mirror of
https://github.com/Jermolene/TiddlyWiki5
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121 lines
3.5 KiB
JavaScript
121 lines
3.5 KiB
JavaScript
/*\
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title: $:/core/modules/utils/dom/scroller.js
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type: application/javascript
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module-type: utils
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Module that creates a $tw.utils.Scroller object prototype that manages scrolling in the browser
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\*/
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(function(){
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/*jslint node: true, browser: true */
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/*global $tw: false */
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"use strict";
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/*
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Event handler for when the `tw-scroll` event hits the document body
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*/
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var PageScroller = function() {
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this.idRequestFrame = null;
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this.requestAnimationFrame = window.requestAnimationFrame ||
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window.webkitRequestAnimationFrame ||
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window.mozRequestAnimationFrame ||
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function(callback) {
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return window.setTimeout(callback, 1000/60);
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};
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this.cancelAnimationFrame = window.cancelAnimationFrame ||
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window.webkitCancelAnimationFrame ||
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window.webkitCancelRequestAnimationFrame ||
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window.mozCancelAnimationFrame ||
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window.mozCancelRequestAnimationFrame ||
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function(id) {
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window.clearTimeout(id);
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};
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};
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PageScroller.prototype.cancelScroll = function() {
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if(this.idRequestFrame) {
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this.cancelAnimationFrame.call(window,this.idRequestFrame);
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this.idRequestFrame = null;
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}
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};
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/*
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Handle an event
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*/
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PageScroller.prototype.handleEvent = function(event) {
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if(event.type === "tw-scroll") {
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return this.scrollIntoView(event.target);
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}
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return true;
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};
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/*
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Handle a scroll event hitting the page document
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*/
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PageScroller.prototype.scrollIntoView = function(element) {
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var duration = $tw.utils.getAnimationDuration();
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// Get the offset bounds of the element
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var bounds = {
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left: element.offsetLeft,
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top: element.offsetTop,
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width: element.offsetWidth,
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height: element.offsetHeight
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};
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// Walk up the tree adjusting the offset bounds by each offsetParent
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while(element.offsetParent) {
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element = element.offsetParent;
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bounds.left += element.offsetLeft;
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bounds.top += element.offsetTop;
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}
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// Now get ready to scroll the body
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this.cancelScroll();
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this.startTime = new Date();
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var scrollPosition = $tw.utils.getScrollPosition(),
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// We'll consider the horizontal and vertical scroll directions separately via this function
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getEndPos = function(targetPos,targetSize,currentPos,currentSize) {
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// If the target is above/left of the current view, then scroll to it's top/left
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if(targetPos <= currentPos) {
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return targetPos;
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// If the target is smaller than the window and the scroll position is too far up, then scroll till the target is at the bottom of the window
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} else if(targetSize < currentSize && currentPos < (targetPos + targetSize - currentSize)) {
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return targetPos + targetSize - currentSize;
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// If the target is big, then just scroll to the top
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} else if(currentPos < targetPos) {
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return targetPos;
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// Otherwise, stay where we are
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} else {
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return currentPos;
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}
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},
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endX = getEndPos(bounds.left,bounds.width,scrollPosition.x,window.innerWidth),
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endY = getEndPos(bounds.top,bounds.height,scrollPosition.y,window.innerHeight);
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// Only scroll if necessary
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if(endX !== scrollPosition.x || endY !== scrollPosition.y) {
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var self = this,
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drawFrame;
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drawFrame = function () {
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var t;
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if(duration <= 0) {
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t = 1;
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} else {
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t = ((new Date()) - self.startTime) / duration;
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}
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if(t >= 1) {
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self.cancelScroll();
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t = 1;
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}
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t = $tw.utils.slowInSlowOut(t);
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window.scrollTo(scrollPosition.x + (endX - scrollPosition.x) * t,scrollPosition.y + (endY - scrollPosition.y) * t);
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if(t < 1) {
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self.idRequestFrame = self.requestAnimationFrame.call(window,drawFrame);
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}
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};
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drawFrame();
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}
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};
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exports.PageScroller = PageScroller;
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})();
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