modules/jpeg_support.js

  1. /**
  2.  * @license
  3.  *
  4.  * Licensed under the MIT License.
  5.  * http://opensource.org/licenses/mit-license
  6.  */
  8. import { jsPDF } from "../jspdf.js";
  10. /**
  11.  * jsPDF jpeg Support PlugIn
  12.  *
  13.  * @name jpeg_support
  14.  * @module
  15.  */
  16. (function(jsPDFAPI) {
  17.   "use strict";
  19.   /**
  20.    * 0xc0 (SOF) Huffman  - Baseline DCT
  21.    * 0xc1 (SOF) Huffman  - Extended sequential DCT
  22.    * 0xc2 Progressive DCT (SOF2)
  23.    * 0xc3 Spatial (sequential) lossless (SOF3)
  24.    * 0xc4 Differential sequential DCT (SOF5)
  25.    * 0xc5 Differential progressive DCT (SOF6)
  26.    * 0xc6 Differential spatial (SOF7)
  27.    * 0xc7
  28.    */
  29.   var markers = [0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7];
  31.   //takes a string imgData containing the raw bytes of
  32.   //a jpeg image and returns [width, height]
  33.   //Algorithm from: http://www.64lines.com/jpeg-width-height
  34.   var getJpegInfo = function(imgData) {
  35.     var width, height, numcomponents;
  36.     var blockLength = imgData.charCodeAt(4) * 256 + imgData.charCodeAt(5);
  37.     var len = imgData.length;
  38.     var result = { width: 0, height: 0, numcomponents: 1 };
  39.     for (var i = 4; i < len; i += 2) {
  40.       i += blockLength;
  41.       if (markers.indexOf(imgData.charCodeAt(i + 1)) !== -1) {
  42.         height = imgData.charCodeAt(i + 5) * 256 + imgData.charCodeAt(i + 6);
  43.         width = imgData.charCodeAt(i + 7) * 256 + imgData.charCodeAt(i + 8);
  44.         numcomponents = imgData.charCodeAt(i + 9);
  45.         result = { width: width, height: height, numcomponents: numcomponents };
  46.         break;
  47.       } else {
  48.         blockLength =
  49.           imgData.charCodeAt(i + 2) * 256 + imgData.charCodeAt(i + 3);
  50.       }
  51.     }
  52.     return result;
  53.   };
  55.   /**
  56.    * @ignore
  57.    */
  58.   jsPDFAPI.processJPEG = function(
  59.     data,
  60.     index,
  61.     alias,
  62.     compression,
  63.     dataAsBinaryString,
  64.     colorSpace
  65.   ) {
  66.     var filter = this.decode.DCT_DECODE,
  67.       bpc = 8,
  68.       dims,
  69.       result = null;
  71.     if (
  72.       typeof data === "string" ||
  73.       this.__addimage__.isArrayBuffer(data) ||
  74.       this.__addimage__.isArrayBufferView(data)
  75.     ) {
  76.       // if we already have a stored binary string rep use that
  77.       data = dataAsBinaryString || data;
  78.       data = this.__addimage__.isArrayBuffer(data)
  79.         ? new Uint8Array(data)
  80.         : data;
  81.       data = this.__addimage__.isArrayBufferView(data)
  82.         ? this.__addimage__.arrayBufferToBinaryString(data)
  83.         : data;
  85.       dims = getJpegInfo(data);
  86.       switch (dims.numcomponents) {
  87.         case 1:
  88.           colorSpace = this.color_spaces.DEVICE_GRAY;
  89.           break;
  90.         case 4:
  91.           colorSpace = this.color_spaces.DEVICE_CMYK;
  92.           break;
  93.         case 3:
  94.           colorSpace = this.color_spaces.DEVICE_RGB;
  95.           break;
  96.       }
  98.       result = {
  99.         data: data,
  100.         width: dims.width,
  101.         height: dims.height,
  102.         colorSpace: colorSpace,
  103.         bitsPerComponent: bpc,
  104.         filter: filter,
  105.         index: index,
  106.         alias: alias
  107.       };
  108.     }
  109.     return result;
  110.   };
  111. })(jsPDF.API);