Merge pull request #1837 from yurydelendik/jbig2-1

JBIG2 implementation

src/parser.js

@@ -253,7 +253,8 @@ var Parser = (function ParserClosure() {
         return new RunLengthStream(stream);
       }
       if (name == 'JBIG2Decode') {
-        error('JBIG2 image format is not currently supprted.');
+        var bytes = stream.getBytes(length);
+        return new Jbig2Stream(bytes, stream.dict);
       }
       warn('filter "' + name + '" not supported yet');
       return stream;

src/stream.js

@@ -979,6 +979,50 @@ var JpxStream = (function JpxStreamClosure() {
   return JpxStream;
 })();
 
+/**
+ * For JBIG2's we use a library to decode these images and
+ * the stream behaves like all the other DecodeStreams.
+ */
+var Jbig2Stream = (function Jbig2StreamClosure() {
+  function Jbig2Stream(bytes, dict) {
+    this.dict = dict;
+    this.bytes = bytes;
+
+    DecodeStream.call(this);
+  }
+
+  Jbig2Stream.prototype = Object.create(DecodeStream.prototype);
+
+  Jbig2Stream.prototype.ensureBuffer = function Jbig2Stream_ensureBuffer(req) {
+    if (this.bufferLength)
+      return;
+
+    var jbig2Image = new Jbig2Image();
+
+    var chunks = [], decodeParams = this.dict.get('DecodeParms');
+    if (decodeParams && decodeParams.has('JBIG2Globals')) {
+      var globalsStream = decodeParams.get('JBIG2Globals');
+      var globals = globalsStream.getBytes();
+      chunks.push({data: globals, start: 0, end: globals.length});
+    }
+    chunks.push({data: this.bytes, start: 0, end: this.bytes.length});
+    var data = jbig2Image.parseChunks(chunks);
+    var dataLength = data.length;
+
+    // JBIG2 had black as 1 and white as 0, inverting the colors
+    for (var i = 0; i < dataLength; i++)
+      data[i] ^= 0xFF;
+
+    this.buffer = data;
+    this.bufferLength = dataLength;
+  };
+  Jbig2Stream.prototype.getChar = function Jbig2Stream_getChar() {
+    error('internal error: getChar is not valid on Jbig2Stream');
+  };
+
+  return Jbig2Stream;
+})();
+
 var DecryptStream = (function DecryptStreamClosure() {
   function DecryptStream(str, decrypt) {
     this.str = str;

src/worker_loader.js

@@ -24,6 +24,7 @@ var files = [
   'stream.js',
   'worker.js',
   'jpx.js',
+  'jbig2.js',
   'bidi.js',
   '../external/jpgjs/jpg.js'
 ];