File: source/data-process.js

/**
 * Function that converts Base64 string into Blob object.
 * This is referenced from devnull69@stackoverflow.com #6850276.
 * @method _base64ToBlob
 * @private
 * @for Skylink
 * @since 0.1.0
 */
Skylink.prototype._base64ToBlob = function(dataURL) {
  var byteString = atob(dataURL);
  // write the bytes of the string to an ArrayBuffer
  var ab = new ArrayBuffer(byteString.length);
  var ia = new Uint8Array(ab);
  for (var j = 0; j < byteString.length; j++) {
    ia[j] = byteString.charCodeAt(j);
  }
  // write the ArrayBuffer to a blob, and you're done
  return new Blob([ab]);
};

/**
 * Function that converts a Blob object into Base64 string.
 * @method _blobToBase64
 * @private
 * @for Skylink
 * @since 0.1.0
 */
Skylink.prototype._blobToBase64 = function(data, callback) {
  var fileReader = new FileReader();
  fileReader.onload = function() {
    // Load Blob as dataurl base64 string
    var base64BinaryString = fileReader.result.split(',')[1];
    callback(base64BinaryString);
  };
  fileReader.readAsDataURL(data);
};

/**
 * Function that converts a Blob object into ArrayBuffer object.
 * @method _blobToArrayBuffer
 * @private
 * @for Skylink
 * @since 0.1.0
 */
Skylink.prototype._blobToArrayBuffer = function(data, callback) {
  var self = this;
  var fileReader = new FileReader();
  fileReader.onload = function() {
    // Load Blob as dataurl base64 string
    if (AdapterJS.webrtcDetectedType === 'plugin') {
      callback(new Int8Array(fileReader.result));
    } else {
      callback(fileReader.result);
    }
  };
  fileReader.readAsArrayBuffer(data);
};

/**
 * Function that chunks Blob object based on the data chunk size provided.
 * If provided Blob object size is lesser than or equals to the chunk size, it should return an array
 *   of length of <code>1</code>.
 * @method _chunkBlobData
 * @private
 * @for Skylink
 * @since 0.5.2
 */
Skylink.prototype._chunkBlobData = function(blob, chunkSize) {
  var chunksArray = [];
  var startCount = 0;
  var endCount = 0;
  var blobByteSize = blob.size;

  if (blobByteSize > chunkSize) {
    // File Size greater than Chunk size
    while ((blobByteSize - 1) > endCount) {
      endCount = startCount + chunkSize;
      chunksArray.push(blob.slice(startCount, endCount));
      startCount += chunkSize;
    }
    if ((blobByteSize - (startCount + 1)) > 0) {
      chunksArray.push(blob.slice(startCount, blobByteSize - 1));
    }
  } else {
    // File Size below Chunk size
    chunksArray.push(blob);
  }
  return chunksArray;
};

/**
 * Function that chunks large string into string chunks based on the data chunk size provided.
 * If provided string length is lesser than or equals to the chunk size, it should return an array
 *   of length of <code>1</code>.
 * @method _chunkDataURL
 * @private
 * @for Skylink
 * @since 0.6.1
 */
Skylink.prototype._chunkDataURL = function(dataURL, chunkSize) {
  var outputStr = dataURL; //encodeURIComponent(dataURL);
  var dataURLArray = [];
  var startCount = 0;
  var endCount = 0;
  var dataByteSize = dataURL.size || dataURL.length;

  if (dataByteSize > chunkSize) {
    // File Size greater than Chunk size
    while ((dataByteSize - 1) > endCount) {
      endCount = startCount + chunkSize;
      dataURLArray.push(outputStr.slice(startCount, endCount));
      startCount += chunkSize;
    }
    if ((dataByteSize - (startCount + 1)) > 0) {
      chunksArray.push(outputStr.slice(startCount, dataByteSize - 1));
    }
  } else {
    // File Size below Chunk size
    dataURLArray.push(outputStr);
  }

  return dataURLArray;
};