Universal Events

NOTE

Universal events are supported since API version 4. Updates will be marked with a superscript to indicate their earliest API version.

Event Description

  • Events are bound to components. When a component meets the event triggering condition, the corresponding event callback in the JS is executed to implement the interaction between the UI and the JS logic layer of the page.

  • The event callback can carry additional information through parameters, such as the dataset on the component and event-specific callback parameters.

Different from private events, universal events can be bound to most components.

Name Parameter Description Bubbling Supported Capturing Supported
touchstart TouchEvent Triggered when the tapping starts. For details about TouchEvent, see Table 2. Yes5+ Yes5+
touchmove TouchEvent Triggered when the tapping moves. Yes5+ Yes5+
touchcancel TouchEvent Triggered when the tapping is interrupted. Yes5+ Yes5+
touchend TouchEvent Triggered when the tapping ends. Yes5+ Yes5+
click - Triggered when a component is clicked. Yes6+ No
doubleclick7+ - Triggered when a component is double-clicked. No
Bubbling is supported since API version 9.
No
longpress - Triggered when a component is long pressed. No
Bubbling is supported since API version 9.
No
swipe5+ SwipeEvent Triggered when a user quickly swipes on a component. For details about SwipeEvent, see Table 4. No
Bubbling is supported since API version 9.
No
attached6+ - Triggered after the current component node is mounted to the render tree. No No
detached6+ - Triggered when the current component node is removed from the render tree. No No
pinchstart7+ PinchEvent Triggered when a pinch operation is started.
For details about PinchEvent, see Table 5.
No No
pinchupdate7+ PinchEvent Triggered when a pinch operation is in progress. No No
pinchend7+ PinchEvent Triggered when a pinch operation is ended. No No
pinchcancel7+ PinchEvent Triggered when a pinch operation is interrupted. No No
dragstart7+ DragEvent Triggered when dragging starts.
For details about DragEvent, see Table 6.
No No
drag7+ DragEvent Triggered when dragging is in progress. No No
dragend7+ DragEvent Triggered when dragging is ended. No No
dragenter7+ DragEvent Triggered when the dragged component enters a drop target. No No
dragover7+ DragEvent Triggered when the dragged component is being dragged over a drop target. No No
dragleave7+ DragEvent Triggered when the dragged component leaves a drop target. No No
drop7+ DragEvent Triggered when the dragged component is dropped on a drop target. No No

NOTE

Events not listed in the preceding table do not support bubbling, such as the change event of the <input> component. For details, see the description of the specific component.

Table 1 BaseEvent

Attribute Type Description
type string Event type, such as click and longpress.
timestamp number Timestamp when the event is triggered.
deviceId6+ number ID of the device that triggers the event.
target6+ Target Target object that triggers the event.

Table 2 TouchEvent (inherited from BaseEvent)

Attribute Type Description
touches Array<TouchInfo> Attribute set of the touch event, including the information array of the touch points on the screen.
changedTouches Array<TouchInfo> Attribute set when a touch event occurs, including the information array of changed touch points on the screen. changedTouches has the same data format as touches and indicates touch point changes, including changes in the number and location of touch points. For example, when the user's finger leaves the screen, which means that the number of touch points changes from 1 to 0, changedTouches has the relevant data generated, but not touches.

Table 3 TouchInfo

Attribute Type Description
globalX number Horizontal distance from the upper left corner of the screen (excluding the status bar), which acts as the origin of coordinates.
globalY number Vertical distance from the upper left corner of the screen (excluding the status bar), which acts as the origin of coordinates.
localX number Horizontal distance from the upper left corner of the touched component, which acts as the origin of coordinates.
localY number Vertical distance from the upper left corner of the touched component, which acts as the origin of coordinates.
size number Touch area.
force6+ number Touch force.

Table 4 SwipeEvent (inherited from BaseEvent)

Attribute Type Description
direction string Swiping direction. The value can be one of the following:
- left: Swipe left.
- right: Swipe right.
- up: Swipe up.
- down: Swipe down.
distance6+ number Swiping distance in the swiping direction.

Table 5 PinchEvent7+

Attribute Type Description
scale number Scale factor.
pinchCenterX number X-coordinate of the pinch center, in px.
pinchCenterY number Y-coordinate of the pinch center, in px.

Table 6 DragEvent7+ (inherited from BaseEvent)

Attribute Type Description
type string Event name.
globalX number Horizontal distance from the upper left corner of the screen, which acts as the origin of coordinates.
globalY number Vertical distance from the upper left corner of the screen, which acts as the origin of coordinates.
timestamp number Timestamp.
dataTransfer9+ DataTransfer Object for data transfer.

Target6+

When a component triggers an event, the event callback receives an event object by default. You can obtain the corresponding information through the event object.

Attribute Type Description
dataSet6+ Object Custom attribute set defined through data-*.

Example

<!-- xxx.hml -->
<div>
  <div data-a="dataA" data-b="dataB" 
    style="width: 100%; height: 50%; background-color: saddlebrown;"@touchstart='touchstartfunc'></div>
</div>
// xxx.js
export default {
  touchstartfunc(msg) {
    console.info(`on touch start, point is: ${msg.touches[0].globalX}`);
    console.info(`on touch start, data is: ${msg.target.dataSet.a}`);
  }
}

DataTransfer9+

Use dataTransfer to transfer data during the drag operation, so you can perform operations on the data when the drag operation is complete.

setData9+

setData(key: string, value: object): boolean

Sets the data associated with the specified key. If there is no data associated with the key, the data will be appended. If there is already data associated with the key, the data will replace the existing data in the same position.

Parameters

Name Type Mandatory Description
key string Yes Data key.
value object Yes Data to be stored.

Return value

Type Description
boolean Operation result. The value true means that the operation is successful, and false means otherwise.

Example

// value in setData can be of a primitive type.
dragStart(e) {
	var isSetOk = e.dataTransfer.setData('name', 1);
},
// value in setData can be of the object type.
dragStart(e) {
	var person = new Object();
	person.name = "tom";
	person.age = 21;
	var isSetOk = e.dataTransfer.setData('person', person);
}

getData9+

getData(key: string): object

Obtains the data associated with the specified key. If no data is associated with the key, an empty string will be returned.

Parameters

Name Type Mandatory Description
key string Yes Data key.

Return value

Type Description
object Obtained data.

Example

dragStart(e) {
	var person = new Object();
	person.name = "tom";
	person.age = 21;
	e.dataTransfer.setData('person', person);
},
dragEnd(e){
	var person = e.dataTransfer.getData('person');
},

clearData9+

clearData(key?: string): boolean

Deletes data associated with the specified key. If there is no data associated with the key, this API will not have any effect. If the key is null, all data will be deleted.

Parameters

Name Type Mandatory Description
key string No Data key.

Return value

Type Description
boolean Operation result. The value true means that the operation is successful, and false means otherwise.

Example

dragEnd(e) {
	var isSuccess = e.dataTransfer.clearData('name');
}

setDragImage9+

setDragImage(pixelmap: PixelMap, offsetX: number,offsetY: number): boolean

Sets a custom drag image.

Parameters

Name Type Mandatory Description
pixelmap PixelMap Yes Image transferred from the frontend.
offsetX number Yes Horizontal offset relative to the image.
offsetY number Yes Vertical offset relative to the image.

Return value

Type Description
boolean Operation result. The value true means that the operation is successful, and false means otherwise.

Example

import image from '@ohos.multimedia.image';

export default {
    createPixelMap() {
        let color = new ArrayBuffer(4 * 96 * 96);
        var buffer = new Uint8Array(color);
        for (var i = 0; i < buffer.length; i++) {
            buffer[i] = (i + 1) % 255;
        }
        let opts = {
            alphaType: 0,
            editable: true,
            pixelFormat: 4,
            scaleMode: 1,
            size: {
                height: 96, width: 96
            }
        }
        const promise = image.createPixelMap(color, opts);
        promise.then((data) => {
            console.error('-create pixmap has info message:' + JSON.stringify(data));
            this.pixelMap = data;
            this.pixelMapReader = data;
        })
    },

    onInit() {
        this.createPixelMap
    },

    dragStart(e) {
        e.dataTransfer.setDragImage(this.pixelMapReader, 50, 50);
    }
}