harmony 鸿蒙Universal Methods

2022-08-09
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Universal Methods

NOTE

This component is supported since API version 4. Updates will be marked with a superscript to indicate their earliest API version.

After a component is assigned the id attribute, you can use the ID to obtain the component objects and call methods on them.

animate

animate( keyframes: Keyframes, options: Options): void

Parameters

Name	Type	Mandatory	Description
keyframes	keyframes	Yes	Animation style.
options	Options	Yes	Array of objects used to set animation attributes. For details, see Options.

Table 1 keyframes

Name	Type	Description
frames	Array<Style>	Array of objects used to set animation attributes. For details, see Style attributes.

Table 2 Style attributes

Name	Type	Default Value	Description
width	number	-	Width set for the component during playback of the animation.
height	number	-	Height set for the component during playback of the animation.
backgroundColor	<color>	none	Background color set for the component during playback of the animation.
opacity	number	1	Opacity set for the component. The value ranges from 0 to 1.
backgroundPosition	string	-	The value format is “x y”, in percentage or pixels. The first value indicates the horizontal position, and the second value indicates the vertical position. If only one value is specified, the other value is 50%.
transformOrigin	string	‘center center’	Origin position of the transformed element. The first value indicates the x-axis position. The value can be left, center, right, a length, or a percentage. The second value indicates the y-axis position. The value can be top, center, bottom, a length, or a percentage.
transform	Transform	-	Transformation type set for a transformed element.
offset	number	-	- The value of offset must be within (0.0, 1.0] and sorted in ascending order if it is provided. - If there are only two frames, offset can be left empty. - If there are more than two frames, offset is mandatory.

Table 3 Options

Name	Type	Default Value	Description
duration	number	0	Duration for playing the animation, in milliseconds.
easing	string	linear	Time curve of the animation. For details about the supported types, see Available values of the easing attribute.
delay	number	0	Delay for the animation start. The default value indicates no delay.
iterations	number \|string	1	Number of times the animation will be played. number indicates a fixed number of playback operations, and Infinity indicates an unlimited number of playback operations.
direction⁶⁺	string	normal	Mode of playing the animation. normal: Plays the animation in forward loop mode. reverse: Plays the animation in reverse loop mode. alternate: Plays the animation in alternating loop mode. When the animation is played for an odd number of times, the playback is in forward direction. When the animation is played for an even number of times, the playback is in backward direction. alternate-reverse: plays the animation in reverse alternating loop mode. When the animation is played for an odd number of times, the playback is in reverse direction. When the animation is played for an even number of times, the playback is in forward direction.
fill	string	none	Start and end styles of the animation. none: No style is applied to the target before or after the animation is executed. forwards: The target keeps the state at the end of the animation (defined in the last key frame) after the animation is executed. backwards⁶⁺: The animation uses the value defined in the first key frame during the animation-delay. When animation-direction is set to normal or alternate, the value in the from key frame is used. When animation-direction is set to reverse or alternate-reverse, the value in the to key frame is used. both: The animation follows the forwards and backwards rules.

Table 4 Available values of the easing attribute

Value	Description
linear	The animation speed keeps unchanged.
ease-in	The animation starts at a low speed and then picks up speed until the end. The cubic-bezier curve (0.42, 0.0, 1.0, 1.0) is used.
ease-out	The animation ends at a low speed. The cubic-bezier curve (0.0, 0.0, 0.58, 1.0) is used.
ease-in-out	The animation starts and ends at a low speed. The cubic-bezier curve (0.42, 0.0, 0.58, 1.0) is used.
friction	The animation uses the friction cubic-bezier curve (0.2, 0.0, 0.2, 1.0).
extreme-deceleration	The animation uses the extreme deceleration cubic-bezier curve (0.0, 0.0, 0.0, 1.0).
sharp	The animation uses the sharp cubic-bezier curve (0.33, 0.0, 0.67, 1.0).
rhythm	The animation uses the rhythm cubic-bezier curve (0.7, 0.0, 0.2, 1.0).
smooth	The animation uses the smooth cubic-bezier curve (0.4, 0.0, 0.4, 1.0).
cubic-bezier(x1, y1, x2, y2)	You can customize an animation speed curve in the cubic-bezier() function. The x and y values of each input parameter must be between 0 and 1.
steps(number, step-position)⁶⁺	The animation uses the step curve. The number must be set and only an integer is supported. step-position is optional. It can be set to start or end. The default value is end.

Return value The animation attributes are as follows.

Name	Type	Description
finished	boolean	Read-only attribute, which indicates whether the animation playback is complete.
pending	boolean	Read-only attribute, which indicates whether the animation is waiting for the completion of other asynchronous operations (for example, start an animation with a delay).
playState	string	Read-write attribute, which indicates the playback status of the animation: - idle: The animation is not running (playback ended or not started). - running: The animation is running. - paused: The animation is paused. - finished: The animation finishes playing.
startTime	number	Read-write attribute, which indicates the animation start time. This attribute is similar to delay in the options attribute.

The animation methods are as follows.

Method	Parameter	Description
play	-	Plays the animation.
finish	-	Ends the animation.
pause	-	Pauses the animation.
cancel	-	Cancels the animation.
reverse	-	Plays the animation in reverse.

The animation events are as follows.

Event	Description
start⁶⁺	The animation starts.
cancel	The animation is forcibly canceled.
finish	The animation playback is complete.
repeat	The animation repeats.

Example

<!-- xxx.hml -->
<div class="container">
  <div id="idName" class="box"></div>
  <div class="buttonBox">
    <button @click="start">
      start
    </button>
    <button @click="cancel">
      cancel
    </button>
  </div>
</div>

/* xxx.css */
.container {
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 100%;
}
.box{
  width: 200px;
  height: 200px;
  background-color: #ff0000;
  margin-top: 30px;
}
.buttonBox{
  margin-top: 30px;
  width: 250px;
  justify-content: space-between;
}
button{
  background-color: #8e8b89;
  color: white;
  width: 100px;
  height: 40px;
  font-size: 24px;
}

// xxx.js
export default {
    data: {
        animation: '',
        options: {},
        frames: {}
    },
    onInit() {
        this.options = {
            duration: 1500,
            easing: 'friction',
            delay: 500,
            fill: 'forwards',
            iterations: 2,
            direction: 'normal',
        };
        this.frames = [
            {
                transform: {
                    translate: '-120px -0px'
                }, opacity: 0.1, offset: 0.0
            },
            {
                transform: {
                    translate: '120px 0px'
                }, opacity: 1.0, offset: 1.0
            }
        ];
    },

    start() {
        this.animation = this.$element('idName').animate(this.frames, this.options);
        this.animation.play();
    },
    cancel() {
        this.animation.cancel();
    }
}

en-us_image_0000001229677045

getBoundingClientRect

getBoundingClientRect(): <Rect>

Obtains the size of the element and its position relative to the window.

Return value

Table 5 Rect⁶⁺

Name	Type	Description
width	number	Width of the element.
height	number	Height of the element.
left	number	Offset between the left boundary of the element and the window.
top	number	Offset between the upper boundary of the element and the window.

Example

// xxx.js
var rect = this.$element('id').getBoundingClientRect();
console.info(`current element position is ${rect.left}, ${rect.top}`);

createIntersectionObserver

createIntersectionObserver(param?: ObserverParam): Observer

Listens for the visibility of the element on the current page.

Parameters

Name	Type	Mandatory	Description
param	ObserverParam	-	Observer callback.

Table 6 ObserverParam⁶⁺

Name	Type	Description
ratios	Array<number>	Range for triggering the observer callback. If the component is not within the range, the observer callback is triggered.

Return value

Table 7 Methods supported Observer⁶⁺

Method	Parameter	Description
observe	callback: function	Subscribes to events of the observed object. The callback method is called when the value is greater than or less than the threshold.
unobserve	-	Unsubscribes from events of the observed object.

Example

// xxx.js
let observer = this.$element('broad').createIntersectionObserver({
  ratios: [0.2, 0.5], // number
});

observer.observe((isVisible, ratio)=> {
    console.info('this element is ' + isVisible + 'ratio is ' + ratio)
})

observer.unobserve()