1 | // Copyright 2014 The Flutter Authors. All rights reserved. |
2 | // Use of this source code is governed by a BSD-style license that can be |
3 | // found in the LICENSE file. |
4 | |
5 | import 'package:flutter/foundation.dart'; |
6 | import 'package:flutter/gestures.dart'; |
7 | import 'package:flutter/rendering.dart'; |
8 | import 'package:flutter/scheduler.dart'; |
9 | import 'package:flutter/services.dart'; |
10 | |
11 | import 'basic.dart'; |
12 | import 'focus_manager.dart'; |
13 | import 'focus_scope.dart'; |
14 | import 'framework.dart'; |
15 | import 'media_query.dart'; |
16 | import 'shortcuts.dart'; |
17 | |
18 | /// Returns the parent [BuildContext] of a given `context`. |
19 | /// |
20 | /// [BuildContext] (or rather, [Element]) doesn't have a `parent` accessor, but |
21 | /// the parent can be obtained using [BuildContext.visitAncestorElements]. |
22 | /// |
23 | /// [BuildContext.getElementForInheritedWidgetOfExactType] returns the same |
24 | /// [BuildContext] if it happens to be of the correct type. To obtain the |
25 | /// previous inherited widget, the search must therefore start from the parent; |
26 | /// this is what [_getParent] is used for. |
27 | /// |
28 | /// [_getParent] is O(1), because it always stops at the first ancestor. |
29 | BuildContext _getParent(BuildContext context) { |
30 | late final BuildContext parent; |
31 | context.visitAncestorElements((Element ancestor) { |
32 | parent = ancestor; |
33 | return false; |
34 | }); |
35 | return parent; |
36 | } |
37 | |
38 | /// An abstract class representing a particular configuration of an [Action]. |
39 | /// |
40 | /// This class is what the [Shortcuts.shortcuts] map has as values, and is used |
41 | /// by an [ActionDispatcher] to look up an action and invoke it, giving it this |
42 | /// object to extract configuration information from. |
43 | /// |
44 | /// See also: |
45 | /// |
46 | /// * [Shortcuts], a widget used to bind key combinations to [Intent]s. |
47 | /// * [Actions], a widget used to map [Intent]s to [Action]s. |
48 | /// * [Actions.invoke], which invokes the action associated with a specified |
49 | /// [Intent] using the [Actions] widget that most tightly encloses the given |
50 | /// [BuildContext]. |
51 | @immutable |
52 | abstract class Intent with Diagnosticable { |
53 | /// Abstract const constructor. This constructor enables subclasses to provide |
54 | /// const constructors so that they can be used in const expressions. |
55 | const Intent(); |
56 | |
57 | /// An intent that is mapped to a [DoNothingAction], which, as the name |
58 | /// implies, does nothing. |
59 | /// |
60 | /// This Intent is mapped to an action in the [WidgetsApp] that does nothing, |
61 | /// so that it can be bound to a key in a [Shortcuts] widget in order to |
62 | /// disable a key binding made above it in the hierarchy. |
63 | static const DoNothingIntent doNothing = DoNothingIntent._(); |
64 | } |
65 | |
66 | /// The kind of callback that an [Action] uses to notify of changes to the |
67 | /// action's state. |
68 | /// |
69 | /// To register an action listener, call [Action.addActionListener]. |
70 | typedef ActionListenerCallback = void Function(Action<Intent> action); |
71 | |
72 | /// Base class for an action or command to be performed. |
73 | /// |
74 | /// {@youtube 560 315 https://www.youtube.com/watch?v=XawP1i314WM} |
75 | /// |
76 | /// [Action]s are typically invoked as a result of a user action. For example, |
77 | /// the [Shortcuts] widget will map a keyboard shortcut into an [Intent], which |
78 | /// is given to an [ActionDispatcher] to map the [Intent] to an [Action] and |
79 | /// invoke it. |
80 | /// |
81 | /// The [ActionDispatcher] can invoke an [Action] on the primary focus, or |
82 | /// without regard for focus. |
83 | /// |
84 | /// ### Action Overriding |
85 | /// |
86 | /// When using a leaf widget to build a more specialized widget, it's sometimes |
87 | /// desirable to change the default handling of an [Intent] defined in the leaf |
88 | /// widget. For instance, [TextField]'s [SelectAllTextIntent] by default selects |
89 | /// the text it currently contains, but in a US phone number widget that |
90 | /// consists of 3 different [TextField]s (area code, prefix and line number), |
91 | /// [SelectAllTextIntent] should instead select the text within all 3 |
92 | /// [TextField]s. |
93 | /// |
94 | /// An overridable [Action] is a special kind of [Action] created using the |
95 | /// [Action.overridable] constructor. It has access to a default [Action], and a |
96 | /// nullable override [Action]. It has the same behavior as its override if that |
97 | /// exists, and mirrors the behavior of its `defaultAction` otherwise. |
98 | /// |
99 | /// The [Action.overridable] constructor creates overridable [Action]s that use |
100 | /// a [BuildContext] to find a suitable override in its ancestor [Actions] |
101 | /// widget. This can be used to provide a default implementation when creating a |
102 | /// general purpose leaf widget, and later override it when building a more |
103 | /// specialized widget using that leaf widget. Using the [TextField] example |
104 | /// above, the [TextField] widget uses an overridable [Action] to provide a |
105 | /// sensible default for [SelectAllTextIntent], while still allowing app |
106 | /// developers to change that if they add an ancestor [Actions] widget that maps |
107 | /// [SelectAllTextIntent] to a different [Action]. |
108 | /// |
109 | /// See the article on [Using Actions and |
110 | /// Shortcuts](https://docs.flutter.dev/development/ui/advanced/actions_and_shortcuts) |
111 | /// for a detailed explanation. |
112 | /// |
113 | /// See also: |
114 | /// |
115 | /// * [Shortcuts], which is a widget that contains a key map, in which it looks |
116 | /// up key combinations in order to invoke actions. |
117 | /// * [Actions], which is a widget that defines a map of [Intent] to [Action] |
118 | /// and allows redefining of actions for its descendants. |
119 | /// * [ActionDispatcher], a class that takes an [Action] and invokes it, passing |
120 | /// a given [Intent]. |
121 | /// * [Action.overridable] for an example on how to make an [Action] |
122 | /// overridable. |
123 | abstract class Action<T extends Intent> with Diagnosticable { |
124 | /// Creates an [Action]. |
125 | Action(); |
126 | |
127 | /// Creates an [Action] that allows itself to be overridden by the closest |
128 | /// ancestor [Action] in the given [context] that handles the same [Intent], |
129 | /// if one exists. |
130 | /// |
131 | /// When invoked, the resulting [Action] tries to find the closest [Action] in |
132 | /// the given `context` that handles the same type of [Intent] as the |
133 | /// `defaultAction`, then calls its [Action.invoke] method. When no override |
134 | /// [Action]s can be found, it invokes the `defaultAction`. |
135 | /// |
136 | /// An overridable action delegates everything to its override if one exists, |
137 | /// and has the same behavior as its `defaultAction` otherwise. For this |
138 | /// reason, the override has full control over whether and how an [Intent] |
139 | /// should be handled, or a key event should be consumed. An override |
140 | /// [Action]'s [callingAction] property will be set to the [Action] it |
141 | /// currently overrides, giving it access to the default behavior. See the |
142 | /// [callingAction] property for an example. |
143 | /// |
144 | /// The `context` argument is the [BuildContext] to find the override with. It |
145 | /// is typically a [BuildContext] above the [Actions] widget that contains |
146 | /// this overridable [Action]. |
147 | /// |
148 | /// The `defaultAction` argument is the [Action] to be invoked where there's |
149 | /// no ancestor [Action]s can't be found in `context` that handle the same |
150 | /// type of [Intent]. |
151 | /// |
152 | /// This is useful for providing a set of default [Action]s in a leaf widget |
153 | /// to allow further overriding, or to allow the [Intent] to propagate to |
154 | /// parent widgets that also support this [Intent]. |
155 | /// |
156 | /// {@tool dartpad} |
157 | /// This sample shows how to implement a rudimentary `CopyableText` widget |
158 | /// that responds to Ctrl-C by copying its own content to the clipboard. |
159 | /// |
160 | /// if `CopyableText` is to be provided in a package, developers using the |
161 | /// widget may want to change how copying is handled. As the author of the |
162 | /// package, you can enable that by making the corresponding [Action] |
163 | /// overridable. In the second part of the code sample, three `CopyableText` |
164 | /// widgets are used to build a verification code widget which overrides the |
165 | /// "copy" action by copying the combined numbers from all three `CopyableText` |
166 | /// widgets. |
167 | /// |
168 | /// ** See code in examples/api/lib/widgets/actions/action.action_overridable.0.dart ** |
169 | /// {@end-tool} |
170 | factory Action.overridable({ |
171 | required Action<T> defaultAction, |
172 | required BuildContext context, |
173 | }) { |
174 | return defaultAction._makeOverridableAction(context); |
175 | } |
176 | |
177 | final ObserverList<ActionListenerCallback> _listeners = ObserverList<ActionListenerCallback>(); |
178 | |
179 | Action<T>? _currentCallingAction; |
180 | // ignore: use_setters_to_change_properties, (code predates enabling of this lint) |
181 | void _updateCallingAction(Action<T>? value) { |
182 | _currentCallingAction = value; |
183 | } |
184 | |
185 | /// The [Action] overridden by this [Action]. |
186 | /// |
187 | /// The [Action.overridable] constructor creates an overridable [Action] that |
188 | /// allows itself to be overridden by the closest ancestor [Action], and falls |
189 | /// back to its own `defaultAction` when no overrides can be found. When an |
190 | /// override is present, an overridable [Action] forwards all incoming |
191 | /// method calls to the override, and allows the override to access the |
192 | /// `defaultAction` via its [callingAction] property. |
193 | /// |
194 | /// Before forwarding the call to the override, the overridable [Action] is |
195 | /// responsible for setting [callingAction] to its `defaultAction`, which is |
196 | /// already taken care of by the overridable [Action] created using |
197 | /// [Action.overridable]. |
198 | /// |
199 | /// This property is only non-null when this [Action] is an override of the |
200 | /// [callingAction], and is currently being invoked from [callingAction]. |
201 | /// |
202 | /// Invoking [callingAction]'s methods, or accessing its properties, is |
203 | /// allowed and does not introduce infinite loops or infinite recursions. |
204 | /// |
205 | /// {@tool snippet} |
206 | /// An example `Action` that handles [PasteTextIntent] but has mostly the same |
207 | /// behavior as the overridable action. It's OK to call |
208 | /// `callingAction?.isActionEnabled` in the implementation of this `Action`. |
209 | /// |
210 | /// ```dart |
211 | /// class MyPasteAction extends Action<PasteTextIntent> { |
212 | /// @override |
213 | /// Object? invoke(PasteTextIntent intent) { |
214 | /// print(intent); |
215 | /// return callingAction?.invoke(intent); |
216 | /// } |
217 | /// |
218 | /// @override |
219 | /// bool get isActionEnabled => callingAction?.isActionEnabled ?? false; |
220 | /// |
221 | /// @override |
222 | /// bool consumesKey(PasteTextIntent intent) => callingAction?.consumesKey(intent) ?? false; |
223 | /// } |
224 | /// ``` |
225 | /// {@end-tool} |
226 | @protected |
227 | Action<T>? get callingAction => _currentCallingAction; |
228 | |
229 | /// Gets the type of intent this action responds to. |
230 | Type get intentType => T; |
231 | |
232 | /// Returns true if the action is enabled and is ready to be invoked. |
233 | /// |
234 | /// This will be called by the [ActionDispatcher] before attempting to invoke |
235 | /// the action. |
236 | /// |
237 | /// If the action's enable state depends on a [BuildContext], subclass |
238 | /// [ContextAction] instead of [Action]. |
239 | bool isEnabled(T intent) => isActionEnabled; |
240 | |
241 | bool _isEnabled(T intent, BuildContext? context) { |
242 | final Action<T> self = this; |
243 | if (self is ContextAction<T>) { |
244 | return self.isEnabled(intent, context); |
245 | } |
246 | return self.isEnabled(intent); |
247 | } |
248 | |
249 | /// Whether this [Action] is inherently enabled. |
250 | /// |
251 | /// If [isActionEnabled] is false, then this [Action] is disabled for any |
252 | /// given [Intent]. |
253 | // |
254 | /// If the enabled state changes, overriding subclasses must call |
255 | /// [notifyActionListeners] to notify any listeners of the change. |
256 | /// |
257 | /// In the case of an overridable `Action`, accessing this property creates |
258 | /// an dependency on the overridable `Action`s `lookupContext`. |
259 | bool get isActionEnabled => true; |
260 | |
261 | /// Indicates whether this action should treat key events mapped to this |
262 | /// action as being "handled" when it is invoked via the key event. |
263 | /// |
264 | /// If the key is handled, then no other key event handlers in the focus chain |
265 | /// will receive the event. |
266 | /// |
267 | /// If the key event is not handled, it will be passed back to the engine, and |
268 | /// continue to be processed there, allowing text fields and non-Flutter |
269 | /// widgets to receive the key event. |
270 | /// |
271 | /// The default implementation returns true. |
272 | bool consumesKey(T intent) => true; |
273 | |
274 | /// Converts the result of [invoke] of this action to a [KeyEventResult]. |
275 | /// |
276 | /// This is typically used when the action is invoked in response to a keyboard |
277 | /// shortcut. |
278 | /// |
279 | /// The [invokeResult] argument is the value returned by the [invoke] method. |
280 | /// |
281 | /// By default, calls [consumesKey] and converts the returned boolean to |
282 | /// [KeyEventResult.handled] if it's true, and [KeyEventResult.skipRemainingHandlers] |
283 | /// if it's false. |
284 | /// |
285 | /// Concrete implementations may refine the type of [invokeResult], since |
286 | /// they know the type returned by [invoke]. |
287 | KeyEventResult toKeyEventResult(T intent, covariant Object? invokeResult) { |
288 | return consumesKey(intent) |
289 | ? KeyEventResult.handled |
290 | : KeyEventResult.skipRemainingHandlers; |
291 | } |
292 | |
293 | /// Called when the action is to be performed. |
294 | /// |
295 | /// This is called by the [ActionDispatcher] when an action is invoked via |
296 | /// [Actions.invoke], or when an action is invoked using |
297 | /// [ActionDispatcher.invokeAction] directly. |
298 | /// |
299 | /// This method is only meant to be invoked by an [ActionDispatcher], or by |
300 | /// its subclasses, and only when [isEnabled] is true. |
301 | /// |
302 | /// When overriding this method, the returned value can be any [Object], but |
303 | /// changing the return type of the override to match the type of the returned |
304 | /// value provides more type safety. |
305 | /// |
306 | /// For instance, if an override of [invoke] returned an `int`, then it might |
307 | /// be defined like so: |
308 | /// |
309 | /// ```dart |
310 | /// class IncrementIntent extends Intent { |
311 | /// const IncrementIntent({required this.index}); |
312 | /// |
313 | /// final int index; |
314 | /// } |
315 | /// |
316 | /// class MyIncrementAction extends Action<IncrementIntent> { |
317 | /// @override |
318 | /// int invoke(IncrementIntent intent) { |
319 | /// return intent.index + 1; |
320 | /// } |
321 | /// } |
322 | /// ``` |
323 | /// |
324 | /// To receive the result of invoking an action, it must be invoked using |
325 | /// [Actions.invoke], or by invoking it using an [ActionDispatcher]. An action |
326 | /// invoked via a [Shortcuts] widget will have its return value ignored. |
327 | /// |
328 | /// If the action's behavior depends on a [BuildContext], subclass |
329 | /// [ContextAction] instead of [Action]. |
330 | @protected |
331 | Object? invoke(T intent); |
332 | |
333 | Object? _invoke(T intent, BuildContext? context) { |
334 | final Action<T> self = this; |
335 | if (self is ContextAction<T>) { |
336 | return self.invoke(intent, context); |
337 | } |
338 | return self.invoke(intent); |
339 | } |
340 | |
341 | /// Register a callback to listen for changes to the state of this action. |
342 | /// |
343 | /// If you call this, you must call [removeActionListener] a matching number |
344 | /// of times, or memory leaks will occur. To help manage this and avoid memory |
345 | /// leaks, use of the [ActionListener] widget to register and unregister your |
346 | /// listener appropriately is highly recommended. |
347 | /// |
348 | /// {@template flutter.widgets.Action.addActionListener} |
349 | /// If a listener had been added twice, and is removed once during an |
350 | /// iteration (i.e. in response to a notification), it will still be called |
351 | /// again. If, on the other hand, it is removed as many times as it was |
352 | /// registered, then it will no longer be called. This odd behavior is the |
353 | /// result of the [Action] not being able to determine which listener |
354 | /// is being removed, since they are identical, and therefore conservatively |
355 | /// still calling all the listeners when it knows that any are still |
356 | /// registered. |
357 | /// |
358 | /// This surprising behavior can be unexpectedly observed when registering a |
359 | /// listener on two separate objects which are both forwarding all |
360 | /// registrations to a common upstream object. |
361 | /// {@endtemplate} |
362 | @mustCallSuper |
363 | void addActionListener(ActionListenerCallback listener) => _listeners.add(listener); |
364 | |
365 | /// Remove a previously registered closure from the list of closures that are |
366 | /// notified when the object changes. |
367 | /// |
368 | /// If the given listener is not registered, the call is ignored. |
369 | /// |
370 | /// If you call [addActionListener], you must call this method a matching |
371 | /// number of times, or memory leaks will occur. To help manage this and avoid |
372 | /// memory leaks, use of the [ActionListener] widget to register and |
373 | /// unregister your listener appropriately is highly recommended. |
374 | /// |
375 | /// {@macro flutter.widgets.Action.addActionListener} |
376 | @mustCallSuper |
377 | void removeActionListener(ActionListenerCallback listener) => _listeners.remove(listener); |
378 | |
379 | /// Call all the registered listeners. |
380 | /// |
381 | /// Subclasses should call this method whenever the object changes, to notify |
382 | /// any clients the object may have changed. Listeners that are added during this |
383 | /// iteration will not be visited. Listeners that are removed during this |
384 | /// iteration will not be visited after they are removed. |
385 | /// |
386 | /// Exceptions thrown by listeners will be caught and reported using |
387 | /// [FlutterError.reportError]. |
388 | /// |
389 | /// Surprising behavior can result when reentrantly removing a listener (i.e. |
390 | /// in response to a notification) that has been registered multiple times. |
391 | /// See the discussion at [removeActionListener]. |
392 | @protected |
393 | @visibleForTesting |
394 | @pragma('vm:notify-debugger-on-exception' ) |
395 | void notifyActionListeners() { |
396 | if (_listeners.isEmpty) { |
397 | return; |
398 | } |
399 | |
400 | // Make a local copy so that a listener can unregister while the list is |
401 | // being iterated over. |
402 | final List<ActionListenerCallback> localListeners = List<ActionListenerCallback>.of(_listeners); |
403 | for (final ActionListenerCallback listener in localListeners) { |
404 | InformationCollector? collector; |
405 | assert(() { |
406 | collector = () => <DiagnosticsNode>[ |
407 | DiagnosticsProperty<Action<T>>( |
408 | 'The $runtimeType sending notification was' , |
409 | this, |
410 | style: DiagnosticsTreeStyle.errorProperty, |
411 | ), |
412 | ]; |
413 | return true; |
414 | }()); |
415 | try { |
416 | if (_listeners.contains(listener)) { |
417 | listener(this); |
418 | } |
419 | } catch (exception, stack) { |
420 | FlutterError.reportError(FlutterErrorDetails( |
421 | exception: exception, |
422 | stack: stack, |
423 | library: 'widgets library' , |
424 | context: ErrorDescription('while dispatching notifications for $runtimeType' ), |
425 | informationCollector: collector, |
426 | )); |
427 | } |
428 | } |
429 | } |
430 | |
431 | Action<T> _makeOverridableAction(BuildContext context) { |
432 | return _OverridableAction<T>(defaultAction: this, lookupContext: context); |
433 | } |
434 | } |
435 | |
436 | /// A helper widget for making sure that listeners on an action are removed properly. |
437 | /// |
438 | /// Listeners on the [Action] class must have their listener callbacks removed |
439 | /// with [Action.removeActionListener] when the listener is disposed of. This widget |
440 | /// helps with that, by providing a lifetime for the connection between the |
441 | /// [listener] and the [Action], and by handling the adding and removing of |
442 | /// the [listener] at the right points in the widget lifecycle. |
443 | /// |
444 | /// If you listen to an [Action] widget in a widget hierarchy, you should use |
445 | /// this widget. If you are using an [Action] outside of a widget context, then |
446 | /// you must call removeListener yourself. |
447 | /// |
448 | /// {@tool dartpad} |
449 | /// This example shows how ActionListener handles adding and removing of |
450 | /// the [listener] in the widget lifecycle. |
451 | /// |
452 | /// ** See code in examples/api/lib/widgets/actions/action_listener.0.dart ** |
453 | /// {@end-tool} |
454 | /// |
455 | @immutable |
456 | class ActionListener extends StatefulWidget { |
457 | /// Create a const [ActionListener]. |
458 | const ActionListener({ |
459 | super.key, |
460 | required this.listener, |
461 | required this.action, |
462 | required this.child, |
463 | }); |
464 | |
465 | /// The [ActionListenerCallback] callback to register with the [action]. |
466 | final ActionListenerCallback listener; |
467 | |
468 | /// The [Action] that the callback will be registered with. |
469 | final Action<Intent> action; |
470 | |
471 | /// {@macro flutter.widgets.ProxyWidget.child} |
472 | final Widget child; |
473 | |
474 | @override |
475 | State<ActionListener> createState() => _ActionListenerState(); |
476 | } |
477 | |
478 | class _ActionListenerState extends State<ActionListener> { |
479 | @override |
480 | void initState() { |
481 | super.initState(); |
482 | widget.action.addActionListener(widget.listener); |
483 | } |
484 | |
485 | @override |
486 | void didUpdateWidget(ActionListener oldWidget) { |
487 | super.didUpdateWidget(oldWidget); |
488 | if (oldWidget.action == widget.action && oldWidget.listener == widget.listener) { |
489 | return; |
490 | } |
491 | oldWidget.action.removeActionListener(oldWidget.listener); |
492 | widget.action.addActionListener(widget.listener); |
493 | } |
494 | |
495 | @override |
496 | void dispose() { |
497 | widget.action.removeActionListener(widget.listener); |
498 | super.dispose(); |
499 | } |
500 | |
501 | @override |
502 | Widget build(BuildContext context) => widget.child; |
503 | } |
504 | |
505 | /// An abstract [Action] subclass that adds an optional [BuildContext] to the |
506 | /// [isEnabled] and [invoke] methods to be able to provide context to actions. |
507 | /// |
508 | /// [ActionDispatcher.invokeAction] checks to see if the action it is invoking |
509 | /// is a [ContextAction], and if it is, supplies it with a context. |
510 | abstract class ContextAction<T extends Intent> extends Action<T> { |
511 | /// Returns true if the action is enabled and is ready to be invoked. |
512 | /// |
513 | /// This will be called by the [ActionDispatcher] before attempting to invoke |
514 | /// the action. |
515 | /// |
516 | /// The optional `context` parameter is the context of the invocation of the |
517 | /// action, and in the case of an action invoked by a [ShortcutManager], via |
518 | /// a [Shortcuts] widget, will be the context of the [Shortcuts] widget. |
519 | @override |
520 | bool isEnabled(T intent, [BuildContext? context]) => super.isEnabled(intent); |
521 | |
522 | /// Called when the action is to be performed. |
523 | /// |
524 | /// This is called by the [ActionDispatcher] when an action is invoked via |
525 | /// [Actions.invoke], or when an action is invoked using |
526 | /// [ActionDispatcher.invokeAction] directly. |
527 | /// |
528 | /// This method is only meant to be invoked by an [ActionDispatcher], or by |
529 | /// its subclasses, and only when [isEnabled] is true. |
530 | /// |
531 | /// The optional `context` parameter is the context of the invocation of the |
532 | /// action, and in the case of an action invoked by a [ShortcutManager], via |
533 | /// a [Shortcuts] widget, will be the context of the [Shortcuts] widget. |
534 | /// |
535 | /// When overriding this method, the returned value can be any Object, but |
536 | /// changing the return type of the override to match the type of the returned |
537 | /// value provides more type safety. |
538 | /// |
539 | /// For instance, if an override of [invoke] returned an `int`, then it might |
540 | /// be defined like so: |
541 | /// |
542 | /// ```dart |
543 | /// class IncrementIntent extends Intent { |
544 | /// const IncrementIntent({required this.index}); |
545 | /// |
546 | /// final int index; |
547 | /// } |
548 | /// |
549 | /// class MyIncrementAction extends ContextAction<IncrementIntent> { |
550 | /// @override |
551 | /// int invoke(IncrementIntent intent, [BuildContext? context]) { |
552 | /// return intent.index + 1; |
553 | /// } |
554 | /// } |
555 | /// ``` |
556 | @protected |
557 | @override |
558 | Object? invoke(T intent, [BuildContext? context]); |
559 | |
560 | @override |
561 | ContextAction<T> _makeOverridableAction(BuildContext context) { |
562 | return _OverridableContextAction<T>(defaultAction: this, lookupContext: context); |
563 | } |
564 | } |
565 | |
566 | /// The signature of a callback accepted by [CallbackAction.onInvoke]. |
567 | /// |
568 | /// Such callbacks are implementations of [Action.invoke]. The returned value |
569 | /// is the return value of [Action.invoke], the argument is the intent passed |
570 | /// to [Action.invoke], and so forth. |
571 | typedef OnInvokeCallback<T extends Intent> = Object? Function(T intent); |
572 | |
573 | /// An [Action] that takes a callback in order to configure it without having to |
574 | /// create an explicit [Action] subclass just to call a callback. |
575 | /// |
576 | /// See also: |
577 | /// |
578 | /// * [Shortcuts], which is a widget that contains a key map, in which it looks |
579 | /// up key combinations in order to invoke actions. |
580 | /// * [Actions], which is a widget that defines a map of [Intent] to [Action] |
581 | /// and allows redefining of actions for its descendants. |
582 | /// * [ActionDispatcher], a class that takes an [Action] and invokes it using a |
583 | /// [FocusNode] for context. |
584 | class CallbackAction<T extends Intent> extends Action<T> { |
585 | /// A constructor for a [CallbackAction]. |
586 | /// |
587 | /// The given callback is used as the implementation of [invoke]. |
588 | CallbackAction({required this.onInvoke}); |
589 | |
590 | /// The callback to be called when invoked. |
591 | /// |
592 | /// This is effectively the implementation of [invoke]. |
593 | @protected |
594 | final OnInvokeCallback<T> onInvoke; |
595 | |
596 | @override |
597 | Object? invoke(T intent) => onInvoke(intent); |
598 | } |
599 | |
600 | /// An action dispatcher that invokes the actions given to it. |
601 | /// |
602 | /// The [invokeAction] method on this class directly calls the [Action.invoke] |
603 | /// method on the [Action] object. |
604 | /// |
605 | /// For [ContextAction] actions, if no `context` is provided, the |
606 | /// [BuildContext] of the [primaryFocus] is used instead. |
607 | /// |
608 | /// See also: |
609 | /// |
610 | /// - [ShortcutManager], that uses this class to invoke actions. |
611 | /// - [Shortcuts] widget, which defines key mappings to [Intent]s. |
612 | /// - [Actions] widget, which defines a mapping between a in [Intent] type and |
613 | /// an [Action]. |
614 | class ActionDispatcher with Diagnosticable { |
615 | /// Creates an action dispatcher that invokes actions directly. |
616 | const ActionDispatcher(); |
617 | |
618 | /// Invokes the given `action`, passing it the given `intent`. |
619 | /// |
620 | /// The action will be invoked with the given `context`, if given, but only if |
621 | /// the action is a [ContextAction] subclass. If no `context` is given, and |
622 | /// the action is a [ContextAction], then the context from the [primaryFocus] |
623 | /// is used. |
624 | /// |
625 | /// Returns the object returned from [Action.invoke]. |
626 | /// |
627 | /// The caller must receive a `true` result from [Action.isEnabled] before |
628 | /// calling this function (or [ContextAction.isEnabled] with the same |
629 | /// `context`, if the `action` is a [ContextAction]). This function will |
630 | /// assert if the action is not enabled when called. |
631 | /// |
632 | /// Consider using [invokeActionIfEnabled] to invoke the action conditionally |
633 | /// based on whether it is enabled or not, without having to check first. |
634 | Object? invokeAction( |
635 | covariant Action<Intent> action, |
636 | covariant Intent intent, [ |
637 | BuildContext? context, |
638 | ]) { |
639 | final BuildContext? target = context ?? primaryFocus?.context; |
640 | assert(action._isEnabled(intent, target), 'Action must be enabled when calling invokeAction' ); |
641 | return action._invoke(intent, target); |
642 | } |
643 | |
644 | /// Invokes the given `action`, passing it the given `intent`, but only if the |
645 | /// action is enabled. |
646 | /// |
647 | /// The action will be invoked with the given `context`, if given, but only if |
648 | /// the action is a [ContextAction] subclass. If no `context` is given, and |
649 | /// the action is a [ContextAction], then the context from the [primaryFocus] |
650 | /// is used. |
651 | /// |
652 | /// The return value has two components. The first is a boolean indicating if |
653 | /// the action was enabled (as per [Action.isEnabled]). If this is false, the |
654 | /// second return value is null. Otherwise, the second return value is the |
655 | /// object returned from [Action.invoke]. |
656 | /// |
657 | /// Consider using [invokeAction] if the enabled state of the action is not in |
658 | /// question; this avoids calling [Action.isEnabled] redundantly. |
659 | (bool, Object?) invokeActionIfEnabled( |
660 | covariant Action<Intent> action, |
661 | covariant Intent intent, [ |
662 | BuildContext? context, |
663 | ]) { |
664 | final BuildContext? target = context ?? primaryFocus?.context; |
665 | if (action._isEnabled(intent, target)) { |
666 | return (true, action._invoke(intent, target)); |
667 | } |
668 | return (false, null); |
669 | } |
670 | } |
671 | |
672 | /// A widget that maps [Intent]s to [Action]s to be used by its descendants |
673 | /// when invoking an [Action]. |
674 | /// |
675 | /// {@youtube 560 315 https://www.youtube.com/watch?v=XawP1i314WM} |
676 | /// |
677 | /// Actions are typically invoked using [Shortcuts]. They can also be invoked |
678 | /// using [Actions.invoke] on a context containing an ambient [Actions] widget. |
679 | /// |
680 | /// {@tool dartpad} |
681 | /// This example creates a custom [Action] subclass `ModifyAction` for modifying |
682 | /// a model, and another, `SaveAction` for saving it. |
683 | /// |
684 | /// This example demonstrates passing arguments to the [Intent] to be carried to |
685 | /// the [Action]. Actions can get data either from their own construction (like |
686 | /// the `model` in this example), or from the intent passed to them when invoked |
687 | /// (like the increment `amount` in this example). |
688 | /// |
689 | /// This example also demonstrates how to use Intents to limit a widget's |
690 | /// dependencies on its surroundings. The `SaveButton` widget defined in this |
691 | /// example can invoke actions defined in its ancestor widgets, which can be |
692 | /// customized to match the part of the widget tree that it is in. It doesn't |
693 | /// need to know about the `SaveAction` class, only the `SaveIntent`, and it |
694 | /// only needs to know about a value notifier, not the entire model. |
695 | /// |
696 | /// ** See code in examples/api/lib/widgets/actions/actions.0.dart ** |
697 | /// {@end-tool} |
698 | /// |
699 | /// See also: |
700 | /// |
701 | /// * [Shortcuts], a widget used to bind key combinations to [Intent]s. |
702 | /// * [Intent], a class that contains configuration information for running an |
703 | /// [Action]. |
704 | /// * [Action], a class for containing and defining an invocation of a user |
705 | /// action. |
706 | /// * [ActionDispatcher], the object that this widget uses to manage actions. |
707 | class Actions extends StatefulWidget { |
708 | /// Creates an [Actions] widget. |
709 | const Actions({ |
710 | super.key, |
711 | this.dispatcher, |
712 | required this.actions, |
713 | required this.child, |
714 | }); |
715 | |
716 | /// The [ActionDispatcher] object that invokes actions. |
717 | /// |
718 | /// This is what is returned from [Actions.of], and used by [Actions.invoke]. |
719 | /// |
720 | /// If this [dispatcher] is null, then [Actions.of] and [Actions.invoke] will |
721 | /// look up the tree until they find an Actions widget that has a dispatcher |
722 | /// set. If no such widget is found, then they will return/use a |
723 | /// default-constructed [ActionDispatcher]. |
724 | final ActionDispatcher? dispatcher; |
725 | |
726 | /// {@template flutter.widgets.actions.actions} |
727 | /// A map of [Intent] keys to [Action<Intent>] objects that defines which |
728 | /// actions this widget knows about. |
729 | /// |
730 | /// For performance reasons, it is recommended that a pre-built map is |
731 | /// passed in here (e.g. a final variable from your widget class) instead of |
732 | /// defining it inline in the build function. |
733 | /// {@endtemplate} |
734 | final Map<Type, Action<Intent>> actions; |
735 | |
736 | /// {@macro flutter.widgets.ProxyWidget.child} |
737 | final Widget child; |
738 | |
739 | // Visits the Actions widget ancestors of the given element using |
740 | // getElementForInheritedWidgetOfExactType. Returns true if the visitor found |
741 | // what it was looking for. |
742 | static bool _visitActionsAncestors(BuildContext context, bool Function(InheritedElement element) visitor) { |
743 | if (!context.mounted) { |
744 | return false; |
745 | } |
746 | InheritedElement? actionsElement = context.getElementForInheritedWidgetOfExactType<_ActionsScope>(); |
747 | while (actionsElement != null) { |
748 | if (visitor(actionsElement)) { |
749 | break; |
750 | } |
751 | // _getParent is needed here because |
752 | // context.getElementForInheritedWidgetOfExactType will return itself if it |
753 | // happens to be of the correct type. |
754 | final BuildContext parent = _getParent(actionsElement); |
755 | actionsElement = parent.getElementForInheritedWidgetOfExactType<_ActionsScope>(); |
756 | } |
757 | return actionsElement != null; |
758 | } |
759 | |
760 | // Finds the nearest valid ActionDispatcher, or creates a new one if it |
761 | // doesn't find one. |
762 | static ActionDispatcher _findDispatcher(BuildContext context) { |
763 | ActionDispatcher? dispatcher; |
764 | _visitActionsAncestors(context, (InheritedElement element) { |
765 | final ActionDispatcher? found = (element.widget as _ActionsScope).dispatcher; |
766 | if (found != null) { |
767 | dispatcher = found; |
768 | return true; |
769 | } |
770 | return false; |
771 | }); |
772 | return dispatcher ?? const ActionDispatcher(); |
773 | } |
774 | |
775 | /// Returns a [VoidCallback] handler that invokes the bound action for the |
776 | /// given `intent` if the action is enabled, and returns null if the action is |
777 | /// not enabled, or no matching action is found. |
778 | /// |
779 | /// This is intended to be used in widgets which have something similar to an |
780 | /// `onTap` handler, which takes a `VoidCallback`, and can be set to the |
781 | /// result of calling this function. |
782 | /// |
783 | /// Creates a dependency on the [Actions] widget that maps the bound action so |
784 | /// that if the actions change, the context will be rebuilt and find the |
785 | /// updated action. |
786 | /// |
787 | /// The value returned from the [Action.invoke] method is discarded when the |
788 | /// returned callback is called. If the return value is needed, consider using |
789 | /// [Actions.invoke] instead. |
790 | static VoidCallback? handler<T extends Intent>(BuildContext context, T intent) { |
791 | final Action<T>? action = Actions.maybeFind<T>(context); |
792 | if (action != null && action._isEnabled(intent, context)) { |
793 | return () { |
794 | // Could be that the action was enabled when the closure was created, |
795 | // but is now no longer enabled, so check again. |
796 | if (action._isEnabled(intent, context)) { |
797 | Actions.of(context).invokeAction(action, intent, context); |
798 | } |
799 | }; |
800 | } |
801 | return null; |
802 | } |
803 | |
804 | /// Finds the [Action] bound to the given intent type `T` in the given `context`. |
805 | /// |
806 | /// Creates a dependency on the [Actions] widget that maps the bound action so |
807 | /// that if the actions change, the context will be rebuilt and find the |
808 | /// updated action. |
809 | /// |
810 | /// The optional `intent` argument supplies the type of the intent to look for |
811 | /// if the concrete type of the intent sought isn't available. If not |
812 | /// supplied, then `T` is used. |
813 | /// |
814 | /// If no [Actions] widget surrounds the given context, this function will |
815 | /// assert in debug mode, and throw an exception in release mode. |
816 | /// |
817 | /// See also: |
818 | /// |
819 | /// * [maybeFind], which is similar to this function, but will return null if |
820 | /// no [Actions] ancestor is found. |
821 | static Action<T> find<T extends Intent>(BuildContext context, { T? intent }) { |
822 | final Action<T>? action = maybeFind(context, intent: intent); |
823 | |
824 | assert(() { |
825 | if (action == null) { |
826 | final Type type = intent?.runtimeType ?? T; |
827 | throw FlutterError( |
828 | 'Unable to find an action for a $type in an $Actions widget ' |
829 | 'in the given context.\n' |
830 | " $Actions.find() was called on a context that doesn't contain an " |
831 | ' $Actions widget with a mapping for the given intent type.\n' |
832 | 'The context used was:\n' |
833 | ' $context\n' |
834 | 'The intent type requested was:\n' |
835 | ' $type' , |
836 | ); |
837 | } |
838 | return true; |
839 | }()); |
840 | return action!; |
841 | } |
842 | |
843 | /// Finds the [Action] bound to the given intent type `T` in the given `context`. |
844 | /// |
845 | /// Creates a dependency on the [Actions] widget that maps the bound action so |
846 | /// that if the actions change, the context will be rebuilt and find the |
847 | /// updated action. |
848 | /// |
849 | /// The optional `intent` argument supplies the type of the intent to look for |
850 | /// if the concrete type of the intent sought isn't available. If not |
851 | /// supplied, then `T` is used. |
852 | /// |
853 | /// If no [Actions] widget surrounds the given context, this function will |
854 | /// return null. |
855 | /// |
856 | /// See also: |
857 | /// |
858 | /// * [find], which is similar to this function, but will throw if |
859 | /// no [Actions] ancestor is found. |
860 | static Action<T>? maybeFind<T extends Intent>(BuildContext context, { T? intent }) { |
861 | Action<T>? action; |
862 | |
863 | // Specialize the type if a runtime example instance of the intent is given. |
864 | // This allows this function to be called by code that doesn't know the |
865 | // concrete type of the intent at compile time. |
866 | final Type type = intent?.runtimeType ?? T; |
867 | assert( |
868 | type != Intent, |
869 | 'The type passed to "find" resolved to "Intent": either a non-Intent ' |
870 | 'generic type argument or an example intent derived from Intent must be ' |
871 | 'specified. Intent may be used as the generic type as long as the optional ' |
872 | '"intent" argument is passed.' , |
873 | ); |
874 | |
875 | _visitActionsAncestors(context, (InheritedElement element) { |
876 | final _ActionsScope actions = element.widget as _ActionsScope; |
877 | final Action<T>? result = _castAction(actions, intent: intent); |
878 | if (result != null) { |
879 | context.dependOnInheritedElement(element); |
880 | action = result; |
881 | return true; |
882 | } |
883 | return false; |
884 | }); |
885 | |
886 | return action; |
887 | } |
888 | |
889 | static Action<T>? _maybeFindWithoutDependingOn<T extends Intent>(BuildContext context, { T? intent }) { |
890 | Action<T>? action; |
891 | |
892 | // Specialize the type if a runtime example instance of the intent is given. |
893 | // This allows this function to be called by code that doesn't know the |
894 | // concrete type of the intent at compile time. |
895 | final Type type = intent?.runtimeType ?? T; |
896 | assert( |
897 | type != Intent, |
898 | 'The type passed to "find" resolved to "Intent": either a non-Intent ' |
899 | 'generic type argument or an example intent derived from Intent must be ' |
900 | 'specified. Intent may be used as the generic type as long as the optional ' |
901 | '"intent" argument is passed.' , |
902 | ); |
903 | |
904 | _visitActionsAncestors(context, (InheritedElement element) { |
905 | final _ActionsScope actions = element.widget as _ActionsScope; |
906 | final Action<T>? result = _castAction(actions, intent: intent); |
907 | if (result != null) { |
908 | action = result; |
909 | return true; |
910 | } |
911 | return false; |
912 | }); |
913 | |
914 | return action; |
915 | } |
916 | |
917 | // Find the [Action] that handles the given `intent` in the given |
918 | // `_ActionsScope`, and verify it has the right type parameter. |
919 | static Action<T>? _castAction<T extends Intent>(_ActionsScope actionsMarker, { T? intent }) { |
920 | final Action<Intent>? mappedAction = actionsMarker.actions[intent?.runtimeType ?? T]; |
921 | if (mappedAction is Action<T>?) { |
922 | return mappedAction; |
923 | } else { |
924 | assert( |
925 | false, |
926 | ' $T cannot be handled by an Action of runtime type ${mappedAction.runtimeType}.' |
927 | ); |
928 | return null; |
929 | } |
930 | } |
931 | |
932 | /// Returns the [ActionDispatcher] associated with the [Actions] widget that |
933 | /// most tightly encloses the given [BuildContext]. |
934 | /// |
935 | /// Will return a newly created [ActionDispatcher] if no ambient [Actions] |
936 | /// widget is found. |
937 | static ActionDispatcher of(BuildContext context) { |
938 | final _ActionsScope? marker = context.dependOnInheritedWidgetOfExactType<_ActionsScope>(); |
939 | return marker?.dispatcher ?? _findDispatcher(context); |
940 | } |
941 | |
942 | /// Invokes the action associated with the given [Intent] using the |
943 | /// [Actions] widget that most tightly encloses the given [BuildContext]. |
944 | /// |
945 | /// This method returns the result of invoking the action's [Action.invoke] |
946 | /// method. |
947 | /// |
948 | /// If the given `intent` doesn't map to an action, then it will look to the |
949 | /// next ancestor [Actions] widget in the hierarchy until it reaches the root. |
950 | /// |
951 | /// This method will throw an exception if no ambient [Actions] widget is |
952 | /// found, or when a suitable [Action] is found but it returns false for |
953 | /// [Action.isEnabled]. |
954 | static Object? invoke<T extends Intent>( |
955 | BuildContext context, |
956 | T intent, |
957 | ) { |
958 | Object? returnValue; |
959 | |
960 | final bool actionFound = _visitActionsAncestors(context, (InheritedElement element) { |
961 | final _ActionsScope actions = element.widget as _ActionsScope; |
962 | final Action<T>? result = _castAction(actions, intent: intent); |
963 | if (result != null && result._isEnabled(intent, context)) { |
964 | // Invoke the action we found using the relevant dispatcher from the Actions |
965 | // Element we found. |
966 | returnValue = _findDispatcher(element).invokeAction(result, intent, context); |
967 | } |
968 | return result != null; |
969 | }); |
970 | |
971 | assert(() { |
972 | if (!actionFound) { |
973 | throw FlutterError( |
974 | 'Unable to find an action for an Intent with type ' |
975 | ' ${intent.runtimeType} in an $Actions widget in the given context.\n' |
976 | ' $Actions.invoke() was unable to find an $Actions widget that ' |
977 | "contained a mapping for the given intent, or the intent type isn't the " |
978 | 'same as the type argument to invoke (which is $T - try supplying a ' |
979 | 'type argument to invoke if one was not given)\n' |
980 | 'The context used was:\n' |
981 | ' $context\n' |
982 | 'The intent type requested was:\n' |
983 | ' ${intent.runtimeType}' , |
984 | ); |
985 | } |
986 | return true; |
987 | }()); |
988 | return returnValue; |
989 | } |
990 | |
991 | /// Invokes the action associated with the given [Intent] using the |
992 | /// [Actions] widget that most tightly encloses the given [BuildContext]. |
993 | /// |
994 | /// This method returns the result of invoking the action's [Action.invoke] |
995 | /// method. If no action mapping was found for the specified intent, or if the |
996 | /// first action found was disabled, or the action itself returns null |
997 | /// from [Action.invoke], then this method returns null. |
998 | /// |
999 | /// If the given `intent` doesn't map to an action, then it will look to the |
1000 | /// next ancestor [Actions] widget in the hierarchy until it reaches the root. |
1001 | /// If a suitable [Action] is found but its [Action.isEnabled] returns false, |
1002 | /// the search will stop and this method will return null. |
1003 | static Object? maybeInvoke<T extends Intent>( |
1004 | BuildContext context, |
1005 | T intent, |
1006 | ) { |
1007 | Object? returnValue; |
1008 | _visitActionsAncestors(context, (InheritedElement element) { |
1009 | final _ActionsScope actions = element.widget as _ActionsScope; |
1010 | final Action<T>? result = _castAction(actions, intent: intent); |
1011 | if (result != null && result._isEnabled(intent, context)) { |
1012 | // Invoke the action we found using the relevant dispatcher from the Actions |
1013 | // element we found. |
1014 | returnValue = _findDispatcher(element).invokeAction(result, intent, context); |
1015 | } |
1016 | return result != null; |
1017 | }); |
1018 | return returnValue; |
1019 | } |
1020 | |
1021 | @override |
1022 | State<Actions> createState() => _ActionsState(); |
1023 | |
1024 | @override |
1025 | void debugFillProperties(DiagnosticPropertiesBuilder properties) { |
1026 | super.debugFillProperties(properties); |
1027 | properties.add(DiagnosticsProperty<ActionDispatcher>('dispatcher' , dispatcher)); |
1028 | properties.add(DiagnosticsProperty<Map<Type, Action<Intent>>>('actions' , actions)); |
1029 | } |
1030 | } |
1031 | |
1032 | class _ActionsState extends State<Actions> { |
1033 | // The set of actions that this Actions widget is current listening to. |
1034 | Set<Action<Intent>>? listenedActions = <Action<Intent>>{}; |
1035 | // Used to tell the marker to rebuild its dependencies when the state of an |
1036 | // action in the map changes. |
1037 | Object rebuildKey = Object(); |
1038 | |
1039 | @override |
1040 | void initState() { |
1041 | super.initState(); |
1042 | _updateActionListeners(); |
1043 | } |
1044 | |
1045 | void _handleActionChanged(Action<Intent> action) { |
1046 | // Generate a new key so that the marker notifies dependents. |
1047 | setState(() { |
1048 | rebuildKey = Object(); |
1049 | }); |
1050 | } |
1051 | |
1052 | void _updateActionListeners() { |
1053 | final Set<Action<Intent>> widgetActions = widget.actions.values.toSet(); |
1054 | final Set<Action<Intent>> removedActions = listenedActions!.difference(widgetActions); |
1055 | final Set<Action<Intent>> addedActions = widgetActions.difference(listenedActions!); |
1056 | |
1057 | for (final Action<Intent> action in removedActions) { |
1058 | action.removeActionListener(_handleActionChanged); |
1059 | } |
1060 | for (final Action<Intent> action in addedActions) { |
1061 | action.addActionListener(_handleActionChanged); |
1062 | } |
1063 | listenedActions = widgetActions; |
1064 | } |
1065 | |
1066 | @override |
1067 | void didUpdateWidget(Actions oldWidget) { |
1068 | super.didUpdateWidget(oldWidget); |
1069 | _updateActionListeners(); |
1070 | } |
1071 | |
1072 | @override |
1073 | void dispose() { |
1074 | super.dispose(); |
1075 | for (final Action<Intent> action in listenedActions!) { |
1076 | action.removeActionListener(_handleActionChanged); |
1077 | } |
1078 | listenedActions = null; |
1079 | } |
1080 | |
1081 | @override |
1082 | Widget build(BuildContext context) { |
1083 | return _ActionsScope( |
1084 | actions: widget.actions, |
1085 | dispatcher: widget.dispatcher, |
1086 | rebuildKey: rebuildKey, |
1087 | child: widget.child, |
1088 | ); |
1089 | } |
1090 | } |
1091 | |
1092 | // An inherited widget used by Actions widget for fast lookup of the Actions |
1093 | // widget information. |
1094 | class _ActionsScope extends InheritedWidget { |
1095 | const _ActionsScope({ |
1096 | required this.dispatcher, |
1097 | required this.actions, |
1098 | required this.rebuildKey, |
1099 | required super.child, |
1100 | }); |
1101 | |
1102 | final ActionDispatcher? dispatcher; |
1103 | final Map<Type, Action<Intent>> actions; |
1104 | final Object rebuildKey; |
1105 | |
1106 | @override |
1107 | bool updateShouldNotify(_ActionsScope oldWidget) { |
1108 | return rebuildKey != oldWidget.rebuildKey |
1109 | || oldWidget.dispatcher != dispatcher |
1110 | || !mapEquals<Type, Action<Intent>>(oldWidget.actions, actions); |
1111 | } |
1112 | } |
1113 | |
1114 | /// A widget that combines the functionality of [Actions], [Shortcuts], |
1115 | /// [MouseRegion] and a [Focus] widget to create a detector that defines actions |
1116 | /// and key bindings, and provides callbacks for handling focus and hover |
1117 | /// highlights. |
1118 | /// |
1119 | /// {@youtube 560 315 https://www.youtube.com/watch?v=R84AGg0lKs8} |
1120 | /// |
1121 | /// This widget can be used to give a control the required detection modes for |
1122 | /// focus and hover handling. It is most often used when authoring a new control |
1123 | /// widget, and the new control should be enabled for keyboard traversal and |
1124 | /// activation. |
1125 | /// |
1126 | /// {@tool dartpad} |
1127 | /// This example shows how keyboard interaction can be added to a custom control |
1128 | /// that changes color when hovered and focused, and can toggle a light when |
1129 | /// activated, either by touch or by hitting the `X` key on the keyboard when |
1130 | /// the "And Me" button has the keyboard focus (be sure to use TAB to move the |
1131 | /// focus to the "And Me" button before trying it out). |
1132 | /// |
1133 | /// This example defines its own key binding for the `X` key, but in this case, |
1134 | /// there is also a default key binding for [ActivateAction] in the default key |
1135 | /// bindings created by [WidgetsApp] (the parent for [MaterialApp], and |
1136 | /// [CupertinoApp]), so the `ENTER` key will also activate the buttons. |
1137 | /// |
1138 | /// ** See code in examples/api/lib/widgets/actions/focusable_action_detector.0.dart ** |
1139 | /// {@end-tool} |
1140 | /// |
1141 | /// This widget doesn't have any visual representation, it is just a detector that |
1142 | /// provides focus and hover capabilities. |
1143 | /// |
1144 | /// It hosts its own [FocusNode] or uses [focusNode], if given. |
1145 | class FocusableActionDetector extends StatefulWidget { |
1146 | /// Create a const [FocusableActionDetector]. |
1147 | const FocusableActionDetector({ |
1148 | super.key, |
1149 | this.enabled = true, |
1150 | this.focusNode, |
1151 | this.autofocus = false, |
1152 | this.descendantsAreFocusable = true, |
1153 | this.descendantsAreTraversable = true, |
1154 | this.shortcuts, |
1155 | this.actions, |
1156 | this.onShowFocusHighlight, |
1157 | this.onShowHoverHighlight, |
1158 | this.onFocusChange, |
1159 | this.mouseCursor = MouseCursor.defer, |
1160 | this.includeFocusSemantics = true, |
1161 | required this.child, |
1162 | }); |
1163 | |
1164 | /// Is this widget enabled or not. |
1165 | /// |
1166 | /// If disabled, will not send any notifications needed to update highlight or |
1167 | /// focus state, and will not define or respond to any actions or shortcuts. |
1168 | /// |
1169 | /// When disabled, adds [Focus] to the widget tree, but sets |
1170 | /// [Focus.canRequestFocus] to false. |
1171 | final bool enabled; |
1172 | |
1173 | /// {@macro flutter.widgets.Focus.focusNode} |
1174 | final FocusNode? focusNode; |
1175 | |
1176 | /// {@macro flutter.widgets.Focus.autofocus} |
1177 | final bool autofocus; |
1178 | |
1179 | /// {@macro flutter.widgets.Focus.descendantsAreFocusable} |
1180 | final bool descendantsAreFocusable; |
1181 | |
1182 | /// {@macro flutter.widgets.Focus.descendantsAreTraversable} |
1183 | final bool descendantsAreTraversable; |
1184 | |
1185 | /// {@macro flutter.widgets.actions.actions} |
1186 | final Map<Type, Action<Intent>>? actions; |
1187 | |
1188 | /// {@macro flutter.widgets.shortcuts.shortcuts} |
1189 | final Map<ShortcutActivator, Intent>? shortcuts; |
1190 | |
1191 | /// A function that will be called when the focus highlight should be shown or |
1192 | /// hidden. |
1193 | /// |
1194 | /// This method is not triggered at the unmount of the widget. |
1195 | final ValueChanged<bool>? onShowFocusHighlight; |
1196 | |
1197 | /// A function that will be called when the hover highlight should be shown or hidden. |
1198 | /// |
1199 | /// This method is not triggered at the unmount of the widget. |
1200 | final ValueChanged<bool>? onShowHoverHighlight; |
1201 | |
1202 | /// A function that will be called when the focus changes. |
1203 | /// |
1204 | /// Called with true if the [focusNode] has primary focus. |
1205 | final ValueChanged<bool>? onFocusChange; |
1206 | |
1207 | /// The cursor for a mouse pointer when it enters or is hovering over the |
1208 | /// widget. |
1209 | /// |
1210 | /// The [mouseCursor] defaults to [MouseCursor.defer], deferring the choice of |
1211 | /// cursor to the next region behind it in hit-test order. |
1212 | final MouseCursor mouseCursor; |
1213 | |
1214 | /// Whether to include semantics from [Focus]. |
1215 | /// |
1216 | /// Defaults to true. |
1217 | final bool includeFocusSemantics; |
1218 | |
1219 | /// The child widget for this [FocusableActionDetector] widget. |
1220 | /// |
1221 | /// {@macro flutter.widgets.ProxyWidget.child} |
1222 | final Widget child; |
1223 | |
1224 | @override |
1225 | State<FocusableActionDetector> createState() => _FocusableActionDetectorState(); |
1226 | } |
1227 | |
1228 | class _FocusableActionDetectorState extends State<FocusableActionDetector> { |
1229 | @override |
1230 | void initState() { |
1231 | super.initState(); |
1232 | SchedulerBinding.instance.addPostFrameCallback((Duration duration) { |
1233 | _updateHighlightMode(FocusManager.instance.highlightMode); |
1234 | }, debugLabel: 'FocusableActionDetector.updateHighlightMode' ); |
1235 | FocusManager.instance.addHighlightModeListener(_handleFocusHighlightModeChange); |
1236 | } |
1237 | |
1238 | @override |
1239 | void dispose() { |
1240 | FocusManager.instance.removeHighlightModeListener(_handleFocusHighlightModeChange); |
1241 | super.dispose(); |
1242 | } |
1243 | |
1244 | bool _canShowHighlight = false; |
1245 | void _updateHighlightMode(FocusHighlightMode mode) { |
1246 | _mayTriggerCallback(task: () { |
1247 | switch (FocusManager.instance.highlightMode) { |
1248 | case FocusHighlightMode.touch: |
1249 | _canShowHighlight = false; |
1250 | case FocusHighlightMode.traditional: |
1251 | _canShowHighlight = true; |
1252 | } |
1253 | }); |
1254 | } |
1255 | |
1256 | // Have to have this separate from the _updateHighlightMode because it gets |
1257 | // called in initState, where things aren't mounted yet. |
1258 | // Since this method is a highlight mode listener, it is only called |
1259 | // immediately following pointer events. |
1260 | void _handleFocusHighlightModeChange(FocusHighlightMode mode) { |
1261 | if (!mounted) { |
1262 | return; |
1263 | } |
1264 | _updateHighlightMode(mode); |
1265 | } |
1266 | |
1267 | bool _hovering = false; |
1268 | void _handleMouseEnter(PointerEnterEvent event) { |
1269 | if (!_hovering) { |
1270 | _mayTriggerCallback(task: () { |
1271 | _hovering = true; |
1272 | }); |
1273 | } |
1274 | } |
1275 | |
1276 | void _handleMouseExit(PointerExitEvent event) { |
1277 | if (_hovering) { |
1278 | _mayTriggerCallback(task: () { |
1279 | _hovering = false; |
1280 | }); |
1281 | } |
1282 | } |
1283 | |
1284 | bool _focused = false; |
1285 | void _handleFocusChange(bool focused) { |
1286 | if (_focused != focused) { |
1287 | _mayTriggerCallback(task: () { |
1288 | _focused = focused; |
1289 | }); |
1290 | widget.onFocusChange?.call(_focused); |
1291 | } |
1292 | } |
1293 | |
1294 | // Record old states, do `task` if not null, then compare old states with the |
1295 | // new states, and trigger callbacks if necessary. |
1296 | // |
1297 | // The old states are collected from `oldWidget` if it is provided, or the |
1298 | // current widget (before doing `task`) otherwise. The new states are always |
1299 | // collected from the current widget. |
1300 | void _mayTriggerCallback({VoidCallback? task, FocusableActionDetector? oldWidget}) { |
1301 | bool shouldShowHoverHighlight(FocusableActionDetector target) { |
1302 | return _hovering && target.enabled && _canShowHighlight; |
1303 | } |
1304 | |
1305 | bool canRequestFocus(FocusableActionDetector target) { |
1306 | final NavigationMode mode = MediaQuery.maybeNavigationModeOf(context) ?? NavigationMode.traditional; |
1307 | switch (mode) { |
1308 | case NavigationMode.traditional: |
1309 | return target.enabled; |
1310 | case NavigationMode.directional: |
1311 | return true; |
1312 | } |
1313 | } |
1314 | |
1315 | bool shouldShowFocusHighlight(FocusableActionDetector target) { |
1316 | return _focused && _canShowHighlight && canRequestFocus(target); |
1317 | } |
1318 | |
1319 | assert(SchedulerBinding.instance.schedulerPhase != SchedulerPhase.persistentCallbacks); |
1320 | final FocusableActionDetector oldTarget = oldWidget ?? widget; |
1321 | final bool didShowHoverHighlight = shouldShowHoverHighlight(oldTarget); |
1322 | final bool didShowFocusHighlight = shouldShowFocusHighlight(oldTarget); |
1323 | if (task != null) { |
1324 | task(); |
1325 | } |
1326 | final bool doShowHoverHighlight = shouldShowHoverHighlight(widget); |
1327 | final bool doShowFocusHighlight = shouldShowFocusHighlight(widget); |
1328 | if (didShowFocusHighlight != doShowFocusHighlight) { |
1329 | widget.onShowFocusHighlight?.call(doShowFocusHighlight); |
1330 | } |
1331 | if (didShowHoverHighlight != doShowHoverHighlight) { |
1332 | widget.onShowHoverHighlight?.call(doShowHoverHighlight); |
1333 | } |
1334 | } |
1335 | |
1336 | @override |
1337 | void didUpdateWidget(FocusableActionDetector oldWidget) { |
1338 | super.didUpdateWidget(oldWidget); |
1339 | if (widget.enabled != oldWidget.enabled) { |
1340 | SchedulerBinding.instance.addPostFrameCallback((Duration duration) { |
1341 | _mayTriggerCallback(oldWidget: oldWidget); |
1342 | }, debugLabel: 'FocusableActionDetector.mayTriggerCallback' ); |
1343 | } |
1344 | } |
1345 | |
1346 | bool get _canRequestFocus { |
1347 | final NavigationMode mode = MediaQuery.maybeNavigationModeOf(context) ?? NavigationMode.traditional; |
1348 | switch (mode) { |
1349 | case NavigationMode.traditional: |
1350 | return widget.enabled; |
1351 | case NavigationMode.directional: |
1352 | return true; |
1353 | } |
1354 | } |
1355 | |
1356 | // This global key is needed to keep only the necessary widgets in the tree |
1357 | // while maintaining the subtree's state. |
1358 | // |
1359 | // See https://github.com/flutter/flutter/issues/64058 for an explanation of |
1360 | // why using a global key over keeping the shape of the tree. |
1361 | final GlobalKey _mouseRegionKey = GlobalKey(); |
1362 | |
1363 | @override |
1364 | Widget build(BuildContext context) { |
1365 | Widget child = MouseRegion( |
1366 | key: _mouseRegionKey, |
1367 | onEnter: _handleMouseEnter, |
1368 | onExit: _handleMouseExit, |
1369 | cursor: widget.mouseCursor, |
1370 | child: Focus( |
1371 | focusNode: widget.focusNode, |
1372 | autofocus: widget.autofocus, |
1373 | descendantsAreFocusable: widget.descendantsAreFocusable, |
1374 | descendantsAreTraversable: widget.descendantsAreTraversable, |
1375 | canRequestFocus: _canRequestFocus, |
1376 | onFocusChange: _handleFocusChange, |
1377 | includeSemantics: widget.includeFocusSemantics, |
1378 | child: widget.child, |
1379 | ), |
1380 | ); |
1381 | if (widget.enabled && widget.actions != null && widget.actions!.isNotEmpty) { |
1382 | child = Actions(actions: widget.actions!, child: child); |
1383 | } |
1384 | if (widget.enabled && widget.shortcuts != null && widget.shortcuts!.isNotEmpty) { |
1385 | child = Shortcuts(shortcuts: widget.shortcuts!, child: child); |
1386 | } |
1387 | return child; |
1388 | } |
1389 | } |
1390 | |
1391 | /// An [Intent] that keeps a [VoidCallback] to be invoked by a |
1392 | /// [VoidCallbackAction] when it receives this intent. |
1393 | class VoidCallbackIntent extends Intent { |
1394 | /// Creates a [VoidCallbackIntent]. |
1395 | const VoidCallbackIntent(this.callback); |
1396 | |
1397 | /// The callback that is to be called by the [VoidCallbackAction] that |
1398 | /// receives this intent. |
1399 | final VoidCallback callback; |
1400 | } |
1401 | |
1402 | /// An [Action] that invokes the [VoidCallback] given to it in the |
1403 | /// [VoidCallbackIntent] passed to it when invoked. |
1404 | /// |
1405 | /// See also: |
1406 | /// |
1407 | /// * [CallbackAction], which is an action that will invoke a callback with the |
1408 | /// intent passed to the action's invoke method. The callback is configured |
1409 | /// on the action, not the intent, like this class. |
1410 | class VoidCallbackAction extends Action<VoidCallbackIntent> { |
1411 | @override |
1412 | Object? invoke(VoidCallbackIntent intent) { |
1413 | intent.callback(); |
1414 | return null; |
1415 | } |
1416 | } |
1417 | |
1418 | /// An [Intent] that is bound to a [DoNothingAction]. |
1419 | /// |
1420 | /// Attaching a [DoNothingIntent] to a [Shortcuts] mapping is one way to disable |
1421 | /// a keyboard shortcut defined by a widget higher in the widget hierarchy and |
1422 | /// consume any key event that triggers it via a shortcut. |
1423 | /// |
1424 | /// This intent cannot be subclassed. |
1425 | /// |
1426 | /// See also: |
1427 | /// |
1428 | /// * [DoNothingAndStopPropagationIntent], a similar intent that will not |
1429 | /// handle the key event, but will still keep it from being passed to other key |
1430 | /// handlers in the focus chain. |
1431 | class DoNothingIntent extends Intent { |
1432 | /// Creates a const [DoNothingIntent]. |
1433 | const factory DoNothingIntent() = DoNothingIntent._; |
1434 | |
1435 | // Make DoNothingIntent constructor private so it can't be subclassed. |
1436 | const DoNothingIntent._(); |
1437 | } |
1438 | |
1439 | /// An [Intent] that is bound to a [DoNothingAction], but, in addition to not |
1440 | /// performing an action, also stops the propagation of the key event bound to |
1441 | /// this intent to other key event handlers in the focus chain. |
1442 | /// |
1443 | /// Attaching a [DoNothingAndStopPropagationIntent] to a [Shortcuts.shortcuts] |
1444 | /// mapping is one way to disable a keyboard shortcut defined by a widget higher |
1445 | /// in the widget hierarchy. In addition, the bound [DoNothingAction] will |
1446 | /// return false from [DoNothingAction.consumesKey], causing the key bound to |
1447 | /// this intent to be passed on to the platform embedding as "not handled" with |
1448 | /// out passing it to other key handlers in the focus chain (e.g. parent |
1449 | /// `Shortcuts` widgets higher up in the chain). |
1450 | /// |
1451 | /// This intent cannot be subclassed. |
1452 | /// |
1453 | /// See also: |
1454 | /// |
1455 | /// * [DoNothingIntent], a similar intent that will handle the key event. |
1456 | class DoNothingAndStopPropagationIntent extends Intent { |
1457 | /// Creates a const [DoNothingAndStopPropagationIntent]. |
1458 | const factory DoNothingAndStopPropagationIntent() = DoNothingAndStopPropagationIntent._; |
1459 | |
1460 | // Make DoNothingAndStopPropagationIntent constructor private so it can't be subclassed. |
1461 | const DoNothingAndStopPropagationIntent._(); |
1462 | } |
1463 | |
1464 | /// An [Action] that doesn't perform any action when invoked. |
1465 | /// |
1466 | /// Attaching a [DoNothingAction] to an [Actions.actions] mapping is a way to |
1467 | /// disable an action defined by a widget higher in the widget hierarchy. |
1468 | /// |
1469 | /// If [consumesKey] returns false, then not only will this action do nothing, |
1470 | /// but it will stop the propagation of the key event used to trigger it to |
1471 | /// other widgets in the focus chain and tell the embedding that the key wasn't |
1472 | /// handled, allowing text input fields or other non-Flutter elements to receive |
1473 | /// that key event. The return value of [consumesKey] can be set via the |
1474 | /// `consumesKey` argument to the constructor. |
1475 | /// |
1476 | /// This action can be bound to any [Intent]. |
1477 | /// |
1478 | /// See also: |
1479 | /// - [DoNothingIntent], which is an intent that can be bound to a [KeySet] in |
1480 | /// a [Shortcuts] widget to do nothing. |
1481 | /// - [DoNothingAndStopPropagationIntent], which is an intent that can be bound |
1482 | /// to a [KeySet] in a [Shortcuts] widget to do nothing and also stop key event |
1483 | /// propagation to other key handlers in the focus chain. |
1484 | class DoNothingAction extends Action<Intent> { |
1485 | /// Creates a [DoNothingAction]. |
1486 | /// |
1487 | /// The optional [consumesKey] argument defaults to true. |
1488 | DoNothingAction({bool consumesKey = true}) : _consumesKey = consumesKey; |
1489 | |
1490 | @override |
1491 | bool consumesKey(Intent intent) => _consumesKey; |
1492 | final bool _consumesKey; |
1493 | |
1494 | @override |
1495 | void invoke(Intent intent) {} |
1496 | } |
1497 | |
1498 | /// An [Intent] that activates the currently focused control. |
1499 | /// |
1500 | /// This intent is bound by default to the [LogicalKeyboardKey.space] key on all |
1501 | /// platforms, and also to the [LogicalKeyboardKey.enter] key on all platforms |
1502 | /// except the web, where ENTER doesn't toggle selection. On the web, ENTER is |
1503 | /// bound to [ButtonActivateIntent] instead. |
1504 | /// |
1505 | /// See also: |
1506 | /// |
1507 | /// * [WidgetsApp.defaultShortcuts], which contains the default shortcuts used |
1508 | /// in apps. |
1509 | /// * [WidgetsApp.shortcuts], which defines the shortcuts to use in an |
1510 | /// application (and defaults to [WidgetsApp.defaultShortcuts]). |
1511 | class ActivateIntent extends Intent { |
1512 | /// Creates an intent that activates the currently focused control. |
1513 | const ActivateIntent(); |
1514 | } |
1515 | |
1516 | /// An [Intent] that activates the currently focused button. |
1517 | /// |
1518 | /// This intent is bound by default to the [LogicalKeyboardKey.enter] key on the |
1519 | /// web, where ENTER can be used to activate buttons, but not toggle selection. |
1520 | /// All other platforms bind [LogicalKeyboardKey.enter] to [ActivateIntent]. |
1521 | /// |
1522 | /// See also: |
1523 | /// |
1524 | /// * [WidgetsApp.defaultShortcuts], which contains the default shortcuts used |
1525 | /// in apps. |
1526 | /// * [WidgetsApp.shortcuts], which defines the shortcuts to use in an |
1527 | /// application (and defaults to [WidgetsApp.defaultShortcuts]). |
1528 | class ButtonActivateIntent extends Intent { |
1529 | /// Creates an intent that activates the currently focused control, |
1530 | /// if it's a button. |
1531 | const ButtonActivateIntent(); |
1532 | } |
1533 | |
1534 | /// An [Action] that activates the currently focused control. |
1535 | /// |
1536 | /// This is an abstract class that serves as a base class for actions that |
1537 | /// activate a control. By default, is bound to [LogicalKeyboardKey.enter], |
1538 | /// [LogicalKeyboardKey.gameButtonA], and [LogicalKeyboardKey.space] in the |
1539 | /// default keyboard map in [WidgetsApp]. |
1540 | abstract class ActivateAction extends Action<ActivateIntent> { } |
1541 | |
1542 | /// An [Intent] that selects the currently focused control. |
1543 | class SelectIntent extends Intent { |
1544 | /// Creates an intent that selects the currently focused control. |
1545 | const SelectIntent(); |
1546 | } |
1547 | |
1548 | /// An action that selects the currently focused control. |
1549 | /// |
1550 | /// This is an abstract class that serves as a base class for actions that |
1551 | /// select something. It is not bound to any key by default. |
1552 | abstract class SelectAction extends Action<SelectIntent> { } |
1553 | |
1554 | /// An [Intent] that dismisses the currently focused widget. |
1555 | /// |
1556 | /// The [WidgetsApp.defaultShortcuts] binds this intent to the |
1557 | /// [LogicalKeyboardKey.escape] and [LogicalKeyboardKey.gameButtonB] keys. |
1558 | /// |
1559 | /// See also: |
1560 | /// - [ModalRoute] which listens for this intent to dismiss modal routes |
1561 | /// (dialogs, pop-up menus, drawers, etc). |
1562 | class DismissIntent extends Intent { |
1563 | /// Creates an intent that dismisses the currently focused widget. |
1564 | const DismissIntent(); |
1565 | } |
1566 | |
1567 | /// An [Action] that dismisses the focused widget. |
1568 | /// |
1569 | /// This is an abstract class that serves as a base class for dismiss actions. |
1570 | abstract class DismissAction extends Action<DismissIntent> { } |
1571 | |
1572 | /// An [Intent] that evaluates a series of specified [orderedIntents] for |
1573 | /// execution. |
1574 | /// |
1575 | /// The first intent that matches an enabled action is used. |
1576 | class PrioritizedIntents extends Intent { |
1577 | /// Creates an intent that is used with [PrioritizedAction] to specify a list |
1578 | /// of intents, the first available of which will be used. |
1579 | const PrioritizedIntents({ |
1580 | required this.orderedIntents, |
1581 | }); |
1582 | |
1583 | /// List of intents to be evaluated in order for execution. When an |
1584 | /// [Action.isEnabled] returns true, that action will be invoked and |
1585 | /// progression through the ordered intents stops. |
1586 | final List<Intent> orderedIntents; |
1587 | } |
1588 | |
1589 | /// An [Action] that iterates through a list of [Intent]s, invoking the first |
1590 | /// that is enabled. |
1591 | /// |
1592 | /// The [isEnabled] method must be called before [invoke]. Calling [isEnabled] |
1593 | /// configures the object by seeking the first intent with an enabled action. |
1594 | /// If the actions have an opportunity to change enabled state, [isEnabled] |
1595 | /// must be called again before calling [invoke]. |
1596 | class PrioritizedAction extends ContextAction<PrioritizedIntents> { |
1597 | late Action<dynamic> _selectedAction; |
1598 | late Intent _selectedIntent; |
1599 | |
1600 | @override |
1601 | bool isEnabled(PrioritizedIntents intent, [ BuildContext? context ]) { |
1602 | final FocusNode? focus = primaryFocus; |
1603 | if (focus == null || focus.context == null) { |
1604 | return false; |
1605 | } |
1606 | for (final Intent candidateIntent in intent.orderedIntents) { |
1607 | final Action<Intent>? candidateAction = Actions.maybeFind<Intent>( |
1608 | focus.context!, |
1609 | intent: candidateIntent, |
1610 | ); |
1611 | if (candidateAction != null && candidateAction._isEnabled(candidateIntent, context)) { |
1612 | _selectedAction = candidateAction; |
1613 | _selectedIntent = candidateIntent; |
1614 | return true; |
1615 | } |
1616 | } |
1617 | return false; |
1618 | } |
1619 | |
1620 | @override |
1621 | void invoke(PrioritizedIntents intent, [ BuildContext? context ]) { |
1622 | _selectedAction._invoke(_selectedIntent, context); |
1623 | } |
1624 | } |
1625 | |
1626 | mixin _OverridableActionMixin<T extends Intent> on Action<T> { |
1627 | // When debugAssertMutuallyRecursive is true, this action will throw an |
1628 | // assertion error when the override calls this action's "invoke" method and |
1629 | // the override is already being invoked from within the "invoke" method. |
1630 | bool debugAssertMutuallyRecursive = false; |
1631 | bool debugAssertIsActionEnabledMutuallyRecursive = false; |
1632 | bool debugAssertIsEnabledMutuallyRecursive = false; |
1633 | bool debugAssertConsumeKeyMutuallyRecursive = false; |
1634 | |
1635 | // The default action to invoke if an enabled override Action can't be found |
1636 | // using [lookupContext]. |
1637 | Action<T> get defaultAction; |
1638 | |
1639 | // The [BuildContext] used to find the override of this [Action]. |
1640 | BuildContext get lookupContext; |
1641 | |
1642 | // How to invoke [defaultAction], given the caller [fromAction]. |
1643 | Object? invokeDefaultAction(T intent, Action<T>? fromAction, BuildContext? context); |
1644 | |
1645 | Action<T>? getOverrideAction({ bool declareDependency = false }) { |
1646 | final Action<T>? override = declareDependency |
1647 | ? Actions.maybeFind(lookupContext) |
1648 | : Actions._maybeFindWithoutDependingOn(lookupContext); |
1649 | assert(!identical(override, this)); |
1650 | return override; |
1651 | } |
1652 | |
1653 | @override |
1654 | void _updateCallingAction(Action<T>? value) { |
1655 | super._updateCallingAction(value); |
1656 | defaultAction._updateCallingAction(value); |
1657 | } |
1658 | |
1659 | Object? _invokeOverride(Action<T> overrideAction, T intent, BuildContext? context) { |
1660 | assert(!debugAssertMutuallyRecursive); |
1661 | assert(() { |
1662 | debugAssertMutuallyRecursive = true; |
1663 | return true; |
1664 | }()); |
1665 | overrideAction._updateCallingAction(defaultAction); |
1666 | final Object? returnValue = overrideAction._invoke(intent, context); |
1667 | overrideAction._updateCallingAction(null); |
1668 | assert(() { |
1669 | debugAssertMutuallyRecursive = false; |
1670 | return true; |
1671 | }()); |
1672 | return returnValue; |
1673 | } |
1674 | |
1675 | @override |
1676 | Object? invoke(T intent, [BuildContext? context]) { |
1677 | final Action<T>? overrideAction = getOverrideAction(); |
1678 | final Object? returnValue = overrideAction == null |
1679 | ? invokeDefaultAction(intent, callingAction, context) |
1680 | : _invokeOverride(overrideAction, intent, context); |
1681 | return returnValue; |
1682 | } |
1683 | |
1684 | bool isOverrideActionEnabled(Action<T> overrideAction) { |
1685 | assert(!debugAssertIsActionEnabledMutuallyRecursive); |
1686 | assert(() { |
1687 | debugAssertIsActionEnabledMutuallyRecursive = true; |
1688 | return true; |
1689 | }()); |
1690 | overrideAction._updateCallingAction(defaultAction); |
1691 | final bool isOverrideEnabled = overrideAction.isActionEnabled; |
1692 | overrideAction._updateCallingAction(null); |
1693 | assert(() { |
1694 | debugAssertIsActionEnabledMutuallyRecursive = false; |
1695 | return true; |
1696 | }()); |
1697 | return isOverrideEnabled; |
1698 | } |
1699 | |
1700 | @override |
1701 | bool get isActionEnabled { |
1702 | final Action<T>? overrideAction = getOverrideAction(declareDependency: true); |
1703 | final bool returnValue = overrideAction != null |
1704 | ? isOverrideActionEnabled(overrideAction) |
1705 | : defaultAction.isActionEnabled; |
1706 | return returnValue; |
1707 | } |
1708 | |
1709 | @override |
1710 | bool isEnabled(T intent, [BuildContext? context]) { |
1711 | assert(!debugAssertIsEnabledMutuallyRecursive); |
1712 | assert(() { |
1713 | debugAssertIsEnabledMutuallyRecursive = true; |
1714 | return true; |
1715 | }()); |
1716 | |
1717 | final Action<T>? overrideAction = getOverrideAction(); |
1718 | overrideAction?._updateCallingAction(defaultAction); |
1719 | final bool returnValue = (overrideAction ?? defaultAction)._isEnabled(intent, context); |
1720 | overrideAction?._updateCallingAction(null); |
1721 | assert(() { |
1722 | debugAssertIsEnabledMutuallyRecursive = false; |
1723 | return true; |
1724 | }()); |
1725 | return returnValue; |
1726 | } |
1727 | |
1728 | @override |
1729 | bool consumesKey(T intent) { |
1730 | assert(!debugAssertConsumeKeyMutuallyRecursive); |
1731 | assert(() { |
1732 | debugAssertConsumeKeyMutuallyRecursive = true; |
1733 | return true; |
1734 | }()); |
1735 | final Action<T>? overrideAction = getOverrideAction(); |
1736 | overrideAction?._updateCallingAction(defaultAction); |
1737 | final bool isEnabled = (overrideAction ?? defaultAction).consumesKey(intent); |
1738 | overrideAction?._updateCallingAction(null); |
1739 | assert(() { |
1740 | debugAssertConsumeKeyMutuallyRecursive = false; |
1741 | return true; |
1742 | }()); |
1743 | return isEnabled; |
1744 | } |
1745 | |
1746 | @override |
1747 | void debugFillProperties(DiagnosticPropertiesBuilder properties) { |
1748 | super.debugFillProperties(properties); |
1749 | properties.add(DiagnosticsProperty<Action<T>>('defaultAction' , defaultAction)); |
1750 | } |
1751 | } |
1752 | |
1753 | class _OverridableAction<T extends Intent> extends ContextAction<T> with _OverridableActionMixin<T> { |
1754 | _OverridableAction({ required this.defaultAction, required this.lookupContext }) ; |
1755 | |
1756 | @override |
1757 | final Action<T> defaultAction; |
1758 | |
1759 | @override |
1760 | final BuildContext lookupContext; |
1761 | |
1762 | @override |
1763 | Object? invokeDefaultAction(T intent, Action<T>? fromAction, BuildContext? context) { |
1764 | if (fromAction == null) { |
1765 | return defaultAction.invoke(intent); |
1766 | } else { |
1767 | final Object? returnValue = defaultAction.invoke(intent); |
1768 | return returnValue; |
1769 | } |
1770 | } |
1771 | |
1772 | @override |
1773 | ContextAction<T> _makeOverridableAction(BuildContext context) { |
1774 | return _OverridableAction<T>(defaultAction: defaultAction, lookupContext: context); |
1775 | } |
1776 | } |
1777 | |
1778 | class _OverridableContextAction<T extends Intent> extends ContextAction<T> with _OverridableActionMixin<T> { |
1779 | _OverridableContextAction({ required this.defaultAction, required this.lookupContext }); |
1780 | |
1781 | @override |
1782 | final ContextAction<T> defaultAction; |
1783 | |
1784 | @override |
1785 | final BuildContext lookupContext; |
1786 | |
1787 | @override |
1788 | Object? _invokeOverride(Action<T> overrideAction, T intent, BuildContext? context) { |
1789 | assert(context != null); |
1790 | assert(!debugAssertMutuallyRecursive); |
1791 | assert(() { |
1792 | debugAssertMutuallyRecursive = true; |
1793 | return true; |
1794 | }()); |
1795 | |
1796 | // Wrap the default Action together with the calling context in case |
1797 | // overrideAction is not a ContextAction and thus have no access to the |
1798 | // calling BuildContext. |
1799 | final Action<T> wrappedDefault = _ContextActionToActionAdapter<T>(invokeContext: context!, action: defaultAction); |
1800 | overrideAction._updateCallingAction(wrappedDefault); |
1801 | final Object? returnValue = overrideAction._invoke(intent, context); |
1802 | overrideAction._updateCallingAction(null); |
1803 | |
1804 | assert(() { |
1805 | debugAssertMutuallyRecursive = false; |
1806 | return true; |
1807 | }()); |
1808 | return returnValue; |
1809 | } |
1810 | |
1811 | @override |
1812 | Object? invokeDefaultAction(T intent, Action<T>? fromAction, BuildContext? context) { |
1813 | if (fromAction == null) { |
1814 | return defaultAction.invoke(intent, context); |
1815 | } else { |
1816 | final Object? returnValue = defaultAction.invoke(intent, context); |
1817 | return returnValue; |
1818 | } |
1819 | } |
1820 | |
1821 | @override |
1822 | ContextAction<T> _makeOverridableAction(BuildContext context) { |
1823 | return _OverridableContextAction<T>(defaultAction: defaultAction, lookupContext: context); |
1824 | } |
1825 | } |
1826 | |
1827 | class _ContextActionToActionAdapter<T extends Intent> extends Action<T> { |
1828 | _ContextActionToActionAdapter({required this.invokeContext, required this.action}); |
1829 | |
1830 | final BuildContext invokeContext; |
1831 | final ContextAction<T> action; |
1832 | |
1833 | @override |
1834 | void _updateCallingAction(Action<T>? value) { |
1835 | action._updateCallingAction(value); |
1836 | } |
1837 | |
1838 | @override |
1839 | Action<T>? get callingAction => action.callingAction; |
1840 | |
1841 | @override |
1842 | bool isEnabled(T intent) => action.isEnabled(intent, invokeContext); |
1843 | |
1844 | @override |
1845 | bool get isActionEnabled => action.isActionEnabled; |
1846 | |
1847 | @override |
1848 | bool consumesKey(T intent) => action.consumesKey(intent); |
1849 | |
1850 | @override |
1851 | void addActionListener(ActionListenerCallback listener) { |
1852 | super.addActionListener(listener); |
1853 | action.addActionListener(listener); |
1854 | } |
1855 | |
1856 | @override |
1857 | void removeActionListener(ActionListenerCallback listener) { |
1858 | super.removeActionListener(listener); |
1859 | action.removeActionListener(listener); |
1860 | } |
1861 | |
1862 | @override |
1863 | @protected |
1864 | void notifyActionListeners() => action.notifyActionListeners(); |
1865 | |
1866 | @override |
1867 | Object? invoke(T intent) => action.invoke(intent, invokeContext); |
1868 | } |
1869 | |