Merge pull request #470 from normana10/master

ItemInfoBox no longer throws exception when no content encoding is present

Author: drewnoakes

Source/com/drew/metadata/heif/boxes/ItemInfoBox.java

@@ -69,13 +69,16 @@ public ItemInfoEntry(SequentialReader reader, Box box) throws IOException
         {
             super(reader, box);
 
+            // 4 Bytes for length, 4 Bytes for type. Reader is indexed from AFTER type but box.size INCLUDES the aforementioned 8 bytes
+            int headerLength = 8;
+
             if ((version == 0) || (version == 1)) {
                 itemID = reader.getUInt16();
                 itemProtectionIndex = reader.getUInt16();
-                itemName = reader.getNullTerminatedString((int)(box.size - reader.getPosition()), Charsets.UTF_8);
-                contentType = reader.getNullTerminatedString((int)(box.size - reader.getPosition()), Charsets.UTF_8);
-                if (box.size - reader.getPosition() > 0) {
-                    extensionType = reader.getNullTerminatedString((int) (box.size - reader.getPosition()), Charsets.UTF_8);
+                itemName = reader.getNullTerminatedString((int)(box.size - reader.getPosition() - headerLength), Charsets.UTF_8);
+                contentType = reader.getNullTerminatedString((int)(box.size - reader.getPosition() - headerLength), Charsets.UTF_8);
+                if (box.size - reader.getPosition() - headerLength > 0) {
+                    extensionType = reader.getNullTerminatedString((int) (box.size - reader.getPosition() - headerLength), Charsets.UTF_8);
                 }
             }
             if (version == 1) {
@@ -92,14 +95,14 @@ public ItemInfoEntry(SequentialReader reader, Box box) throws IOException
                 itemProtectionIndex = reader.getUInt16();
                 itemType = reader.getString(4);
 
-                itemName = reader.getNullTerminatedString((int)(box.size - reader.getPosition()), Charsets.UTF_8);
+                itemName = reader.getNullTerminatedString((int)(box.size - reader.getPosition() - headerLength), Charsets.UTF_8);
                 if (itemType.equals("mime")) {
-                    contentType = reader.getNullTerminatedString((int)(box.size - reader.getPosition()), Charsets.UTF_8);
-                    if (box.size - reader.getPosition() > 0) {
-                        contentEncoding = reader.getNullTerminatedString((int)(box.size - reader.getPosition()), Charsets.UTF_8);
+                    contentType = reader.getNullTerminatedString((int)(box.size - reader.getPosition() - headerLength), Charsets.UTF_8);
+                    if (box.size - reader.getPosition() - headerLength > 0) {
+                        contentEncoding = reader.getNullTerminatedString((int)(box.size - reader.getPosition() - headerLength), Charsets.UTF_8);
                     }
                 } else if (itemType.equals("uri ")) {
-                    itemUriType = reader.getString((int)(box.size - reader.getPosition()));
+                    itemUriType = reader.getString((int)(box.size - reader.getPosition() - headerLength));
                 }
             }
         }