1966192 - Frame iteration for view transition capture should iterate in paint order / respect z-index.

Status: RESOLVED FIXED

(Core :: Layout, defect)

Description

[Boris Chiou [:boris]]

This is for

1. css/css-view-transitions/css-tags-paint-order.html
2. css/css-view-transitions/css-tags-paint-order-with-entry.html

In these two tests, we set z-index in one of the captured elements

#one {
  background: green;
  width: 100px;
  height: 100px;
  position: relative;
  z-index: 1;
  view-transition-name: one;
}
#two {
  background: yellow;
  width: 100px;
  height: 100px;
  view-transition-name: two;
}

In this example, we expected the green one overlaps the yellow one. However, in Gecko, the yellow one overlaps the green one.

Comment 1

[Emilio Cobos Álvarez (:emilio)]

This is basically this FIXME.

Comment 2

[Boris Chiou [:boris]]

Attachment: Bug 1966192 - Sort the frames with z-index order when capturing old state and new state.

An ideal way is to iterate the display list because they are sorted.
However, we add special view transition display items after capturing
the old state, so the display list is not suitable for capturing new
state. Therefore, we still have to sort the frame list in z-index order.

However, we only need to sort them when capturing old and new states, so
it should not have much impact on the entire performance.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/ba9671e42f99
https://hg.mozilla.org/integration/autoland/rev/f0a32c9d6ab5
Sort the frames with z-index order when capturing old state and new state. r=view-transitions-reviewers,emilio

Comment 4

[Iulian Moraru]

https://hg.mozilla.org/mozilla-central/rev/f0a32c9d6ab5