Class MinimalEncoder

java.lang.Object
com.google.zxing.datamatrix.encoder.MinimalEncoder

public final class MinimalEncoder extends Object
Encoder that encodes minimally Algorithm: Uses Dijkstra to produce mathematically minimal encodings that are in some cases smaller than the results produced by the algorithm described in annex S in the specification ISO/IEC 16022:200(E). The biggest improvment of this algorithm over that one is the case when the algorithm enters the most inefficient mode, the B256 mode. The algorithm from the specification algorithm will exit this mode only if it encounters digits so that arbitrarily inefficient results can be produced if the postfix contains no digits. Multi ECI support and ECI switching: For multi language content the algorithm selects the most compact representation using ECI modes. Note that unlike the compaction algorithm used for QR-Codes, this implementation operates in two stages and therfore is not mathematically optimal. In the first stage, the input string is encoded minimally as a stream of ECI character set selectors and bytes encoded in the selected encoding. In this stage the algorithm might for example decide to encode ocurrences of the characters "ŐŜ" (O-double-acute, S-circumflex) in UTF-8 by a single ECI or alternatively by multiple ECIs that switch between IS0-8859-2 and ISO-8859-3 (e.g. in the case that the input contains many * characters from ISO-8859-2 (Latin 2) and few from ISO-8859-3 (Latin 3)). In a second stage this stream of ECIs and bytes is minimally encoded using the various Data Matrix encoding modes. While both stages encode mathematically minimally it is not ensured that the result is mathematically minimal since the size growth for inserting an ECI in the first stage can only be approximated as the first stage does not know in which mode the ECI will occur in the second stage (may, or may not require an extra latch to ASCII depending on the current mode). The reason for this shortcoming are difficulties in implementing it in a straightforward and readable manner. GS1 support FNC1 delimiters can be encoded in the input string by using the FNC1 character specified in the encoding function. When a FNC1 character is specified then a leading FNC1 will be encoded and all ocurrences of delimiter characters while result in FNC1 codewords in the symbol.
  • Field Details

    • C40_SHIFT2_CHARS

      static final char[] C40_SHIFT2_CHARS
  • Constructor Details

    • MinimalEncoder

      private MinimalEncoder()
  • Method Details

    • isExtendedASCII

      static boolean isExtendedASCII(char ch, int fnc1)
    • isInC40Shift1Set

      private static boolean isInC40Shift1Set(char ch)
    • isInC40Shift2Set

      private static boolean isInC40Shift2Set(char ch, int fnc1)
    • isInTextShift1Set

      private static boolean isInTextShift1Set(char ch)
    • isInTextShift2Set

      private static boolean isInTextShift2Set(char ch, int fnc1)
    • encodeHighLevel

      public static String encodeHighLevel(String msg)
      Performs message encoding of a DataMatrix message
      Parameters:
      msg - the message
      Returns:
      the encoded message (the char values range from 0 to 255)
    • encodeHighLevel

      public static String encodeHighLevel(String msg, Charset priorityCharset, int fnc1, SymbolShapeHint shape)
      Performs message encoding of a DataMatrix message
      Parameters:
      msg - the message
      priorityCharset - The preferred Charset. When the value of the argument is null, the algorithm chooses charsets that leads to a minimal representation. Otherwise the algorithm will use the priority charset to encode any character in the input that can be encoded by it if the charset is among the supported charsets.
      fnc1 - denotes the character in the input that represents the FNC1 character or -1 if this is not a GS1 bar code. If the value is not -1 then a FNC1 is also prepended.
      shape - requested shape.
      Returns:
      the encoded message (the char values range from 0 to 255)
    • encode

      static byte[] encode(String input, Charset priorityCharset, int fnc1, SymbolShapeHint shape, int macroId)
      Encodes input minimally and returns an array of the codewords
      Parameters:
      input - The string to encode
      priorityCharset - The preferred Charset. When the value of the argument is null, the algorithm chooses charsets that leads to a minimal representation. Otherwise the algorithm will use the priority charset to encode any character in the input that can be encoded by it if the charset is among the supported charsets.
      fnc1 - denotes the character in the input that represents the FNC1 character or -1 if this is not a GS1 bar code. If the value is not -1 then a FNC1 is also prepended.
      shape - requested shape.
      macroId - Prepends the specified macro function in case that a value of 5 or 6 is specified.
      Returns:
      An array of bytes representing the codewords of a minimal encoding.
    • addEdge

      static void addEdge(MinimalEncoder.Edge[][] edges, MinimalEncoder.Edge edge)
    • getNumberOfC40Words

      static int getNumberOfC40Words(MinimalEncoder.Input input, int from, boolean c40, int[] characterLength)
      Returns:
      the number of words in which the string starting at from can be encoded in c40 or text mode. The number of characters encoded is returned in characterLength. The number of characters encoded is also minimal in the sense that the algorithm stops as soon as a character encoding fills a C40 word competely (three C40 values). An exception is at the end of the string where two C40 values are allowed (according to the spec the third c40 value is filled with 0 (Shift 1) in this case).
    • addEdges

      static void addEdges(MinimalEncoder.Input input, MinimalEncoder.Edge[][] edges, int from, MinimalEncoder.Edge previous)
    • encodeMinimally

      static MinimalEncoder.Result encodeMinimally(MinimalEncoder.Input input)