[web] Fix Scene clip bounds. Trigger resize on DPR Change. #50161
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| // Copyright 2013 The Flutter Authors. All rights reserved. | ||
| // Use of this source code is governed by a BSD-style license that can be | ||
| // found in the LICENSE file. | ||
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| import 'dart:async'; | ||
| import 'dart:js_interop'; | ||
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| import 'package:meta/meta.dart'; | ||
| import 'package:ui/src/engine/display.dart'; | ||
| import 'package:ui/src/engine/dom.dart'; | ||
| import 'package:ui/ui.dart' as ui show Display; | ||
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| /// Provides a stream of `devicePixelRatio` changes for the given display. | ||
| /// | ||
| /// Note that until the Window Management API is generally available, this class | ||
| /// only monitors the global `devicePixelRatio` property, provided by the default | ||
| /// [EngineFlutterDisplay.instance]. | ||
| /// | ||
| /// See: https://developer.mozilla.org/en-US/docs/Web/API/Window_Management_API | ||
| class DisplayDprStream { | ||
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| DisplayDprStream( | ||
| this._display, { | ||
| @visibleForTesting DebugDisplayDprStreamOverrides? overrides, | ||
| }) : _currentDpr = _display.devicePixelRatio, | ||
| _debugOverrides = overrides { | ||
| // Start listening to DPR changes. | ||
| _subscribeToMediaQuery(); | ||
| } | ||
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| /// A singleton instance of DisplayDprStream. | ||
| static DisplayDprStream instance = | ||
| DisplayDprStream(EngineFlutterDisplay.instance); | ||
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There was a problem hiding this comment. Do we want to continue with the singleton pattern? I was under the impression that we were removing all singletons except one top-level class (was it There was a problem hiding this comment. Yeah, we're still using the singleton pattern for things that are ONE only (browser globals). (I tried to make this instance-based (by passing a Display), hoping that this API1 will be eventually usable, but it's still unclear to me from the docs how it can be used to monitor DPR changes, though!) FootnotesThere was a problem hiding this comment. In one of our recent-ish discussions, we entertained the idea of keeping only ONE singleton in the engine (e.g. E.g. instead of It was just a discussion though. We haven't made any real changes in the code base following that discussion. But I think at some point we should start moving to that pattern. There was a problem hiding this comment. Ah, I understand now! Yes, I could move this to a singleton of the EnginePlatformDispatcher instead of being a loose object. There was a problem hiding this comment. I think the litmus test is that code that consumes an external service should not go through a static to get a reference to that service. I don't insist that this is fixed in this PR, unless we already switched modes to a singleton-free design. There was a problem hiding this comment. I changed this a little bit. The CustomElement dimensions provider now just requires a Stream passed by its constructor. For now, the abstract factory class of DimensionsProviders knows where to get that stream from (the singleton instance), but it's very likely that it could just be created from there. Anyway, I'm going to |
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| // The display object that will provide the DPR information. | ||
| final ui.Display _display; | ||
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| // Last reported value of DPR. | ||
| double _currentDpr; | ||
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| // Controls the [dprChanged] broadcast Stream. | ||
| final StreamController<double> _dprStreamController = | ||
| StreamController<double>.broadcast(); | ||
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| // Object that fires a `change` event for the `_currentDpr`. | ||
| late DomEventTarget _dprMediaQuery; | ||
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| // Creates the media query for the latest known DPR value, and adds a change listener to it. | ||
| void _subscribeToMediaQuery() { | ||
| if (_debugOverrides?.getMediaQuery != null) { | ||
| _dprMediaQuery = _debugOverrides!.getMediaQuery!(_currentDpr); | ||
| } else { | ||
| _dprMediaQuery = domWindow.matchMedia('(resolution: ${_currentDpr}dppx)'); | ||
| } | ||
| _dprMediaQuery.addEventListenerWithOptions( | ||
| 'change', | ||
| createDomEventListener(_onDprMediaQueryChange), | ||
| <String, Object>{ | ||
| // We only listen `once` because this event only triggers once when the | ||
| // DPR changes from `_currentDpr`. Once that happens, we need a new | ||
| // `_dprMediaQuery` that is watching the new `_currentDpr`. | ||
| // | ||
| // By using `once`, we don't need to worry about detaching the event | ||
| // listener from the old mediaQuery after we're done with it. | ||
| 'once': true, | ||
| 'passive': true, | ||
| }, | ||
| ); | ||
| } | ||
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| // Handler of the _dprMediaQuery 'change' event. | ||
| // | ||
| // This calls subscribe again because events are listened to with `once: true`. | ||
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| JSVoid _onDprMediaQueryChange(DomEvent _) { | ||
| _currentDpr = _display.devicePixelRatio; | ||
| _dprStreamController.add(_currentDpr); | ||
| // Re-subscribe... | ||
| _subscribeToMediaQuery(); | ||
| } | ||
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| /// A stream that emits the latest value of [EngineFlutterDisplay.instance.devicePixelRatio]. | ||
| Stream<double> get dprChanged => _dprStreamController.stream; | ||
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| // The overrides object that is used for testing. | ||
| final DebugDisplayDprStreamOverrides? _debugOverrides; | ||
| } | ||
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| @visibleForTesting | ||
| class DebugDisplayDprStreamOverrides { | ||
| DebugDisplayDprStreamOverrides({ | ||
| this.getMediaQuery, | ||
| }); | ||
| final DomEventTarget Function(double currentValue)? getMediaQuery; | ||
| } | ||
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