PDFBOX-5963: get base encoding if available

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1924031 13f79535-47bb-0310-9956-ffa450edef68

Author: THausherr

pdfbox/src/main/java/org/apache/pdfbox/pdmodel/font/encoding/DictionaryEncoding.java

@@ -74,7 +74,20 @@ public DictionaryEncoding(COSName baseEncoding, COSArray differences)
     public DictionaryEncoding(COSDictionary fontEncoding)
     {
         encoding = fontEncoding;
-        baseEncoding = null;
+        COSName name = encoding.getCOSName(COSName.BASE_ENCODING);
+        if (name != null)
+        {
+            baseEncoding = Encoding.getInstance(name); // null when the name is invalid
+            if (baseEncoding != null)
+            {
+                codeToName.putAll(baseEncoding.codeToName);
+                inverted.putAll(baseEncoding.inverted);
+            }
+        }
+        else
+        {
+            baseEncoding = null;
+        }
         applyDifferences();
     }