1495323 - ReflowInput::FontSizeInflationListMarginAdjustment unnecessarily computes amount of font size inflation

Status: RESOLVED FIXED

(Core :: Layout, enhancement)

Description

[Jan Henning [:JanH]]

... even when we don't do anything with that value because the condition in the line right below is false [1].

[1] https://dxr.mozilla.org/mozilla-central/rev/3632445ae3db388e7b214b83acec5a042391a7bb/layout/generic/ReflowInput.cpp#131-132

Comment 1

[Jan Henning [:JanH]]

Attachment: Bug 1495323 - Don't retrieve font size inflation for margin calculation unless really required. r?dbaron

Once again, calculating the amount of font size inflation isn't as expensive as
it used to be, but there's still no need to do it unnecessarily. The current
code does this unconditionally as part of computing a frame's margins

Additionally, calculating the font size inflation for frames that we don't
actually want to inflate also messes with the planned writing mode assertions
from bug 1428670. In some special cases (e.g. the scroll bars), a frame might
use a different writing mode (horizontal/vertical) than its parent without
creating a new font inflation flow root at the boundary. As long as we never
want to apply font size inflation for that frame this is okay, but if the margin
computation then runs the font inflation calculation regardless, we have a
problem.

Comment 2

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Comment on attachment 9013408 [details]
Bug 1495323 - Don't retrieve font size inflation for margin calculation unless really required. r?dbaron

David Baron :dbaron: 🏴󠁵󠁳󠁣󠁡󠁿 ⌚UTC-7 has approved the revision.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a080d82d994e
Don't retrieve font size inflation for margin calculation unless really required. r=dbaron

Comment 4

[Raul Gurzau (:RaulG)]

https://hg.mozilla.org/mozilla-central/rev/a080d82d994e