Move JpegStream and JpxStream to their own files

src/core/jpeg_stream.js

@@ -0,0 +1,112 @@
+/* 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 { createObjectURL, shadow } from '../shared/util';
+import { DecodeStream } from './stream';
+import { isDict } from './primitives';
+import { JpegImage } from './jpg';
+
+/**
+ * Depending on the type of JPEG a JpegStream is handled in different ways. For
+ * JPEG's that are supported natively such as DeviceGray and DeviceRGB the image
+ * data is stored and then loaded by the browser.  For unsupported JPEG's we use
+ * a library to decode these images and the stream behaves like all the other
+ * DecodeStreams.
+ */
+var JpegStream = (function JpegStreamClosure() {
+  function JpegStream(stream, maybeLength, dict, params) {
+    // Some images may contain 'junk' before the SOI (start-of-image) marker.
+    // Note: this seems to mainly affect inline images.
+    var ch;
+    while ((ch = stream.getByte()) !== -1) {
+      if (ch === 0xFF) { // Find the first byte of the SOI marker (0xFFD8).
+        stream.skip(-1); // Reset the stream position to the SOI.
+        break;
+      }
+    }
+    this.stream = stream;
+    this.maybeLength = maybeLength;
+    this.dict = dict;
+    this.params = params;
+
+    DecodeStream.call(this, maybeLength);
+  }
+
+  JpegStream.prototype = Object.create(DecodeStream.prototype);
+
+  Object.defineProperty(JpegStream.prototype, 'bytes', {
+    get: function JpegStream_bytes() {
+      // If this.maybeLength is null, we'll get the entire stream.
+      return shadow(this, 'bytes', this.stream.getBytes(this.maybeLength));
+    },
+    configurable: true,
+  });
+
+  JpegStream.prototype.ensureBuffer = function JpegStream_ensureBuffer(req) {
+    if (this.bufferLength) {
+      return;
+    }
+    var jpegImage = new JpegImage();
+
+    // Checking if values need to be transformed before conversion.
+    var decodeArr = this.dict.getArray('Decode', 'D');
+    if (this.forceRGB && Array.isArray(decodeArr)) {
+      var bitsPerComponent = this.dict.get('BitsPerComponent') || 8;
+      var decodeArrLength = decodeArr.length;
+      var transform = new Int32Array(decodeArrLength);
+      var transformNeeded = false;
+      var maxValue = (1 << bitsPerComponent) - 1;
+      for (var i = 0; i < decodeArrLength; i += 2) {
+        transform[i] = ((decodeArr[i + 1] - decodeArr[i]) * 256) | 0;
+        transform[i + 1] = (decodeArr[i] * maxValue) | 0;
+        if (transform[i] !== 256 || transform[i + 1] !== 0) {
+          transformNeeded = true;
+        }
+      }
+      if (transformNeeded) {
+        jpegImage.decodeTransform = transform;
+      }
+    }
+    // Fetching the 'ColorTransform' entry, if it exists.
+    if (isDict(this.params)) {
+      var colorTransform = this.params.get('ColorTransform');
+      if (Number.isInteger(colorTransform)) {
+        jpegImage.colorTransform = colorTransform;
+      }
+    }
+
+    jpegImage.parse(this.bytes);
+    var data = jpegImage.getData(this.drawWidth, this.drawHeight,
+                                 this.forceRGB);
+    this.buffer = data;
+    this.bufferLength = data.length;
+    this.eof = true;
+  };
+
+  JpegStream.prototype.getBytes = function JpegStream_getBytes(length) {
+    this.ensureBuffer();
+    return this.buffer;
+  };
+
+  JpegStream.prototype.getIR = function JpegStream_getIR(forceDataSchema) {
+    return createObjectURL(this.bytes, 'image/jpeg', forceDataSchema);
+  };
+
+  return JpegStream;
+})();
+
+export {
+  JpegStream,
+};