Fix JBIG2 symbol offsets in text regions

src/core/jbig2.js

@@ -552,8 +552,9 @@ var Jbig2Image = (function Jbig2ImageClosure() {
             (rdh >> 1) + rdy, false, refinementAt,
             decodingContext);
         }
-        var offsetT = t - ((referenceCorner & 1) ? 0 : symbolHeight);
+        var offsetT = t - ((referenceCorner & 1) ? 0 : (symbolHeight - 1));
-        var offsetS = currentS - ((referenceCorner & 2) ? symbolWidth : 0);
+        var offsetS = currentS -
+          ((referenceCorner & 2) ? (symbolWidth - 1) : 0);
         var s2, t2, symbolRow;
         if (transposed) {
           // Place Symbol Bitmap from T1,S1

test/pdfs/.gitignore

@@ -199,6 +199,7 @@
 !issue6387.pdf
 !issue6410.pdf
 !issue8586.pdf
+!jbig2_symbol_offset.pdf
 !gradientfill.pdf
 !bug903856.pdf
 !bug850854.pdf

test/test_manifest.json

@@ -818,6 +818,12 @@
        "type": "eq",
        "forms": true
     },
+    {  "id": "jbig2_symbol_offset",
+       "file": "pdfs/jbig2_symbol_offset.pdf",
+       "md5": "6b22a0f838008fa4d8cb5b40ba095c48",
+       "rounds": 1,
+       "type": "eq"
+    },
     {  "id": "bug1046314",
        "file": "pdfs/bug1046314.pdf",
        "md5": "fc658439f44cd2dd27c8bee7e7a8344e",