Merge pull request #9046 from Snuffleupagus/ccitt-jbig2-stream-refactor

Extract the actual decoding in `CCITTFaxStream` into a new `CCITTFaxDecoder` "class", which the new `CCITTFaxStream` depends on

src/core/ccitt_stream.js

@@ -0,0 +1,66 @@
+/* Copyright 2012 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { Dict, isDict } from './primitives';
+import { CCITTFaxDecoder } from './ccitt';
+import { DecodeStream } from './stream';
+
+var CCITTFaxStream = (function CCITTFaxStreamClosure() {
+  function CCITTFaxStream(str, maybeLength, params) {
+    this.str = str;
+    this.dict = str.dict;
+
+    if (!isDict(params)) {
+      params = Dict.empty;
+    }
+
+    const source = {
+      next() {
+        return str.getByte();
+      },
+    };
+    this.ccittFaxDecoder = new CCITTFaxDecoder(source, {
+      K: params.get('K'),
+      EndOfLine: params.get('EndOfLine'),
+      EncodedByteAlign: params.get('EncodedByteAlign'),
+      Columns: params.get('Columns'),
+      Rows: params.get('Rows'),
+      EndOfBlock: params.get('EndOfBlock'),
+      BlackIs1: params.get('BlackIs1'),
+    });
+
+    DecodeStream.call(this, maybeLength);
+  }
+
+  CCITTFaxStream.prototype = Object.create(DecodeStream.prototype);
+
+  CCITTFaxStream.prototype.readBlock = function() {
+    while (!this.eof) {
+      let c = this.ccittFaxDecoder.readNextChar();
+      if (c === -1) {
+        this.eof = true;
+        return;
+      }
+      this.ensureBuffer(this.bufferLength + 1);
+      this.buffer[this.bufferLength++] = c;
+    }
+  };
+
+  return CCITTFaxStream;
+})();
+
+export {
+  CCITTFaxStream,
+};

src/core/jbig2_stream.js

@@ -0,0 +1,79 @@
+/* Copyright 2012 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { isDict, isStream } from './primitives';
+import { DecodeStream } from './stream';
+import { Jbig2Image } from './jbig2';
+import { shadow } from '../shared/util';
+
+/**
+ * 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(stream, maybeLength, dict, params) {
+    this.stream = stream;
+    this.maybeLength = maybeLength;
+    this.dict = dict;
+    this.params = params;
+
+    DecodeStream.call(this, maybeLength);
+  }
+
+  Jbig2Stream.prototype = Object.create(DecodeStream.prototype);
+
+  Object.defineProperty(Jbig2Stream.prototype, 'bytes', {
+    get() {
+      // If this.maybeLength is null, we'll get the entire stream.
+      return shadow(this, 'bytes', this.stream.getBytes(this.maybeLength));
+    },
+    configurable: true,
+  });
+
+  Jbig2Stream.prototype.ensureBuffer = function(req) {
+    if (this.bufferLength) {
+      return;
+    }
+
+    var jbig2Image = new Jbig2Image();
+
+    var chunks = [];
+    if (isDict(this.params)) {
+      var globalsStream = this.params.get('JBIG2Globals');
+      if (isStream(globalsStream)) {
+        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;
+    this.eof = true;
+  };
+
+  return Jbig2Stream;
+})();
+
+export {
+  Jbig2Stream,
+};

src/core/parser.js

@@ -14,8 +14,8 @@
  */
 
 import {
-  Ascii85Stream, AsciiHexStream, CCITTFaxStream, FlateStream, Jbig2Stream,
-  JpegStream, JpxStream, LZWStream, NullStream, PredictorStream, RunLengthStream
+  Ascii85Stream, AsciiHexStream, FlateStream, JpegStream, JpxStream, LZWStream,
+  NullStream, PredictorStream, RunLengthStream
 } from './stream';
 import {
   assert, FormatError, info, isNum, isString, MissingDataException, StreamType,
@@ -24,6 +24,8 @@ import {
 import {
   Cmd, Dict, EOF, isCmd, isDict, isEOF, isName, Name, Ref
 } from './primitives';
+import { CCITTFaxStream } from './ccitt_stream';
+import { Jbig2Stream } from './jbig2_stream';
 
 var MAX_LENGTH_TO_CACHE = 1000;