kinsoku #

Japanese text processing library for kinsoku (禁則処理 - line breaking rules), character classification, yakumono adjustment, and kerning.

Features #

• Kinsoku Shori (禁則処理): Japanese line breaking rules

  • Line-start prohibition (行頭禁則, gyoto kinsoku)
  • Line-end prohibition (行末禁則, gyomatsu kinsoku)
  • Hanging characters (ぶら下げ, burasage)
  • Pushing-in characters (追い込み, oikomi)
  • Separation prohibition for paired characters (……, ‥‥, ――, etc.)

• Character Classification: Identify character types

  • Kanji (漢字)
  • Hiragana (ひらがな)
  • Katakana (カタカナ)
  • Latin alphabet
  • Numbers
  • Punctuation
  • Yakumono (約物 - Japanese typography symbols)
  • Space

• Yakumono Adjustment: Fine-tune punctuation and symbol positioning

  • Half-width yakumono handling
  • Gyoto indent for opening brackets
  • Consecutive yakumono spacing

• Kerning: Spacing adjustments between character pairs

  • Kerning pairs for Japanese punctuation
  • Oikomi (push-in) adjustment calculations

• Text Alignment: Line-level alignment options

  • TextAlignment.start (天付き): Align to top/left
  • TextAlignment.center: Center alignment
  • TextAlignment.end (地付き): Align to bottom/right

Related Packages #

This package is part of the Japanese text layout suite:

Installation #

Add this to your package's pubspec.yaml file:

dependencies:
  kinsoku: ^0.3.0

Then run:

dart pub get

Usage #

Basic Character Classification #

import 'package:kinsoku/kinsoku.dart';

void main() {
  // Classify characters
  print(CharacterClassifier.classify('あ')); // CharacterType.hiragana
  print(CharacterClassifier.classify('漢')); // CharacterType.kanji
  print(CharacterClassifier.classify('A'));  // CharacterType.latin

  // Check character properties
  print(CharacterClassifier.isSmallKana('ゃ'));  // true
  print(CharacterClassifier.isLongVowelMark('ー')); // true
}

Kinsoku Processing #

import 'package:kinsoku/kinsoku.dart';

void main() {
  final text = 'これは禁則処理のテストです。';

  // Check if we can break at a specific position
  final canBreak = KinsokuProcessor.canBreakAt(text, 10);
  print('Can break at position 10: $canBreak');

  // Find the best break position
  final breakPos = KinsokuProcessor.findBreakPosition(text, 10);
  print('Best break position near 10: $breakPos');

  // Check if a character can hang at line end
  print(KinsokuProcessor.canHangAtLineEnd('。'));  // true
  print(KinsokuProcessor.canHangAtLineEnd('ー'));  // false
}

Yakumono Adjustment #

import 'package:kinsoku/kinsoku.dart';

void main() {
  // Adjust yakumono position
  final basePos = Position(100, 200);
  final adjusted = YakumonoAdjuster.adjustPosition(
    '。',
    basePos,
    fontSize: 16.0,
    adjustYakumono: true,
  );
  print('Adjusted position: (${adjusted.x}, ${adjusted.y})');

  // Check yakumono properties
  print(YakumonoAdjuster.isHalfWidthYakumono('。'));  // true
  print(YakumonoAdjuster.getYakumonoWidth('。'));     // 0.5
  print(YakumonoAdjuster.getGyotoIndent('「'));       // 0.1
}

Text Alignment #

import 'package:kinsoku/kinsoku.dart';

void main() {
  // Use TextAlignment for line-level alignment
  final alignment = TextAlignment.end; // 地付き (bottom/right alignment)

  switch (alignment) {
    case TextAlignment.start:
      print('天付き - Align to start');
      break;
    case TextAlignment.center:
      print('Center alignment');
      break;
    case TextAlignment.end:
      print('地付き - Align to end');
      break;
  }
}

Kerning #

import 'package:kinsoku/kinsoku.dart';

void main() {
  // Get kerning between two characters
  final kerning = KerningProcessor.getKerning('。', '、');
  print('Kerning between 。 and 、: $kerning');  // -0.5

  // Calculate oikomi adjustment
  final adjustment = KerningProcessor.calculateOikomiAdjustment(
    'テキスト',
    0,
    4,
    100.0,  // target width
    110.0,  // current width
  );
  print('Oikomi adjustment: $adjustment');
}

ICU-based Kinsoku Processing (Optional) #

For full Unicode UAX #14 compliance with customizable rules, use the ICU-based processor:

Installation Requirements #

Install the ICU library on your system:

• macOS: brew install icu4c
• Linux: sudo apt install libicu-dev
• Windows: Download ICU binaries from unicode-org/icu

Usage #

import 'package:kinsoku/icu.dart';

void main() {
  // Default UAX #14 rules
  final processor = ICUKinsokuProcessor();

  // Or use JIS X 4051-inspired rules
  final jisProcessor = ICUKinsokuProcessor.withJISX4051Rules();

  // Check if we can break at a position
  final text = 'これは禁則処理のテストです。';
  final canBreak = processor.canBreakAt(text, 10);

  // Find all break positions
  final breaks = processor.getAllBreakPositions(text);
  print('Break positions: $breaks');

  // Clean up
  processor.dispose();
}

Custom Rules #

Define custom break iterator rules using ICU syntax:

final customRules = r'''
# Define character classes
$CL_OP = [\u0028 \u300C];  # Opening brackets: （「
$CL_CL = [\u0029 \u300D];  # Closing brackets: ）」
$CL_PC = [\u3002 \u3001];  # Periods and commas: 。、

# Break rules
× $CL_OP;   # No break after opening brackets
$CL_CL ×;   # No break before closing brackets
$CL_PC ×;   # No break before periods/commas
÷;          # Default: allow break
''';

final processor = ICUKinsokuProcessor.withCustomRules(customRules);

Configuration-based Rules #

Use the KinsokuConfig class for easier customization:

final config = KinsokuConfig(
  gyotoKinsoku: {'。', '、', '）', '」'},      // Line-start forbidden
  gyomatsuKinsoku: {'（', '「'},              // Line-end forbidden
  burasageAllowed: {'。', '、'},              // Can hang
  pairedCharacters: {'…', '‥'},              // Must stay together
);

final rules = config.toICURules();
final processor = ICUKinsokuProcessor.withCustomRules(rules);

ICU vs Pure Dart Comparison #

JIS X 4051:2004 Complete Compliance #

The ICU processor provides full compliance with JIS X 4051:2004:

Complete Character Class Implementation

Line Breaking Rules

• Gyoto Kinsoku (行頭禁則): 70+ characters cannot appear at line start
• Gyomatsu Kinsoku (行末禁則): 25+ characters cannot appear at line end
• Paired Separation (分離禁止): ……, ‥‥, ――, etc. must stay together
• Consecutive Punctuation: ！！, ？？, ！？, ？！ cannot be separated
• Special Handling: Currency symbols (¥£€), small kana, iteration marks

See example/icu_example.dart for comprehensive examples.

Pure Dart Package #

This is a pure Dart package with no Flutter dependencies. The core functionality works everywhere:

• Flutter applications
• Web applications
• Server-side Dart applications
• Command-line tools
• Any Dart environment

The ICU-based processor requires native ICU library and works on:

• macOS, Linux, Windows (desktop)
• Server environments
• (Not available on web or mobile platforms)

License #

MIT License - see LICENSE file for details

Contributing #

Contributions are welcome! Please feel free to submit a Pull Request.

References #

• JIS X 4051:2004 - Japanese document composition method
• W3C Requirements for Japanese Text Layout (JLREQ)
• CSS Text Module Level 3/4