1202320 - PresShell::AsyncPanZoomEnabled() returns false in B2G root process

Status: RESOLVED FIXED

(Core :: Panning and Zooming, defect)

Description

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

|APZCCallbackHelper::FireSingleTapEvent| will fire eMouseMove, eMouseDown, and eMouseUp after NS_TOUCH_END. 

Currently, AccessibleCaretEventHub transits to NoAction immediately after processed the long tap event.  If we select a very long word on rocket bar (as long as the rocket bar itself), those mouse events will deselect the selected word.

Comment 1

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

It seems to be an APZ issue. On b2g main process, mPresShell->AsyncPanZoomEnabled() always turns false in [1] so AccessibleCaretEventHub will inject a fake long tap event.

However, even if APZ seems disabled on b2g process, eMouseLongTap is still fired by the following steps.
1. Launch rocket bar by tapping "search or enter address" from home screen.
2. Type some text.
3. Long tap on a word.
4. A word is selected by the triggering of eMouseLongTap event.

However, eMouseLongTap does not fired if I launch rocket bar from an arbitrary app. For example:
1. Launch Phone app.
2. Tap the status bar to launch the rocket bar.
3. Type some text.
3. Long tap on a word.
4. eMouseLongTap does not fired in this case. Select a word by a fake long tap event, and suffer from the symptom described in comment 0.

Kats, I might need your help here. AFAIK, APZ should be enabled all processes on B2G. Not sure if this is related to bug 1162064.

[1] https://dxr.mozilla.org/mozilla-central/rev/56f5ffd44b7f13d5db5bd497018f428dcbb28fc4/layout/base/AccessibleCaretEventHub.cpp#415

Comment 2

[Kartikaya Gupta (email:[e-mail])]

Sorry, I'm not able to reproduce this issue (following the STR in comment 1) on an Aries device running latest master. From both the homescreen and the phone app I'm able to select words just fine in the rocketbar. Please let me know if I misunderstood something.

And yes, the APZ should be enabled in the b2g root process. It maybe that nsPresShell::AsyncPanZoomEnabled() is not finding a root view or widget and is falling down to the "false" case at the bottom. If so, we can replace that false with a call to gfxPlatform::AsyncPanZoomEnabled() instead.

Comment 3

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

Kats, thank you for the quick response. After updating my repository to the latest master, I can always got the eMouseLongTap event in rocketbar.

I found that widget is nullptr in nsPresShell::AsyncPanZoomEnabled() in the b2g root process. I'll upload a patch to use gfxPlatform::AsyncPanZoomEnabled() as the fallback in nsPresShell::AsyncPanZoomEnabled().

Comment 4

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

Attachment: Fall back to platform APZ enabled in PresShell.

If root view or widget cannot be found, use platform value of
AsyncPanZoomEnabled.

Comment 5

[Kartikaya Gupta (email:[e-mail])]

Comment on attachment 8658127 [details] [diff] [review]
Fall back to platform APZ enabled in PresShell.

Review of attachment 8658127 [details] [diff] [review]:
-----------------------------------------------------------------

I don't think I actually understand what the problem is, but this patch should be harmless so I'm fine with landing it.

Comment 6

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

If APZ is enabled, the carets will listen eMouseLongTap event to select a word. However if APZ is disabled, caret will use a timer to simulate a long tap event to select a word itself. On B2G, the simulated long tap shouldn't be used.

Comment 7

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=480c21544cee

Comment 8

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/022245b323cf

Comment 9

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/022245b323cf