File: source/data-process.js

  1. /**
  2.  * Function that converts Base64 string into Blob object.
  3.  * This is referenced from devnull69@stackoverflow.com #6850276.
  4.  * @method _base64ToBlob
  5.  * @private
  6.  * @for Skylink
  7.  * @since 0.1.0
  8.  */
  9. Skylink.prototype._base64ToBlob = function(dataURL) {
  10.   var byteString = atob(dataURL);
  11.   // write the bytes of the string to an ArrayBuffer
  12.   var ab = new ArrayBuffer(byteString.length);
  13.   var ia = new Uint8Array(ab);
  14.   for (var j = 0; j < byteString.length; j++) {
  15.     ia[j] = byteString.charCodeAt(j);
  16.   }
  17.   // write the ArrayBuffer to a blob, and you're done
  18.   return new Blob([ab]);
  19. };
  20.  
  21. /**
  22.  * Function that converts a Blob object into Base64 string.
  23.  * @method _blobToBase64
  24.  * @private
  25.  * @for Skylink
  26.  * @since 0.1.0
  27.  */
  28. Skylink.prototype._blobToBase64 = function(data, callback) {
  29.   var fileReader = new FileReader();
  30.   fileReader.onload = function() {
  31.     // Load Blob as dataurl base64 string
  32.     var base64BinaryString = fileReader.result.split(',')[1];
  33.     callback(base64BinaryString);
  34.   };
  35.   fileReader.readAsDataURL(data);
  36. };
  37.  
  38. /**
  39.  * Function that converts a Blob object into ArrayBuffer object.
  40.  * @method _blobToArrayBuffer
  41.  * @private
  42.  * @for Skylink
  43.  * @since 0.1.0
  44.  */
  45. Skylink.prototype._blobToArrayBuffer = function(data, callback) {
  46.   var self = this;
  47.   var fileReader = new FileReader();
  48.   fileReader.onload = function() {
  49.     // Load Blob as dataurl base64 string
  50.     if (AdapterJS.webrtcDetectedType === 'plugin') {
  51.       callback(new Int8Array(fileReader.result));
  52.     } else {
  53.       callback(fileReader.result);
  54.     }
  55.   };
  56.   fileReader.readAsArrayBuffer(data);
  57. };
  58.  
  59. /**
  60.  * Function that chunks Blob object based on the data chunk size provided.
  61.  * If provided Blob object size is lesser than or equals to the chunk size, it should return an array
  62.  *   of length of <code>1</code>.
  63.  * @method _chunkBlobData
  64.  * @private
  65.  * @for Skylink
  66.  * @since 0.5.2
  67.  */
  68. Skylink.prototype._chunkBlobData = function(blob, chunkSize) {
  69.   var chunksArray = [];
  70.   var startCount = 0;
  71.   var endCount = 0;
  72.   var blobByteSize = blob.size;
  73.  
  74.   if (blobByteSize > chunkSize) {
  75.     // File Size greater than Chunk size
  76.     while ((blobByteSize - 1) > endCount) {
  77.       endCount = startCount + chunkSize;
  78.       chunksArray.push(blob.slice(startCount, endCount));
  79.       startCount += chunkSize;
  80.     }
  81.     if ((blobByteSize - (startCount + 1)) > 0) {
  82.       chunksArray.push(blob.slice(startCount, blobByteSize - 1));
  83.     }
  84.   } else {
  85.     // File Size below Chunk size
  86.     chunksArray.push(blob);
  87.   }
  88.   return chunksArray;
  89. };
  90.  
  91. /**
  92.  * Function that chunks large string into string chunks based on the data chunk size provided.
  93.  * If provided string length is lesser than or equals to the chunk size, it should return an array
  94.  *   of length of <code>1</code>.
  95.  * @method _chunkDataURL
  96.  * @private
  97.  * @for Skylink
  98.  * @since 0.6.1
  99.  */
  100. Skylink.prototype._chunkDataURL = function(dataURL, chunkSize) {
  101.   var outputStr = dataURL; //encodeURIComponent(dataURL);
  102.   var dataURLArray = [];
  103.   var startCount = 0;
  104.   var endCount = 0;
  105.   var dataByteSize = dataURL.size || dataURL.length;
  106.  
  107.   if (dataByteSize > chunkSize) {
  108.     // File Size greater than Chunk size
  109.     while ((dataByteSize - 1) > endCount) {
  110.       endCount = startCount + chunkSize;
  111.       dataURLArray.push(outputStr.slice(startCount, endCount));
  112.       startCount += chunkSize;
  113.     }
  114.     if ((dataByteSize - (startCount + 1)) > 0) {
  115.       chunksArray.push(outputStr.slice(startCount, dataByteSize - 1));
  116.     }
  117.   } else {
  118.     // File Size below Chunk size
  119.     dataURLArray.push(outputStr);
  120.   }
  121.  
  122.   return dataURLArray;
  123. };
  124.