Trigger deferred scrollbar fade-out without forwarding wheel events [chromium/src : main]

[Byungwoo Lee (Gerrit)]

Attention needed from Robert Flack

Byungwoo Lee voted and added 1 comment

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File-level comment, Patchset 2 (Latest):

Byungwoo Lee . resolved

Hello Robert, this is the CL that fade-out scrollbars without forwarding wheel events.

Could you please take a look? Thank you!

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[Byungwoo Lee (Gerrit)]

Attention needed from Robert Flack

Byungwoo Lee added 1 comment

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File-level comment, Patchset 5 (Latest):

Byungwoo Lee . resolved

The browser test is flacky. I'll rewrite the test and activate this CL again.
Sorry for the confusion!

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[Byungwoo Lee (Gerrit)]

Attention needed from Robert Flack

Byungwoo Lee added 1 comment

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File-level comment, Patchset 1 (Latest):

Byungwoo Lee . resolved

Hello Robert,

This is the CL that fade-out scrollbars without forwarding wheel events. (I submitted new CL to simplify the patch set history, and abandoned the old one)

The flaky browser test is guarded with IS_MAC build flag since the wheel scroll latching browser test is flaky on android even if it is an empty test.
  
Could you please review this? Thank you again!

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[Byungwoo Lee (Gerrit)]

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[Robert Flack (Gerrit)]

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Robert Flack added 1 comment

File third_party/blink/renderer/platform/widget/input/input_handler_proxy.h

Line 160, Patchset 1 (Latest): DROP_EVENT_AND_FADEOUT_SCROLLBARS,

Robert Flack . unresolved

I'm not comfortable adding a special one-off disposition for these events that is essentially equivalent to DID_NOT_HANDLE_NON_BLOCKING - i.e. the main thread needs to be sent the events and they aren't cancellable.

There must be a better way to prevent the unexpected behavior.

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[Vladimir Levin (Gerrit)]

Attention needed from Byungwoo Lee

Vladimir Levin added 6 comments

Patchset-level comments

File-level comment, Patchset 1 (Latest):

Vladimir Levin . resolved

(just a driveby review)

File third_party/blink/renderer/core/input/mouse_wheel_event_manager.h

Line 46, Patchset 1 (Latest): void FadeOutScrollbarsOnCurrentFrame();

Vladimir Levin . unresolved

nit: we typically would name this something like FadeOutScrollbarsInternal if it's just a helper called from the public function

File third_party/blink/renderer/core/layout/scrollbars_test.cc

Line 198, Patchset 1 (Latest): event.wheel_ticks_x = event.delta_x / 10;

Vladimir Levin . unresolved

nit: is 10 a magic number? why 10?

File third_party/blink/renderer/platform/widget/input/input_handler_proxy.h

Line 160, Patchset 1 (Latest): DROP_EVENT_AND_FADEOUT_SCROLLBARS,

Vladimir Levin . unresolved

This sounds more like a directive than a disposition. That doesn't seem correct. This should still be a DROP_EVENT and necessary other plumbing needs to be added to schedule a scrollbar fade out

File third_party/blink/renderer/platform/widget/input/input_handler_proxy.cc

Line 1163, Patchset 1 (Latest): return DROP_EVENT_AND_FADEOUT_SCROLLBARS;

Vladimir Levin . unresolved

I think we can just directly request a scrollbar fadeout here maybe?

File third_party/blink/renderer/platform/widget/input/widget_input_handler_manager.cc

Line 1046, Patchset 1 (Latest): event_disposition = InputHandlerProxy::DROP_EVENT;

Vladimir Levin . unresolved

This confirms that FADEOUT_SCROLBLAR part seems to just a way to get from input_handler to widget_input_handler_manager and post a task. Maybe we can do direct plumbing instead

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