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index.js
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'use strict';
if(typeof require === 'function') {
var postcss = require('postcss');
var postcssUnEpub = require('./postcss-unepub.js');
}
const breakAvoidVals = ['avoid', 'avoid-page'];
const breakForceVals = ['always', 'all', 'page', 'left', 'right', 'recto', 'verso'];
function getIframeHTML(headElements) {
return `<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
${headElements}
<style type="text/css">
body {
display: block !important;
position: absolute !important;
left: 0 !important;
right: 0 !important;
bottom: 0 !important;
margin: 0 !important;
padding: 0 !important;
}
</style>
</head>
<body>
</body>
</html>`;
}
// async version of setTimeout(arg, 0);
async function nextTick(func) {
return new Promise((resolve, reject) => {
setTimeout(() => {
func().then(resolve)
}, 0);
});
}
// TODO Debug function. Not used in production
var nextStep;
async function waitForPress(func) {
return new Promise((resolve, reject) => {
nextStep = () => {
func().then(resolve)
};
});
}
// TODO Debug function. Not used in production
async function wait(func, delay) {
return new Promise((resolve, reject) => {
setTimeout(() => {
func().then(resolve)
}, delay);
});
}
async function waitForElementLoad(el) {
if(el.complete) return true;
return new Promise(function(cb) {
el.onload = cb;
el.onerror = cb;
});
}
function toLower(str) {
if(!str) return str;
return str.toLowerCase();
}
function parseDOM(str, mimetype) {
var parser = new DOMParser();
var doc = parser.parseFromString(str, mimetype);
// Check for errors according to:
// see https://developer.mozilla.org/en-US/docs/Web/API/DOMParser
var errs = doc.getElementsByTagName('parsererror');
if(errs.length) {
var txt = errs[0].textContent;
txt = txt.replace(/Below is a rendering.*/i, ''); // remove useless message
txt = txt.replace(':', ': ').replace(/\s+/, ' '); // improve formatting
throw new Error("Parsing XML failed: " + txt);
}
return doc;
}
function getXMLDocEncoding(doc, firstChild) {
// If the document has xml header like:
// <?xml version="1.0" encoding="ISO-8859-2"?>
// then this always overrides any
// <meta charset="utf-8"/> or <meta content="text/html; charset=utf-8"/>
// This is true in firefox, webkit and chrome
// As of February 2020 this works in WebKit and Chrome
if(doc.xmlEncoding) {
return doc.xmlEncoding;
}
// For some reason firefox decided to remove Document.xmlEncoding
// which is the only way to do this without manual parsing:
// https://developer.mozilla.org/en-US/docs/Web/API/Document/xmlEncoding
// Now there seems to be no way to detect XML encoding
// other than manually parsing the <?xml> tag
if(!firstChild.textContent) return undefined;
const m = firstChild.textContent.match(/\?xml[^\?]+encoding=['"]([^'"]+)['"]/);
if(m && m.length > 1) {
return m[1];
}
return undefined;
}
// Unfortunately neither document.characterSet
// nor document.inputEncoding are set correctly
// on a Document or XMLDocument created by DOMParser
// so we have to do it manually
function getDocEncoding(doc, firstChild) {
var encoding;
if(doc instanceof XMLDocument) {
encoding = getXMLDocEncoding(doc, firstChild);
if(encoding) return encoding;
}
var r = new RegExp(/charset\=([^;\s]+)/i);
var els = doc.querySelectorAll("head > meta[charset], head > meta[content]");
var el, attr, m;
for(el of els) {
// <meta http-equiv="Content-Type" content="text/xhtml; charset=utf-8"/>
attr = el.getAttribute('content');
if(attr) {
m = attr.match(r);
if(m && m.length > 1) {
encoding = m[1];
}
}
// <meta charset="utf-8"/>
attr = el.getAttribute('charset');
if(attr) {
encoding = attr;
}
}
return encoding || 'utf-8';
}
function isXHTML(doc) {
if(doc.querySelector('html').getAttribute('xmlns')) {
return true;
}
return false;
}
// Takes an arrayBuffer
// and returns a parsed Document or XMLDocument (autodetected)
// converted to utf-8 from whatever the native encoding was
async function parseHTML(arrayBuffer) {
var firstChild;
// Assume UTF-8 until we know different
const utf8Decoder = new TextDecoder('utf-8');
var str = utf8Decoder.decode(arrayBuffer);
var doc = parseDOM(str, 'text/html');
// If it's XHTML then re-parse with correct mime-type
const isX = isXHTML(doc);
if(isX) {
firstChild = doc.firstChild;
doc = parseDOM(str, 'application/xhtml+xml');
}
// Detect encoding
const encoding = getDocEncoding(doc, firstChild);
if(encoding.toLowerCase() !== 'utf-8') {
const decoder = new TextDecoder(encoding);
str = decoder.decode(arrayBuffer);
if(isX) {
doc = parseDOM(str, 'application/xhtml+xml');
} else {
doc = parseDOM(str, 'text/html');
}
}
return {doc, encoding: encoding};
}
// type is 'blob', 'text', 'json' or 'arrayBuffer'
// default type is 'text'
async function request(uri, type) {
var req = new Request(uri);
var resp = await fetch(req);
// If .status is 0 then resp.ok does not have a useful value.
// This can happen with non-http URI schemes
if(resp.status && (!resp.ok || resp.status < 200 || resp.status > 299)) {
throw new Error("Failed to get: " + uri);
}
if(!type) return await resp.text();
return await resp[type]();
}
async function requestHTML(uri) {
return new Promise((resolve, reject) => {
var xhr = new XMLHttpRequest;
xhr.open('GET', uri);
xhr.responseType = 'document';
xhr.onload = function() {
if(xhr.readyState === xhr.DONE) {
if(xhr.status < 200 || xhr.status >= 300) {
reject(new Error("Failed to get: " + uri));
return;
}
resolve(xhr.responseXML);
}
}
xhr.onerror = function() {
reject(new Error("Failed to get: " + uri));
}
xhr.send();
});
}
// Traverse recursively to next node in a DOM tree
// and shallow-copy it to the equivalent location in the target DOM tree
// while tracking tree depth
function appendNextNode(node, target, depth) {
var tmp;
if(node.childNodes.length) {
node = node.firstChild;
depth++;
tmp = node.cloneNode(); // shallow copy
target.appendChild(tmp);
target = tmp;
} else if(node.nextSibling) {
node = node.nextSibling;
tmp = node.cloneNode();
target.parentNode.appendChild(tmp);
target = tmp;
} else {
while(node) {
node = node.parentNode;
// Don't proceed past body element in source document
if(toLower(node.tagName) === 'body') return {};
target = target.parentNode;
depth--;
if(node && node.nextSibling) {
node = node.nextSibling;
tmp = node.cloneNode();
target.parentNode.appendChild(tmp);
target = tmp;
break;
}
}
}
if(!node) return {}; // no more pages
return {node, target, depth};
}
function appendAsFirstChild(parent, node) {
if(!parent.firstChild) {
return parent.appendChild(node);
}
return parent.insertBefore(node, parent.firstChild);
}
// Traverse backwards through siblings and parents
// until a <thead> or a <tr> containing a <th> is found
// then return the <thead> or <tr>
// Returns null if no such element is found
// or if that element is an ancestor of the starting node
function findPrevTableHeader(node) {
var tagName;
var isAncestor = true; // is the found header and ancestor of node?
while(node) {
tagName = toLower(node.tagName);
if(tagName === 'table' || tagName === 'body') {
return null;
}
if(!isAncestor) {
if(tagName === 'thead') {
return node;
} else if(tagName === 'tr') {
for(let c of node.childNodes) {
if(toLower(c.tagName) === 'th') {
return node;
}
}
}
}
if(node.previousSibling) {
// no longer dealing with a direct ancestor
if(tagName === 'tr' || tagName === 'thead') {
isAncestor = false;
}
node = node.previousSibling
} else {
if(tagName === 'tbody') {
isAncestor = false;
}
node = node.parentNode;
}
}
}
// Shallow clone the structure of ancestors back up to <body>
// If repeatTableHeader is true then the first <thead>
// (or <tr> which contains <th>) will be copied as
// the first child of <table>
function cloneAncestors(node, repeatTableHeader) {
var ret, tmp;
var innerMost;
var header;
const startNode = node;
while(node.parentNode && toLower(node.parentNode.tagName) !== 'body') {
tmp = node.parentNode.cloneNode() // shallow clone
if(!innerMost) innerMost = tmp;
if(repeatTableHeader && toLower(node.parentNode.tagName) === 'table') {
header = findPrevTableHeader(startNode);
if(header) {
tmp.appendChild(header.cloneNode(true));
}
}
if(ret) {
tmp.appendChild(ret);
}
ret = tmp;
node = node.parentNode;
}
return {
tree: ret,
innerMost: innerMost
};
}
// Get next node in document order recursively
// TODO unused
function nextNode(node) {
if(node.childNodes.length) {
return node.firstChild;
} else if(node.nextSibling) {
return node.nextSibling;
} else {
while(node) {
node = node.parentNode;
if(node && node.nextSibling) {
return node.nextSibling;
}
}
}
return null;
}
function createIframeContainer(allowScripts) {
var iframeElement = document.createElement('iframe');
iframeElement.sandbox = "allow-same-origin";
if(allowScripts) {
iframeElement.sandbox += " allow-scripts";
}
iframeElement.scrolling = 'no';
iframeElement.style.position = 'absolute';
iframeElement.style.display = 'block';
iframeElement.style.top = '0';
iframeElement.style.left = '0';
iframeElement.style.width = '100%';
iframeElement.style.height = '100%';
iframeElement.style.border = 'none';
iframeElement.style.overflow = 'hidden';
return iframeElement;
}
class Paginator {
constructor(containerID, opts) {
this.opts = Object.assign({
loadScripts: false,
loadCSS: true,
preprocessCSS: true,
cacheForwardPagination: true,
repeatTableHeader: false,
detectEncoding: true,
baseURI: undefined
}, opts || {})
// Does the page currently overflow elements at the top?
// If this is false then the page overflows at the bottom
this.overflowTop = false;
if(this.opts.columnLayout) {
this.columnLayout = true;
}
this.curPage = 0;
this.pages = {};
// List of <style> elements injected using
// the .injectCSS or .injectCSSbyURI API
this.injectedCSS = [];
// Create iframe container element
this.containerElement = document.getElementById(containerID);
this.iframeElement = createIframeContainer(this.opts.loadScripts);
this.containerElement.appendChild(this.iframeElement);
// Add HTML to iframe document
var headTags = '';
if(this.opts.baseURI) {
let baseEl = document.createElement('BASE');
baseEl.href = this.opts.baseURI;
headTags = baseEl.outerHTML;
}
this.iDoc = this.iframeElement.contentWindow.document;
this.iDoc.open();
this.iDoc.write(getIframeHTML(headTags));
this.iDoc.close();
this.page = this.iDoc.body;
this.setOverflowBottom();
// Use column-based layout? (slow on WebKit but may be more accurate)
if(this.columnLayout) {
this.pageRight = this.page.getBoundingClientRect().right;
this.page.style.columnWidth = this.page.offsetWidth + 'px';
} else {
this.pageBottom = this.page.getBoundingClientRect().bottom;
this.pageTop = this.page.getBoundingClientRect().top;
}
}
async load(chapterURI) {
this.doc = await this.loadChapter(chapterURI);
if(this.opts.loadCSS) {
await this.loadCSS();
}
if(this.opts.loadScripts) {
this.loadScripts();
}
return await this.firstPage();
}
getDocumentLanguage() {
}
getDocumentEncoding() {
}
// Traverse recursively to previous node in a DOM tree
// and copy it to the equivalent location in the target DOM tree
// if it doesn't already exist, while tracking tree depth.
// Shallow copy is preferred when possible, but is not always
// viable while traversing in reverse order
// since a node should never be added without its ancestor nodes
appendPrevNode(node, target, depth) {
var tmp;
var forceAvoidInside;
if(node.previousSibling) {
node = node.previousSibling;
tmp = node.cloneNode();
appendAsFirstChild(target.parentNode, tmp);
target = tmp;
if(!forceAvoidInside && this.shouldBreak(node) === 'avoid-inside') {
forceAvoidInside = {node, target, depth};
}
while(node.childNodes.length) {
node = node.lastChild;
tmp = node.cloneNode();
target.appendChild(tmp);
target = tmp;
depth++;;
if(!forceAvoidInside && this.shouldBreak(node) === 'avoid-inside') {
forceAvoidInside = {node, target, depth};
}
}
} else if(node.parentNode) {
node = node.parentNode;
// Don't proceed past body element in source document
if(toLower(node.tagName) === 'body') return {};
// This should never happen
if(!target.parentNode) {
console.error("failure in appendPrevNode()");
return {};
}
target = target.parentNode;
depth--;
}
if(!node) return {}; // no more pages
return {node, target, depth, forceAvoidInside};
}
async processCSS(css, uri) {
uri = uri || 'unnamed';
if(!this.opts.preprocessCSS || !postcss) {
return css;
}
var result = await postcss([postcssUnEpub])
.process(css, {from: uri, to: uri+'.out'});
return result.css;
}
async loadCSS() {
// handle <link rel="stylesheet" href="<uri>">
// and <style> tags
var els = this.doc.querySelectorAll("head > link[rel=stylesheet], head > style");
var el, uri, css, type, result;
for(el of els) {
try {
if(toLower(el.tagName) === 'link') {
if(el.getAttribute('disabled')) continue;
uri = el.getAttribute('href');
if(!uri) continue;
css = await request(this.opts.baseURI + uri);
} else { // <style> tags
css = el.innerHTML;
}
css = await this.processCSS(css, uri);
} catch(err) {
console.error(err);
continue;
}
this._injectCSS(css);
}
}
cloneElements(target, els) {
var el, tmp;
for(el of els) {
tmp = el.cloneNode(true);
target.appendChild(tmp);
}
}
loadScripts() {
const head = this.iDoc.querySelector("head");
var els = this.doc.querySelectorAll("head > script");
this.cloneElements(head, els);
const html = this.iDoc.querySelector("html");
var els = this.doc.querySelectorAll("html > script");
this.cloneElements(html, els);
}
async injectCSSByURI(uri, opts) {
var css;
css = await request(uri);
return this.injectCSS(css, opts);
}
async injectCSS(css, opts) {
opts = Object.assign({
order: 'after',
preprocess: true
}, opts || {});
if(opts.preprocessCSS) {
css = await this.processCSS(css);
}
var el = this._injectCSS(css, (opts.order === 'before'));
this.injectedCSS.push(el);
return el;
}
clearCSS(clearAll) {
var els;
if(clearAll) {
els = this.iDoc.querySelectorAll("head > link[rel=stylesheet], head > style");
} else {
els = this.injectedCSS;
}
var el;
for(el of els) {
el.parentNode.removeChild(el);
}
this.injectedCSS = [];
}
_injectCSS(css, before) {
const style = this.iDoc.createElement('STYLE');
style.type = "text/css";
style.innerHTML = css;
const head = this.iDoc.querySelector("head");
if(before) {
appendAsFirstChild(head, style);
} else {
head.appendChild(style);
}
return style;
}
// Make page overflow at top
setOverflowTop() {
this.overflowTop = true;
this.page.style.top = '';
}
// Make page overflow at bottom (like a normal page)
setOverflowBottom() {
this.overflowTop = false;
this.page.style.top = '0';
}
// Traverse node's ancestors until an element is found
getFirstElementAncestor(node) {
while(node.nodeType !== Node.ELEMENT_NODE) {
node = node.parentNode;
if(toLower(node.tagName) === 'body') return null;
}
return node;
}
getAncestorsCombinedBottomSpacing(el) {
if(!el) return 0;
var spacing = 0;
while(toLower(el.tagName) !== 'body') {
spacing += this.getBottomSpacing(el);
el = el.parentNode;
}
return spacing;
}
getAncestorsCombinedTopSpacing(el) {
if(!el) return 0;
var spacing = 0;
while(toLower(el.tagName) !== 'body') {
spacing += this.getTopSpacing(el);
el = el.parentNode;
}
return spacing;
}
// Get combined bottom-padding and bottom-spacing of element
getBottomSpacing(el) {
if(!el) return 0;
const style = this.iframeElement.contentWindow.getComputedStyle(el);
return (parseFloat(style.getPropertyValue('padding-bottom')) || 0) + (parseFloat(style.getPropertyValue('margin-bottom')) || 0);
}
// Get combined top-padding and top-spacing of element
getTopSpacing(el) {
if(!el) return 0;
const style = this.iframeElement.contentWindow.getComputedStyle(el);
return (parseFloat(style.getPropertyValue('padding-top')) || 0) + (parseFloat(style.getPropertyValue('margin-top')) || 0);
}
// Does the node overflow the bottom/top of the page
async didOverflow(node, topOverflow) {
var el;
var rect;
var edge;
var spacing;
// TODO can we use a similar simplified method for bottom overflow?
if(topOverflow) {
// If it's an image, wait for it to load
if(toLower(node.tagName) === 'img') {
await waitForElementLoad(node);
}
if(this.page.getBoundingClientRect().top < 0) {
return true;
}
return false;
}
if(node.getBoundingClientRect) {
// If it's an image, wait for it to load
if(toLower(node.tagName) === 'img') {
await waitForElementLoad(node);
}
rect = node.getBoundingClientRect();
el = node;
} else { // handle text nodes
const range = this.iDoc.createRange();
range.selectNode(node);
rect = range.getBoundingClientRect();
el = this.getFirstElementAncestor(node);
}
if(el) {
spacing = this.getAncestorsCombinedBottomSpacing(el)
} else {
spacing = 0;
}
if(this.columnLayout) {
// TODO add support for top overflow
if(Math.round(rect.right) > Math.floor(this.pageRight)) {
return true;
}
} else {
edge = Math.round(rect.bottom + spacing);
if(edge > Math.floor(this.pageBottom)) {
return true;
}
}
return false
}
// Warning: Changing the way nodes are counted here
// will break existing bookmarks.
//
// If given a node, it will traverse the DOM, counting nodes
// until it finds the node and then return the count.
// If given a count it will do the same but return the node
// when it reaches the specified count
findNodeOrCount(startNode, nodeOrCount) {
var nodeCount;
var nodeToFind;
if(typeof nodeOrCount === 'number') {
nodeCount = nodeOrCount;
} else {
nodeToFind = nodeOrCount;
}
var node = startNode;
var count = 0;
while(node) {
if(nodeCount) {
if(count === nodeCount) {
return node;
}
} else if(nodeToFind) {
if(node === nodeToFind) {
return count;
}
}
if(node.childNodes.length) {
node = node.firstChild;
} else if(node.nextSibling) {
node = node.nextSibling;
} else {
// Don't proceed past body element in source document
if(toLower(node.tagName) === 'body') return null;
while(node) {
node = node.parentNode;
if(node && node.nextSibling) {
node = node.nextSibling;
break;
}
}
}
if(node) {
count++;
}
}
return null;
}
// Must match the way prev appendPrevNode() traverses
getPrevNode(node) {
// Don't proceed past body element in source document
if(toLower(node.tagName) === 'body') return node;
if(node.previousSibling) {
node = node.previousSibling;
while(node.childNodes.length) {
node = node.lastChild;
}
} else if(node.parentNode) {
node = node.parentNode;
}
return node;
}
// Find the exact offset in a text node just before the overflow occurs
// by using document.createRange() for a part of the text and adjusting
// the part of the text included in the range until the range
// doesn't overflow.
// Uses binary search to speed up the process.
// Returns -1 if offset could not be found.
findOverflowOffset(node, topOverflow) {
const range = this.iDoc.createRange();
range.selectNode(node);
range.setStart(node, 0);
const el = this.getFirstElementAncestor(node);
if(this.columnLayout) {
var pageRight = Math.ceil(this.pageRight);
} else {
var pageBottom = Math.floor(this.pageBottom);
}
const len = node.textContent.length;
range.setEnd(node, len - 1);
var prev = 0;
var tooFar = false;
var prevTooFar;
var dist, halfDist, bottom, top;
if(len === 0) return 0;
if(len === 1) return 1;
// init binary search
// `i` is the index into the text
var i = Math.round((len-1) / 2);
if(len === 2) {
i = 1;
}
var spacing;
if(!topOverflow) {
spacing = this.getAncestorsCombinedBottomSpacing(el)
} else {
spacing = this.getAncestorsCombinedTopSpacing(el)
}
while(true) {
if(i < 0) i = 0;
if(i > len - 1) i = len - 1;
if(!topOverflow) {
range.setEnd(node, i);
} else {
range.setStart(node, i);
}
prevTooFar = tooFar;
if(this.columnLayout) {
// TODO make this work with topOverflow
if(range.getBoundingClientRect().right > pageRight) {
tooFar = true;
} else {
tooFar = false;
}
} else {
if(!topOverflow) {
bottom = Math.round(range.getBoundingClientRect().bottom + spacing);
if(bottom > pageBottom) {
tooFar = true;
} else {
tooFar = false;
}
} else {
top = Math.round(range.getBoundingClientRect().top - spacing);
if(top < 0) {
tooFar = true;
} else {
tooFar = false;
}
}
}
dist = Math.abs(prev - i);
// Switch to incremental search if we moved less than 3 chars
// since last loop iteration
if(dist < 3) {
if(dist === 1) {
if(tooFar && !prevTooFar) return prev;
if(!tooFar && prevTooFar) return i;
}
if(dist === 0) {
// This only happens when topOverflow is true
// and all possible offsets result in overflow
if(i === len - 1) {
return i;
}
return -1;
}
prev = i;
if(!topOverflow) {
i += ((tooFar) ? -1 : 1);
} else {
i += ((tooFar) ? 1 : -1);
}
continue;
}
// binary search
halfDist = Math.round(dist / 2);
prev = i;
if(!topOverflow) {
i += ((tooFar) ? -halfDist : halfDist);
} else {
i += ((tooFar) ? halfDist : -halfDist);
}
}
}
// Check for CSS break-inside, break-before and break-after
// as well as <tr> elements which should always avoid breaks inside
shouldBreak(node) {
if(node.nodeType !== Node.ELEMENT_NODE) return;
if(toLower(node.tagName) === 'tr') {
return 'avoid-inside';
}
var val;
const styles = window.getComputedStyle(node);
val = styles.getPropertyValue('break-inside');
if(breakAvoidVals.indexOf(val) >= 0) {
return 'avoid-inside';
}
val = styles.getPropertyValue('break-before');
if(breakForceVals.indexOf(val) >= 0) {
return 'before';
}
val = styles.getPropertyValue('break-after');
if(breakForceVals.indexOf(val) >= 0) {
return 'after';
}
return null;
}
async gotoKnownPage(pageNumber) {
// Do we know the starting node+offset of the page?
var pageRef = this.pages[pageNumber];
if(!pageRef) return false;
const nextPageRef = await this.paginate(pageRef.node, pageRef.offset);
if(!this.pages[pageNumber + 1]) {
this.pages[pageNumber+1] = nextPageRef;
}
this.curPage = pageNumber;
return true;