1273068 - background-clip:text left ghost image after text animated

Status: RESOLVED FIXED

(Core :: Layout, defect)

Description

[u459114]

Attachment: text animation

background text disappear while child text object animating. See the attachment.

Comment 1

[u459114]

Both 48(using glyph path) and 49(using mask) have this problem

Comment 2

[u459114]

Attachment: text animation

Comment 3

[u459114]

Attachment: text animation

Two problem here
1. nsDisplayBackgroundColor::GetOpaqueRegion should respect bg-clip value. Easy to fix.
2. After animation of a text object start, that text frame is pulled out from frame tree(I _guess_), so we can not build correct mask from it. Have no idea how to fix it so far

Comment 4

[u459114]

Attachment: MozReview Request: Bug 1273068 - Part 1. nsDisplayBackgroundColor::GetOpaqueRegion should respect bg-clip value

Review commit: https://reviewboard.mozilla.org/r/52824/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/52824/

Comment 5

[yisibl]

Chrome and Safari seems to have this problems too.

Comment 6

[Xidorn Quan [:xidorn] UTC+10]

It seems background-clip: text is a feature difficult to implement correctly... Chrome and Safari has various different issues with the testcase. I'd suggest it not be a blocker of shipping background-clip: text.

And actually it is not clear what exactly should happen when the text has animation. I, as a web developer, would expect the clipped background would move with the text. But if that is too difficult to implement, and no vendor wants to do it, we need to ensure documenting this behavior in the spec.

Comment 7

[u459114]

Like I said, two problems here. The first one is a blocker, has ghost image on the screen is just too low. The second one may not be a blocker.

Comment 8

[u459114]

Attachment: ghost_image.png

Comment 9

[u459114]

Hi Jonathan,
This bug(ghost image) happens with background-color only, since I didn't handle nsDisplayBackgroundColor::GetOpaqueRegion well. This bug exists since bug 759568

Comment 10

[yisibl]

(In reply to Xidorn Quan [:xidorn] (UTC+10) from comment #6)
> It seems background-clip: text is a feature difficult to implement
> correctly... Chrome and Safari has various different issues with the
> testcase. I'd suggest it not be a blocker of shipping background-clip: text.
> 
> And actually it is not clear what exactly should happen when the text has
> animation. I, as a web developer, would expect the clipped background would
> move with the text. But if that is too difficult to implement, and no vendor
> wants to do it, we need to ensure documenting this behavior in the spec.

As a developer, we hope that the text background can be dynamically cut. Support for absolute positioning and transform.

Comment 11

[Jonathan Kew [:jfkthame]]

Comment on attachment 8752847 [details]
MozReview Request: Bug 1273068 - Part 1. nsDisplayBackgroundColor::GetOpaqueRegion should respect bg-clip value

https://reviewboard.mozilla.org/r/52824/#review49938

Looks reasonable to me.

I'd suggest splitting off a separate bug for the second issue here (which probably doesn't need to block shipping the feature, especially as other browsers also struggle with it), so that we can close this bug and keep track of the other separately.

Comment 12

[u459114]

(In reply to Jonathan Kew (:jfkthame) from comment #11)
> I'd suggest splitting off a separate bug for the second issue here (which
> probably doesn't need to block shipping the feature, especially as other
> browsers also struggle with it), so that we can close this bug and keep
> track of the other separately.
Done. bug 1273569

Comment 13

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/71f52a621b18

Comment 14

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/71f52a621b18