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dart / monorepo / / 9fadc3e8d7b205da209d3638427d084d43927ec0
commit9fadc3e8d7b205da209d3638427d084d43927ec0[log] [tgz]
authorSimon Friis Vindum <simonfv@gmail.com>Wed Feb 21 01:36:08 2024 +0100
committerdart-internal-monorepo <dart-internal-monorepo@dart-ci-internal.iam.gserviceaccount.com>Tue Feb 20 16:41:15 2024 -0800
tree787385f028521a162bbc45a10d52b0fb066076dd
parente6ef9c934bcd249fa95e3903a46e9fb85c4354e3 [diff]
Fix initialization of time in repeat on AnimationController (#142887)

This PR fixes #142885.

The issue is that in `_RepeatingSimulation` the initial time is calculated as follows:

```
(initialValue / (max - min)) * (period.inMicroseconds / Duration.microsecondsPerSecond)
```

This calculation does not work in general. For instance, if `max` is 300, `min` is 100, and `initialValue` is 100 then `initialValue / (max - min)` is 1/2 when it should be 0

The current tests work by happenstance because the numbers used happen to work. To reveal the bug I've added some more tests similar to the existing ones but with different numbers.

A "side-effect" of the incorrect calculation is that if `initialValue` is 0, then the animation will always start from `min` no matter what. For instance, in one of the tests, an `AnimationController` with the value 0 is told to `repeat` between 0.5 and 1.0, and this starts the animation from 0.5. To preserve this behavior, and to more generally handle the case where the initial value is out of bounds, this PR clamps the initial value to be within the lower and upper bounds of the repetition.

Just for reference, this calculation was introduced at https://github.com/flutter/flutter/pull/25125.
https://dart.googlesource.com/external/github.com/flutter/flutter/+/6c78e36ccb3d65b6082d6f451c397cd9329992f4
2 files changed
tree: 787385f028521a162bbc45a10d52b0fb066076dd
  1. ci/
  2. tools/
  3. .gitignore
  4. commits.json
  5. DEPS
  6. OWNERS
  7. README.md
README.md

Monorepo

A gclient solution for checking out Dart and Flutter source trees

Monorepo is:

  • Optimized for Tip-of-Tree testing: The Monorepo DEPS used to check out Dart and Flutter dependencies comes from the Flutter engine DEPS with updated dependencies from Dart.

Checking out Monorepo

With depot_tools installed and on your path, create a directory for your monorepo checkout and run these commands to create a gclient solution in that directory:

mkdir monorepo
cd monorepo
gclient config --unmanaged https://dart.googlesource.com/monorepo
gclient sync -D

This gives you a checkout in the monorepo directory that contains:

monorepo/
  DEPS - the DEPS used for this gclient checkout
  commits.json - the pinned commits for Dart, flutter/engine,
                 and flutter/flutter
  tools/ - scripts used to create monorepo DEPS
engine/src/ - the flutter/buildroot repo
    flutter/ - the flutter/engine repo
    out/ - the build directory, where Flutter engine builds are created
    third_party/ - Flutter dependencies checked out by DEPS
      dart/ - the Dart SDK checkout.
        third_party - Dart dependencies, also used by Flutter
flutter/ - the flutter/flutter repo

Building Flutter engine

Flutter's instructions for building the engine are at Compiling the engine

They can be followed closely, with a few changes:

  • Googlers working on Dart do not need to switch to Fuchsia's Goma RBE, except for Windows. The GOMA_DIR enviroment variable can just point to the .cipd_bin directory in a depot_tools installation, and just goma_ctl ensure_start is sufficient.
  • The --no-prebuilt-dart-sdk option has to be added to every gn command, so that the build is set up to build and use a local Dart SDK.
  • The --full-dart-sdk option must be added to gn for the host build target if you will be building web or desktop apps.

Example build commands that work on linux:

MONOREPO_PATH=$PWD
if [[ ! $PATH =~ (^|:)$MONOREPO_PATH/flutter/bin(:|$) ]]; then
  PATH=$MONOREPO_PATH/flutter/bin:$PATH
fi

export GOMA_DIR=$(dirname $(command -v gclient))/.cipd_bin
goma_ctl ensure_start

pushd engine/src
flutter/tools/gn --goma --no-prebuilt-dart-sdk --unoptimized --full-dart-sdk
autoninja -C out/host_debug_unopt
popd

Building Flutter apps

The Flutter commands used to build and run apps will use the locally built Flutter engine and Dart SDK, instead of the one downloaded by the Flutter tool, if the --local-engine option is provided.

For example, to build and run the Flutter spinning square sample on the web platform,

MONOREPO_PATH=$PWD
cd flutter/examples/layers
flutter --local-engine=host_debug_unopt \
  -d chrome run widgets/spinning_square.dart
cd $MONOREPO_PATH

To build for desktop, specify the desktop platform device in flutter run as -d macos or -d linux or -d windows. You may also need to run the command

flutter create --platforms=windows,macos,linux

on existing apps, such as sample apps. New apps created with flutter create already include these support files. Details of desktop support are at Desktop Support for Flutter

Testing

Tests in the Flutter source tree can be run with the flutter test command, run in the directory of a package containing tests. For example:

MONOREPO_PATH=$PWD
cd flutter/packages/flutter
flutter test --local-engine=host_debug_unopt
cd $MONOREPO_PATH

Troubleshooting

Please file an issue or email the dart-engprod team with any problems with or questions about using monorepo.

We will update this documentation to address them.

  • flutter commands may download the engine and Dart SDK files for the configured channel, even though they will be using the local engine and its SDK.

Windows

  • On Windows, gclient sync needs to be run in an administrator session, because some installed dependencies create symlinks.