AccessibilityExtensionAbility {
  onAccessibilityConnect(): void {
    console.log('AxExtensionAbility onAccessibilityConnect');
  }
}

AccessibilityExtensionAbility.onAccessibilityDisconnect

onAccessibilityDisconnect(): void;

Called when the AccessibilityExtensionAbility is successfully disconnected from the system service. In this API, you can implement the service logic of resource release and exit. This API can be overridden as required.

System API: This is a system API.

Required permissions: ohos.permission.ACCESSIBILITY_EXTENSION_ABILITY

System capability: SystemCapability.BarrierFree.Accessibility.Core

Error codes

For details about the error codes, see Universal Error Codes.

ID	Error Message
201	Permission verification failed. The application does not have the permission required to call the API.
202	Permission verification failed. A non-system application calls a system API.

Example

import { AccessibilityExtensionAbility } from '@kit.AccessibilityKit';

class MyAccessibilityExtensionAbility extends AccessibilityExtensionAbility {
  onAccessibilityDisconnect(): void {
    console.log('AxExtensionAbility onAccessibilityDisconnect');
  }
}

AccessibilityExtensionAbility.onAccessibilityEventInfo

onAccessibilityEventInfo(event: AccessibilityEventInfo): void;

Called when a specified event occurs in an application. In this API, you can implement event-specific service logic. Generally, this API needs to be overridden.

System API: This is a system API.

Required permissions: ohos.permission.ACCESSIBILITY_EXTENSION_ABILITY

System capability: SystemCapability.BarrierFree.Accessibility.Core

Parameters

Name	Type	Mandatory	Description
event	AccessibilityEventInfo	Yes	Accessibility event information.

Error codes

For details about the error codes, see Universal Error Codes.

ID	Error Message
201	Permission verification failed. The application does not have the permission required to call the API.
202	Permission verification failed. A non-system application calls a system API.

Example

import { AccessibilityExtensionAbility, AccessibilityEventInfo, AccessibilityEventType } from '@kit.AccessibilityKit';

class MyAccessibilityExtensionAbility extends AccessibilityExtensionAbility {
  onAccessibilityEventInfo(event: AccessibilityEventInfo): void {
    console.log('AxExtensionAbility onAccessibilityEventInfo');
    if (event.eventType === AccessibilityEventType.TYPE_CLICK) {
      console.log('AxExtensionAbility onAccessibilityEventInfo: click');
    }
  }
}

AccessibilityExtensionAbility.onAccessibilityKeyEvent

onAccessibilityKeyEvent(keyEvent: KeyEvent): boolean;

Called when a physical key is pressed. In this API, you can determine whether to consume the event based on the service.

System API: This is a system API.

Required permissions: ohos.permission.ACCESSIBILITY_EXTENSION_ABILITY

System capability: SystemCapability.BarrierFree.Accessibility.Core

Parameters

Name	Type	Mandatory	Description
keyEvent	KeyEvent	Yes	Key event.

Return value

Type	Description
boolean	Returns true if the event is consumed and will not be transferred; returns false otherwise.

Error codes

For details about the error codes, see Universal Error Codes.

ID	Error Message
201	Permission verification failed. The application does not have the permission required to call the API.
202	Permission verification failed. A non-system application calls a system API.

Example

import { AccessibilityExtensionAbility } from '@kit.AccessibilityKit';
import { KeyEvent, KeyCode } from '@kit.InputKit';

class MyAccessibilityExtensionAbility extends AccessibilityExtensionAbility {
  onAccessibilityKeyEvent(keyEvent: KeyEvent): boolean {
    console.log('AxExtensionAbility onAccessibilityKeyEvent');
    if (keyEvent.key.code === KeyCode.KEYCODE_VOLUME_UP) {
      console.log('AxExtensionAbility onAccessibilityKeyEvent: intercept 16');
      return true;
    }
    return false;
  }
}