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Greasemonkey script for downloading a DRM-free copy of your Dark Horse digital comics
// ==UserScript==
// @name Dark Horse Downloader
// @namespace http://schiff.io/
// @version 0.1
// @description Download a DRM-free copy of your Dark Horse digital comics.
// @author Hayden Schiff (oxguy3)
// @match https://digital.darkhorse.com/read/*
// @match https://digital.darkhorse.com/bookshelf*
// @include https://*.cloudfront.net/*
// @grant GM_xmlhttpRequest
// @require https://cdnjs.cloudflare.com/ajax/libs/jszip/3.1.3/jszip.js
// ==/UserScript==
/**
* DARK HORSE DOWNLOADER
* Made by Hayden Schiff (oxguy3), license is Creative Commons Zero.
*
* This script makes it really easy to download a DRM-free copy of your digital
* comics on Dark Horse Digital. Simply go to your Dark Horse bookshelf at
* <https://digital.darkhorse.com/bookshelf>, then disable "Stack by Series" and
* switch to Gallery View if you haven't already. You will now see a "Download"
* button below all your comics.
*
* When you click the download button for any of your comics, it'll open the
* reader for that comic, then start downloading the comic. A red box in the
* middle of the screen will show you the progress of the download (be warned
* that things will be a bit laggy while it's downloading. Once it's done, a
* .CBZ file will pop into your downloads (if you aren't familiar, a .CBZ file
* is just a zip file full of JPGs. You can easily open it with a reader app
* or convert to PDF or whatever).
*/
(function() {
'use strict';
var pagesDone = 0;
var pagesTotal = 0;
// we include some other domains that we don't actually need to execute code on
if (window.location.host != "digital.darkhorse.com") {
return;
}
// from http://stackoverflow.com/a/10073761/992504
function padToFive(number) {
if (number<=99999) { number = ("0000"+number).slice(-5); }
return number;
}
// from http://stackoverflow.com/a/15832662/992504
function downloadURI(uri, name) {
var link = document.createElement("a");
link.download = name;
link.href = uri;
document.body.appendChild(link);
link.click();
document.body.removeChild(link);
}
// This is part of a hack to use base64 to work around Greasemonkey's lack of support
// for responseType:blob on XHRs. Source: http://stackoverflow.com/a/8781262/992504
function customBase64Encode(inputStr) {
var
bbLen = 3,
enCharLen = 4,
inpLen = inputStr.length,
inx = 0,
jnx,
keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
+ "0123456789+/=",
output = "",
paddingBytes = 0;
var
bytebuffer = new Array (bbLen),
encodedCharIndexes = new Array (enCharLen);
while (inx < inpLen) {
for (jnx = 0; jnx < bbLen; ++jnx) {
/*--- Throw away high-order byte, as documented at:
https://developer.mozilla.org/En/Using_XMLHttpRequest#Handling_binary_data
*/
if (inx < inpLen)
bytebuffer[jnx] = inputStr.charCodeAt (inx++) & 0xff;
else
bytebuffer[jnx] = 0;
}
/*--- Get each encoded character, 6 bits at a time.
index 0: first 6 bits
index 1: second 6 bits
(2 least significant bits from inputStr byte 1
+ 4 most significant bits from byte 2)
index 2: third 6 bits
(4 least significant bits from inputStr byte 2
+ 2 most significant bits from byte 3)
index 3: forth 6 bits (6 least significant bits from inputStr byte 3)
*/
encodedCharIndexes[0] = bytebuffer[0] >> 2;
encodedCharIndexes[1] = ( (bytebuffer[0] & 0x3) << 4) | (bytebuffer[1] >> 4);
encodedCharIndexes[2] = ( (bytebuffer[1] & 0x0f) << 2) | (bytebuffer[2] >> 6);
encodedCharIndexes[3] = bytebuffer[2] & 0x3f;
//--- Determine whether padding happened, and adjust accordingly.
paddingBytes = inx - (inpLen - 1);
switch (paddingBytes) {
case 1:
// Set last character to padding char
encodedCharIndexes[3] = 64;
break;
case 2:
// Set last 2 characters to padding char
encodedCharIndexes[3] = 64;
encodedCharIndexes[2] = 64;
break;
default:
break; // No padding - proceed
}
/*--- Now grab each appropriate character out of our keystring,
based on our index array and append it to the output string.
*/
for (jnx = 0; jnx < enCharLen; ++jnx)
output += keyStr.charAt ( encodedCharIndexes[jnx] );
}
return output;
}
function incrementPagesDoneCounter() {
pagesDone++;
if (pagesDone % 5 == 0) {
document.getElementById("dhdl_status").textContent = "Downloading "+pagesDone+" of "+pagesTotal+" pages...";
}
}
// add download buttons to the bookshelf
if (window.location.pathname == "/bookshelf") {
// TODO: check if "stack by series" is enabled, and if so, don't add the download buttons
var books = document.getElementsByClassName("bookshelf-item");
for (var i = 0; i < books.length; i++) {
var book = books[i];
var btn = document.createElement("a");
btn.setAttribute("href", "/read/" + book.id + "#download");
btn.setAttribute("class", "button blue collection-read");
btn.setAttribute("style", "margin-top: 6px;");
btn.textContent = "Download";
book.appendChild(btn);
}
} else if (window.location.pathname.startsWith("/read/")) {
if (window.location.hash == "#download") {
// create box for showing status of download
var box = document.createElement("div");
box.id = "dhdl_box";
box.setAttribute("style", "background-color:#ffaaaa; border:2px solid #111; border-radius:5px; opacity:0.9; text-align:center; font-size:22px; width:400px; height:150px; margin:auto; position:absolute; top:0; left:0; bottom:0; right:0; z-index:10000;");
var boxTitle = document.createElement("h1");
boxTitle.textContent = "Dark Horse Downloader";
box.appendChild(boxTitle);
var boxStatus = document.createElement("p");
boxStatus.id = "dhdl_status";
boxStatus.textContent = "Starting up...";
box.appendChild(boxStatus);
document.body.appendChild(box);
var bookTitle = document.getElementById("bookreader-title").getElementsByTagName("h2")[0].textContent;
var bookTitleSafe = bookTitle.replace(/\s+/gi, ' ').replace(/[^a-z0-9 ]/gi, '_');
var pageUrls = [];
for (var i = 0; i < book_manifest.pages.length; i++) {
var page = book_manifest.pages[i];
var url = window.location.protocol + "//" + window.location.host + book_manifest.base_url + page.src_image;
pageUrls.push(url);
}
pagesTotal = book_manifest.pages.length;
console.log(pageUrls);
var zip = new JSZip();
Promise.all(pageUrls.map(function(url, index) {
return new Promise(function(resolve) {
GM_xmlhttpRequest({
method: "GET",
url: url,
onload: function(response) {
zip.file(padToFive(index)+".jpg", customBase64Encode(response.responseText), {
base64: true
});
incrementPagesDoneCounter();
resolve();
},
overrideMimeType: 'text/plain; charset=x-user-defined'
});
});
})).then(function() {
document.getElementById("dhdl_status").textContent = "Creating zip file...";
zip.generateAsync({
type: "blob"
}).then(function(content) {
document.getElementById("dhdl_status").textContent = "Done!";
downloadURI(URL.createObjectURL(content), bookTitleSafe+".cbz");
setTimeout(function(){
document.body.removeChild(box);
}, 3000);
});
});
}
}
})();
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