[Android] Add display corner radii support. by ksokolovskyi · Pull Request #179219 · flutter/flutter

ksokolovskyi · 2025-11-28T15:08:23Z

Description

This PR focuses only on the Android side.

As was discussed in #97349, the iOS API for getting display corner radii is private. The only safe way to get the radii values is to generate a lookup table ahead and use its values at runtime. I would be happy to work on the iOS implementation in a separate PR after this lands.

Adds displayCornerRadii in the physical pixels to the engine's window metrics
Adds displayCornerRadii support on the Android API 31+
Adds displayCornerRadii in the logical pixels to the MediaQuery
Adds and updates tests

Pre-launch Checklist

I read the Contributor Guide and followed the process outlined there for submitting PRs.
I read the Tree Hygiene wiki page, which explains my responsibilities.
I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
I signed the CLA.
I listed at least one issue that this PR fixes in the description above.
I updated/added relevant documentation (doc comments with ///).
I added new tests to check the change I am making, or this PR is test-exempt.
I followed the breaking change policy and added Data Driven Fixes where supported.
All existing and new tests are passing.

gemini-code-assist

Code Review

This PR adds support for display corner radii on Android. The changes span across the engine and framework to expose this new information. The implementation looks solid, with new APIs in dart:ui and MediaQuery to access the corner radii. Tests have been added to cover the new functionality. I've found a critical issue in the copyWith method in MediaQueryData that will cause a compilation error, and another suggestion to improve API consistency. Please see my detailed comments.

ksokolovskyi · 2025-11-28T15:12:29Z

Hi @justinmc, I assigned you as a reviewer as you took part in the issue discussion.

Could you please take a look at this PR when you have time?

mdebbar

The web stubs look good to me!

mboetger

Android-side plumbing looks good. One question below. Also we'll need someone from the framework to look at this, I believe.

mboetger

LGTM from the Android side - please wait to submit until you get LGTMs from the web and framework side though.

mboetger · 2025-12-08T19:47:27Z

I know why the Google testing is failing - I can fix it. I had to make a similar change in #176063 in the JNI (will need to rebase it if that one lands first).

ksokolovskyi · 2025-12-08T20:00:17Z

I know why the Google testing is failing - I can fix it. I had to make a similar change in #176063 in the JNI (will need to rebase it if that one lands first).

Thanks a lot for taking a look at the Google Testing failure!
I will do a rebase after your PR is merged.

Co-authored-by: Matt Boetger <matt.boetger@gmail.com>

ksokolovskyi · 2025-12-09T20:45:37Z

@mboetger, could you please take a look at why Google Testing failed?

mboetger · 2025-12-09T21:32:09Z

@mboetger, could you please take a look at why Google Testing failed?

Working on it.

justinmc

LGTM with nits 👍 Thank you for doing this @ksokolovskyi, it's going to be a big improvement for predictive back!

Is there any reason to think that we couldn't reuse the same mechanism to pass this value from iOS as well some day? Seems like it should work to me but want to make sure.

A major edge case: What about a foldable phone that the user unfolds? Does that change the radius values?

justinmc · 2025-12-18T19:34:47Z

+  @override
+  String toString() {


Consider mixing in Diagnosticable and using debugFillProperties here. https://github.com/flutter/flutter/blob/master/docs/contributing/Style-guide-for-Flutter-repo.md#override-tostring

This sounds great, but Diagnosticable is defined in flutter/lib/src/foundation and thus can't be used in engine layer.

Darn you're right.

justinmc · 2025-12-18T19:41:42Z

+  int get hashCode => Object.hash(topLeft, topRight, bottomRight, bottomLeft);
+
+  @override
+  String toString() {


Same Diagnosticable comment here.

This is not possible as discussed elsewhere.

justinmc · 2025-12-18T19:43:53Z

      0.0, // maxWidth
      0.0, // minHeight
      0.0, // maxHeight
+      -1.0, // display corner radius top left


I guess we're assuming that the radius is always circular. Is that an assumption that the Android and iOS APIs make too?

Both platforms represent device corner radii as a single scalar value rather than an elliptical X/Y pair.

On Android, the RoundedCorner API specifically defines the corner as a 'quarter circle approximation' and only provides a single getRadius() value.

On iOS, Apple uses 'continuous' curves (squircles) for a smoother look. Still, they are defined by a single radius value available via the private _displayCornerRadius property.

Got it, thanks for reassuring me 👍

ksokolovskyi · 2026-01-05T14:10:34Z

Hi @justinmc, thanks a lot for your review!

Is there any reason to think that we couldn't reuse the same mechanism to pass this value from iOS as well some day? Seems like it should work to me but want to make sure.

As was discussed in #97349, the iOS API for getting display corner radii is private. The only safe way to get the radii values is to generate a lookup table ahead and use its values at runtime. I would be happy to work on the iOS implementation in a separate PR after this lands.

A major edge case: What about a foldable phone that the user unfolds? Does that change the radius values?

I don't have a physical foldable device, but I tried to run a demo on the Pixel 9 Pro Fold emulator, and the display corner radius values are updated according to the fold status.

Code sample

import 'package:flutter/material.dart';

void main() {
  runApp(const App());
}

class App extends StatelessWidget {
  const App({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Screen(),
    );
  }
}

class Screen extends StatefulWidget {
  const Screen({super.key});

  @override
  State<Screen> createState() => _ScreenState();
}

class _ScreenState extends State<Screen> with SingleTickerProviderStateMixin {
  @override
  Widget build(BuildContext context) {
    print('dpr: ${MediaQuery.devicePixelRatioOf(context)}');

    return Scaffold(
      body: Padding(
        padding: const EdgeInsets.all(20),
        child: Center(
          child: DisplayCornerRadiiReactor(),
        ),
      ),
    );
  }
}

class DisplayCornerRadiiReactor extends StatefulWidget {
  const DisplayCornerRadiiReactor({super.key});

  @override
  State<DisplayCornerRadiiReactor> createState() =>
      _DisplayCornerRadiiReactorState();
}

class _DisplayCornerRadiiReactorState extends State<DisplayCornerRadiiReactor> {
  @override
  Widget build(BuildContext context) {
    return Column(
      mainAxisSize: MainAxisSize.min,
      spacing: 20,
      children: [
        Text(
          'displayCornerRadii: ${View.of(context).displayCornerRadii}',
          textAlign: TextAlign.center,
          style: TextStyle(fontSize: 20),
        ),
        Text(
          'displayCornerRadii: ${MediaQuery.displayCornerRadiiOf(context)}',
          textAlign: TextAlign.center,
          style: TextStyle(fontSize: 20),
        ),
      ],
    );
  }
}

foldable.mp4

justinmc

LGTM 👍 . Thanks for the followup. Let's wait for a web review and then this is good to go.

justinmc · 2026-01-16T23:12:52Z

      0.0, // maxWidth
      0.0, // minHeight
      0.0, // maxHeight
+      -1.0, // display corner radius top left


Got it, thanks for reassuring me 👍

justinmc · 2026-01-16T23:15:03Z

+  @override
+  String toString() {


Darn you're right.

justinmc · 2026-01-16T23:15:50Z

+  int get hashCode => Object.hash(topLeft, topRight, bottomRight, bottomLeft);
+
+  @override
+  String toString() {


This is not possible as discussed elsewhere.

ksokolovskyi · 2026-01-19T07:54:13Z

@justinmc thanks for your review!
We already have a LGTM from @mdebbar #179219 (review)
Or you would like to get another look from the web team?

justinmc · 2026-01-20T23:15:32Z

Ah I missed that, sorry 😅 .

I reran one test that appeared to be a flake, otherwise this is ready to land.

ksokolovskyi · 2026-01-21T20:00:16Z

Thanks a lot, everyone, for your reviews and feedback!

…r#179219)

Closes flutter#97349 Unblocks flutter#178463 ### Description This PR focuses only on the Android side. As was discussed in flutter#97349, the iOS API for getting display corner radii is private. The only safe way to get the radii values is to generate a lookup table ahead and use its values at runtime. I would be happy to work on the iOS implementation in a separate PR after this lands. - Adds `displayCornerRadii` in the physical pixels to the engine's window metrics - Adds `displayCornerRadii` support on the Android API 31+ - Adds `displayCornerRadii` in the logical pixels to the `MediaQuery` - Adds and updates tests ## Pre-launch Checklist - [X] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [X] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [X] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [X] I signed the [CLA]. - [X] I listed at least one issue that this PR fixes in the description above. - [X] I updated/added relevant documentation (doc comments with `///`). - [X] I added new tests to check the change I am making, or this PR is [test-exempt]. - [X] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [X] All existing and new tests are passing.  [Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview [Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md [test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests [Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md [Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement [CLA]: https://cla.developers.google.com/ [flutter/tests]: https://github.com/flutter/tests [breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes [Discord]: https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md [Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md --------- Co-authored-by: Matt Boetger <matt.boetger@gmail.com>

refer to commit: 697572a("[Android] Add display corner radii support. (flutter#179219)") Signed-off-by: Yongqin Liu <yongqin.liu@linaro.org>

ksokolovskyi requested a review from a team as a code owner November 28, 2025 15:08

ksokolovskyi requested a review from justinmc November 28, 2025 15:09

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Comment thread engine/src/flutter/shell/platform/android/io/flutter/embedding/android/FlutterView.java

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Comment thread ...ne/src/flutter/shell/platform/android/test/io/flutter/embedding/android/FlutterViewTest.java Outdated

ksokolovskyi and others added 3 commits December 9, 2025 12:21

Add display corner radii support.

9e8c8f2

Add MediaQuery.displayCornerRadii property.

bc20d94

Apply review suggestion.

d194b89

Co-authored-by: Matt Boetger <matt.boetger@gmail.com>

ksokolovskyi force-pushed the add-display-corner-radii branch from 426843b to d194b89 Compare December 9, 2025 11:22

Fix issues after master merge.

f6c7fd3

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Merge branch 'master' into add-display-corner-radii

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ksokolovskyi added 2 commits January 5, 2026 12:12

Merge branch 'master' into add-display-corner-radii

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Merge branch 'master' into add-display-corner-radii

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ksokolovskyi requested a review from justinmc January 13, 2026 18:59

Merge branch 'master' into add-display-corner-radii

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Merge branch 'master' into add-display-corner-radii

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Merged via the queue into flutter:master with commit 697572a Jan 21, 2026
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Roll Flutter from 48c247582e45 to 2dc633eb1168 (142 revisions) flutter/packages#10850

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697572a67 [Android] Add display corner radii support. (flutter/flutte…

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…r#179219)

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Roll Flutter from 48c247582e45 to baa9e3215220 (143 revisions) flutter/packages#10853

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…r#179219)

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Roll Flutter from 48c247582e45 to dbed04aa32e5 (144 revisions) flutter/packages#10856

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697572a67 [Android] Add display corner radii support. (flutter/flutte…

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…r#179219)

justinmc mentioned this pull request Jan 23, 2026

Add displayCornerRadii support to predictive back transitions. #181326

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ksokolovskyi commented Nov 28, 2025

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