ant-design/components/upload/utils.tsx

import { RcFile, UploadFile } from './interface';

export function T() {
  return true;
}

// Fix IE file.status problem
// via coping a new Object
export function fileToObject(file: RcFile): UploadFile {
  return {
    ...file,
    lastModified: file.lastModified,
    lastModifiedDate: file.lastModifiedDate,
    name: file.name,
    size: file.size,
    type: file.type,
    uid: file.uid,
    percent: 0,
    originFileObj: file,
  } as UploadFile;
}

/**
 * 生成Progress percent: 0.1 -> 0.98
 *   - for ie
 */
export function genPercentAdd() {
  let k = 0.1;
  const i = 0.01;
  const end = 0.98;
  return function(s: number) {
    let start = s;
    if (start >= end) {
      return start;
    }

    start += k;
    k = k - i;
    if (k < 0.001) {
      k = 0.001;
    }
    return start;
  };
}

export function getFileItem(file: UploadFile, fileList: UploadFile[]) {
  const matchKey = file.uid !== undefined ? 'uid' : 'name';
  return fileList.filter(item => item[matchKey] === file[matchKey])[0];
}

export function removeFileItem(file: UploadFile, fileList: UploadFile[]) {
  const matchKey = file.uid !== undefined ? 'uid' : 'name';
  const removed = fileList.filter(item => item[matchKey] !== file[matchKey]);
  if (removed.length === fileList.length) {
    return null;
  }
  return removed;
}

// ==================== Default Image Preview ====================
const extname = (url: string) => {
  if (!url) {
    return '';
  }
  const temp = url.split('/');
  const filename = temp[temp.length - 1];
  const filenameWithoutSuffix = filename.split(/#|\?/)[0];
  return (/\.[^./\\]*$/.exec(filenameWithoutSuffix) || [''])[0];
};
const isImageFileType = (type: string): boolean => !!type && type.indexOf('image/') === 0;
export const isImageUrl = (file: UploadFile): boolean => {
  if (isImageFileType(file.type)) {
    return true;
  }
  const url: string = (file.thumbUrl || file.url) as string;
  const extension = extname(url);
  if (/^data:image\//.test(url) || /(webp|svg|png|gif|jpg|jpeg|bmp|dpg)$/i.test(extension)) {
    return true;
  } else if (/^data:/.test(url)) {
    // other file types of base64
    return false;
  } else if (extension) {
    // other file types which have extension
    return false;
  }
  return true;
};

const MEASURE_SIZE = 200;
export function previewImage(file: File | Blob): Promise<string> {
  return new Promise(resolve => {
    if (!isImageFileType(file.type)) {
      resolve('');
      return;
    }

    const canvas = document.createElement('canvas');
    canvas.width = MEASURE_SIZE;
    canvas.height = MEASURE_SIZE;
    canvas.style.cssText = `position: fixed; left: 0; top: 0; width: ${MEASURE_SIZE}px; height: ${MEASURE_SIZE}px; z-index: 9999; display: none;`;
    document.body.appendChild(canvas);
    const ctx = canvas.getContext('2d');
    const img = new Image();
    img.onload = function() {
      const { width, height } = img;

      let drawWidth = MEASURE_SIZE;
      let drawHeight = MEASURE_SIZE;
      let offsetX = 0;
      let offsetY = 0;

      if (width < height) {
        drawHeight = height * (MEASURE_SIZE / width);
        offsetY = -(drawHeight - drawWidth) / 2;
      } else {
        drawWidth = width * (MEASURE_SIZE / height);
        offsetX = -(drawWidth - drawHeight) / 2;
      }

      ctx!.drawImage(img, offsetX, offsetY, drawWidth, drawHeight);
      const dataURL = canvas.toDataURL();
      document.body.removeChild(canvas);

      resolve(dataURL);
    };
    img.src = window.URL.createObjectURL(file);
  });
}