85 lines
1.9 KiB
JavaScript
85 lines
1.9 KiB
JavaScript
import { log } from '/imports/ui/services/api';
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export default class VisibilityEvent {
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constructor () {
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this._onVisible = null;
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this._onHidden = null;
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this._handleVisibilityChange = this._handleVisibilityChange.bind(this);
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this._registerVisibilityEvent();
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}
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onVisible (f) {
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this._onVisible = f;
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}
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onHidden(f) {
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this._onHidden = f;
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}
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removeEventListeners() {
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let event = this._getVisibilityEvent();
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document.removeEventListener(event, this._handleVisibilityChange, false);
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}
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_handleVisibilityChange () {
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if (!this._isHidden()) {
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if (this._onVisible) {
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this._onVisible();
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}
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} else {
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if (this._onHidden) {
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this._onHidden();
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}
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}
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}
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_getHiddenProp () {
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let prefixes = ['webkit', 'moz', 'ms', 'o'];
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// if 'hidden' is natively supported just return it
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if ('hidden' in document) return 'hidden';
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// otherwise loop over all the known prefixes unti we find one
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for (var i = 0; i < prefixes.length; i++) {
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if ((prefixes[i] + 'Hidden') in document) {
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return prefixes[i] + 'Hidden';
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}
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}
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// otherwise it's not supported
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return null;
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}
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_isHidden () {
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var prop = this._getHiddenProp();
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if (!prop) {
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return false;
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}
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return document[prop];
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}
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_getVisibilityEvent() {
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let hidden, visibilityChange;
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if (typeof document.hidden !== "undefined") {
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visibilityChange = "visibilitychange";
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} else if (typeof document.msHidden !== "undefined") {
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visibilityChange = "msvisibilitychange";
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} else if (typeof document.webkitHidden !== "undefined") {
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visibilityChange = "webkitvisibilitychange";
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}
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return visibilityChange;
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}
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_registerVisibilityEvent () {
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let event = this._getVisibilityEvent();
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document.addEventListener(event, this._handleVisibilityChange, false);
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}
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}
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