From ac64595afaef7135b2d190c4d19adc8886520b50 Mon Sep 17 00:00:00 2001
From: srowen <srowen@59b500cc-1b3d-0410-9834-0bbf25fbcc57>
Date: Fri, 13 Nov 2009 09:49:49 +0000
Subject: [PATCH] Be more conservative about choosing Kanji mode. Since we
 don't support mixed mode, can only use it when the input is all double-byte
 Kanji.

git-svn-id: https://zxing.googlecode.com/svn/trunk@1107 59b500cc-1b3d-0410-9834-0bbf25fbcc57
---
 .../google/zxing/qrcode/encoder/Encoder.java  | 25 +++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/core/src/com/google/zxing/qrcode/encoder/Encoder.java b/core/src/com/google/zxing/qrcode/encoder/Encoder.java
index 1bfd1b055..6d59f32eb 100644
--- a/core/src/com/google/zxing/qrcode/encoder/Encoder.java
+++ b/core/src/com/google/zxing/qrcode/encoder/Encoder.java
@@ -174,11 +174,12 @@ public final class Encoder {
 
   /**
    * Choose the best mode by examining the content. Note that 'encoding' is used as a hint;
-   * if it is Shift_JIS then we assume the input is Kanji and return {@link Mode#KANJI}.
+   * if it is Shift_JIS, and the input is only double-byte Kanji, then we return {@link Mode#KANJI}.
    */
   public static Mode chooseMode(String content, String encoding) {
     if ("Shift_JIS".equals(encoding)) {
-      return Mode.KANJI;
+      // Choose Kanji mode if all input are double-byte characters
+      return isOnlyDoubleByteKanji(content) ? Mode.KANJI : Mode.BYTE;
     }
     boolean hasNumeric = false;
     boolean hasAlphanumeric = false;
@@ -200,6 +201,26 @@ public final class Encoder {
     return Mode.BYTE;
   }
 
+  private static boolean isOnlyDoubleByteKanji(String content) {
+    byte[] bytes;
+    try {
+      bytes = content.getBytes("Shift_JIS");
+    } catch (UnsupportedEncodingException uee) {
+      return false;
+    }
+    int length = bytes.length;
+    if (length % 2 != 0) {
+      return false;
+    }
+    for (int i = 0; i < length; i += 2) {
+      int byte1 = bytes[i] & 0xFF;
+      if ((byte1 < 0x81 || byte1 > 0x9F) && (byte1 < 0xE0 || byte1 > 0xEB)) {
+        return false;
+      }
+    }
+    return true;
+  }
+
   private static int chooseMaskPattern(BitVector bits, ErrorCorrectionLevel ecLevel, int version,
       ByteMatrix matrix) throws WriterException {