Add support for stylus buttons by CodeDoctorDE · Pull Request #183369 · flutter/flutter

CodeDoctorDE · 2026-03-08T08:31:02Z

Continuation of #165323.

Now we have stylus support on windows with the last pull request.

This pull request now adds support for invertedStylus and stylus buttons (primary + secondary).

The pull request shouldn't have any breaking changes other than the pointer event shows the correct button bitmap instead of 1 always on a stylus input.

Should completly fix: #102836.

Tested on my notebook:

repo for the demo code: https://github.com/CodeDoctorDE/flutter-input-demo

This pull request is currently a draft and my next steps is to add tests

Pre-launch Checklist

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Piinks · 2026-05-11T21:57:19Z

@flutter/windows-reviewers can someone take a look?

CodeDoctorDE · 2026-05-12T05:40:21Z

I updated it again and improved the tracking of the button.
Additionally I added tests for this new stylus button detection.

This pr also sucessfully works on my flutter input demo:

gemini-code-assist

Code Review

This pull request adds support for inverted stylus devices and specific stylus buttons to the Windows embedder by refactoring pointer event handling to track button states per pointer ID. This allows for the detection of button transitions during pointer updates. The changes include new enums in the embedder API, helper functions for Win32 flag translation, and expanded unit tests. Feedback identifies a misleading comment in the flag translation logic, a redundant code block in the pointer info processing, and suggests simplifying the logic for identifying released buttons during pointer-up events.

loic-sharma · 2026-05-12T17:18:35Z

cc @mattkae

CodeDoctorDE · 2026-05-16T20:52:02Z

Addressed the reviews, ran the tests and tested it also in my flutter input demo.

Theoretically I can also add button detection on pointer hover but I'm not sure if this is also implemented on other platforms. In this case, the first bit in the button mask is 0.

CodeDoctorDE · 2026-05-24T20:14:06Z

I didn't touched any mac cis, so i think these fails can be ignored?

loic-sharma · 2026-05-26T20:16:47Z

@CodeDoctorDE I restarted those tests. If they fail again, please rebase your changes off the latest master commit.

mattkae

I have no hardware with which to test this, but the code looks sensible to me!

loic-sharma

Thanks for the excellent patch, LGTM!

…ols, improve move pointer event, remove pointer_buttons_ variable and rename button to buttons

CodeDoctorDE · 2026-05-29T12:55:00Z

i saw it was downgraded yesterday, i rebased based on the latest master

loic-sharma

Re-LGTM

CodeDoctorDE · 2026-06-01T20:05:36Z

I'm confused right now, last time i checked this page the linux ci failed? But if everything is green then i don't need to do something :)

loic-sharma · 2026-06-04T18:19:19Z

Reason for revert: This PR causes the Windows windows_host_engine_test to fail. cc @CodeDoctorDE

Example failures:

https://ci.chromium.org/ui/p/flutter/builders/prod/Windows%20windows_host_engine_test/7765/overview

Example failures:

Note: Google Test filter = FlutterWindowTest.OnMousePointerDown
[==========] Running 1 test from 1 test suite.
[----------] Global test environment set-up.
[----------] 1 test from FlutterWindowTest
[ RUN      ] FlutterWindowTest.OnMousePointerDown
[ERROR:flutter/shell/platform/windows/direct_manipulation.cc(182)] CoCreateInstance(CLSID_DirectManipulationManager, nullptr, CLSCTX_INPROC_SERVER, IID_IDirectManipulationManager, &manager_) failed

GMOCK WARNING:
Uninteresting mock function call - returning directly.
    Function call: OnWindowStateEvent(4-byte object <00-00 00-00>)
NOTE: You can safely ignore the above warning unless this call should not happen.  Do not suppress it by adding an EXPECT_CALL() if you don't mean to enforce the call.  See https://github.com/google/googletest/blob/main/docs/gmock_cook_book.md#knowing-when-to-expect-useoncall for details.
../../../flutter/shell/platform/windows/flutter_window_unittests.cc(845): error: Actual function call count doesn't match EXPECT_CALL(delegate, OnPointerDown(45, 50, kFlutterPointerDeviceKindMouse, kDefaultPointerDeviceId, kFlutterPointerButtonMousePrimary, 0, 0))...
         Expected: to be called once
           Actual: never called - unsatisfied and active

[  FAILED  ] FlutterWindowTest.OnMousePointerDown (8 ms)
[----------] 1 test from FlutterWindowTest (8 ms total)

[----------] Global test environment tear-down
[==========] 1 test from 1 test suite ran. (8 ms total)
[  PASSED  ] 0 tests.
[  FAILED  ] 1 test, listed below:
[  FAILED  ] FlutterWindowTest.OnMousePointerDown

 1 FAILED TEST
[145/740] FlutterWindowTest.OnMousePointerDown returned/aborted with exit code 1 (75 ms)
[146/740] FlutterWindowTest.OnMousePointerDown (76 ms)

flutteractionsbot · 2026-06-04T18:21:29Z

Successfully created revert PR: #187581

CodeDoctorDE · 2026-06-04T18:28:54Z

Oh strange, I ran the tests before commiting. I will investigate it

loic-sharma · 2026-06-04T18:40:05Z

@CodeDoctorDE No worries! Normally our presubmit checks would've caught this, but the Windows embedder unit tests are currently suppressed due to capacity issues: #186597

This is what the test looks like currently if it fails, it's very easy to miss a failure:

CodeDoctorDE · 2026-06-04T19:06:53Z

I looked at it again and these problems seems like to be because of wrong test code (I added) where I don't have POINTER_FLAG_FIRSTBUTTON added to the pointer flags:

-          pointer_info->pointerFlags = POINTER_FLAG_INCONTACT;
+          pointer_info->pointerFlags = POINTER_FLAG_INCONTACT |
+                                       POINTER_FLAG_FIRSTBUTTON |
+                                       POINTER_FLAG_DOWN;

This should be the correct pointer flags since down and first button should be always there
https://learn.microsoft.com/windows/win32/inputmsg/pointer-flags-contants

With these changes the tests succeed again

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 8, 2026

CodeDoctorDE changed the title ~~Windows/pointer buttons~~ Add support for stylus buttons Mar 8, 2026

CodeDoctorDE force-pushed the windows/pointer-buttons branch from 85c78f0 to a356acd Compare May 12, 2026 04:01

CodeDoctorDE marked this pull request as ready for review May 12, 2026 05:40

CodeDoctorDE requested review from a team and loic-sharma as code owners May 12, 2026 05:40

gemini-code-assist Bot reviewed May 12, 2026

View reviewed changes

Comment thread engine/src/flutter/shell/platform/windows/flutter_window.cc Outdated

Comment thread engine/src/flutter/shell/platform/windows/flutter_window.cc Outdated

Comment thread engine/src/flutter/shell/platform/windows/flutter_window.cc Outdated

jmagman added the CICD Run CI/CD label May 12, 2026