pdfkit2/js/image/jpeg.js

A PDF generation library for Node.js

(function() {
  var JPEG, fs,
    indexOf = [].indexOf || function(item) { for (var i = 0, l = this.length; i < l; i++) { if (i in this && this[i] === item) return i; } return -1; };

  fs = require('fs');

  JPEG = (function() {
    var MARKERS;

    MARKERS = [0xFFC0, 0xFFC1, 0xFFC2, 0xFFC3, 0xFFC5, 0xFFC6, 0xFFC7, 0xFFC8, 0xFFC9, 0xFFCA, 0xFFCB, 0xFFCC, 0xFFCD, 0xFFCE, 0xFFCF];

    function JPEG(data, label) {
      var channels, marker, pos;
      this.data = data;
      this.label = label;
      if (this.data.readUInt16BE(0) !== 0xFFD8) {
        throw "SOI not found in JPEG";
      }
      pos = 2;
      while (pos < this.data.length) {
        marker = this.data.readUInt16BE(pos);
        pos += 2;
        if (indexOf.call(MARKERS, marker) >= 0) {
          break;
        }
        pos += this.data.readUInt16BE(pos);
      }
      if (indexOf.call(MARKERS, marker) < 0) {
        throw "Invalid JPEG.";
      }
      pos += 2;
      this.bits = this.data[pos++];
      this.height = this.data.readUInt16BE(pos);
      pos += 2;
      this.width = this.data.readUInt16BE(pos);
      pos += 2;
      channels = this.data[pos++];
      this.colorSpace = (function() {
        switch (channels) {
          case 1:
            return 'DeviceGray';
          case 3:
            return 'DeviceRGB';
          case 4:
            return 'DeviceCMYK';
        }
      })();
      this.obj = null;
    }

    JPEG.prototype.embed = function(document) {
      if (this.obj) {
        return;
      }
      this.obj = document.ref({
        Type: 'XObject',
        Subtype: 'Image',
        BitsPerComponent: this.bits,
        Width: this.width,
        Height: this.height,
        ColorSpace: this.colorSpace,
        Filter: 'DCTDecode'
      });
      if (this.colorSpace === 'DeviceCMYK') {
        this.obj.data['Decode'] = [1.0, 0.0, 1.0, 0.0, 1.0, 0.0, 1.0, 0.0];
      }
      this.obj.end(this.data);
      return this.data = null;
    };

    return JPEG;

  })();

  module.exports = JPEG;

}).call(this);