obniz/obniz/libs/utils/util.js

obniz sdk for javascript

class ObnizUtil {
  constructor(obniz) {
    this.obniz = obniz;
  }

  createCanvasContext(width, height) {
    if (this.obniz.isNode) {
      try {
        const { createCanvas } = require('canvas');
        return createCanvas(this.width, this.height);
      } catch (e) {
        throw new Error(
          'obniz.js require node-canvas to draw rich contents. see more detail on docs'
        );
      }
    } else {
      let canvas = document.createElement('canvas');
      canvas.width = width;
      canvas.height = height;
      canvas.style['-webkit-font-smoothing'] = 'none';
      let body = document.getElementsByTagName('body')[0];
      body.appendChild(canvas);

      let ctx = canvas.getContext('2d');
      return ctx;
    }
  }

  static _keyFilter(params, keys) {
    let filterdParams = {};
    if (typeof params !== 'object') {
      return filterdParams;
    }
    filterdParams = Object.keys(params)
      .filter(key => keys.includes(key))
      .reduce((obj, key) => {
        obj[key] = params[key];
        return obj;
      }, {});

    return filterdParams;
  }

  /**
   *
   * @return {String} key name of not found.
   */
  static _requiredKeys(params, keys) {
    if (typeof params !== 'object') {
      return keys[0];
    }

    for (let index in keys) {
      if (!(keys[index] in params)) {
        return keys[index];
      }
    }
    return null;
  }

  static dataArray2string(data) {
    let string = null;
    try {
      const StringDecoder = require('string_decoder').StringDecoder;
      if (StringDecoder) {
        string = new StringDecoder('utf8').write(Buffer.from(data));
      }
    } catch (e) {
      //this.obniz.error(e);
    }
    return string;
  }

  static string2dataArray(str) {
    const buf = Buffer.from(str);
    return [...buf];
  }
}

module.exports = ObnizUtil;