89 lines
2.7 KiB
Dart
89 lines
2.7 KiB
Dart
import 'package:flutter/material.dart';
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/// Reusable focus memory tracker for screens with multiple focusable items.
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/// Tracks which item was last focused and provides focus restoration.
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class FocusMemoryTracker {
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final Map<String, FocusNode> _nodes = {};
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final Set<String> _focused = {};
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final VoidCallback? _onFocusChanged;
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final String _debugLabelPrefix;
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String? _lastFocusedKey;
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FocusMemoryTracker({VoidCallback? onFocusChanged, String debugLabelPrefix = 'focus'})
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: _onFocusChanged = onFocusChanged,
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_debugLabelPrefix = debugLabelPrefix;
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/// Get or create a focus node for the given key
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FocusNode get(String key, {String? debugLabel}) {
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return _nodes.putIfAbsent(key, () {
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final node = FocusNode(debugLabel: debugLabel ?? '${_debugLabelPrefix}_$key');
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node.addListener(() {
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final wasFocused = _focused.contains(key);
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if (node.hasFocus && !wasFocused) {
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_focused.add(key);
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_lastFocusedKey = key;
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_onFocusChanged?.call();
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} else if (!node.hasFocus && wasFocused) {
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_focused.remove(key);
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_onFocusChanged?.call();
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}
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});
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return node;
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});
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}
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/// Get the last focused key (for focus restoration)
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String? get lastFocusedKey => _lastFocusedKey;
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/// Check if a key is currently focused
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bool isFocused(String key) => _focused.contains(key);
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/// Get a node without creating it (returns null if not found)
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FocusNode? nodeFor(String key) => _nodes[key];
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/// Restore focus to the last focused item, or fallback if provided
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/// Returns true if focus was successfully restored
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bool restoreFocus({String? fallbackKey}) {
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// Try to restore last focused item
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if (_lastFocusedKey != null) {
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final node = _nodes[_lastFocusedKey];
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if (node != null) {
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node.requestFocus();
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return true;
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}
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}
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// Fallback: focus the provided key if available
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if (fallbackKey != null) {
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final node = _nodes[fallbackKey];
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if (node != null) {
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node.requestFocus();
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return true;
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}
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}
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return false;
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}
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/// Remove nodes not in the given set of valid keys (prunes stale nodes)
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void pruneExcept(Set<String> validKeys) {
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final toRemove = _nodes.keys.where((k) => !validKeys.contains(k)).toList();
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for (final key in toRemove) {
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_nodes[key]?.dispose();
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_nodes.remove(key);
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_focused.remove(key);
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}
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// Clear last focused if it was pruned
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if (_lastFocusedKey != null && !validKeys.contains(_lastFocusedKey)) {
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_lastFocusedKey = null;
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}
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}
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/// Dispose all nodes
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void dispose() {
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for (final node in _nodes.values) {
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node.dispose();
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}
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_nodes.clear();
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_focused.clear();
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}
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}
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