Project import generated by Copybara.
GitOrigin-RevId: 63746295f1a5ab5a619056791995793d65529e62
diff --git a/node_modules/mdl-ext/src/utils/resize-observer.js b/node_modules/mdl-ext/src/utils/resize-observer.js
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+
+/**
+ * An API for observing changes to Element’s size.
+ *
+ * @See https://wicg.github.io/ResizeObserver/
+ * @ee https://github.com/pelotoncycle/resize-observer
+ *
+ */
+
+import intervalFunction from './interval-function';
+
+((window, document) => {
+ 'use strict';
+
+ if (typeof window.ResizeObserver !== 'undefined') {
+ return;
+ }
+
+ document.resizeObservers = [];
+
+ /**
+ * The content rect is defined in section 2.3 ResizeObserverEntry of the spec
+ * @param target the element to calculate the content rect for
+ * @return {{top: (Number|number), left: (Number|number), width: number, height: number}}
+ *
+ * Note:
+ * Avoid using margins on the observed element. The calculation can return incorrect values when margins are involved.
+ *
+ * The following CSS will report incorrect width (Chrome OSX):
+ *
+ * <div id="outer" style="width: 300px; height:300px; background-color: green;overflow:auto;">
+ * <div id="observed" style="width: 400px; height:400px; background-color: yellow; margin:30px; border: 20px solid red; padding:10px;">
+ * </div>
+ * </div>
+ *
+ * The calculated width is 280. The actual (correct) width is 340 since Chrome clips the margin.
+ *
+ * Use an outer container if you really need a "margin":
+ *
+ * <div id="outer" style="width: 300px; height:300px; background-color: green;overflow:auto; padding:30px;">
+ * <div id="observed" style="width: 400px; height:400px; background-color: yellow; margin: 0; border: 20px solid red; padding:10px;">
+ * </div>
+ * </div>
+ *
+ * A more detailed explanation can be fund here:
+ * http://stackoverflow.com/questions/21064101/understanding-offsetwidth-clientwidth-scrollwidth-and-height-respectively
+ */
+ const getContentRect = target => {
+ const cs = window.getComputedStyle(target);
+ const r = target.getBoundingClientRect();
+ const top = parseFloat(cs.paddingTop) || 0;
+ const left = parseFloat(cs.paddingLeft) || 0;
+ const width = r.width - (
+ (parseFloat(cs.marginLeft) || 0) +
+ (parseFloat(cs.marginRight) || 0) +
+ (parseFloat(cs.borderLeftWidth) || 0) +
+ (parseFloat(cs.borderRightWidth) || 0) +
+ (left) +
+ (parseFloat(cs.paddingRight) || 0)
+ );
+ const height = r.height - (
+ (parseFloat(cs.marginTop) || 0) +
+ (parseFloat(cs.marginBottom) || 0) +
+ (parseFloat(cs.borderTopWidth) || 0) +
+ (parseFloat(cs.borderBottomWidth) || 0) +
+ (top) +
+ (parseFloat(cs.paddingBottom) || 0)
+ );
+ return {width: width, height: height, top: top, left: left};
+ };
+
+ const dimensionHasChanged = (target, lastWidth, lastHeight) => {
+ const {width, height} = getContentRect(target);
+ return width !== lastWidth || height !== lastHeight;
+ };
+
+
+ /**
+ * ResizeObservation holds observation information for a single Element.
+ * @param target
+ * @return {{target: *, broadcastWidth, broadcastHeight, isOrphan: (function()), isActive: (function())}}
+ * @constructor
+ */
+ const ResizeObservation = target => {
+ const {width, height} = getContentRect(target);
+
+ return {
+ target: target,
+ broadcastWidth: width,
+ broadcastHeight: height,
+
+ isOrphan() {
+ return !this.target || !this.target.parentNode;
+ },
+ isActive() {
+ return dimensionHasChanged(this.target, this.broadcastWidth, this.broadcastHeight);
+ }
+ };
+ };
+
+ /**
+ * A snapshot of the observed element
+ * @param target
+ * @param rect
+ * @return {{target: *, contentRect: *}}
+ * @constructor
+ */
+ const ResizeObserverEntry = (target, rect) => {
+ return {
+ target: target,
+ contentRect: rect
+ };
+ };
+
+
+ /**
+ * The ResizeObserver is used to observe changes to Element's content rect.
+ */
+ class ResizeObserver {
+
+ /**
+ * Constructor for instantiating new Resize observers.
+ * @param callback void (sequence<ResizeObserverEntry> entries). The function which will be called on each resize.
+ * @throws {TypeError}
+ */
+ constructor( callback ) {
+
+ if(typeof callback !== 'function') {
+ throw new TypeError('callback parameter must be a function');
+ }
+
+ this.callback_ = callback;
+ this.observationTargets_ = [];
+ this.activeTargets_ = [];
+
+ document.resizeObservers.push(this);
+ }
+
+ /**
+ * A list of ResizeObservations. It represents all Elements being observed.
+ *
+ * @return {Array}
+ */
+ get observationTargets() {
+ return this.observationTargets_;
+ }
+
+ /**
+ * A list of ResizeObservations. It represents all Elements whose size has
+ * changed since last observation broadcast that are eligible for broadcast.
+ *
+ * @return {Array}
+ */
+ get activeTargets() {
+ return this.activeTargets_;
+ }
+
+ /**
+ * Adds target to the list of observed elements.
+ * @param {HTMLElement} target The target to observe
+ */
+ observe(target) {
+ if(target) {
+ if (!(target instanceof HTMLElement)) {
+ throw new TypeError('target parameter must be an HTMLElement');
+ }
+ if (!this.observationTargets_.find(t => t.target === target)) {
+ this.observationTargets_.push(ResizeObservation(target));
+ resizeController.start();
+ }
+ }
+ }
+
+ /**
+ * Removes target from the list of observed elements.
+ * @param target The target to remove
+ */
+ unobserve(target) {
+ const i = this.observationTargets_.findIndex(t => t.target === target);
+ if(i > -1) {
+ this.observationTargets_.splice(i, 1);
+ }
+ }
+
+ /**
+ * Stops the ResizeObserver instance from receiving notifications of resize changes.
+ * Until the observe() method is used again, observer's callback will not be invoked.
+ */
+ disconnect() {
+ this.observationTargets_ = [];
+ this.activeTargets_ = [];
+ }
+
+ /**
+ * Removes the ResizeObserver from the list of observers
+ */
+ destroy() {
+ this.disconnect();
+ const i = document.resizeObservers.findIndex(o => o === this);
+ if(i > -1) {
+ document.resizeObservers.splice(i, 1);
+ }
+ }
+
+ deleteOrphansAndPopulateActiveTargets_() {
+
+ // Works, but two iterations
+ //this.observationTargets_ = this.observationTargets_.filter( resizeObervation => !resizeObervation.isOrphan());
+ //this.activeTargets_ = this.observationTargets_.filter( resizeObervation => resizeObervation.isActive());
+
+ // Same result as above, one iteration
+ /*
+ this.activeTargets_ = [];
+ let n = this.observationTargets_.length-1;
+ while(n >= 0) {
+ if(this.observationTargets_[n].isOrphan()) {
+ this.observationTargets_.splice(n, 1);
+ }
+ else if(this.observationTargets_[n].isActive()) {
+ this.activeTargets_.push(this.observationTargets_[n]);
+ }
+ n -= 1;
+ }
+ */
+
+ // Same result as above - but reduce is cooler :-)
+ this.activeTargets_ = this.observationTargets_.reduceRight( (prev, resizeObservation, index, arr) => {
+ if(resizeObservation.isOrphan()) {
+ arr.splice(index, 1);
+ }
+ else if(resizeObservation.isActive()) {
+ prev.push(resizeObservation);
+ }
+ return prev;
+ }, []);
+ }
+
+ broadcast_() {
+ this.deleteOrphansAndPopulateActiveTargets_();
+ if (this.activeTargets_.length > 0) {
+ const entries = [];
+ for (const resizeObservation of this.activeTargets_) {
+ const rect = getContentRect(resizeObservation.target);
+ resizeObservation.broadcastWidth = rect.width;
+ resizeObservation.broadcastHeight = rect.height;
+ entries.push(ResizeObserverEntry(resizeObservation.target, rect));
+ }
+ this.callback_(entries);
+ this.activeTargets_ = [];
+ }
+ }
+ }
+
+
+ //let interval = require('./interval-function');
+
+ /**
+ * Broadcasts Element.resize events
+ * @return {{start: (function()), stop: (function())}}
+ * @constructor
+ */
+ const ResizeController = () => {
+
+ const shouldStop = () => {
+ return document.resizeObservers.findIndex( resizeObserver => resizeObserver.observationTargets.length > 0 ) > -1;
+ };
+
+ const execute = () => {
+ //console.log('***** Execute');
+ for(const resizeObserver of document.resizeObservers) {
+ resizeObserver.broadcast_();
+ }
+
+ return shouldStop();
+ };
+
+ const interval = intervalFunction(200);
+
+ return {
+ start() {
+ if(!interval.started) {
+ //console.log('***** Start poll');
+ interval.start(execute);
+ }
+ }
+ };
+ };
+
+ window.ResizeObserver = ResizeObserver;
+
+ const resizeController = ResizeController();
+ //console.log('***** ResizeObserver ready');
+
+})(window, document);