Download PDF from Tsinghua University Electronic Course Reserves Service Platform
// ==UserScript==
// @name Tsinghua E-Reserves Lib Downloader
// @namespace anyi.fan
// @version 0.2.2
// @license GPL-3.0 License
// @description Download PDF from Tsinghua University Electronic Course Reserves Service Platform
// @author A1phaN
// @match https://ereserves.lib.tsinghua.edu.cn/readkernel/ReadJPG/JPGJsNetPage/*
// @grant none
// ==/UserScript==
const MAX_RETRY = 10;
const QUERY_INTERVAL = 100;
const sleep = time => new Promise(res => setTimeout(res, time));
const getImage = async (url, retry = MAX_RETRY) => {
const img = new Image();
img.src = url;
img.style.display = 'none';
const data = new Promise((res, rej) => {
img.onload = () => {
const canvas = document.createElement('canvas');
canvas.width = img.width;
canvas.height = img.height;
canvas.getContext('2d')?.drawImage(img, 0, 0, img.width, img.height);
res([img, canvas.toDataURL('image/jpeg')]);
};
img.onerror = err => {
retry > 0 ? res(getImage(url, retry - 1)) : rej(err);
};
});
document.body.appendChild(img);
return data;
};
(async () => {
const scanId = document.querySelector('#scanid')?.value;
const bookId = location.href.split('/').at(-1);
const bookNameElement = document.querySelector('#p_bookname');
const bookName = bookNameElement.innerText;
const BotuReadKernel = document.cookie.split(';')
.map(c => c.trim())
.find(c => c.startsWith('BotuReadKernel='))
?.split('=')[1];
if (!scanId || !BotuReadKernel || !bookName) return;
await new Promise(res => {
if (window.jspdf) return res();
const script = document.createElement('script');
script.src = 'https://cdnjs.cloudflare.com/ajax/libs/jspdf/2.5.1/jspdf.umd.min.js';
script.onload = res;
document.body.appendChild(script);
});
if (!window.jspdf) return;
const button = document.createElement('span');
button.className = 'fucBtn icon iconfont';
button.style = 'margin-left: 8px; position: relative; top: 2px;';
button.innerHTML =
`<svg
t="1703917701009"
viewBox="0 0 1024 1024"
version="1.1"
xmlns="http://www.w3.org/2000/svg"
p-id="5061"
height="2rem"
>
<path
d="M896 672c-17.066667 0-32 14.933333-32 32v128c0 6.4-4.266667 10.666667-10.666667 10.666667H170.666667c-6.4 0-10.666667-4.266667-10.666667-10.666667v-128c0-17.066667-14.933333-32-32-32s-32 14.933333-32 32v128c0 40.533333 34.133333 74.666667 74.666667 74.666667h682.666666c40.533333 0 74.666667-34.133333 74.666667-74.666667v-128c0-17.066667-14.933333-32-32-32z"
fill="#ddd"
p-id="5062"
></path>
<path
d="M488.533333 727.466667c6.4 6.4 14.933333 8.533333 23.466667 8.533333s17.066667-2.133333 23.466667-8.533333l213.333333-213.333334c12.8-12.8 12.8-32 0-44.8-12.8-12.8-32-12.8-44.8 0l-157.866667 157.866667V170.666667c0-17.066667-14.933333-32-32-32s-34.133333 14.933333-34.133333 32v456.533333L322.133333 469.333333c-12.8-12.8-32-12.8-44.8 0-12.8 12.8-12.8 32 0 44.8l211.2 213.333334z"
fill="#ddd"
p-id="5063"
></path>
</svg>`;
document.querySelector('.option-list').appendChild(button);
const downloadPDF = async () => {
try {
button.onclick = null;
let doc = null;
let page = 1;
const chapters = await (
await fetch(
'/readkernel/KernelAPI/BookInfo/selectJgpBookChapters',
{
body: `SCANID=${scanId}`,
headers: {
Botureadkernel: BotuReadKernel,
'Content-Type': 'application/x-www-form-urlencoded;charset=UTF-8',
},
method: 'POST',
},
)
).json();
if (chapters.code !== 1 || !Array.isArray(chapters.data)) {
alert('Get chapters data failed!');
return;
}
for (let chap = 0; chap < chapters.data.length; ++chap) {
bookNameElement.innerText = `${bookName}（正在获取第 ${chap + 1} 章...）`;
const chapter = chapters.data[chap];
const chapterData = await (
await fetch(
'/readkernel/KernelAPI/BookInfo/selectJgpBookChapter',
{
body: `EMID=${chapter.EMID}&BOOKID=${bookId}`,
headers: {
Botureadkernel: BotuReadKernel,
'Content-Type': 'application/x-www-form-urlencoded;charset=UTF-8',
},
method: 'POST',
},
)
).json();
if (chapterData.code !== 1 || !Array.isArray(chapterData.data.JGPS)) {
alert(`Get chapter ${chap + 1} ${chapter.EFRAGMENTNAME} data failed!`);
return;
}
for (let i = 0; i < chapterData.data.JGPS.length; ++i) {
const jpg = chapterData.data.JGPS[i];
try {
const [img, dataURL] = await getImage(`/readkernel/JPGFile/DownJPGJsNetPage?filePath=${jpg.hfsKey}`);
if (!doc) {
doc = new jspdf.jsPDF({ format: [img.width, img.height], unit: 'px' });
} else {
doc.addPage([img.width, img.height]);
}
doc.addImage(dataURL, 'JPEG', 0, 0, img.width, img.height);
bookNameElement.innerText = `${bookName}（正在获取第 ${chap + 1} 章，已完成: ${i + 1} / ${chapterData.data.JGPS.length}）`;
await sleep(QUERY_INTERVAL);
} catch(e) {
alert(`Get page ${i + 1} of chapter ${chap + 1} ${chapter.EFRAGMENTNAME} failed!`);
return;
}
}
doc.outline.add(null, chapter.EFRAGMENTNAME, { pageNumber: page });
page += chapterData.data.JGPS.length;
}
if (doc) {
const filename = `${bookName}.pdf`;
try {
doc.save(filename);
} catch(e) {
if (e instanceof RangeError && e.message === 'Invalid string length') {
// jsPDF exceeds the maximum string length
doc.__private__.resetCustomOutputDestination();
const content = doc.__private__.out('');
content.pop();
const blob = new Blob(
content.map((line, idx) => {
const str = idx === content.length - 1 ? line : line + '\n';
const arrayBuffer = new ArrayBuffer(str.length);
const uint8Array = new Uint8Array(arrayBuffer);
for (let i = 0; i < str.length; ++i) {
uint8Array[i] = str.charCodeAt(i);
}
return arrayBuffer;
}),
{ type: 'application/pdf' },
);
const a = document.createElement('a');
a.download = filename;
a.rel = 'noopener';
a.href = URL.createObjectURL(blob);
a.click();
} else {
alert(`Unexpected Error when saving pdf: ${e?.message ?? e}`);
}
}
}
bookNameElement.innerText = `${bookName}（下载完成）`;
} finally {
button.onclick = downloadPDF;
}
};
button.onclick = downloadPDF;
})();
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