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ImageDownloaderLib

Image downloader for manga download scripts.

当前为 2022-12-03 提交的版本，查看 最新版本。

此脚本不应直接安装。它是供其他脚本使用的外部库，要使用该库请加入元指令 // @require https://update.cn-greasyfork.org/scripts/451810/1124333/ImageDownloaderLib.js 

  1. function ImageDownloader({
  2.   getImagePromises,
  3.   isOKToDownload = () => true,
  4.   title = `package_${Date.now()}`,
  5.   zipOptions = {},
  6.   imageSuffix = 'jpg',
  7.   cssVerticalDistance = 'top: 80px',
  8.   cssHorizontalDistance = 'left: 80px'
  9. }) {
  10.   // create download button element
  11.   const dlBtn = document.createElement('button');
  12.   dlBtn.textContent = 'Download';
  13.   dlBtn.style = `
  14.     position: fixed;
  15.     ${cssVerticalDistance};
  16.     ${cssHorizontalDistance};
  17.     z-index: 9999999;
  18.  
  19.     width: 128px;
  20.     height: 48px;
  21.  
  22.     display: flex;
  23.     justify-content: center;
  24.     align-items: center;
  25.  
  26.     font-size: 14px;
  27.     font-family: 'Consolas', 'Monaco', 'Microsoft YaHei';
  28.     color: #fff;
  29.  
  30.     background-color: #0984e3;
  31.     border: none;
  32.     border-radius: 4px;
  33.     cursor: pointer;
  34.   `;
  35.  
  36.   // setup click event callback
  37.   dlBtn.onclick = function () {
  38.     if (!isOKToDownload()) return;
  39.  
  40.     dlBtn.disabled = true;
  41.     dlBtn.textContent = "Processing";
  42.     dlBtn.style.backgroundColor = '#aaa';
  43.     dlBtn.style.cursor = 'not-allowed';
  44.     download(getImagePromises, title, zipOptions);
  45.   }
  46.  
  47.   // add button to body
  48.   document.body.appendChild(dlBtn);
  49.  
  50.   // download
  51.   async function download(getImagePromises, title, zipOptions) {
  52.     // get promises of images
  53.     const imagePromises = getImagePromises();
  54.  
  55.     // setup progress updater
  56.     setupProgressUpdater(imagePromises);
  57.  
  58.     // wait until all promises are resolved
  59.     const images = await Promise.all(imagePromises);
  60.  
  61.     // create zip
  62.     const zip = new JSZip(); // JSZip library should be imported already
  63.     const folder = zip.folder(title);
  64.     images.forEach((image, index) => {
  65.       const filename = `${String(index + 1).padStart(images.length >= 100 ? String(images.length).length : 2, '0')}.${imageSuffix}`;
  66.       folder.file(filename, image, zipOptions);
  67.     });
  68.  
  69.     // pop up download window
  70.     const content = await zip.generateAsync({ type: "blob" });
  71.     saveAs(content, `${title}.zip`); // FileSaver library should be imported already
  72.  
  73.     // change the text of download button
  74.     dlBtn.innerText = "Completed";
  75.   }
  76.  
  77.   function setupProgressUpdater(imagePromises) {
  78.     const timer = setInterval(() => {
  79.       const statePromises = imagePromises.map(getPromiseState);
  80.       Promise
  81.         .all(statePromises)
  82.         .then(states => {
  83.           const fulfillCount = states.filter(state => state === 'fulfilled').length;
  84.           dlBtn.textContent = `Processing\n(${fulfillCount}/${states.length})`;
  85.  
  86.           if (fulfillCount === states.length) {
  87.             dlBtn.textContent = "Zipping";
  88.             clearInterval(timer);
  89.           }
  90.         });
  91.     }, 200);
  92.   }
  93.  
  94.   async function getPromiseState(targetPromise) {
  95.     const uniqueFlag = {};
  96.     return Promise.race([targetPromise, uniqueFlag]).then(
  97.       (raceResult) => raceResult === uniqueFlag ? 'pending' : 'fulfilled',
  98.       () => 'rejected'
  99.     );
  100.   }
  101. }