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 immediately on the **first** call, then ignores
       7              : /// subsequent calls until [DebouncerConfig.delay] has elapsed.
       8              : ///
       9              : /// Ideal for button clicks and submit actions where you want instant
      10              : /// feedback but need to prevent accidental double-submission.
      11              : ///
      12              : /// Timeline:
      13              : /// ```
      14              : /// calls:  --A--B--C-----------
      15              : /// fires:  --A
      16              : /// ```
      17              : class LeadingEdgeStrategy extends DebouncerStrategy {
      18            1 :   const LeadingEdgeStrategy();
      19              : 
      20            1 :   @override
      21              :   void execute(
      22              :       VoidCallback action,
      23              :       DebouncerConfig config,
      24              :       Timer? currentTimer,
      25              :       void Function(Timer?) updateTimer,
      26              :       ) {
      27            1 :     final isIdle = currentTimer == null || !currentTimer.isActive;
      28            1 :     currentTimer?.cancel();
      29              : 
      30              :     // Schedule a cooldown timer (action won't fire again until this expires).
      31            5 :     updateTimer(Timer(config.delay, () => updateTimer(null)));
      32              : 
      33              :     if (isIdle) {
      34            1 :       action();
      35              :     }
      36              :   }
      37              : }