fis_lib_measure/lib/process/items/factory.dart

import 'package:fis_measure/interfaces/process/items/item.dart';
import 'package:fis_measure/interfaces/process/items/item_metas.dart';
import 'package:fis_measure/interfaces/process/items/types.dart';
import 'package:fis_measure/process/items/item.dart';
import 'package:fis_measure/process/primitives/combos/lwh_straightline.dart';
import 'package:fis_measure/process/primitives/ellipse.dart';
import 'package:fis_measure/process/primitives/polyline.dart';
import 'package:fis_measure/process/primitives/straightline.dart';

/// 测量项创建器
///
/// [meta] 测量项元信息
///
/// [parent] 父项
typedef MeasureItemCreator = MeasureItem Function(
  ItemMeta meta,
  IMeasureItem? parent,
);

/// 测量项工厂
class MeasureItemFactory {
  MeasureItemFactory._();

  static MeasureItemFactory? _singletonInstance;
  static MeasureItemFactory get _singleton {
    if (_singletonInstance == null) {
      _singletonInstance = MeasureItemFactory._();
      _registerItemCreators();
    }
    return _singletonInstance!;
  }

  final _itemCreatorMap = <String, MeasureItemCreator>{};

  void _register(String typeName, MeasureItemCreator creator,
      [String? suffix]) {
    final key = _buildKey(typeName, suffix);
    _itemCreatorMap[key] = creator;
  }

  MeasureItemCreator? _findCreator(String typeName) {
    final key = typeName; //_buildKey(typeName, suffix);
    if (_itemCreatorMap.containsKey(key)) {
      return _itemCreatorMap[key];
    }
    return null;
  }

  String _buildKey(String typeName, [String? suffix]) {
    return suffix == null ? typeName : '${typeName}_$suffix';
  }

  /// 创建测量项
  ///
  /// [meta] 元信息
  ///
  /// [parent] 父项
  static MeasureItem? createItem(ItemMeta meta, [IMeasureItem? parent]) {
    if (meta.measureType.isEmpty) return null;

    final creator = _singleton._findCreator(meta.measureType);
    if (creator == null) return null;

    final item = creator.call(meta, parent);
    return item;
  }

  static void _registerItemCreators() {
    _singleton._register(MeasureTypes.Distance, StraightLine.createDistance);
    _singleton._register(
        MeasureTypes.Volume, LWHStraightLine.createVolume, "LWH");

    //Ellipse
    _singleton._register(
        MeasureTypes.AreaPerimeterEllipse, Ellipse.createAreaPerimeter);
    _singleton._register(MeasureTypes.VolumeEllipse, Ellipse.createVolume);

    //Polylines
    _singleton._register(
        MeasureTypes.AreaPerimeterPolyline, Polyline.createAreaPerimeter);
  }
}