1132885 - destination-over not working when using drop-shadow in Skia canvas

Status: NEW

(Core :: Graphics, defect)

Description

[Gilles]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/40.0.2214.111 Safari/537.36

Steps to reproduce:

This problem was found on FireFox 35 on Windows XP and Vista. FireFox 35 on Mac or Linux did not show this problem.

destination-over compositing is not working when drawing using shadowBlur.

See the fiddle
http://jsfiddle.net/p9se6z3L/1/




Actual results:

the white box with drop shadow is painted over the blue box. It should be painted in the background instead.


Expected results:

The blue box should remain in foreground as it happens in other browsers and FF on Mac and Linux.

Comment 1

[Matthias Versen [:Matti]]

I can confirm the issue on WIndows7 and Firefox35+Firefox trunk but only if I start Firefox with disabled HWA

Gilles: 
Can you confirm that the graphic hardware acceleration isn't working on your system ?
about:support (enter as url) -> Graphics -> GP accelerated windows is 0

Comment 2

[Alice0775 White]

[Tracking Requested - why for this release]: regression


Pushlog with disabled HWA:
https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=aae54a60278d&tochange=947d7ce90e26

Suspect: 947d7ce90e26	George Wright — Bug 976184 - Apply a drop shadow image filter to our SkPaint when drawing a surface with a shadow r=mattwoodrow

Comment 3

[Lawrence Mandel [:lmandel] (use needinfo)]

If bug 976184 is to blame, this issue goes back to Firefox 30 (July 22, 2014). Unless there is a reason to uplift a fix, I think we can let a fix ride the train when it's ready. I'm not going to track at this point. Please renom for tracking if there if you think this needs to be fixed in 37.

Comment 4

[George Wright (:gw280) (needinfo me!)]

This is likely a bug with Skia itself. This is also low enough impact (in my opinion) that I agree with Lawrence that a fix should just ride the trains.

Milan - who is in charge of bugfixes for Skia now?

Comment 5

[Milan Sreckovic [:milan] (needinfo for best results)]

Confirmed this happens with Skia canvas, on other platforms as well.

Comment 6

[kevin]

(In reply to George Wright (:gw280) (:gwright) from comment #4)
> This is likely a bug with Skia itself. This is also low enough impact (in my
> opinion) that I agree with Lawrence that a fix should just ride the trains.
> 
> Milan - who is in charge of bugfixes for Skia now?

This bug is causing a major problem drawing a drop shadow for a website I help run (www.collage.com) on Firefox for Mac. Is there a work-around for achieving something equivalent to destination-over without hitting this bug that doesn't require redrawing onto a new canvas with the content underneath, or is that the best option?

Comment 7

[Lee Salzman [:lsalzman]]

(In reply to kevin from comment #6)
> (In reply to George Wright (:gw280) (:gwright) from comment #4)
> > This is likely a bug with Skia itself. This is also low enough impact (in my
> > opinion) that I agree with Lawrence that a fix should just ride the trains.
> > 
> > Milan - who is in charge of bugfixes for Skia now?
> 
> This bug is causing a major problem drawing a drop shadow for a website I
> help run (www.collage.com) on Firefox for Mac. Is there a work-around for
> achieving something equivalent to destination-over without hitting this bug
> that doesn't require redrawing onto a new canvas with the content
> underneath, or is that the best option?

Is this bug fixed for you in the latest release? We've done a lot of reworking of how canvas shadows are handled with Skia, and I believe that would have taken care of it, but it would be nice if you can verify.

Comment 8

[BugBot [:suhaib / :marco/ :calixte]]

Clear a needinfo that is pending on an inactive user.

Inactive users most likely will not respond; if the missing information is essential and cannot be collected another way, the bug maybe should be closed as INCOMPLETE.

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