MinimalEncoder class
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 "\u0150\u015C" (O-double-acute, S-circumflex) is ECI(UTF-8), BYTE(\u0150\u015C) while prepending one or more times the same leading character as in "\u0150\u0150\u015C", the most compact representation uses two ECIs so that the string is encoded as ECI(ISO-8859-2), BYTE(\u0150\u0150), ECI(ISO-8859-3), BYTE(\u015C).
@author Alex Geller
Constructors
- MinimalEncoder(String stringToEncode, Encoding? priorityCharset, bool isGS1, ErrorCorrectionLevel ecLevel)
- Creates a MinimalEncoder
Properties
- ecLevel → ErrorCorrectionLevel
-
final
- encoders → ECIEncoderSet
-
final
- hashCode → int
-
The hash code for this object.
no setterinherited
- isGS1 → bool
-
final
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
- stringToEncode → String
-
final
Methods
-
addEdge(
List< List< edges, int position, Edge edge) → voidList< >Edge?> > -
addEdges(
Version version, List< List< edges, int from, Edge? previous) → voidList< >Edge?> > -
canEncode(
Mode mode, int c) → bool -
doEncode(
Version? version) → ResultList -
encodeSpecificVersion(
Version version) → ResultList -
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a nonexistent method or property is accessed.
inherited
-
toString(
) → String -
A string representation of this object.
inherited
Operators
-
operator ==(
Object other) → bool -
The equality operator.
inherited
Static Methods
-
encode(
String stringToEncode, Version? version, Encoding? priorityCharset, bool isGS1, ErrorCorrectionLevel ecLevel) → ResultList - Encodes the string minimally
-
getCompactedOrdinal(
Mode? mode) → int -
getVersion(
VersionSize versionSize) → Version -
getVersionSize(
Version version) → VersionSize -
isAlphanumeric(
int c) → bool -
isDoubleByteKanji(
int c) → bool -
isNumeric(
int c) → bool