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TiddlyWiki5/core/modules/utils/dom/scroller.js
Jeremy Ruston 0154b2a54e Revised implementation of scrolling behaviour
Now we use a "tw-scroll" event to request scrolling
2012-11-26 16:08:52 +00:00

82 lines
2.0 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";
/*
Event handler for when the `tw-scroll` event hits the document body
*/
var PageScroller = function() {
this.timerId = null;
};
PageScroller.prototype.cancelScroll = function() {
if(this.timerId) {
window.clearInterval(this.timerId);
this.timerId = null;
}
};
/*
Handle an event
*/
PageScroller.prototype.handleEvent = function(event) {
if(event.type === "tw-scroll") {
return this.handleScrollEvent(event);
}
return true;
};
/*
Handle a scroll event hitting the page document
*/
PageScroller.prototype.handleScrollEvent = function(event) {
// Get the offset bounds of the element
var domNode = event.target,
bounds = {
left: domNode.offsetLeft,
top: domNode.offsetTop,
width: domNode.offsetWidth,
height: domNode.offsetHeight
};
// Walk up the tree adjusting the offset bounds by each offsetParent
while(domNode.offsetParent) {
domNode = domNode.offsetParent;
bounds.left += domNode.offsetLeft;
bounds.top += domNode.offsetTop;
}
// Now scroll the body
var scrollPosition = $tw.utils.getScrollPosition();
this.cancelScroll();
this.startTime = new Date();
this.startX = scrollPosition.x;
this.startY = scrollPosition.y;
this.endX = bounds.left;
this.endY = bounds.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.cancelScroll();
t = 1;
}
t = $tw.utils.slowInSlowOut(t);
window.scrollTo(self.startX + (self.endX - self.startX) * t,self.startY + (self.endY - self.startY) * t);
}, 10);
}
};
exports.PageScroller = PageScroller;
})();