Font encoding fix

src/main/java/org/verapdf/pd/font/Encoding.java

@@ -25,6 +25,8 @@
 
 import java.util.HashMap;
 import java.util.Map;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
 /**
  * Represents encoding of font as given in font dictionary.
@@ -33,6 +35,10 @@
  */
 public class Encoding {
 
+    private static final Logger LOGGER = Logger.getLogger(Encoding.class.getCanonicalName());
+
+    private static final Encoding EMPTY = new Encoding(null);
+
     private static final String NOTDEF = ".notdef";
 
     private String[] predefinedEncoding;
@@ -72,33 +78,35 @@ public Encoding(ASAtom baseEncoding, Map<Integer, String> differences) {
         }
     }
 
+    public static Encoding empty() {
+        return EMPTY;
+    }
+
     /**
      * Gets name of char for it's code via this encoding.
      *
      * @param code is character code.
-     * @return glyph name for given character code.
+     * @return glyph name for given character code or null if the internal font encoding should be used.
      */
     public String getName(int code) {
         if (code >= 0) {
             if (differences == null) {
                 if (code < predefinedEncoding.length) {
                     return predefinedEncoding[code];
                 } else {
-                    return NOTDEF;
+                    // if no predefined encoding, the null result for using font encoding
+                    return (predefinedEncoding.length != 0) ? NOTDEF : null;
                 }
             } else {
                 String diffRes = this.differences.get(code);
-                if (diffRes == null) {
-                    if (code < predefinedEncoding.length) {
-                        diffRes = predefinedEncoding[code];
-                    } else {
-                        diffRes = NOTDEF;
-                    }
+                if (diffRes == null && predefinedEncoding.length != 0) {
+                    diffRes = (code < predefinedEncoding.length) ? predefinedEncoding[code] : NOTDEF;
                 }
                 return diffRes;
             }
         } else {
-            return NOTDEF;
+            LOGGER.log(Level.WARNING, "Invalid glyph code: " + code);
+            return null;
         }
     }
 

src/main/java/org/verapdf/pd/font/PDFont.java

@@ -142,7 +142,7 @@ private static Encoding getEncodingMappingFromCOSObject(COSObject e) {
                 return encodingObj;
             }
         }
-        return null;
+        return Encoding.empty();
     }
 
     /**

src/main/java/org/verapdf/pd/font/type1/PDType1Font.java

@@ -241,13 +241,9 @@ public Double getWidth(int code) {
     @Override
     public float getWidthFromProgram(int code) {
         Encoding pdEncoding = this.getEncodingMapping();
-        if (pdEncoding != null) {
-            String glyphName = pdEncoding.getName(code);
-            if (glyphName != null) {
-                return this.getFontProgram().getWidth(glyphName);
-            }
-        }
-        return this.getFontProgram().getWidth(code);
+        String glyphName = pdEncoding.getName(code);
+        FontProgram fontProgram = this.getFontProgram();
+        return glyphName != null ? fontProgram.getWidth(glyphName) : fontProgram.getWidth(code);
     }
 
     @Override