1973507 - Track Anchor Positioning anchor names and rects during abspos reflows

Status: RESOLVED FIXED

(Core :: Layout: Positioned, enhancement, P3)

Description

[Jonathan Watt [:jwatt]]

During reflow we want to keep track of the anchors that are used by an Anchor Positioned element, and the rects of those anchors relative to the anchor positioned frame. We'll need suitable invalidation for this cached information.

Comment 1

[David Shin[:dshin]]

Attachment: Bug 1973507: Add cached storage for referenced anchors into reflow. r=#anchor-positioning-reviewers,#layout

Upcoming change adds a new frame property that will save this. Manipulating
the frame property requires non-const nsIFrame pointer, which is not ideal
given that that instantiation sites of resolution parameters often are const
qualified. Ideally, we avoid adding const casts, so we add a separate field
to act as a cache.

Abspos frames that may reference anchors have a clear, single reflow site
in nsAbsoluteContainingBlock, which keep things simple.

Non-abspos frames that reference anchors will always have their references
resolve to be invalid - If they switch to abspos, they need to be moved or
reconstructed anyway, so we don't have to worry about them.

Comment 2

[David Shin[:dshin]]

Attachment: Bug 1973507: Use added the cached storage to skip anchor lookups whenever possible. r=#anchor-positioning-reviewers,#layout

Since we need to track and store anchor references anyway, this ends up being
a neat side effect. It is assumed that the cached storage is provided afresh
whenever a new reflow happens, so that we avoid using stale anchor references.

Comment 3

[David Shin[:dshin]]

Attachment: Bug 1973507: Add and use a frame property for anchor positioned frames to keep track of its anchors, and their offset & size. r=#anchor-positioning-reviewers,#layout

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/990f35f1acef
https://hg.mozilla.org/integration/autoland/rev/0aa660fda704
Add cached storage for referenced anchors into reflow. r=layout-reviewers,emilio
https://github.com/mozilla-firefox/firefox/commit/72d49fd509ae
https://hg.mozilla.org/integration/autoland/rev/ff3ff4420c7a
Use added the cached storage to skip anchor lookups whenever possible. r=layout-reviewers,emilio
https://github.com/mozilla-firefox/firefox/commit/4e12ddde5cb3
https://hg.mozilla.org/integration/autoland/rev/cd58755162c4
Add and use a frame property for anchor positioned frames to keep track of its anchors, and their offset & size. r=layout-reviewers,emilio
https://github.com/mozilla-firefox/firefox/commit/76763c471404
https://hg.mozilla.org/integration/autoland/rev/81140ebea290
apply code formatting via Lando

Comment 5

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/0aa660fda704
https://hg.mozilla.org/mozilla-central/rev/ff3ff4420c7a
https://hg.mozilla.org/mozilla-central/rev/cd58755162c4
https://hg.mozilla.org/mozilla-central/rev/81140ebea290