xterm.dart/lib/frontend/cache.dart

import 'package:flutter/painting.dart';
import 'package:quiver/collection.dart';

class TextLayoutCache {
  TextLayoutCache(this.textDirection, int maximumSize)
      : _cache = LruMap<TextSpan, TextPainter>(maximumSize: maximumSize);

  final LruMap<TextSpan, TextPainter> _cache;
  final TextDirection textDirection;

  TextPainter getOrPerformLayout(TextSpan text) {
    final cachedPainter = _cache[text];
    if (cachedPainter != null) {
      return cachedPainter;
    } else {
      return _performAndCacheLayout(text);
    }
  }

  TextPainter _performAndCacheLayout(TextSpan text) {
    final textPainter = TextPainter(text: text, textDirection: textDirection);
    textPainter.layout();

    _cache[text] = textPainter;

    return textPainter;
  }

  int get length {
    return _cache.length;
  }
}

final textLayoutCache = TextLayoutCache(TextDirection.ltr, 1024);

class TextLayoutCacheV2 {
  TextLayoutCacheV2(this.textDirection, int maximumSize)
      : _cache = LruMap<int, TextPainter>(maximumSize: maximumSize);

  final LruMap<int, TextPainter> _cache;
  final TextDirection textDirection;

  TextPainter getOrPerformLayout(TextSpan text, int key) {
    final cachedPainter = _cache[key];
    if (cachedPainter != null) {
      return cachedPainter;
    } else {
      return _performAndCacheLayout(text, key);
    }
  }

  TextPainter _performAndCacheLayout(TextSpan text, int key) {
    final textPainter = TextPainter(text: text, textDirection: textDirection);
    textPainter.layout();

    _cache[key] = textPainter;

    return textPainter;
  }

  int get length {
    return _cache.length;
  }
}

final textLayoutCacheV2 = TextLayoutCacheV2(TextDirection.ltr, 1024);

// class CodePointCache {
//   CodePointCache(int maximumSize)
//       : _cache = LruMap<int, String>(maximumSize: maximumSize);

//   final LruMap<int, String> _cache;

//   String getOrConstruct(int codePoint) {
//     final cachedString = _cache[codePoint];
//     if (cachedString != null) {
//       return cachedString;
//     } else {
//       return _constructAndCacheString(codePoint);
//     }
//   }

//   String _constructAndCacheString(int codePoint) {
//     final string = String.fromCharCode(codePoint);

//     _cache[codePoint] = string;

//     return string;
//   }
// }

// final codePointCache = CodePointCache(1024);