Package com.google.zxing.qrcode.encoder

Class MinimalEncoder

java.lang.Object

com.google.zxing.qrcode.encoder.MinimalEncoder

final class MinimalEncoder
extends java.lang.Object

Encoder that encodes minimally Algorithm: The eleventh commandment was "Thou Shalt Compute" or "Thou Shalt Not Compute" - I forget which (Alan Perilis). This implementation computes. As an alternative, the QR-Code specification suggests heuristics like this one: If initial input data is in the exclusive subset of the Alphanumeric character set AND if there are less than [6,7,8] characters followed by data from the remainder of the 8-bit byte character set, THEN select the 8- bit byte mode ELSE select Alphanumeric mode; This is probably right for 99.99% of cases but there is at least this one counter example: The string "AAAAAAa" encodes 2 bits smaller as ALPHANUMERIC(AAAAAA), BYTE(a) than by encoding it as BYTE(AAAAAAa). Perhaps that is the only counter example but without having proof, it remains unclear. ECI switching: In multi language content the algorithm selects the most compact representation using ECI modes. For example the most compact representation of the string "ŐŜ" (O-double-acute, S-circumflex) is ECI(UTF-8), BYTE(ŐŜ) while prepending one or more times the same leading character as in "ŐŐŜ", the most compact representation uses two ECIs so that the string is encoded as ECI(ISO-8859-2), BYTE(ŐŐ), ECI(ISO-8859-3), BYTE(Ŝ).

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private class	MinimalEncoder.Edge
(package private) class	MinimalEncoder.ResultList
private static class	MinimalEncoder.VersionSize

Field Summary

Fields

Modifier and Type	Field	Description
private ErrorCorrectionLevel	ecLevel
private ECIEncoderSet	encoders
private boolean	isGS1
private java.lang.String	stringToEncode

Constructor Summary

Constructors

Constructor	Description
MinimalEncoder(java.lang.String stringToEncode, java.nio.charset.Charset priorityCharset, boolean isGS1, ErrorCorrectionLevel ecLevel)	Creates a MinimalEncoder

Method Summary

Modifier and Type	Method	Description
(package private) void	addEdge(MinimalEncoder.Edge[][][] edges, int position, MinimalEncoder.Edge edge)
(package private) void	addEdges(Version version, MinimalEncoder.Edge[][][] edges, int from, MinimalEncoder.Edge previous)
(package private) boolean	canEncode(Mode mode, char c)
(package private) MinimalEncoder.ResultList	encode(Version version)
(package private) static MinimalEncoder.ResultList	encode(java.lang.String stringToEncode, Version version, java.nio.charset.Charset priorityCharset, boolean isGS1, ErrorCorrectionLevel ecLevel)	Encodes the string minimally
(package private) MinimalEncoder.ResultList	encodeSpecificVersion(Version version)
(package private) static int	getCompactedOrdinal(Mode mode)
(package private) static Version	getVersion(MinimalEncoder.VersionSize versionSize)
(package private) static MinimalEncoder.VersionSize	getVersionSize(Version version)
(package private) static boolean	isAlphanumeric(char c)
(package private) static boolean	isDoubleByteKanji(char c)
(package private) static boolean	isNumeric(char c)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

stringToEncode

private final java.lang.String stringToEncode

isGS1

private final boolean isGS1

encoders

private final ECIEncoderSet encoders

ecLevel

private final ErrorCorrectionLevel ecLevel

Constructor Detail

MinimalEncoder

MinimalEncoder(java.lang.String stringToEncode,
               java.nio.charset.Charset priorityCharset,
               boolean isGS1,
               ErrorCorrectionLevel ecLevel)

Creates a MinimalEncoder

Parameters:

stringToEncode - 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.

isGS1 - true if a FNC1 is to be prepended; false otherwise

ecLevel - The error correction level.

See Also:

MinimalEncoder.ResultList.getVersion()

Method Detail

encode

static MinimalEncoder.ResultList encode(java.lang.String stringToEncode,
                                        Version version,
                                        java.nio.charset.Charset priorityCharset,
                                        boolean isGS1,
                                        ErrorCorrectionLevel ecLevel)
                                 throws WriterException

Encodes the string minimally

Parameters:

stringToEncode - The string to encode

version - The preferred Version. A minimal version is computed (see method when the value of the argument is null

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.

isGS1 - true if a FNC1 is to be prepended; false otherwise

ecLevel - The error correction level.

Returns:

An instance of ResultList representing the minimal solution.

Throws:

WriterException

See Also:

MinimalEncoder.ResultList.getBits(com.google.zxing.common.BitArray), MinimalEncoder.ResultList.getVersion(), MinimalEncoder.ResultList.getSize()

encode

MinimalEncoder.ResultList encode(Version version)
                          throws WriterException

Throws:

WriterException

getVersionSize

static MinimalEncoder.VersionSize getVersionSize(Version version)

getVersion

static Version getVersion(MinimalEncoder.VersionSize versionSize)

isNumeric

static boolean isNumeric(char c)

isDoubleByteKanji

static boolean isDoubleByteKanji(char c)

isAlphanumeric

static boolean isAlphanumeric(char c)

canEncode

boolean canEncode(Mode mode,
                  char c)

getCompactedOrdinal

static int getCompactedOrdinal(Mode mode)

addEdge

void addEdge(MinimalEncoder.Edge[][][] edges,
             int position,
             MinimalEncoder.Edge edge)

addEdges

void addEdges(Version version,
              MinimalEncoder.Edge[][][] edges,
              int from,
              MinimalEncoder.Edge previous)

encodeSpecificVersion

MinimalEncoder.ResultList encodeSpecificVersion(Version version)
                                         throws WriterException

Throws:

WriterException