662521 - After scrolling lines (vert. scroll) and characters (horz. scroll) visibly snap to full pixels

Status: RESOLVED INVALID

(Firefox for Android Graveyard :: General, defect, P1)

Description

[Thomas Arend [:tarend]]

Still unresolved - see Bug 630743. Opening a new bug since 630743 is closed while the problem still exists.

(1) scroll text

Result: text lines jump slightly before they settle (documented in http://dl.dropbox.com/u/686313/scrolling.webm )
Expected: no jumping lines

Comment 1

[Naoki Hirata :nhirata (please use needinfo instead of cc)]

related/dup of bug 656041?

Comment 2

[Tony Chung [:tchung]]

Thomas, what do you want to do about this bug?

Comment 3

[Kevin Brosnan [Ex-Mozilla]]

So this seems to be present in the current v5 beta, though I can't reproduce in v6 or v7.

Comment 4

[Mark Finkle (:mfinkle) (use needinfo?)]

(In reply to comment #3)
> So this seems to be present in the current v5 beta, though I can't reproduce
> in v6 or v7.

If this is the case, we can close the bug.

Comment 5

[Thomas Arend [:tarend]]

I can still reproduce this in our latest nightly

Comment 6

[Naoki Hirata :nhirata (please use needinfo instead of cc)]

I can reproduce this as well at http://m.theatlantic.com/infocus/
1. go to http://m.theatlantic.com/infocus/
2. pan down fast
3. and let it settle

The text wiggles a little before completely stopping.

Comment 7

[Asa Dotzler [:asa]]

This is pretty awful. I see it on a majority of the pages I read in nightly builds on both a Galaxy Tab and a Transformer.  I know advocacy comments aren't terribly helpful, but this is the number one reason I have to put the tablet down after using it for a while. It's almost nauseating. We would never let this ship on desktop and I don't think we should be shipping this on mobile. Basic readability issues while scrolling is not a something we should be pushing off.

Comment 8

[Martijn Wargers (dead)]

Fwiw, I hardly notice this issue.

Comment 9

[Thomas Arend [:tarend]]

I completely agree with Comment 7. It is clearly visible on a Galaxy Tab 7" or 10.1". It is a bit more subtle on a smaller screen, but makes us look "blurry" and definitely not professional. I tried to prioritize this bug before but got overruled. I am nominating this bug again and hope we can get it fixed soon. It is because of this and several other "subtle" issues that we don't appear as smooth, fast, and professional as we should be, especially compared to other browsers out there. We can't afford these bugs - they are not "just" polish but are part of our user experience.

Comment 10

[Martijn Wargers (dead)]

I wonder if there's a relationship with bug 501028 here.
It seems to me this is more likely a Core->Layout:text issue or Graphics issue to me.

Comment 11

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Bug 681192 might help here.

Comment 12

[Andreas Gal :gal]

Doug and I looked at this today and I discussed this with dbaron on Friday. A possible theory is that during scrolling we arrive at a sub-pixel scroll offset and when we re-render we snap lines to whole pixels, causing the line jumping. This also happens with vertical scrolling and individual characters (some, not all) jump a pixel.

Comment 13

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Let's see if bug 681192 affects it.

Comment 14

[Andreas Gal :gal]

doug is testing your patch

Comment 15

[Doug Turner (:dougt)]

I applied the 3 patches in the bug (as-is) and I don't see a major improvement (build temporary here:  people.mozilla.org/~dougt/fennec.apk).

Comment 16

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Bug 681192 is not quite complete yet. Alongside the patches in that bug, we need to also choose final zoom levels more carefully ... something like https://bugzilla.mozilla.org/show_bug.cgi?id=681192#c15.

Comment 17

[Robert O'Callahan (:roc) (email my personal email if necessary)]

(but we may also need to bump appunitsperdevpixel up, to 240 or something)

Andreas says that this bug happens with no zoom (1 CSS pixel == 1 device pixel) so this probably doesn't need bug 681192 though.

Comment 18

[Asa Dotzler [:asa]]

Robert, is it your thinking that this would be "fixed" by bug 681192, that this might be "improved" by bug 681192, or that we should try to tackle this as a distinct issue until we have a fix for bug 681192?

Comment 19

[Robert O'Callahan (:roc) (email my personal email if necessary)]

"improved"

Comment 20

[Christopher Blizzard (:blizzard)]

How do we get to fixed?

Comment 21

[Andreas Gal :gal]

This still looks mighty **** with a nightly build in my tablet. I will make the title a bit clearer.

Comment 22

[Kevin Brosnan [Ex-Mozilla]]

Tracking '-' as this issue does not reproduce in Native trunk.