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efm.js
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efm.js
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/*
* EFM - Epub for Monocle
*
* A pure-javascript implementation of the book data object for Monocle.
*
* Copyright (c) 2013 Robert Schroll
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
MIMETYPES = {
png: "image/png",
gif: "image/gif",
jpg: "image/jpeg",
jpeg: "image/jpeg",
js: "text/javascript",
css: "text/css",
svg: "image/svg+xml",
};
URL_TAGS = {
img: "src",
link: "href",
image: "xlink:href", // Image in in-line SVG. (Calibre uses these for covers.)
};
// Get the directory portion of path. The path separator is '/', for
// use with zip files.
function getDir(path) {
return path.split('/').slice(0,-1).join('/');
}
// Join and normalize the two paths. The path separator is '/', for use
// with zip files.
function joinPaths(path1, path2) {
var path = path1.split('/').concat(path2.split('/')),
normpath = [];
for (var i in path) {
var dir = path[i];
if (dir == "..")
normpath.pop();
else if (dir != "." && dir != "")
normpath.push(dir);
}
return normpath.join('/');
}
// A book data object for the Epub file 'epubfile', a HTML5 File object.
// The callback will be called when this object is fully initialized,
// with this object as an argument.
function Epub(epubfile, callback) {
var files = {}; // Maps filename to zip.Entry
var spine = []; // List of filenames in spine
var contents = []; // Table of contents
var metadata = {}; // Maps keys to metadata
var data_urls = {}; // Maps filename to data URL of file contents
var num_data_urls = 0;
zip.createReader(new zip.BlobReader(epubfile), function (zipReader) {
zipReader.getEntries(function (entries) {
for (var i in entries) {
var e = entries[i];
files[e.filename] = e;
}
zipReader.close();
getComponent("META-INF/container.xml", findOPF);
// This starts a chain of callbacks, which will eventually
// end with onLoaded().
});
}, console.error);
// Find the location of the OPF file from container.xml
function findOPF(xml) {
var doc = new DOMParser().parseFromString(xml, "text/xml");
var opffn = doc.getElementsByTagName("rootfile")[0].getAttribute("full-path");
getComponent(opffn, parseOPF(getDir(opffn)));
};
// Parse the OPF file to get the spine, the table of contents, and
// the metadata.
function parseOPF(reldir) {
return function (xml) {
var doc = new DOMParser().parseFromString(xml, "text/xml");
var idmap = {};
var nav_href = null;
// Parse manifest
var manifest = doc.getElementsByTagName("manifest")[0];
var items = manifest.getElementsByTagName("item");
for (var i=0; i<items.length; i++) {
var item = items[i];
var id = item.getAttribute("id");
var href = item.getAttribute("href");
idmap[id] = joinPaths(reldir, href);
var props = item.getAttribute("properties");
if (props != null && props.split(" ").indexOf("nav") > -1)
nav_href = idmap[id];
}
// Parse spine
var spineel = doc.getElementsByTagName("spine")[0];
var sitems = spineel.getElementsByTagName("itemref");
for (var i=0; i<sitems.length; i++) {
var id = sitems[i].getAttribute("idref");
spine.push(idmap[id]);
}
// Parse table of contents
if (nav_href != null) { // Epub3 navigation
getComponent(nav_href, parseNav(getDir(nav_href)));
} else { // Epub2 navigation
var ncxfile = idmap[spineel.getAttribute("toc")];
if (ncxfile != undefined)
getComponent(ncxfile, parseNCX(getDir(ncxfile)));
}
// Parse metadata
var metadatael = doc.getElementsByTagName("metadata")[0];
for (var i=0; i<metadatael.childNodes.length; i++) {
var node = metadatael.childNodes[i];
if (node.nodeType == 1 && node.firstChild != null)
metadata[node.localName] = node.firstChild.nodeValue;
}
// Make data URLs for auxillary files, for future use
for (var fn in files) {
if (spine.indexOf(fn) == -1 && ["mimetype", "META-INF/container.xml"].indexOf(fn) == -1) {
num_data_urls += 1;
getEncodedComponent(fn, function (f) {
return function (data) {
data_urls[f] = data;
num_data_urls -= 1;
if (num_data_urls == 0)
onLoaded();
};
}(fn));
}
}
if (num_data_urls == 0) {
onLoaded();
}
};
};
// Parse the Epub3 table of contents.
function parseNav(reldir) {
return function (navdata) {
var navdoc = new DOMParser().parseFromString(navdata, "text/xml");
var navs = navdoc.getElementsByTagName("nav");
for (var i=0; i<navs.length; i++) {
var nav = navs[i];
if (nav.getAttribute("epub:type") == "toc")
contents = parseNavList(nav.getElementsByTagName("ol")[0], reldir);
}
};
};
function parseNavList(element, reldir) {
var children = [];
for (var i=0; i<element.childNodes.length; i++) {
var node = element.childNodes[i];
if (node.nodeType == 1 && node.nodeName == "li") {
var link = node.getElementsByTagName("a")[0];
if (link != undefined) {
var child = { title: link.firstChild.nodeValue,
src: joinPaths(reldir, link.getAttribute("href")) };
var olist = node.getElementsByTagName("ol")[0];
if (olist != undefined)
child["children"] = parseNavList(olist, reldir);
children.push(child);
}
}
}
return children;
};
// Parse the Epub2 table of contents.
function parseNCX(reldir) {
return function (ncxdata) {
var ncx = new DOMParser().parseFromString(ncxdata, "text/xml");
var navmap = ncx.getElementsByTagName("navMap")[0];
contents = parseNCXChildren(navmap, reldir);
};
};
function parseNCXChildren(element, reldir) {
var children = [];
for (var i=0; i<element.childNodes.length; i++) {
var node = element.childNodes[i];
if (node.nodeType == 1 && node.nodeName == "navPoint") {
var child = {};
var nav_label = node.getElementsByTagName("text")[0];
child["title"] = nav_label.firstChild.nodeValue;
var content = node.getElementsByTagName("content")[0];
child["src"] = joinPaths(reldir, content.getAttribute("src"));
var child_nav = parseNCXChildren(node, reldir);
if (child_nav.length > 0)
child["children"] = child_nav;
children.push(child);
}
}
return children;
};
// Part of Monocle's book data object interface.
this.getComponents = function () {
return spine;
};
// Part of Monocle's book data object interface.
this.getContents = function () {
return contents;
};
// Part of Monocle's book data object interface.
// Note that (X|HT)ML files are parsed and URLs in <img> and <link>
// to resouces in the Epub are replaced with data URLs.
function getComponent(id, callback) {
var reldir = getDir(id);
var ext = id.split('.').slice(-1)[0];
if (["html", "htm", "xhtml", "xml"].indexOf(ext) != -1) {
files[id].getData(new zip.TextWriter(), function (data) {
var doc = new DOMParser().parseFromString(data, "text/xml");
for (var tag in URL_TAGS) {
var attribute = URL_TAGS[tag];
var elements = doc.getElementsByTagName(tag);
for (var i=0; i<elements.length; i++) {
var element = elements[i];
var path = joinPaths(reldir, element.getAttribute(attribute));
var data_url = data_urls[path];
if (data_url != undefined)
element.setAttribute(attribute, data_url);
}
}
callback(new XMLSerializer().serializeToString(doc));
});
} else {
files[id].getData(new zip.TextWriter(), function (data) {
callback(data);
});
}
};
this.getComponent = getComponent;
// Return the content, via the callback, as a data URL.
function getEncodedComponent(id, callback) {
var mime = MIMETYPES[id.split('.').slice(-1)[0]];
files[id].getData(new zip.Data64URIWriter(mime), function (data) {
callback(data);
});
};
// Part of Monocle's book data object interface.
this.getMetaData = function (key) {
return metadata[key];
};
// Called at the end of the initialization process. At this point,
// the object is ready to be passed to a Monocle.Reader.
var onLoaded = (function(self) {
return function () {
callback(self);
}
})(this);
}