webdriver: Enable `pointerMove` to perform smooth transition over specified duration by yezhizhen · Pull Request #42946 · servo/servo

yezhizhen · 2026-03-02T08:28:31Z

Enable pointerMove to perform a smooth transition over specified duration.

Sync move/scroll interval with default tick duraiton in testdriver:

servo/tests/wpt/tests/resources/testdriver-actions.js

Lines 34 to 38 in a60a8b1

    
              * @param {number} [defaultTickDuration] - The default duration of a 
        
              * tick. Be default this is set ot 16ms, which is one frame time 
        
              * based on 60Hz display. 
        
              */ 
        
             function Actions(defaultTickDuration=16) {

Fully process all pending pointer moves within this tick. This is one of the conditions that is required to finish this tick. Previously, the pending move events might be processed in next Tick, if they have long duration.

before-fix.mp4

post-fix.mp4

Testing: Added a WPT test. I'm surprised it is not covered by existing tests, given the huge behaviour difference.
Fixes: #42950
Part of #41620

Signed-off-by: Euclid Ye <[email protected]>

yezhizhen · 2026-03-02T12:52:06Z

Adding a test. We can assert more than 10 mousemove, with changing coordinates.

servo-wpt-sync · 2026-03-02T13:26:13Z

🤖 Opened new upstream WPT pull request (web-platform-tests/wpt#58169) with upstreamable changes.

Signed-off-by: Euclid Ye <[email protected]>

servo-wpt-sync · 2026-03-02T13:54:24Z

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#58169).

servo-wpt-sync · 2026-03-02T13:58:17Z

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#58169).

servo-wpt-sync · 2026-03-03T02:53:00Z

✍ Updated existing upstream WPT pull request (web-platform-tests/wpt#58169) title and body.

servo-wpt-sync · 2026-03-03T03:06:47Z

✍ Updated existing upstream WPT pull request (web-platform-tests/wpt#58169) title and body.

servo-wpt-sync · 2026-03-03T03:14:50Z

✍ Updated existing upstream WPT pull request (web-platform-tests/wpt#58169) title and body.

yezhizhen · 2026-03-03T03:16:51Z

Reported bug: SeleniumHQ/selenium#12736

Interesting. It seems chromedriver/safaridriver is not spec-compliant, and also blinks. They both only get 2 mousemove events eventually, failing the new test.
Safaridriver
Chromedriver

mrobinson

Seems reasonable to me, but I'll wait for the resolution of the issue with the test.

mrobinson · 2026-03-03T15:21:24Z

components/webdriver_server/actions.rs

        // asynchronously wait for an implementation defined amount of time to pass.
+
+        // Asynchronously wait means do not block browser to process event loop.
+        // In the context of Servo, it means block the webdriver server thread.


Should this say:

Suggested change

// In the context of Servo, it means block the webdriver server thread.

// In the context of Servo, it means not blocking the webdriver server thread.

?

No. That's why we sleep the server thread right below.

yezhizhen · 2026-03-03T15:40:44Z

components/webdriver_server/actions.rs

        // asynchronously wait for an implementation defined amount of time to pass.
+
+        // Asynchronously wait means do not block browser to process event loop.
+        // In the context of Servo, it means block the webdriver server thread.


Suggested change

// In the context of Servo, it means block the webdriver server thread.

// In the context of Servo, it means blocking the webdriver server thread.

yezhizhen · 2026-03-03T15:43:19Z

Seems reasonable to me, but I'll wait for the resolution of the issue with the test.

I don't know who we can find to resolve this. The test seems fairly straightforward :(
The smooth move is part of spec, but only Firefox has implemented this.
And chromedriver team never responded: SeleniumHQ/selenium#12736

Scroll and PointerMove is quite similar. We did so for `PointeMove` in #42289 + #42946. Imagine having 3 non-zero duration scroll actions with origin at different Elements. Previously we would wait for one to be fully dispatched before moving to next action, instead of interspersed. We also consolidate `PendingPointerMove` and newly added `PendingScroll` into `enum PendingActions`. Testing: [Existing tests behaviour not changing.](https://github.com/servo/servo/actions/runs/22887005716). Added a wdspec test. Previously: `['wheel', 'wheel', 'wheel', 'wheel', 'wheel', 'wheel', 'wheel', 'wheel', 'wheel', 'move']` Now: `['wheel', 'move', 'wheel', 'move', 'wheel', 'move', 'move', 'wheel', 'wheel', 'move', 'move', 'wheel', 'wheel', 'move', 'move', 'wheel']` --------- Signed-off-by: Euclid Ye <[email protected]>

yezhizhen added 3 commits March 2, 2026 12:09

Update some doc

a83d5d6

Signed-off-by: Euclid Ye <[email protected]>

Fix pointermove asynchronism

ec514f9

Signed-off-by: Euclid Ye <[email protected]>

change interval to 16ms

b521f5c

Signed-off-by: Euclid Ye <[email protected]>

yezhizhen requested a review from xiaochengh March 2, 2026 08:28

servo-highfive added the S-awaiting-review There is new code that needs to be reviewed. label Mar 2, 2026

yezhizhen changed the title ~~webdriver: Process pending PointerMoves fully within this tick; Sync interval with defaultTickDuration~~ webdriver: Process pending PointerMoves fully within this tick; Sync interval with testdriver defaultTickDuration Mar 2, 2026

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yezhizhen changed the title ~~webdriver: Process pending PointerMoves fully within this tick; Sync interval with testdriver defaultTickDuration~~ webdriver: Enable pointerMove to perform smooth transition over specified duration Mar 2, 2026

yezhizhen marked this pull request as draft March 2, 2026 12:52

yezhizhen marked this pull request as ready for review March 2, 2026 13:22

servo-wpt-sync mentioned this pull request Mar 2, 2026

webdriver: Enable pointerMove to perform smooth transition over specified duration web-platform-tests/wpt#58169

Merged

Mousemove should transition smoothly over specified duration

d0e2e19

Signed-off-by: Euclid Ye <[email protected]>

yezhizhen force-pushed the fix-pending-moves branch from 51d6993 to d0e2e19 Compare March 2, 2026 13:49

Clean-up red dot post-test

8e7d0f5

Signed-off-by: Euclid Ye <[email protected]>

mrobinson reviewed Mar 3, 2026

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yezhizhen commented Mar 3, 2026

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mrobinson approved these changes Mar 4, 2026

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servo-highfive removed the S-awaiting-review There is new code that needs to be reviewed. label Mar 4, 2026

yezhizhen added this pull request to the merge queue Mar 6, 2026

servo-highfive added the S-awaiting-merge The PR is in the process of compiling and running tests on the automated CI. label Mar 6, 2026

Merged via the queue into servo:main with commit cab4416 Mar 6, 2026
33 checks passed

yezhizhen deleted the fix-pending-moves branch March 6, 2026 02:36

servo-highfive removed the S-awaiting-merge The PR is in the process of compiling and running tests on the automated CI. label Mar 6, 2026

yezhizhen mentioned this pull request Mar 10, 2026

webdriver: Support interspersed scroll actions via event queue #43126

Merged

servo-wpt-sync mentioned this pull request Mar 10, 2026

webdriver: Support interspersed scroll actions via event queue web-platform-tests/wpt#58388

Merged

	* @param {number} [defaultTickDuration] - The default duration of a
	* tick. Be default this is set ot 16ms, which is one frame time
	* based on 60Hz display.
	*/
	function Actions(defaultTickDuration=16) {

	// In the context of Servo, it means block the webdriver server thread.
	// In the context of Servo, it means not blocking the webdriver server thread.

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