useTrackedSignal

Creates a new **TrackedSignal** and subscribes to it.

Creates a new TrackedSignal and subscribes to it.

A TrackedSignal extends standard signals by maintaining a record of its previous value alongside its current value. This allows you to inspect history changes, calculate delta differences, or perform custom transition animations.

You can access both the current value using .value and the previous value using .previousValue.

Parameters#

value: The initial value of the signal.
options: The options for the signal.
keys: A list of objects to watch. If any key changes, the signal is re-created.

Example#

import 'package:flutter/material.dart';
import 'package:flutter_hooks/flutter_hooks.dart';
import 'package:signals_hooks/signals_hooks.dart';

class DeltaCounterWidget extends HookWidget {
  const DeltaCounterWidget({super.key});

  @override
  Widget build(BuildContext context) {
    final count = useTrackedSignal(0);

    return Column(
      children: [
        Text('Current: ${count.value}'),
        Text('Previous: ${count.previousValue ?? "N/A"}'),
        ElevatedButton(
          onPressed: () => count.value++,
          child: const Text('Increment'),
        ),
      ],
    );
  }
}