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ImageDownloaderLib

Image downloader for manga download scripts.

Version vom 03.12.2022. Aktuellste Version

Dieses Skript sollte nicht direkt installiert werden. Es handelt sich hier um eine Bibliothek für andere Skripte, welche über folgenden Befehl in den Metadaten eines Skriptes eingebunden wird // @require https://update.greasyfork.org/scripts/451810/1124333/ImageDownloaderLib.js 

function ImageDownloader({
  getImagePromises,
  isOKToDownload = () => true,
  title = `package_${Date.now()}`,
  zipOptions = {},
  imageSuffix = 'jpg',
  cssVerticalDistance = 'top: 80px',
  cssHorizontalDistance = 'left: 80px'
}) {
  // create download button element
  const dlBtn = document.createElement('button');
  dlBtn.textContent = 'Download';
  dlBtn.style = `
    position: fixed;
    ${cssVerticalDistance};
    ${cssHorizontalDistance};
    z-index: 9999999;

    width: 128px;
    height: 48px;

    display: flex;
    justify-content: center;
    align-items: center;

    font-size: 14px;
    font-family: 'Consolas', 'Monaco', 'Microsoft YaHei';
    color: #fff;

    background-color: #0984e3;
    border: none;
    border-radius: 4px;
    cursor: pointer;
  `;

  // setup click event callback
  dlBtn.onclick = function () {
    if (!isOKToDownload()) return;

    dlBtn.disabled = true;
    dlBtn.textContent = "Processing";
    dlBtn.style.backgroundColor = '#aaa';
    dlBtn.style.cursor = 'not-allowed';
    download(getImagePromises, title, zipOptions);
  }

  // add button to body
  document.body.appendChild(dlBtn);

  // download
  async function download(getImagePromises, title, zipOptions) {
    // get promises of images
    const imagePromises = getImagePromises();

    // setup progress updater
    setupProgressUpdater(imagePromises);

    // wait until all promises are resolved
    const images = await Promise.all(imagePromises);

    // create zip
    const zip = new JSZip(); // JSZip library should be imported already
    const folder = zip.folder(title);
    images.forEach((image, index) => {
      const filename = `${String(index + 1).padStart(images.length >= 100 ? String(images.length).length : 2, '0')}.${imageSuffix}`;
      folder.file(filename, image, zipOptions);
    });

    // pop up download window
    const content = await zip.generateAsync({ type: "blob" });
    saveAs(content, `${title}.zip`); // FileSaver library should be imported already

    // change the text of download button
    dlBtn.innerText = "Completed";
  }

  function setupProgressUpdater(imagePromises) {
    const timer = setInterval(() => {
      const statePromises = imagePromises.map(getPromiseState);
      Promise
        .all(statePromises)
        .then(states => {
          const fulfillCount = states.filter(state => state === 'fulfilled').length;
          dlBtn.textContent = `Processing\n(${fulfillCount}/${states.length})`;

          if (fulfillCount === states.length) {
            dlBtn.textContent = "Zipping";
            clearInterval(timer);
          }
        });
    }, 200);
  }

  async function getPromiseState(targetPromise) {
    const uniqueFlag = {};
    return Promise.race([targetPromise, uniqueFlag]).then(
      (raceResult) => raceResult === uniqueFlag ? 'pending' : 'fulfilled',
      () => 'rejected'
    );
  }
}