Fix Wi-Fi QR code decode fail

ZXing generate QR code with default encoding ISO-8859-1,
the generated QR code is wrong encoded if there is a
character outside of the charset.

Generate QR code of UTF-8 encoding.

Bug: 131851854
Test: manual
Change-Id: I96a5e72a978c654b62d89b3b11dd3016bf0ee1df

src/com/android/settings/wifi/qrcode/QrCodeGenerator.java

@@ -20,10 +20,16 @@ import android.graphics.Bitmap;
 import android.graphics.Color;
 
 import com.google.zxing.BarcodeFormat;
+import com.google.zxing.EncodeHintType;
 import com.google.zxing.MultiFormatWriter;
 import com.google.zxing.WriterException;
 import com.google.zxing.common.BitMatrix;
 
+import java.nio.charset.CharsetEncoder;
+import java.nio.charset.StandardCharsets;
+import java.util.HashMap;
+import java.util.Map;
+
 public final class QrCodeGenerator {
     /**
      * Generates a barcode image with {@code contents}.
@@ -34,8 +40,13 @@ public final class QrCodeGenerator {
      */
     public static Bitmap encodeQrCode(String contents, int size)
             throws WriterException, IllegalArgumentException {
+        final Map<EncodeHintType, Object> hints = new HashMap<>();
+        if (!isIso88591(contents)) {
+            hints.put(EncodeHintType.CHARACTER_SET, StandardCharsets.UTF_8.name());
+        }
+
         final BitMatrix qrBits = new MultiFormatWriter().encode(contents, BarcodeFormat.QR_CODE,
-                size, size);
+                size, size, hints);
         final Bitmap bitmap = Bitmap.createBitmap(size, size, Bitmap.Config.RGB_565);
         for (int x = 0; x < size; x++) {
             for (int y = 0; y < size; y++) {
@@ -44,4 +55,9 @@ public final class QrCodeGenerator {
         }
         return bitmap;
     }
+
+    private static boolean isIso88591(String contents) {
+        CharsetEncoder encoder = StandardCharsets.ISO_8859_1.newEncoder();
+        return encoder.canEncode(contents);
+    }
 }