1156636 - Dragging a selection-caret starts panning at a large zoom-in scale

Status: RESOLVED FIXED

(Core :: Panning and Zooming, defect)

Description

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

Attachment: test html

Steps to reproduce:
1. Open the attached html on B2G browser.
2. Pinch zoom-in the html to the scale as the attached image.
3. Long tap the text "456" to make selection-carets shown.
4. Drag a selection-caret.

Actual result:
APZ starts panning while dragging a selection-caret.

Expected result:
APZ does not panning while dragging a selection-caret.

Comment 1

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

Attachment: 2015-04-21-02-58-50.png

Comment 2

[Botond Ballo [:botond]]

I can reproduce this problem intermittently, when trying to drag the starting caret to the left.

Comment 3

[Botond Ballo [:botond]]

Whether or not the problem occurs is correlated with whether APZ hit testing for the touch-start returns HitLayer (we get panning) or HitDispatchToContentRegion (no panning).

Comment 4

[Morris Tseng [:mtseng] [:Morris] (Inactive)]

In content side, event regions would multiply post scale(mParameters.mX/YScale) [1]. But apz perform hit test in layer coordinate space which means post scale doesn't consider in this space [2]. So, if we pinch-zoom, the event regions are wrong. I'll upload a patch which remove multiplying post scale in FrameLayerBuilder.


[1]: https://dxr.mozilla.org/mozilla-central/source/layout/base/FrameLayerBuilder.cpp#3049 
[2]: https://dxr.mozilla.org/mozilla-central/source/gfx/layers/apz/src/HitTestingTreeNode.cpp#179

Comment 5

[Morris Tseng [:mtseng] [:Morris] (Inactive)]

Attachment: Remove post scale multiplication for event regions.

Comment 6

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

Why are we drawing the selection caret so big anyway? At really high zoom levels the carets take up half the screen. I thought we accounted for that somewhere and scaled them down so that they were always the same visual size?

Comment 7

[Morris Tseng [:mtseng] [:Morris] (Inactive)]

(In reply to Kartikaya Gupta (email:[e-mail]) from comment #6)
> Why are we drawing the selection caret so big anyway? At really high zoom
> levels the carets take up half the screen. I thought we accounted for that
> somewhere and scaled them down so that they were always the same visual size?

We are planning to implement it in bug 1068525!

Comment 8

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

Great, thanks!

Comment 9

[Morris Tseng [:mtseng] [:Morris] (Inactive)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=4db206f0d408
Looks like we have some infrastructure error in last try.

Re-submit a try.
https://treeherder.mozilla.org/#/jobs?repo=try&revision=324e68a4bbaf

Comment 10

[Morris Tseng [:mtseng] [:Morris] (Inactive)]

B2G ICS Emulator debug M20 looks like a known issue. Shouldn't relevent to this bug.

Comment 11

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/c9073aaaf9a6

Comment 12

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/c9073aaaf9a6

Comment 13

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/c9073aaaf9a6