lenye_base/check_image_size.js

基础方法

'use strict';

require('./get_tag.js');
var is_string = require('./is_string.js');

/**
 * Check image size
 * @param {(Object|String)} image - image information，allow File Object or Data URLs
 * @param {Object} [options={}] - Check options
 */
var DEFAULT = {
  enabledMaxSize: false,
  enabledNatural: false,
  ratio: 1
};

var checkImageSize = function (image) {
  var _ref = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : DEFAULT,
      enabledMaxSize = _ref.enabledMaxSize,
      enabledNatural = _ref.enabledNatural,
      ratio = _ref.ratio;

  return new Promise((resolve, reject) => {
    /**
     * Check type of image
     */
    if (image instanceof File) {
      var reader = new FileReader();

      reader.onload = () => {
        checkSize(reader.result);
      };

      reader.readAsDataURL(image);
    } else if (is_string(image)) {
      checkSize(image);
    }
    /**
     * Check picture size
     * @param {String} data：Data URL
     */


    function checkSize(url) {
      var image = new Image();
      image.src = url;

      image.onload = () => {
        var w = image.width / ratio;
        var h = image.height / ratio;

        if (enabledMaxSize) {
          var nw = Math.min(w, 750 / 2);
          h = h * (nw / w);
          w = nw;
        }

        if (enabledNatural) {
          w = image.naturalWidth / ratio;
          h = image.naturalHeight / ratio;
        }

        w = w >> 0;
        h = h >> 0;
        resolve({
          width: w,
          height: h
        });
      };

      image.onerror = e => {
        reject(e);
      };
    }
  });
};

module.exports = checkImageSize;