De-bounce and throttle

function_extension.dart

///
/// [Author] Alex (https://github.com/AlexV525)
/// [Date] 2020-12-26 11:51
///
import 'dart:async';

import 'package:flutter/foundation.dart';

/// 防抖和节流
///
/// 需要注意的是，在方法里进行 [setState] 后，防抖节流都会失效，函数会重新生成新实例。
extension DebounceThrottlingExtension on Function {
  /// 防抖 (debounce)
  VoidCallback debounce([Duration duration = const Duration(seconds: 1)]) {
    assert(duration != null && duration > Duration.zero);
    Timer _debounce;
    return () {
      // 还在时间之内，抛弃上一次
      // 执行最后一次
      if (_debounce?.isActive ?? false) {
        _debounce.cancel();
      }
      _debounce = Timer(duration, () {
        this.call();
      });
    };
  }

  /// 节流 (throttle)
  VoidCallback throttle([Duration duration = const Duration(seconds: 1)]) {
    assert(duration != null && duration > Duration.zero);
    Timer _throttle;
    return () {
      print(_throttle);
      // 执行第一次
      if (_throttle?.isActive ?? false) {
        return;
      }
      this.call();
      _throttle = Timer(duration, () {});
    };
  }
}

/// 而下面的两个方法没有这种顾虑。

/// 防抖
VoidCallback debounce(
  VoidCallback callback, [
  Duration duration = const Duration(seconds: 1),
]) {
  assert(callback != null);
  assert(duration != null && duration > Duration.zero);
  Timer _debounce;
  return () {
    // 还在时间之内，抛弃上一次
    // 执行最后一次
    if (_debounce?.isActive ?? false) {
      _debounce.cancel();
    }
    _debounce = Timer(duration, () {
      callback.call();
    });
  };
}

/// 节流
VoidCallback throttle(
  VoidCallback callback, [
  Duration duration = const Duration(seconds: 1),
]) {
  assert(callback != null);
  assert(duration != null && duration > Duration.zero);
  Timer _throttle;
  return () {
    // 执行第一次
    if (_throttle?.isActive ?? false) {
      return;
    }
    callback.call();
    _throttle = Timer(duration, () {});
  };
}