Factor out ECI-related code for reuse with Data Matrix later.

git-svn-id: https://zxing.googlecode.com/svn/trunk@534 59b500cc-1b3d-0410-9834-0bbf25fbcc57

core/src/com/google/zxing/common/CharacterSetECI.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2008 ZXing authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.zxing.common;
+
+import java.util.Hashtable;
+
+/**
+ * Encapsulates a Character Set ECI, according to "Extended Channel Interpretations" 5.3.1.1
+ * of ISO 18004.
+ *
+ * @author srowen@google.com (Sean Owen)
+ */
+public final class CharacterSetECI extends ECI {
+
+  private static final Hashtable VALUE_TO_ECI;
+  static {
+    VALUE_TO_ECI = new Hashtable(29);
+    // TODO figure out if these values are even right!
+    addCharacterSet(0, "Cp437");
+    addCharacterSet(1, "ISO8859_1");
+    addCharacterSet(2, "Cp437");
+    addCharacterSet(3, "ISO8859_1");
+    addCharacterSet(4, "ISO8859_2");
+    addCharacterSet(5, "ISO8859_3");
+    addCharacterSet(6, "ISO8859_4");
+    addCharacterSet(7, "ISO8859_5");
+    addCharacterSet(8, "ISO8859_6");
+    addCharacterSet(9, "ISO8859_7");
+    addCharacterSet(10, "ISO8859_8");
+    addCharacterSet(11, "ISO8859_9");
+    addCharacterSet(12, "ISO8859_10");
+    addCharacterSet(13, "ISO8859_11");
+    addCharacterSet(15, "ISO8859_13");
+    addCharacterSet(16, "ISO8859_14");
+    addCharacterSet(17, "ISO8859_15");
+    addCharacterSet(18, "ISO8859_16");
+    addCharacterSet(20, "SJIS");
+  }
+
+  private final String encodingName;
+
+  private CharacterSetECI(int value, String encodingName) {
+    super(value);
+    this.encodingName = encodingName;
+  }
+
+  public String getEncodingName() {
+    return encodingName;
+  }
+
+  private static void addCharacterSet(int value, String encodingName) {
+    VALUE_TO_ECI.put(new Integer(value), new CharacterSetECI(value, encodingName));
+  }
+
+  public static CharacterSetECI getCharacterSetECIByValue(int value) {
+    CharacterSetECI eci = (CharacterSetECI) VALUE_TO_ECI.get(new Integer(value));
+    if (eci == null) {
+      throw new IllegalArgumentException("Unsupported value: " + value);
+    }
+    return eci;
+  }
+
+}

core/src/com/google/zxing/common/ECI.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2008 ZXing authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.zxing.common;
+
+/**
+ * Superclass of classes encapsulating types ECIs, according to "Extended Channel Interpretations" 5.3
+ * of ISO 18004.
+ *
+ * @author srowen@google.com (Sean Owen)
+ */
+public abstract class ECI {
+
+  private final int value;
+
+  ECI(int value) {
+    this.value = value;
+  }
+
+  public int getValue() {
+    return value;
+  }
+
+  public static ECI getECIByValue(int value) {
+    if (value < 0 || value > 999999) {
+      throw new IllegalArgumentException("Bad ECI value: " + value);
+    }
+    if (value < 900) { // Character set ECIs use 000000 - 000899
+      return CharacterSetECI.getCharacterSetECIByValue(value);
+    }
+    throw new IllegalArgumentException("Unsupported ECI value: " + value);
+  }
+
+}

core/src/com/google/zxing/qrcode/decoder/DecodedBitStreamParser.java

@@ -18,6 +18,7 @@ package com.google.zxing.qrcode.decoder;
 
 import com.google.zxing.ReaderException;
 import com.google.zxing.common.BitSource;
+import com.google.zxing.common.CharacterSetECI;
 
 import java.io.UnsupportedEncodingException;
 
@@ -74,7 +75,7 @@ final class DecodedBitStreamParser {
           fc1InEffect = true;
         } else if (mode.equals(Mode.ECI)) {
           // Count doesn't apply to ECI
-          int value = ECI.parseECI(bits);
+          int value = parseECIValue(bits);
           try {
             currentCharacterSetECI = CharacterSetECI.getCharacterSetECIByValue(value);
           } catch (IllegalArgumentException iae) {
@@ -290,5 +291,22 @@ final class DecodedBitStreamParser {
     }
     return canBeISO88591 ? ISO88591 : SHIFT_JIS;
   }
+  
+  private static int parseECIValue(BitSource bits) {
+    int firstByte = bits.readBits(8);
+    if ((firstByte & 0x80) == 0) {
+      // just one byte
+      return firstByte & 0x7F;
+    } else if ((firstByte & 0xC0) == 0x80) {
+      // two bytes
+      int secondByte = bits.readBits(8);
+      return ((firstByte & 0x3F) << 8) | secondByte;
+    } else if ((firstByte & 0xE0) == 0xC0) {
+      // three bytes
+      int secondThirdBytes = bits.readBits(16);
+      return ((firstByte & 0x1F) << 16) | secondThirdBytes;
+    }
+    throw new IllegalArgumentException("Bad ECI bits starting with byte " + firstByte);
+  }
 
 }