prepare for multiple apps

2026-04-06 12:23:11 +02:00
parent bd1600e8dc
commit 5afc323f04
904 changed files with 29 additions and 29 deletions
@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 2024-2026 Fabian Freund.
+ *
+ * This file is part of WebLibre
+ * (see https://weblibre.eu).
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+import 'dart:async';
+import 'package:flutter/foundation.dart';
+
+/// A ValueNotifier that acts as a proxy for another ValueNotifier,
+/// sampling its values based on a given duration.
+class SampledValueNotifier<T> extends ValueNotifier<T> {
+  /// The source ValueNotifier to sample from
+  final ValueNotifier<T> _source;
+
+  /// The duration to sample at
+  final Duration _sampleDuration;
+
+  /// Timer for sampling
+  Timer? _timer;
+
+  /// Whether a value has changed since the last sample
+  bool _hasNewValue = false;
+
+  /// Subscription to the source ValueNotifier
+  late final VoidCallback _sourceListener;
+
+  /// Creates a SampledValueNotifier that samples values from [source]
+  /// at the specified [sampleDuration].
+  SampledValueNotifier({
+    required ValueNotifier<T> source,
+    required Duration sampleDuration,
+  }) : _source = source,
+       _sampleDuration = sampleDuration,
+       super(source.value) {
+    // Set up listener for source changes
+    _sourceListener = () {
+      _hasNewValue = true;
+
+      // Start timer if not already running
+      if (_timer == null || !_timer!.isActive) {
+        _startTimer();
+      }
+    };
+
+    _source.addListener(_sourceListener);
+    _startTimer();
+  }
+
+  /// Starts the sampling timer
+  void _startTimer() {
+    _timer?.cancel();
+    _timer = Timer.periodic(_sampleDuration, _onSampleTime);
+  }
+
+  /// Called when it's time to sample
+  void _onSampleTime(Timer timer) {
+    if (_hasNewValue) {
+      value = _source.value;
+      _hasNewValue = false;
+    }
+  }
+
+  @override
+  void dispose() {
+    _timer?.cancel();
+    _source.removeListener(_sourceListener);
+
+    super.dispose();
+  }
+}
+
+extension ValueNotifierSampleExtension<T> on ValueNotifier<T> {
+  /// Creates a new ValueNotifier that samples this ValueNotifier's values
+  /// at the specified [duration].
+  ///
+  /// The returned ValueNotifier must be disposed when no longer needed.
+  ValueNotifier<T> sampleTime(Duration duration) {
+    return SampledValueNotifier<T>(source: this, sampleDuration: duration);
+  }
+}