fix for Unable to parse the attached JPEG Lossless file correctly #5

Author: rii-mango

src/decoder.js

@@ -67,8 +67,9 @@ jpeg.lossless.Decoder = jpeg.lossless.Decoder || function (buffer, numBytes) {
     this.yDim = 0;
     this.xLoc = 0;
     this.yLoc = 0;
-        this.numBytes = 0;
-        this.outputData = null;
+    this.numBytes = 0;
+    this.outputData = null;
+    this.restarting = false;
 
     if (typeof numBytes !== "undefined") {
         this.numBytes = numBytes;
@@ -84,7 +85,8 @@ jpeg.lossless.Decoder.TABLE = [0, 1, 5, 6, 14, 15, 27, 28, 2, 4, 7, 13, 16, 26,
     10, 19, 23, 32, 39, 45, 52, 54, 20, 22, 33, 38, 46, 51, 55, 60, 21, 34, 37, 47, 50, 56, 59, 61, 35, 36, 48, 49, 57, 58, 62, 63];
 jpeg.lossless.Decoder.MAX_HUFFMAN_SUBTREE = 50;
 jpeg.lossless.Decoder.MSB = 0x80000000;
-
+jpeg.lossless.Decoder.RESTART_MARKER_BEGIN = 0xFFD0;
+jpeg.lossless.Decoder.RESTART_MARKER_END = 0xFFD7;
 
 /*** Prototype Methods ***/
 
@@ -302,6 +304,7 @@ jpeg.lossless.Decoder.prototype.decode = function (buffer, offset, length, numBy
             }
 
             for (mcuNum = 0; mcuNum < this.restartInterval; mcuNum+=1) {
+                this.restarting = (mcuNum == 0);
                 current = this.decodeUnit(pred, temp, index);
                 this.output(pred);
 
@@ -319,7 +322,8 @@ jpeg.lossless.Decoder.prototype.decode = function (buffer, offset, length, numBy
                 }
             }
 
-            if (!((current >= 0xFFD0) && (current <= 0xFFD7))) {
+            if (!((current >= jpeg.lossless.Decoder.RESTART_MARKER_BEGIN) &&
+                (current <= jpeg.lossless.Decoder.RESTART_MARKER_END))) {
                 break; //current=MARKER
             }
         }
@@ -444,17 +448,29 @@ jpeg.lossless.Decoder.prototype.decodeRGB = function (prev, temp, index) {
 jpeg.lossless.Decoder.prototype.decodeSingle = function (prev, temp, index) {
     /*jslint bitwise: true */
 
-    var value, i;
+    var value, i, n, nRestart;
 
-    prev[0] = this.selector();
+    if (this.restarting) {
+        this.restarting = false;
+        prev[0] = (1 << (this.frame.precision - 1));
+    } else {
+        prev[0] = this.selector();
+    }
 
     for (i = 0; i < this.nBlock[0]; i+=1) {
         value = this.getHuffmanValue(this.dcTab[0], temp, index);
         if (value >= 0xFF00) {
             return value;
         }
 
-        prev[0] += this.getn(prev, value, temp, index);
+        n = this.getn(prev, value, temp, index);
+        nRestart = (n >> 8);
+
+        if ((nRestart >= jpeg.lossless.Decoder.RESTART_MARKER_BEGIN) && (nRestart <= jpeg.lossless.Decoder.RESTART_MARKER_END)) {
+            return nRestart;
+        }
+
+        prev[0] += n;
     }
 
     return 0;