Merge pull request #9729 from Snuffleupagus/gulp-image_decoders

Add a `gulp image_decoders` command to package the image decoders (i.e. jpg.js, jpx.js, jbig2.js) separately, and publish them in pdfjs-dist

src/core/jbig2.js

@@ -1192,6 +1192,47 @@ var Jbig2Image = (function Jbig2ImageClosure() {
     return visitor.buffer;
   }
 
+  function parseJbig2(data) {
+    let position = 0, end = data.length;
+
+    if (data[position] !== 0x97 || data[position + 1] !== 0x4A ||
+        data[position + 2] !== 0x42 || data[position + 3] !== 0x32 ||
+        data[position + 4] !== 0x0D || data[position + 5] !== 0x0A ||
+        data[position + 6] !== 0x1A || data[position + 7] !== 0x0A) {
+      throw new Jbig2Error('parseJbig2 - invalid header.');
+    }
+
+    let header = Object.create(null);
+    position += 8;
+    const flags = data[position++];
+    header.randomAccess = !(flags & 1);
+    if (!(flags & 2)) {
+      header.numberOfPages = readUint32(data, position);
+      position += 4;
+    }
+
+    let segments = readSegments(header, data, position, end);
+    let visitor = new SimpleSegmentVisitor();
+    processSegments(segments, visitor);
+
+    const { width, height, } = visitor.currentPageInfo;
+    const bitPacked = visitor.buffer;
+    let imgData = new Uint8ClampedArray(width * height);
+    let q = 0, k = 0;
+    for (let i = 0; i < height; i++) {
+      let mask = 0, buffer;
+      for (let j = 0; j < width; j++) {
+        if (!mask) {
+          mask = 128; buffer = bitPacked[k++];
+        }
+        imgData[q++] = (buffer & mask) ? 0 : 255;
+        mask >>= 1;
+      }
+    }
+
+    return { imgData, width, height, };
+  }
+
   function SimpleSegmentVisitor() {}
 
   SimpleSegmentVisitor.prototype = {
@@ -2095,9 +2136,16 @@ var Jbig2Image = (function Jbig2ImageClosure() {
   function Jbig2Image() {}
 
   Jbig2Image.prototype = {
-    parseChunks: function Jbig2Image_parseChunks(chunks) {
+    parseChunks(chunks) {
       return parseJbig2Chunks(chunks);
     },
+
+    parse(data) {
+      const { imgData, width, height, } = parseJbig2(data);
+      this.width = width;
+      this.height = height;
+      return imgData;
+    },
   };
 
   return Jbig2Image;

src/core/jpeg_stream.js

@@ -63,7 +63,10 @@ let JpegStream = (function JpegStreamClosure() {
     if (this.eof) {
       return;
     }
-    let jpegImage = new JpegImage();
+    let jpegOptions = {
+      decodeTransform: undefined,
+      colorTransform: undefined,
+    };
 
     // Checking if values need to be transformed before conversion.
     let decodeArr = this.dict.getArray('Decode', 'D');
@@ -81,16 +84,17 @@ let JpegStream = (function JpegStreamClosure() {
         }
       }
       if (transformNeeded) {
-        jpegImage.decodeTransform = transform;
+        jpegOptions.decodeTransform = transform;
       }
     }
     // Fetching the 'ColorTransform' entry, if it exists.
     if (isDict(this.params)) {
       let colorTransform = this.params.get('ColorTransform');
       if (Number.isInteger(colorTransform)) {
-        jpegImage.colorTransform = colorTransform;
+        jpegOptions.colorTransform = colorTransform;
       }
     }
+    const jpegImage = new JpegImage(jpegOptions);
 
     jpegImage.parse(this.bytes);
     let data = jpegImage.getData(this.drawWidth, this.drawHeight,

src/core/jpg.js

@@ -94,9 +94,9 @@ var JpegImage = (function JpegImageClosure() {
   var dctSqrt2 =  5793;   // sqrt(2)
   var dctSqrt1d2 = 2896;  // sqrt(2) / 2
 
-  function JpegImage() {
-    this.decodeTransform = null;
-    this.colorTransform = -1;
+  function JpegImage({ decodeTransform = null, colorTransform = -1, } = {}) {
+    this._decodeTransform = decodeTransform;
+    this._colorTransform = colorTransform;
   }
 
   function buildHuffmanTable(codeLengths, values) {
@@ -1013,7 +1013,7 @@ var JpegImage = (function JpegImageClosure() {
       }
 
       // decodeTransform contains pairs of multiplier (-256..256) and additive
-      var transform = this.decodeTransform;
+      const transform = this._decodeTransform;
       if (transform) {
         for (i = 0; i < dataLength;) {
           for (j = 0, k = 0; j < numComponents; j++, i++, k += 2) {
@@ -1030,7 +1030,7 @@ var JpegImage = (function JpegImageClosure() {
         return !!this.adobe.transformCode;
       }
       if (this.numComponents === 3) {
-        if (this.colorTransform === 0) {
+        if (this._colorTransform === 0) {
           // If the Adobe transform marker is not present and the image
           // dictionary has a 'ColorTransform' entry, explicitly set to `0`,
           // then the colours should *not* be transformed.
@@ -1039,7 +1039,7 @@ var JpegImage = (function JpegImageClosure() {
         return true;
       }
       // `this.numComponents !== 3`
-      if (this.colorTransform === 1) {
+      if (this._colorTransform === 1) {
         // If the Adobe transform marker is not present and the image
         // dictionary has a 'ColorTransform' entry, explicitly set to `1`,
         // then the colours should be transformed.