This auto-formats all *.dart files in the repository outside of the
`engine` subdirectory and enforces that these files stay formatted with
a presubmit check.
**Reviewers:** Please carefully review all the commits except for the
one titled "formatted". The "formatted" commit was auto-generated by
running `dev/tools/format.sh -a -f`. The other commits were hand-crafted
to prepare the repo for the formatting change. I recommend reviewing the
commits one-by-one via the "Commits" tab and avoiding Github's "Files
changed" tab as it will likely slow down your browser because of the
size of this PR.
---------
Co-authored-by: Kate Lovett <katelovett@google.com>
Co-authored-by: LongCatIsLooong <31859944+LongCatIsLooong@users.noreply.github.com>
This PR is to add a new page transition for Material 3.
The new builder matches the latest Android page transition behavior;
while the new page slides in from right to left, it fades in at the same
time and the old page slides out from right to left, fading out at the
same time. When both pages are fading in/out, the black background might
show up, so I added a `ColoredBox` for the slides-out page whose color
defaults to `ColorScheme.surface`. The `backgroundColor` property can be
used to customize the default transition color.
This demo shows the forward and backward behaviors.
https://github.com/user-attachments/assets/a806f25d-8564-4cad-8dfc-eb4585294181
Fixes: https://github.com/flutter/flutter/issues/142352
## Pre-launch Checklist
- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.
