fix: show window after first frame callback by rkishan516 · Pull Request #183454 · flutter/flutter

rkishan516 · 2026-03-10T15:24:42Z

This PR adds first frame callback to FlutterWindowView such that we only show window after first frame.

Pre-launch Checklist

google-cla · 2026-03-10T15:24:54Z

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

gemini-code-assist

Code Review

This pull request introduces a mechanism to defer showing a window until after the first frame has been rendered, preventing a blank window from flashing. It adds a SetFirstFrameCallback method to FlutterWindowsView, which is invoked from OnFramePresented (for GPU rendering) and PresentSoftwareBitmap (for software rendering). The HostWindow is updated to use this callback to call ShowWindow. The changes are accompanied by a comprehensive set of unit tests.

gemini-code-assist · 2026-03-10T16:12:43Z

+  std::scoped_lock lock(first_frame_callback_mutex_);
+  if (first_frame_callback_) {
+    fml::closure callback = std::move(first_frame_callback_);
+    first_frame_callback_ = nullptr;
+    engine_->task_runner()->PostTask(std::move(callback));
+  }


To minimize the duration the mutex is held, it's a good practice to release the lock before performing operations that might block or take time, like posting a task to another thread. You can achieve this by moving the callback out of the locked scope and then posting it. Using std::swap is an idiomatic and safe way to extract the callback while ensuring the member is cleared.

Suggested change

std::scoped_lock lock(first_frame_callback_mutex_);

if (first_frame_callback_) {

fml::closure callback = std::move(first_frame_callback_);

first_frame_callback_ = nullptr;

engine_->task_runner()->PostTask(std::move(callback));

}

fml::closure callback_to_fire;

{

std::scoped_lock lock(first_frame_callback_mutex_);

callback_to_fire.swap(first_frame_callback_);

}

if (callback_to_fire) {

engine_->task_runner()->PostTask(std::move(callback_to_fire));

}

knopp · 2026-03-10T20:29:12Z

This adds the callback, but seems to be missing the rest? Also with multi-window, I think this should be happening transparently without user intervention.

EDIT: Nevermind, I missed the host_window part :)

knopp · 2026-03-10T20:34:48Z

One thing to consider here, we now by default show all windows created, with no way to create hidden window. Or to hide window at all.

Also this is something we should do on other platforms as long as we figure out the right approach (i.e. opacity vs show/hide, and maybe way to disable the behavior if user wants to create hidden window and show it later). On macOS this is currently done, but only for tooltips and popups.

rkishan516 · 2026-03-11T01:02:45Z

One thing to consider here, we now by default show all windows created, with no way to create hidden window. Or to hide window at all.

Also this is something we should do on other platforms as long as we figure out the right approach (i.e. opacity vs show/hide, and maybe way to disable the behavior if user wants to create hidden window and show it later). On macOS this is currently done, but only for tooltips and popups.

I was thinking along the same lines, but that might need discussion on how we want to do it. May be I can create another PR which does add iniitial configuration to RegularWindowController and we can decide, how we want move from there.

This is minimal change which just removes the flicker of first frame. I don't think this change should affect adding visible flag decision.

robert-ancell

Looks good, thanks!

…r#183454)

flutter/flutter@e79bf6c...fb03253 2026-03-27 kevmoo@users.noreply.github.com flutter_driver: remove @internal annotation on field (flutter/flutter#184235) 2026-03-27 engine-flutter-autoroll@skia.org Roll Skia from 5299de75c97b to 8c705ac86366 (2 revisions) (flutter/flutter#184245) 2026-03-27 engine-flutter-autoroll@skia.org Roll Packages from 0dd2410 to 7ae082a (5 revisions) (flutter/flutter#184248) 2026-03-27 engine-flutter-autoroll@skia.org Roll Skia from 9beded929d5a to 5299de75c97b (1 revision) (flutter/flutter#184243) 2026-03-27 engine-flutter-autoroll@skia.org Roll Skia from 4f4f07084ef0 to 9beded929d5a (4 revisions) (flutter/flutter#184237) 2026-03-27 engine-flutter-autoroll@skia.org Roll Dart SDK from ea1bce22b45b to dfd1f8af3c52 (2 revisions) (flutter/flutter#184234) 2026-03-27 engine-flutter-autoroll@skia.org Roll Skia from 1b7154852825 to 4f4f07084ef0 (1 revision) (flutter/flutter#184231) 2026-03-27 engine-flutter-autoroll@skia.org Roll Skia from aec9a7ab7ed9 to 1b7154852825 (1 revision) (flutter/flutter#184230) 2026-03-27 34465683+rkishan516@users.noreply.github.com fix: show window after first frame callback (flutter/flutter#183454) 2026-03-27 engine-flutter-autoroll@skia.org Roll Dart SDK from 7587a31814c6 to ea1bce22b45b (1 revision) (flutter/flutter#184228) 2026-03-27 okorohelijah@google.com skip interactive keyboard tests (flutter/flutter#183757) 2026-03-26 git@reb0.org Build engine for windows_arm on beta and stable (flutter/flutter#176385) 2026-03-26 engine-flutter-autoroll@skia.org Roll Skia from bee5a06ef578 to aec9a7ab7ed9 (4 revisions) (flutter/flutter#184222) 2026-03-26 magder@google.com Update iOS/macOS flutter_tools CODEOWNERS (flutter/flutter#183287) 2026-03-26 evanwall@buffalo.edu Update changelog for 3.41.6 stable hotfix (flutter/flutter#184220) 2026-03-26 47866232+chunhtai@users.noreply.github.com Updates scroll cache extent doc (flutter/flutter#184142) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC stuartmorgan@google.com,tarrinneal@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Packages: 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

This PR adds first frame callback to FlutterWindowView such that we only show window after first frame. ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [AI contribution guidelines] and understand my responsibilities, or I am not using AI tools. - [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.

…r#11379) flutter/flutter@e79bf6c...fb03253 2026-03-27 kevmoo@users.noreply.github.com flutter_driver: remove @internal annotation on field (flutter/flutter#184235) 2026-03-27 engine-flutter-autoroll@skia.org Roll Skia from 5299de75c97b to 8c705ac86366 (2 revisions) (flutter/flutter#184245) 2026-03-27 engine-flutter-autoroll@skia.org Roll Packages from 0dd2410 to 7ae082a (5 revisions) (flutter/flutter#184248) 2026-03-27 engine-flutter-autoroll@skia.org Roll Skia from 9beded929d5a to 5299de75c97b (1 revision) (flutter/flutter#184243) 2026-03-27 engine-flutter-autoroll@skia.org Roll Skia from 4f4f07084ef0 to 9beded929d5a (4 revisions) (flutter/flutter#184237) 2026-03-27 engine-flutter-autoroll@skia.org Roll Dart SDK from ea1bce22b45b to dfd1f8af3c52 (2 revisions) (flutter/flutter#184234) 2026-03-27 engine-flutter-autoroll@skia.org Roll Skia from 1b7154852825 to 4f4f07084ef0 (1 revision) (flutter/flutter#184231) 2026-03-27 engine-flutter-autoroll@skia.org Roll Skia from aec9a7ab7ed9 to 1b7154852825 (1 revision) (flutter/flutter#184230) 2026-03-27 34465683+rkishan516@users.noreply.github.com fix: show window after first frame callback (flutter/flutter#183454) 2026-03-27 engine-flutter-autoroll@skia.org Roll Dart SDK from 7587a31814c6 to ea1bce22b45b (1 revision) (flutter/flutter#184228) 2026-03-27 okorohelijah@google.com skip interactive keyboard tests (flutter/flutter#183757) 2026-03-26 git@reb0.org Build engine for windows_arm on beta and stable (flutter/flutter#176385) 2026-03-26 engine-flutter-autoroll@skia.org Roll Skia from bee5a06ef578 to aec9a7ab7ed9 (4 revisions) (flutter/flutter#184222) 2026-03-26 magder@google.com Update iOS/macOS flutter_tools CODEOWNERS (flutter/flutter#183287) 2026-03-26 evanwall@buffalo.edu Update changelog for 3.41.6 stable hotfix (flutter/flutter#184220) 2026-03-26 47866232+chunhtai@users.noreply.github.com Updates scroll cache extent doc (flutter/flutter#184142) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC stuartmorgan@google.com,tarrinneal@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Packages: 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

rkishan516 requested a review from a team as a code owner March 10, 2026 15:24

github-actions Bot added engine flutter/engine related. See also e: labels. platform-windows Building on or for Windows specifically a: desktop Running on desktop team-windows Owned by the Windows platform team labels Mar 10, 2026

rkishan516 force-pushed the multi-window-first-frame branch from 9ddbef3 to 5aa26d9 Compare March 10, 2026 15:39

gemini-code-assist Bot reviewed Mar 10, 2026

View reviewed changes

loic-sharma requested a review from mattkae March 10, 2026 17:34

rkishan516 force-pushed the multi-window-first-frame branch from 5aa26d9 to ee3a266 Compare March 10, 2026 17:57

rkishan516 requested a review from knopp March 12, 2026 14:30

robert-ancell reviewed Mar 25, 2026

View reviewed changes

Comment thread engine/src/flutter/shell/platform/windows/flutter_windows_view_unittests.cc

robert-ancell previously approved these changes Mar 25, 2026

View reviewed changes

rkishan516 added 2 commits March 26, 2026 06:33

fix: show window after first frame callback

0db5c20

chore: add empty line as per feedback

3cb3801

rkishan516 dismissed robert-ancell’s stale review via 3cb3801 March 26, 2026 01:07

rkishan516 force-pushed the multi-window-first-frame branch from ee3a266 to 3cb3801 Compare March 26, 2026 01:07

rkishan516 added the CICD Run CI/CD label Mar 26, 2026

Merge branch 'master' into multi-window-first-frame

ee79a7a

github-actions Bot removed the CICD Run CI/CD label Mar 26, 2026

rkishan516 added the CICD Run CI/CD label Mar 26, 2026

robert-ancell approved these changes Mar 27, 2026

View reviewed changes

robert-ancell added the autosubmit Merge PR when tree becomes green via auto submit App label Mar 27, 2026

robert-ancell added this pull request to the merge queue Mar 27, 2026

Merged via the queue into flutter:master with commit 464d889 Mar 27, 2026
190 of 191 checks passed

flutter-dashboard Bot removed the autosubmit Merge PR when tree becomes green via auto submit App label Mar 27, 2026

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Mar 27, 2026

464d889e5 fix: show window after first frame callback (flutter/flutte…

1a6254f

…r#183454)

engine-flutter-autoroll mentioned this pull request Mar 27, 2026

Roll Flutter from e79bf6cbc140 to 3ba0d6d76345 (13 revisions) flutter/packages#11374

Closed

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Mar 27, 2026

464d889e5 fix: show window after first frame callback (flutter/flutte…

1246fa2

…r#183454)

engine-flutter-autoroll mentioned this pull request Mar 27, 2026

Roll Flutter from e79bf6cbc140 to b6efd1a1c3cd (14 revisions) flutter/packages#11377

Closed

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Mar 27, 2026

464d889e5 fix: show window after first frame callback (flutter/flutte…

1d40bee

…r#183454)

engine-flutter-autoroll mentioned this pull request Mar 27, 2026

Roll Flutter from e79bf6cbc140 to f86cb4b233d1 (15 revisions) flutter/packages#11378

Closed

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Mar 27, 2026

464d889e5 fix: show window after first frame callback (flutter/flutte…

69ababd

…r#183454)

engine-flutter-autoroll mentioned this pull request Mar 27, 2026

Roll Flutter from e79bf6cbc140 to fb03253e32ce (16 revisions) flutter/packages#11379

Merged

Piinks mentioned this pull request Mar 27, 2026

Flutter Notable Commits - 2026 #181433

Open

rkishan516 deleted the multi-window-first-frame branch April 8, 2026 15:50

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

fix: show window after first frame callback#183454

fix: show window after first frame callback#183454
robert-ancell merged 3 commits into
flutter:masterfrom
rkishan516:multi-window-first-frame

rkishan516 commented Mar 10, 2026

Uh oh!

google-cla Bot commented Mar 10, 2026

Uh oh!

gemini-code-assist Bot left a comment

Uh oh!

gemini-code-assist Bot Mar 10, 2026

Uh oh!

knopp commented Mar 10, 2026 •

edited

Loading

Uh oh!

knopp commented Mar 10, 2026

Uh oh!

rkishan516 commented Mar 11, 2026 •

edited

Loading

Uh oh!

Uh oh!

robert-ancell left a comment

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Uh oh!

Conversation

rkishan516 commented Mar 10, 2026

Pre-launch Checklist

Uh oh!

google-cla Bot commented Mar 10, 2026

Uh oh!

gemini-code-assist Bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

gemini-code-assist Bot Mar 10, 2026

Choose a reason for hiding this comment

Uh oh!

knopp commented Mar 10, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

knopp commented Mar 10, 2026

Uh oh!

rkishan516 commented Mar 11, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Uh oh!

robert-ancell left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

knopp commented Mar 10, 2026 •

edited

Loading

rkishan516 commented Mar 11, 2026 •

edited

Loading