kashida library

Finding kashida (tatweel) insertion points and priorities, driven by a small pattern language.

Compile rules with compilePatternText or requiredBuiltinPatternSet, then either findKashidaPoints, insertKashida, layoutParagraph, or KashidaText.

Matching and measure-based layout come from kashida_core (re-exported here). This package adds Flutter measuring and the KashidaText widget.

Classes

BackslashWithoutDigit
\ appeared without a preceding priority digit.
CaretNotFollowed
^ was not followed by {, @, or =.
CompileErrorKind
What went wrong on a pattern line.
ConflictingWeights
Two weights were assigned to the same connection.
EmptyGroupName
@ or = was not followed by a group name.
EmptyGroupSet
A {} group set contained no members.
ExpectedDigitAfterBackslash
\ was not followed by a digit.
IncreasingPriority
A base\min weight used a minimum higher than the base priority.
InvalidLengthGuard
A […] length guard could not be parsed.
KashidaAnalysis
Cleaned text and the kashida points that refer to it.
KashidaLine
One wrapped line of KashidaWords.
KashidaPoint
A point where a kashida may be inserted.
KashidaText
Justified Arabic/Syriac paragraph using patternSet and style.
KashidaWord
A word on a justified line, with kashida slots into text.
NoLetters
A pattern line contained no joining letters.
PatternSet
A compiled set of kashida insertion patterns.
StrayCharacter
An unexpected character appeared in the pattern.
TextWidthCache
Reuses one TextPainter and memoizes widths for a fixed style/scaler/direction.
TokenAfterTrailingBoundary
A token appeared after a trailing . word boundary.
UnknownGroupName
A @Name or =Name token used an unknown Joining_Group.
UnknownImport
A use line named an unknown built-in pattern set.
UnterminatedGroupSet
A { group set was not closed before the end of the line.
UnterminatedLengthGuard
A [ length guard was not closed before the end of the line.
WeightOutsideRun
A weight was placed on a . boundary rather than inside the run.

Enums

KashidaFillStyle
How leftover line width is filled with tatweel.

Constants

kashida → const String
kashidaCodepoint → const int

Functions

builtinPatternSet(String name) → PatternSet?
The compiled built-in set named name, or null if it is unknown.
builtinPatternSetNames() → List<String>
Names of the built-in pattern sets, in a stable order.
compilePatternText(String text) → PatternSet
Compiles pattern text into a PatternSet.
fillStyleFor(PatternSet set) → KashidaFillStyle
Default fill for a pattern set: Syriac builtins use KashidaFillStyle.syriac.
findKashidaPoints(String text, PatternSet set, {bool removeExistingKashida = true}) → KashidaAnalysis
Kashida insertion points for text under the given pattern set.
findKashidaPointsIn(String text, PatternSet set) → List<KashidaPoint>
Insertion points in text without stripping existing tatweel.
findKashidaPointsPatterns(String text, PatternSet set) → List<KashidaPoint>
Same as findKashidaPointsIn (historical name from raqim-kashida).
insertKashida(String text, PatternSet set, {bool removeExistingKashida = true, int count = 1, int minPriority = 0}) → String
Finds kashida points in text and inserts count tatweels at each.
insertKashidaAt(String text, Iterable<KashidaPoint> points, {int count = 1, int minPriority = 0}) → String
Inserts count tatweels after each grapheme listed in points.
isBuiltinPatternSet(String name) → bool
Whether name is one of builtinPatternSetNames.
layoutParagraph(String text, PatternSet set, {required double width, required KashidaMeasure measure, int minKashidas = 1, int maxKashidas = 4, bool justified = true, bool justifyLastLine = false, bool applyKashida = true, bool removeExistingKashida = true, KashidaFillStyle? fill}) → List<KashidaLine>
Wraps text to width and optionally fills lines with tatweel.
layoutParagraphStyled(String text, PatternSet set, TextStyle style, {required double width, TextScaler textScaler = TextScaler.noScaling, TextDirection textDirection = TextDirection.rtl, int minKashidas = 1, int maxKashidas = 4, bool justified = true, bool justifyLastLine = false, bool applyKashida = true, bool removeExistingKashida = true, KashidaFillStyle? fill, TextWidthCache? cache}) → List<KashidaLine>
layoutParagraph measured with style (typically your on-screen font).
measureTextWidth(String text, TextStyle style, {TextScaler textScaler = TextScaler.noScaling, TextDirection textDirection = TextDirection.rtl}) → double
Pixel width of text in style, using Flutter's text layout.
requiredBuiltinPatternSet(String name) → PatternSet
The compiled built-in set named name.
stripBareTatweel(String text) → String
text with bare tatweel (U+0640) removed.

Typedefs

KashidaMeasure = double Function(String text)
Measures the width of a string in the caller's units (pixels, ems, …).

Exceptions / Errors

CompileError
An error while compiling pattern text.