[webview_flutter_android] Adds opt out of `displayCutout` and `systemBars` Android inset changes by bparrishMines · Pull Request #11192 · flutter/packages

bparrishMines · 2026-03-06T20:03:14Z

For WebView versions >=144, support has been added for displayCutout() insets and systemBars() insets. This is causing WebViews to incorrectly report that it is obscured by a system bar or display cutout as demonstrated in this issue.

This adds the opt out for inset changes as explained in this chromium doc. It seems Flutter handles safe areas for platform views, so the WebView can zero out inset changes to the View.

iOS does something similar. And it also sets UIScrollView.contentInsetAdjustmentBehavior to Never. My assumption was that this was never done for Android, because WebViews didn't receive these inset changes until this version.

Fixes flutter/flutter#182208

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bparrishMines · 2026-03-09T21:32:33Z

@flutter/android-reviewers This adds an opt out to newly supported insets on chromium. My assumption for this PR is that these insets are handled by Flutter (similar to iOS), but wanted to ensure this is fine with Android team members.

gemini-code-assist

Code Review

This pull request introduces an opt-out mechanism for displayCutout and systemBars Android inset changes in webview_flutter_android. The changes involve updating Pigeon files to add a new method for setting an inset listener, implementing this logic on the Android native side, and calling it from the Dart AndroidWebViewController. The tests have been updated accordingly.

My main feedback concerns the implementation of the inset listener on the Android side, where padding is being applied to the View. This seems to contradict the goal of letting Flutter handle safe areas, as stated in the comments and PR description. I've left a specific comment with a suggestion to address this.

_{Note: Security Review did not run due to the size of the PR.}

gemini-code-assist · 2026-03-09T21:32:44Z

...ew_flutter_android/android/src/main/java/io/flutter/plugins/webviewflutter/ViewProxyApi.java

+          final Insets allInsets = windowInsets.getInsets(finalTypeMask);
+          pigeon_instance.setPadding(
+              allInsets.left, allInsets.top, allInsets.right, allInsets.bottom);
+          return new WindowInsetsCompat.Builder(windowInsets)
+              .setInsets(finalTypeMask, Insets.NONE)
+              .build();


The comment in android_webview_controller.dart states that "Flutter handles these internally", and the PR description mentions that the desired behavior is similar to iOS's contentInsetAdjustmentBehavior = .never. Both of these suggest that the web content should extend into the safe areas (i.e., underlap system bars and cutouts).

However, applying padding to the native View here will shrink the web content area, preventing it from drawing into the safe areas. This seems to contradict the intended goal of letting Flutter manage the safe area.

If the intention is to let Flutter handle safe areas, you should probably only consume the insets to prevent the WebView from applying them, but not apply any padding to the View itself. This would allow the web content to render edge-to-edge.

Could you clarify if this padding is intended? If not, these lines should be removed, and the corresponding test in ViewTest.java should be updated.

Suggested change

final Insets allInsets = windowInsets.getInsets(finalTypeMask);

pigeon_instance.setPadding(

allInsets.left, allInsets.top, allInsets.right, allInsets.bottom);

return new WindowInsetsCompat.Builder(windowInsets)

.setInsets(finalTypeMask, Insets.NONE)

.build();

return new WindowInsetsCompat.Builder(windowInsets)

.setInsets(finalTypeMask, Insets.NONE)

.build();

Confirmed that an edge-edge WebView still works.

Can you confirm the behavior of a full screen flutter web view on a device with a simulated or actual tall cutout.
You can test on any physical device (or maybe emulator) by running adb shell cmd overlay enable com.android.internal.display.cutout.emulation.tall

reidbaker

At a high level I like that we are opting out of chromes auto system bars instead of creating a path to ignore our own insets logic when showing in chrome. I need to get this a more through review but directionally I am for this change.

reidbaker

If you have screenshots of the before and after behavior could you include them in this pr? If you dont and it is cumbersome to get them then feel free to ignore this request.

reidbaker · 2026-03-10T18:13:02Z

...ew_flutter_android/android/src/main/java/io/flutter/plugins/webviewflutter/ViewProxyApi.java

+  public void setInsetListenerToSetInsetsToZero(
+      @NonNull View pigeon_instance, @NonNull List<? extends WindowInsets> insets) {
+    int insetsTypeMask = 0;
+    for (WindowInsets inset : insets) {


Can you add comment here that indicates why SYTEM_BARS and DISPLAY_CUTOUT where chosen and how to know when a new item should be added to this list.

Additionally why use the all caps ints instead of WindowInsets.Type.systemBars()?

reidbaker · 2026-03-10T18:15:45Z

...ew_flutter_android/android/src/main/java/io/flutter/plugins/webviewflutter/ViewProxyApi.java

+    ViewCompat.setOnApplyWindowInsetsListener(
+        pigeon_instance,
+        (view, windowInsets) -> {
+          if (finalTypeMask == 0) {


Can you add a comment explaining that this is checking to see if we set any bitwise values to make the code easier to skim without having someone need to understand why we are comparing to zero.

reidbaker · 2026-03-10T18:19:36Z

...ew_flutter_android/android/src/main/java/io/flutter/plugins/webviewflutter/ViewProxyApi.java

+          }
+
+          final Insets allInsets = windowInsets.getInsets(finalTypeMask);
+          pigeon_instance.setPadding(


What does setting the padding here on the pigeon_instance do?

reidbaker · 2026-03-10T18:21:07Z

...ew_flutter_android/android/src/main/java/io/flutter/plugins/webviewflutter/ViewProxyApi.java

+            return windowInsets;
+          }
+
+          final Insets allInsets = windowInsets.getInsets(finalTypeMask);


I allInsets here is actually only the set of insets we care about ignoring. Can you help me understand how it is different from windowInsets at this line and also how it is more "all" than just the window insets?

reidbaker · 2026-03-10T18:24:01Z

...ew_flutter_android/android/src/main/java/io/flutter/plugins/webviewflutter/ViewProxyApi.java

+          return new WindowInsetsCompat.Builder(windowInsets)
+              .setInsets(finalTypeMask, Insets.NONE)


I think this line is saying to copy the existing windowInsets then to set all the ones we care about "consuming" to Insets.NONE.

If that is correct i think this line could be made more readable with the following changes.

Suggested change

return new WindowInsetsCompat.Builder(windowInsets)

.setInsets(finalTypeMask, Insets.NONE)

// Consume insects that are already handled by flutter.

return new WindowInsetsCompat.Builder(windowInsets)

.setInsets(activeInsetsHandledByFlutter, Insets.NONE)

Additionally if we cant define a list to import in both locations I think the code that is "already" handling the insets should be cross linked. As a result the case statements probably become another loop.

reidbaker · 2026-03-10T18:29:03Z

...ew_flutter_android/android/src/main/java/io/flutter/plugins/webviewflutter/ViewProxyApi.java

+          final Insets allInsets = windowInsets.getInsets(finalTypeMask);
+          pigeon_instance.setPadding(
+              allInsets.left, allInsets.top, allInsets.right, allInsets.bottom);
+          return new WindowInsetsCompat.Builder(windowInsets)
+              .setInsets(finalTypeMask, Insets.NONE)
+              .build();


Can you confirm the behavior of a full screen flutter web view on a device with a simulated or actual tall cutout.
You can test on any physical device (or maybe emulator) by running adb shell cmd overlay enable com.android.internal.display.cutout.emulation.tall

bparrishMines added 6 commits March 5, 2026 16:05

update example app

55c4ce0

implementation

6bb5a99

Merge branch 'main' of github.com:flutter/packages into webview_safe_…

8e10a01

…area

formatting

3b3d6c6

java test

32856f9

update unit tests

ce2a9b3

github-actions bot added platform-android p: webview_flutter labels Mar 6, 2026

bparrishMines added 7 commits March 6, 2026 15:04

add destruction back

bc04474

version bump and undo example app

57ca57c

formatting

49a3867

docs

74bfe0f

fix docs

cfdf061

update pigeon

07c8699

fix docs again

31fa299

bparrishMines changed the title ~~Webview safe area~~ [webview_flutter_android] Adds opt out of displayCutout and systemBars Android inset changes Mar 6, 2026

bparrishMines marked this pull request as ready for review March 9, 2026 21:24

bparrishMines requested review from a team and stuartmorgan-g March 9, 2026 21:24

gemini-code-assist bot reviewed Mar 9, 2026

View reviewed changes

reidbaker reviewed Mar 10, 2026

View reviewed changes

		return new WindowInsetsCompat.Builder(windowInsets)
		.setInsets(finalTypeMask, Insets.NONE)

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bparrishMines commented Mar 6, 2026 •

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