Dynamic view sizing [dart:ui] #48090

goderbauer · 2023-11-15T21:29:37Z

This PR makes the following changes to the public dart:ui API:

It adds the FlutterView.pysicalConstraints property that describes max and min width and height for a view. The framework is allowed to size the FlutterView to any Size that meets these constraints.
It adds an optional size argument to FlutterView.render. The framework provides the chosen Size that meets the aforementioned constraints to the render method. If the FlutterView.pysicalConstraints are tight (minHeight == maxHeight and minWidth == maxWidth) the argument is optional to remain backwards compatible. In all other cases, a Size must be provided.
It adds a ViewConstraints class, which is basically the dart:ui version of BoxConstraints (This is similar to how we have ViewPadding in dart:ui to mirror EdgeInsets from the framework). It describes the constraints of a FlutterView, i.e. it powers the FlutterView.pysicalConstraints property.

This change does not wire anything up to the embedders. For now, FlutterView.pysicalConstraints just returns tight constraints for the embedder-provided size of the view (FlutterView.physicalSize) and the size provided to FlutterView.render is ignored (after it is checked that it meets the constrains).

This PR enables the framework to implement the new dynamic view sizing and embedders to separately expose the new functionality to their clients.

Presubmits will fail until flutter/flutter#138565 is submitted to the framework.

DO NOT SUBMIT until flutter/flutter#138648 is ready.

lib/web_ui/lib/src/engine/window.dart

goderbauer · 2023-11-16T20:38:28Z

Quick note: The framework tests are failing until flutter/flutter#138565 is submitted to the framework to prepare for this PR.

lib/ui/window.dart

dkwingsmt · 2023-11-21T22:27:28Z

lib/ui/platform_dispatcher.dart

  final double devicePixelRatio;

-  /// The size requested for the view in logical pixels.
+  /// The size requested for the view in physical pixels.


How did we find out this should be physical instead of logical? Is it a bug fix or a behavior change?

The value was always in physical pixels, it was just documented wrong. Luckily, it is a doc comment on a private class, so the doc was never actually public.

Backup evidence that this has always been in physical pixels and we just documented it wrong: This value is returned by the physicalSize getter on FlutterView:

engine/lib/ui/window.dart

Line 163 in dba80be

Size get physicalSize => _viewConfiguration.size;

I've found Physical vs Logical pixels is painful in the web, especially if one trusts the docs :P

ditman

LGTM!

(Here's the changes I did to get web support)

lib/ui/window.dart

lib/web_ui/lib/platform_dispatcher.dart

lib/web_ui/lib/src/engine/window.dart

dkwingsmt

LGTM

gspencergoog · 2023-11-27T17:19:05Z

lib/ui/platform_dispatcher.dart

+  });
+
+  /// Creates view constraints that is respected only by the given size.
+  ViewConstraints.tight(Size size)


Why can't this be const?

size.width and size.height are invalid constant values, according to Dart (In theory, they could be getters that do some crazy computation using information only available at runtime.). Since they are used in the initializer list below, the constructor cannot be const, sadly.

(Same applies to the existing BoxConstraints.tight constructor)

Ahh, right, makes sense. Too bad there's no way to make a final property not be overridable with a getter.

Towards #134501. Required to roll flutter/engine#48090 into the framework. **DO NOT SUBMIT until #138648 and flutter/engine#48090 are ready.**

auto-submit · 2023-11-27T17:56:59Z

auto label is removed for flutter/engine/48090, due to - The status or check suite Linux Framework Smoke Tests has failed. Please fix the issues identified (or deflake) before re-applying this label.

dkwingsmt · 2023-11-27T18:48:35Z

lib/ui/window.dart

+  ///
+  /// At startup, the constraints for the view may not be known before Dart code
+  /// runs. If this value is observed early in the application lifecycle, it may
+  /// report constraints with all dimensions set to zero.


Does "constraints with all dimensions set to zero" mean the resulting size must be 0? I don't know if this sentence needs to be said, because the sentence alone feels important on the surface but it's really just a temporary state. And the constraints are less like "known" but more like "set" by the engine.

Yes, it means the only size allowed will be zero. It matches what was previously documented on physicalSize.

dkwingsmt · 2023-11-27T18:49:46Z

lib/ui/window.dart

+  /// This value does not take into account any on-screen keyboards or other
+  /// system UI. If the constraints are tight, the [padding] and [viewInsets]


Does "not take into account" mean the size include or exclude these system UI? I think "include/exclude" will be clearer.

(This is using the same terms we use on physicalSize to document the same thing). I find include/exclude more confusing because it depends on your perspective whether the padding is included or excluded.

dkwingsmt · 2023-11-27T18:51:10Z

lib/ui/window.dart

+  /// be obscured by system UI. If the constraints are loose, this information
+  /// is not known upfront.


What do you mean by "this information is not known"? Shall we just assert that only tight constraints can have non-zero padding and insets?

This is basically describing platform limitations. No platform currently makes it possible to know this information upfront, but in theory a platform could provide it.

Towards #134501. Required to roll flutter/engine#48090 into the framework. Two new subclasses of FlutterView were added recently for testing (in #138849) that I missed in my previous PR (#138565).

Co-authored-by: David Iglesias <ditman@gmail.com>

…139103) flutter/engine@0a098bd...2be7191 2023-11-27 goderbauer@google.com Dynamic view sizing [dart:ui] (flutter/engine#48090) 2023-11-27 dnfield@google.com Roll shaderc to google/shaderc@37e2553 (flutter/engine#48415) 2023-11-27 skia-flutter-autoroll@skia.org Roll Skia from 4c964f8c4738 to 600986ba305d (6 revisions) (flutter/engine#48419) 2023-11-27 1961493+harryterkelsen@users.noreply.github.com [canvaskit] Enable multiview rendering (flutter/engine#48301) 2023-11-27 30870216+gaaclarke@users.noreply.github.com [Impeller] updated gaussian blur tests to use device private textures (flutter/engine#48417) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-engine-flutter-autoroll Please CC jacksongardner@google.com,rmistry@google.com,zra@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

Towards #134501. This change is based on flutter/engine#48090. It changes the `RenderView` to be dynamically sized based on its content if the `FlutterView` it is configured with allows it (i.e. the `FlutterView` has loose `FlutterView.physicalConstraints`). For that, it uses those `physicalConstraints` as input to the layout algorithm by passing them on to its child (after translating them to logical constraints via the device pixel ratio). The resulting `Size` that the `RenderView` would like to be is then communicated back to the engine by passing it to the `FlutterView.render` call. Tests will fail until flutter/engine#48090 has rolled into the framework.

Towards flutter#134501. Required to roll flutter/engine#48090 into the framework. **DO NOT SUBMIT until flutter#138648 and flutter/engine#48090 are ready.**

Towards flutter#134501. Required to roll flutter/engine#48090 into the framework. Two new subclasses of FlutterView were added recently for testing (in flutter#138849) that I missed in my previous PR (flutter#138565).

…lutter#139103) flutter/engine@0a098bd...2be7191 2023-11-27 goderbauer@google.com Dynamic view sizing [dart:ui] (flutter/engine#48090) 2023-11-27 dnfield@google.com Roll shaderc to google/shaderc@37e2553 (flutter/engine#48415) 2023-11-27 skia-flutter-autoroll@skia.org Roll Skia from 4c964f8c4738 to 600986ba305d (6 revisions) (flutter/engine#48419) 2023-11-27 1961493+harryterkelsen@users.noreply.github.com [canvaskit] Enable multiview rendering (flutter/engine#48301) 2023-11-27 30870216+gaaclarke@users.noreply.github.com [Impeller] updated gaussian blur tests to use device private textures (flutter/engine#48417) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-engine-flutter-autoroll Please CC jacksongardner@google.com,rmistry@google.com,zra@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

Towards flutter#134501. This change is based on flutter/engine#48090. It changes the `RenderView` to be dynamically sized based on its content if the `FlutterView` it is configured with allows it (i.e. the `FlutterView` has loose `FlutterView.physicalConstraints`). For that, it uses those `physicalConstraints` as input to the layout algorithm by passing them on to its child (after translating them to logical constraints via the device pixel ratio). The resulting `Size` that the `RenderView` would like to be is then communicated back to the engine by passing it to the `FlutterView.render` call. Tests will fail until flutter/engine#48090 has rolled into the framework.

github-actions bot added the platform-web Code specifically for the web engine label Nov 15, 2023

goderbauer commented Nov 15, 2023

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goderbauer force-pushed the dynamic-view-sizing branch from b195365 to a6e7539 Compare November 16, 2023 19:23

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Prepare for dynamically sized views flutter/flutter#138565

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goderbauer marked this pull request as ready for review November 16, 2023 20:37

This was referenced Nov 20, 2023

Do not send frames to engine in automated tests flutter/flutter#138651

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Dynamic view sizing flutter/flutter#138648

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Prepare for dynamically sized views - pt. 2 flutter/flutter#139079

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goderbauer added 2 commits November 27, 2023 11:53

++

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more wiring

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goderbauer and others added 10 commits November 27, 2023 11:53

web

4477242

format

a1ae04b

tests

f570dd7

add euqlas

6aafa7f

constify

d951f4d

toString

6352a82

remove assert

eb7b1c8

Update lib/ui/window.dart

6b8542a

Co-authored-by: David Iglesias <ditman@gmail.com>

Update lib/ui/window.dart

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Co-authored-by: David Iglesias <ditman@gmail.com>

Update lib/web_ui/lib/src/engine/window.dart

92a4dd2

Co-authored-by: David Iglesias <ditman@gmail.com>

goderbauer force-pushed the dynamic-view-sizing branch from 34ae397 to 92a4dd2 Compare November 27, 2023 20:23

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Roll Flutter Engine from 0a098bd6f761 to 2be719150ea9 (5 revisions) flutter/flutter#139103

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2be719150 Dynamic view sizing [dart:ui] (flutter/engine#48090)

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cbracken mentioned this pull request May 28, 2025

Enable support for dynamic view resizing flutter/flutter#169605

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cbracken mentioned this pull request Jun 12, 2025

Enable support for dynamic view resizing flutter/flutter#170499

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LouiseHsu mentioned this pull request Aug 12, 2025

Engine Support for Dynamic View Resizing flutter/flutter#173610

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		/// This value does not take into account any on-screen keyboards or other
		/// system UI. If the constraints are tight, the [padding] and [viewInsets]

		/// be obscured by system UI. If the constraints are loose, this information
		/// is not known upfront.

Dynamic view sizing [dart:ui] #48090

Dynamic view sizing [dart:ui] #48090

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