Function resizeImage

samples/Whiteboard/wwwroot/script.js:17–66

(data, maxSize)

}

async function resizeImage(data, maxSize) {
  return new Promise(resolve => {
    if (!maxSize) {
      resolve();
      return;
    }
    let dataURLToBlob = dataURL => {
      let BASE64_MARKER = ';base64,';
      if (dataURL.indexOf(BASE64_MARKER) == -1) {
        let parts = dataURL.split(',');
        let contentType = parts[0].split(':')[1];
        let raw = parts[1];

        return new Blob([raw], { type: contentType });
      }

      let parts = dataURL.split(BASE64_MARKER);
      let contentType = parts[0].split(':')[1];
      let raw = window.atob(parts[1]);
      let rawLength = raw.length;

      let uInt8Array = new Uint8Array(rawLength);

      for (let i = 0; i < rawLength; ++i) {
        uInt8Array[i] = raw.charCodeAt(i);
      }

      return new Blob([uInt8Array], { type: contentType });
    }

    let reader = new FileReader();
    reader.onload = readerEvent => {
      let image = new Image();
      image.onload = function () {
        let canvas = document.createElement('canvas');
        let ratio = Math.max(image.width / maxSize, image.height / maxSize);
        if (ratio < 1) {
          resolve();
          return;
        }
        canvas.width = image.width / ratio;
        canvas.height = image.height / ratio;
        canvas.getContext('2d').drawImage(image, 0, 0, canvas.width, canvas.height);
        resolve(dataURLToBlob(canvas.toDataURL('image/jpeg')));
      }
      image.src = readerEvent.target.result;
    }
    reader.readAsDataURL(data);
  });
}

let Diagram = function (element, tools) {
  let id;