2a09d1a4
 liuqimichale
添加宜春 天水 宣化
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import {createRectInit, getContentRect} from './utils/geometry.js';
/**
* Class that is responsible for computations of the content rectangle of
* provided DOM element and for keeping track of it's changes.
*/
export default class ResizeObservation {
/**
* Reference to the observed element.
*
* @type {Element}
*/
target;
/**
* Broadcasted width of content rectangle.
*
* @type {number}
*/
broadcastWidth = 0;
/**
* Broadcasted height of content rectangle.
*
* @type {number}
*/
broadcastHeight = 0;
/**
* Reference to the last observed content rectangle.
*
* @private {DOMRectInit}
*/
contentRect_ = createRectInit(0, 0, 0, 0);
/**
* Creates an instance of ResizeObservation.
*
* @param {Element} target - Element to be observed.
*/
constructor(target) {
this.target = target;
}
/**
* Updates content rectangle and tells whether it's width or height properties
* have changed since the last broadcast.
*
* @returns {boolean}
*/
isActive() {
const rect = getContentRect(this.target);
this.contentRect_ = rect;
return (
rect.width !== this.broadcastWidth ||
rect.height !== this.broadcastHeight
);
}
/**
* Updates 'broadcastWidth' and 'broadcastHeight' properties with a data
* from the corresponding properties of the last observed content rectangle.
*
* @returns {DOMRectInit} Last observed content rectangle.
*/
broadcastRect() {
const rect = this.contentRect_;
this.broadcastWidth = rect.width;
this.broadcastHeight = rect.height;
return rect;
}
}
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