Line data    Source code

       1              : import 'dart:async';
       2              : import 'package:flutter/foundation.dart';
       3              : import '../debouncer_config.dart';
       4              : import 'debounce_strategy.dart';
       5              : 
       6              : /// Fires the action on **both** the leading and trailing edge.
       7              : ///
       8              : /// - Leading fire: immediate on first call.
       9              : /// - Trailing fire: once more after [DebouncerConfig.delay] has passed
      10              : ///   since the last call — but only if there were additional calls after
      11              : ///   the initial leading fire.
      12              : ///
      13              : /// Timeline:
      14              : /// ```
      15              : /// calls:  --A--B--C-----------
      16              : /// fires:  --A----------------C
      17              : /// ```
      18              : class BothEdgeStrategy extends DebouncerStrategy {
      19            1 :   const BothEdgeStrategy();
      20              : 
      21            1 :   @override
      22              :   void execute(
      23              :       VoidCallback action,
      24              :       DebouncerConfig config,
      25              :       Timer? currentTimer,
      26              :       void Function(Timer?) updateTimer,
      27              :       ) {
      28            0 :     final isIdle = currentTimer == null || !currentTimer.isActive;
      29              : 
      30            0 :     currentTimer?.cancel();
      31              : 
      32              :     // Always schedule a trailing fire.
      33            4 :     updateTimer(Timer(config.delay, () {
      34            1 :       action();
      35            1 :       updateTimer(null);
      36              :     }));
      37              : 
      38              :     // Leading fire on first call only.
      39              :     if (isIdle) {
      40            1 :       action();
      41              :     }
      42              :   }
      43              : }