1598978 - Vertical scrollbar thumb position (or size) is wrong with dynamic toolbar

Status: ASSIGNED

(Core :: Panning and Zooming, defect, P3)

Description

[Hiroyuki Ikezoe (:hiro)]

This was probably regressed by bug 1586144.

Steps to reproduce;

1. Open http://bokand.github.io/demo/urlbarsize.html
2. Scroll down as possible
3. See the scrollbar thumb position, it's not at the bottom

I am filing this issue in "Panning and Zooming" but "Layout: Scrolling and Overflow" might be more reasonable place. I did initially guess that we teak the position (or size?) in APZC but we maybe could do something in the first place when we generate FrameMetrics on the main-thread.

Comment 1

[Hiroyuki Ikezoe (:hiro)]

Maybe we need to tweak the value in nsSliderFrame::BuildDisplayListForChildren?

Comment 2

[Botond Ballo [:botond]]

Setting status flags based on likely regression range.

Comment 3

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

Downgrading to P3 since nobody else seems to have noticed this problem and it doesn't seem important enough to warrant a P2

Comment 4

[Botond Ballo [:botond]]

The (I suspect related) issue of the vertical position of horizontal scroll thumbs is pretty glaring.

STR:

1. Run Fenix nightly
2. Navigate to planet.mozilla.org
3. Scroll down to cause the dynamic toolbar to hide

The horizontal scrollbar remains positioned above the expanded position of the dynamic toolbar, above a few lines of page content that is visible with the toolbar hidden (and continues to be positioned there even after subsequent scrolling).

Comment 5

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

Indeed, that is more immediately obvious. When I follow your STR I also see a bit of white at the bottom, like the page is being clipped a little too short. The clip seems to be about halfway between the misplaced horizontal scrollbar and the bottom of the screen, so I'm guessing it's a missing scale factor in the setVerticalClipping implementation or something like that.

Comment 6

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

Ok, let's bump this back to P2 since the horizontal scrollbar does look quite bad when it's out of place. Hiro, do you have cycles to work on this? I can file another bug about the clipping problem.

Comment 7

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

Filed https://github.com/mozilla-mobile/fenix/issues/8784 for the clipping problem.

Comment 8

[Hiroyuki Ikezoe (:hiro)]

Yep, I can take a look.

Comment 9

[Hiroyuki Ikezoe (:hiro)]

Hmm I am confused on my local Fenix build the horizontal scrollbar thumb is moved properly...

Comment 10

[Hiroyuki Ikezoe (:hiro)]

Attachment: horizontal-scrollbar-with-dynamictoolbar.webm

I am hoping this video can be played on other machines.

Comment 11

[Hiroyuki Ikezoe (:hiro)]

so the vertical scrollbar issue seems to be specific for WebRender, I filed bug 1618432.

Comment 12

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

Thanks! I'll downgrade this back to P3 then, and we can use it to track the original problem as described in comment 0.