For JPX decoding only read next packet after checking for byte aligning.

This patch makes the image from mozilla#5349 appear correctly, the artefacts
for the last packet are fixed in mozilla#5426.
This patch also optimizes some "in-checks" and adds a few header parsings.

src/core/jpx.js

@@ -15,7 +15,7 @@
  * limitations under the License.
  */
 /* globals ArithmeticDecoder, globalScope, log2, readUint16, readUint32,
-           warn */
+           info, warn */
 
 'use strict';
 
@@ -63,18 +63,52 @@ var JpxImage = (function JpxImageClosure() {
         var dataLength = lbox - headerSize;
         var jumpDataLength = true;
         switch (tbox) {
-          case 0x6A501A1A: // 'jP\032\032'
-            // TODO
-            break;
           case 0x6A703268: // 'jp2h'
             jumpDataLength = false; // parsing child boxes
             break;
           case 0x636F6C72: // 'colr'
-            // TODO
+            // Colorspaces are not used, the CS from the PDF is used.
+            var method = data[position];
+            var precedence = data[position + 1];
+            var approximation = data[position + 2];
+            if (method === 1) {
+              // enumerated colorspace
+              var colorspace = readUint32(data, position + 3);
+              switch (colorspace) {
+                case 16: // this indicates a sRGB colorspace
+                case 17: // this indicates a grayscale colorspace
+                case 18: // this indicates a YUV colorspace
+                  break;
+                default:
+                  warn('Unknown colorspace ' + colorspace);
+                  break;
+              }
+            } else if (method === 2) {
+              info('ICC profile not supported');
+            }
             break;
           case 0x6A703263: // 'jp2c'
             this.parseCodestream(data, position, position + dataLength);
             break;
+          case 0x6A502020: // 'jP\024\024'
+            if (0x0d0a870a !== readUint32(data, position)) {
+              warn('Invalid JP2 signature');
+            }
+            break;
+          // The following header types are valid but currently not used:
+          case 0x6A501A1A: // 'jP\032\032'
+          case 0x66747970: // 'ftyp'
+          case 0x72726571: // 'rreq'
+          case 0x72657320: // 'res '
+          case 0x69686472: // 'ihdr'
+            break;
+          default:
+            var headerType = String.fromCharCode((tbox >> 24) & 0xFF,
+                                                 (tbox >> 16) & 0xFF,
+                                                 (tbox >> 8) & 0xFF,
+                                                 tbox & 0xFF);
+            warn('Unsupported header type ' + tbox + ' (' + headerType + ')');
+            break;
         }
         if (jumpDataLength) {
           position += dataLength;
@@ -788,11 +822,11 @@ var JpxImage = (function JpxImageClosure() {
     var tile = context.tiles[tileIndex];
     var packetsIterator = tile.packetsIterator;
     while (position < dataLength) {
-      var packet = packetsIterator.nextPacket();
+      alignToByte();
       if (!readBits(1)) {
-        alignToByte();
         continue;
       }
+      var packet = packetsIterator.nextPacket();
       var layerNumber = packet.layerNumber;
       var queue = [], codeblock;
       for (var i = 0, ii = packet.codeblocks.length; i < ii; i++) {
@@ -803,13 +837,13 @@ var JpxImage = (function JpxImageClosure() {
         var codeblockIncluded = false;
         var firstTimeInclusion = false;
         var valueReady;
-        if ('included' in codeblock) {
+        if (codeblock['included'] !== undefined) {
           codeblockIncluded = !!readBits(1);
         } else {
           // reading inclusion tree
           precinct = codeblock.precinct;
           var inclusionTree, zeroBitPlanesTree;
-          if ('inclusionTree' in precinct) {
+          if (precinct['inclusionTree'] !== undefined) {
             inclusionTree = precinct.inclusionTree;
           } else {
             // building inclusion and zero bit-planes trees
@@ -874,7 +908,7 @@ var JpxImage = (function JpxImageClosure() {
       while (queue.length > 0) {
         var packetItem = queue.shift();
         codeblock = packetItem.codeblock;
-        if (!('data' in codeblock)) {
+        if (codeblock['data'] === undefined) {
           codeblock.data = [];
         }
         codeblock.data.push({
@@ -904,7 +938,7 @@ var JpxImage = (function JpxImageClosure() {
       if (blockWidth === 0 || blockHeight === 0) {
         continue;
       }
-      if (!('data' in codeblock)) {
+      if (codeblock['data'] === undefined) {
         continue;
       }
 
@@ -1159,10 +1193,10 @@ var JpxImage = (function JpxImageClosure() {
     var tile = context.tiles[tileIndex];
     for (var c = 0; c < componentsCount; c++) {
       var component = tile.components[c];
-      var qcdOrQcc = (c in context.currentTile.QCC ?
+      var qcdOrQcc = (context.currentTile.QCC[c] !== undefined ?
         context.currentTile.QCC[c] : context.currentTile.QCD);
       component.quantizationParameters = qcdOrQcc;
-      var codOrCoc = (c in context.currentTile.COC ?
+      var codOrCoc = (context.currentTile.COC[c] !== undefined  ?
         context.currentTile.COC[c] : context.currentTile.COD);
       component.codingStyleParameters = codOrCoc;
     }
@@ -1191,7 +1225,7 @@ var JpxImage = (function JpxImageClosure() {
         while (currentLevel < this.levels.length) {
           level = this.levels[currentLevel];
           var index = i + j * level.width;
-          if (index in level.items) {
+          if (level.items[index] !== undefined) {
             value = level.items[index];
             break;
           }