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TiddlyWiki5/core/modules/utils/dom/scroller.js

62 lines
1.6 KiB
JavaScript

/*\
title: $:/core/modules/utils/dom/scroller.js
type: application/javascript
module-type: utils
Module that creates a $tw.utils.Scroller object prototype that manages scrolling in the browser
\*/
(function(){
/*jslint node: true, browser: true */
/*global $tw: false */
"use strict";
var slowInSlowOut = function(t) {
return (1 - ((Math.cos(t * Math.PI) + 1) / 2));
};
/*
Creates a Scroller object
*/
var Scroller = function() {
};
Scroller.prototype.cancel = function() {
if(this.timerId) {
window.clearInterval(this.timerId);
this.timerId = null;
}
};
/*
Smoothly scroll an element back into view if needed
element: element or clientrect object
*/
Scroller.prototype.scrollIntoView = function(element) {
var elementBounds = element instanceof HTMLElement ? $tw.utils.getBoundingPageRect(element) : element,
scrollPosition = $tw.utils.getScrollPosition();
this.cancel();
this.startTime = new Date();
this.startX = scrollPosition.x;
this.startY = scrollPosition.y;
this.endX = elementBounds.left;
this.endY = elementBounds.top;
if((this.endX < this.startX) || (this.endX > (this.startX + window.innerWidth)) || (this.endY < this.startY) || (this.endY > (this.startY + window.innerHeight))) {
var self = this;
this.timerId = window.setInterval(function() {
var t = ((new Date()) - self.startTime) / $tw.config.preferences.animationDuration;
if(t >= 1) {
self.cancel();
t = 1;
}
t = slowInSlowOut(t);
window.scrollTo(self.startX + (self.endX - self.startX) * t,self.startY + (self.endY - self.startY) * t);
}, 10);
}
};
exports.Scroller = Scroller;
})();