1237825 - Find the root scroll frame even if the root element doesn't have a primary frame

Status: RESOLVED FIXED

(Core :: Layout, defect)

Description

[Timothy Nikkel (:tnikkel)]

This is a weird and tricky case.

Comment 1

[Timothy Nikkel (:tnikkel)]

Attachment: patch

Typical structure is

viewportframe mContent=null
  htmlscrollframe mContent=rootelement
    canvasframe mContent=rootelement
      blockframe mContent=rootelement
        ...


with rootelement->GetPrimaryFrame() == blockframe

But if the blockframe isn't created because it is displaynone (or it has a failed -moz-binding) we get

viewportframe mContent=null
  htmlscrollframe mContent=rootelement
    canvasframe mContent=rootelement

with rootelement->GetPrimaryFrame() == null

So we just need to be able to get the presshell given the content node only.

Comment 2

[Timothy Nikkel (:tnikkel)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=5bcda7e04d00

Comment 3

[Markus Stange [:mstange]]

Comment on attachment 8705397 [details] [diff] [review]
patch

Review of attachment 8705397 [details] [diff] [review]:
-----------------------------------------------------------------

r+ assuming you add the null check or have a good justification for why it's not necessary.

::: layout/base/nsLayoutUtils.cpp
@@ +857,5 @@
>    nsIFrame* frame = aContent->GetPrimaryFrame();
> +  if (aContent->OwnerDoc()->GetRootElement() == aContent) {
> +    nsIPresShell* presShell = frame ? frame->PresContext()->PresShell() : nullptr;
> +    if (!presShell) {
> +      presShell = aContent->OwnerDoc()->GetShell();

presShell can still be null after this line, right? Don't you need to null check it before using it below?

Comment 4

[Timothy Nikkel (:tnikkel)]

I'll add the null. Probably wasn't bitter by it because we likely only call it if we have a frame, and at least a presshell.

Comment 5

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/980596816271

Comment 6

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/980596816271