bunige-pagedjs-template/reload-in-place.js

118 lines
3.8 KiB
JavaScript

// Reload-in-place v2.0
// Nicolas Taffin + Sameh Chafik - 2020
// MIT License https://opensource.org/licenses/MIT
// A simple script to add your pagedjs project. On reload, it will make the web browser scroll to the place it was before reload.
// Useful when styling or proof correcting your book. Multi docs compatible and doesn't wait for complete compilation to go.
console.log("reload in place");
// separate human / machine scroll
var machineScroll = false;
// check pagedJS ended compilation
var pagedjsEnd = false;
class pagedjsEnded extends Paged.Handler {
constructor(chunker, polisher, caller) {
super(chunker, polisher, caller);
}
afterRendered(pages) {
pagedjsEnd = true;
}
}
Paged.registerHandlers(pagedjsEnded);
// set a "unique" filename based on title element, in case several books are opened
var fileTitle = document.getElementsByTagName("title")[0].text;
function getDocHeight() {
var D = document;
return Math.max(
D.body.scrollHeight, D.documentElement.scrollHeight,
D.body.offsetHeight, D.documentElement.offsetHeight,
D.body.clientHeight, D.documentElement.clientHeight
)
}
function saveAmountScrolled(){
var scrollArray = [];
var scrollTop = window.pageYOffset || (document.documentElement || document.body.parentNode || document.body).scrollTop
if (!machineScroll) {
var scrollLeft = window.pageXOffset || (document.documentElement || document.body.parentNode || document.body).scrollLeft
scrollArray.push({ X: Math.round(scrollLeft), Y: Math.round(scrollTop) });
console.log("Saved ", scrollArray);
localStorage[fileTitle] = JSON.stringify(scrollArray);
}
}
// on Load, blur or opacify the page, and try to join ASAP
// last saved position, or at least last compiled page
window.onload = moveFast;
function moveFast() {
machineScroll= true;
var styleEl = document.createElement('style');
document.head.appendChild(styleEl);
var styleSheet = styleEl.sheet;
styleSheet.insertRule('.pagedjs_pages { filter: blur(10px); }', 0);
//styleSheet.insertRule('.pagedjs_pages { opacity: 0.1; }', 0);
var savedData = localStorage.getItem(fileTitle);
if (savedData) {
var scrollArray = JSON.parse(savedData);
var scrollTop = scrollArray[0].Y;
var scrollLeft = scrollArray[0].X;
} else {
var scrollTop = 0;
var scrollLeft = 0;
}
var winheight= window.innerHeight || (document.documentElement || document.body).clientHeight
window.currentInterval = setInterval(function(){
var docheight = getDocHeight();
if ( scrollTop > 0 && scrollTop > docheight - winheight && !pagedjsEnd) {
window.scrollTo(scrollLeft,docheight);
} else {
window.scrollTo(scrollLeft,scrollTop);
clearInterval(window.currentInterval);
setTimeout(function(){
window.scrollTo(scrollLeft,scrollTop);
machineScroll = false;
styleSheet.deleteRule(0);
}, 500); // Delay to start
}
}, 50); // refresh frequency
};
// slow down a bit save position pace
var slowSave = debounce(function() {
if(!machineScroll) {
saveAmountScrolled();
}
}, 100); // save frequency
function debounce(func, wait, immediate) {
var timeout;
return function() {
var context = this, args = arguments;
var later = function() {
timeout = null;
if (!immediate) func.apply(context, args);
};
var callNow = immediate && !timeout;
clearTimeout(timeout);
timeout = setTimeout(later, wait);
if (callNow) func.apply(context, args);
};
};
// Scroll triggers save, but not immediately on load
setTimeout(function(){
window.addEventListener('scroll', slowSave);
}, 1000); // wait a bit before starting position save