1001550 - "WARNING: Found a non-root APZ with no handoff parent" when changing wallpapers

Status: RESOLVED FIXED

(Core :: Panning and Zooming, defect)

Description

[Botond Ballo [:botond]]

The STR in bug 1000634 shows the following APZ warnings being given:

[Parent 861] WARNING: Found a non-root APZ with no handoff parent: file ../../../gfx/layers/apz/src/APZCTreeManager.cpp, line 909
[Parent 861] WARNING: Found a non-root APZ with no handoff parent: file ../../../gfx/layers/apz/src/APZCTreeManager.cpp, line 909
[Parent 861] WARNING: Found a non-root APZ with no handoff parent: file ../../../gfx/layers/apz/src/APZCTreeManager.cpp, line 909
[Parent 861] WARNING: Found a non-root APZ with no handoff parent: file ../../../gfx/layers/apz/src/APZCTreeManager.cpp, line 909
[Parent 861] WARNING: Found a non-root APZ with no handoff parent: file ../../../gfx/layers/apz/src/APZCTreeManager.cpp, line 909

These warnings indicate a bug in the layout code that computes scroll handoff parents (introduced in bug 982888). We should investigate them.

Comment 1

[Gregor Wagner [:gwagner]]

These warnings are very common on b2g

Comment 2

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

I'll take a look at this.

Comment 3

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

Attachment: Patch

Needs more testing.

Comment 4

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

Comment on attachment 8414778 [details] [diff] [review]
Patch

Review of attachment 8414778 [details] [diff] [review]:
-----------------------------------------------------------------

Did some more testing. Verified this doesn't regress bug 982888.

Comment 5

[Timothy Nikkel (:tnikkel)]

Comment on attachment 8414778 [details] [diff] [review]
Patch

Do this only when we are ignoringViewPortScrolling?

Comment 6

[Botond Ballo [:botond]]

Comment on attachment 8414778 [details] [diff] [review]
Patch

Review of attachment 8414778 [details] [diff] [review]:
-----------------------------------------------------------------

::: layout/base/nsLayoutUtils.cpp
@@ +2685,5 @@
> +    ViewID id = FrameMetrics::NULL_SCROLL_ID;
> +    if (presContext->IsRootContentDocument()) {
> +      if (nsIFrame* rootScrollFrame = presShell->GetRootScrollFrame()) {
> +        if (nsIContent* content = rootScrollFrame->GetContent()) {
> +          id = nsLayoutUtils::FindOrCreateIDFor(content);

Does this make the call to FindOrCreateIDFor() in nsDisplayList::PaintForFrame() redundant?

Comment 7

[Timothy Nikkel (:tnikkel)]

It'll just find the same id. So not a big deal I think.

Comment 8

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

(In reply to Timothy Nikkel (:tn) from comment #5)
> Do this only when we are ignoringViewPortScrolling?

Fixed and landed: https://hg.mozilla.org/integration/mozilla-inbound/rev/5a7de0eb94fe

Comment 9

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/5a7de0eb94fe