Closed Bug 786667 Opened 12 years ago Closed 12 years ago

Opaque foreground content is invalidated by occluded background content on gaia lockscreen

Categories

(Core :: Layout, defect)

Product:
Core
Component:
Layout
Type:
defect
Priority:
Not set
Severity:
normal

Tracking

()

Status:
RESOLVED FIXED

People

(Reporter: gal, Unassigned)

References

Details

B2G uses a background image in the lock screen that covers the entire screen. Yet, with paint flashing turned on we can see content being rendered behind it.

STR:
1. Enable paint flashing.
2. Open the browser, start loading a page, a CSS animated loading bar should be visible.
3. Turn off the screen.
4. Turn the screen back on.
5. You should see at the height of the loading bar constant repainting.
It's not clear that the background content is being painted.  However, the background content is most definitely invalidating the foreground content.
Summary: we render content behind the B2G lockscreen → Opaque foreground content is invalidated by occluded background content on gaia lockscreen
I think this is mostly expected. DLBI will fix this.

Forcing the lock screen into its own layer might help.
Is it worth asking why that's mostly expected or not really?
Suppressing invalidation when there's opaque content on top of the invalid content is hard because you have to do potentially expensive analysis to determine whether there is such opaque content. You certainly don't want to do complex analysis during each Invalidate() call, because those are frequent. You can accumulate invalid regions somewhere and then do analysis on those later, to amortize that work --- and we can sort of do that with layers, which is why I think ensuring the lock screen is in its own layer might help.
Fair enough.  We haven't had to resort to any magic layerizing tricks yet, and if dlbi is as close as it sounds we can wait for that and may not have to start.
I suspect you really wanted to CC Matt, the DLBI guy :-)
DLBI fixes this.
Depends on: dlbi
Status: NEW → RESOLVED
Closed: 12 years ago
Resolution: --- → FIXED
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