Only pass encoding hint in automatic if UTF-8

If zxing is not explicitly told a barcode is UTF-8, it may render it
incorrectly. Which caused
#2555.

However, when an encode hint is set, it will cause zxing to set an ECI
hint inside the barcode, which some scanners may trip over and cause
scanning failures, leading to
#2921.

This change only passes the encoding in automatic mode if zxing
explicitly guesses it to be UTF-8, and otherwise doesn't pass anything,
to keep the ECI empty. This might need to be expanded for other types
like SJIS, but as nobody ever reported such a bug let's assume it's not
necessary for now.

Author: TheLastProject

app/src/main/java/protect/card_locker/BarcodeImageWriterTask.java

@@ -22,6 +22,7 @@
 import java.lang.ref.WeakReference;
 import java.nio.charset.Charset;
 import java.util.Map;
+import java.util.Objects;
 
 import protect.card_locker.async.CompatCallable;
 
@@ -190,7 +191,16 @@ private Bitmap generate() {
         } else {
             String guessedEncoding = StringUtils.guessEncoding(cardId.getBytes(), new ArrayMap<>());
             Log.d(TAG, "Guessed encoding: " + guessedEncoding);
-            encodeHints.put(EncodeHintType.CHARACTER_SET, Charset.forName(guessedEncoding));
+
+            // We don't want to pass the gussed encoding as an encoding hint unless it is UTF-8 as
+            // zxing is likely to add the mentioned encoding hint as ECI inside the barcode.
+            //
+            // Due to many barcode scanners in the wild being badly coded they may trip over ECI
+            // info existing and fail to scan, such as in https://github.com/CatimaLoyalty/Android/issues/2921
+            if (Objects.equals(guessedEncoding, "UTF8")) {
+                Log.d(TAG, "Guessed encoding is UTF8, so passing as encoding hint");
+                encodeHints.put(EncodeHintType.CHARACTER_SET, Charset.forName(guessedEncoding));
+            }
         }
 
         BitMatrix bitMatrix;