Do not try to load main/default asset image if only higher-res variants exist (#128143) Fixes https://github.com/flutter/flutter/issues/127090. https://github.com/flutter/flutter/pull/122505 did a few things to speed up the first asset load that a flutter app performs. One of those things was to not include the main asset in its own list of variants in the asset manifest. The idea was that we know that the main asset always exists, so including it in its list of variants is a waste of storage space and loading time (even if the cost was tiny). However, the assumption that the main asset always exists is wrong. From [Declaring resolution-aware image assets](https://docs.flutter.dev/ui/assets-and-images#resolution-aware), which predates https://github.com/flutter/flutter/pull/122505: > Each entry in the asset section of the pubspec.yaml should correspond to a real file, with the exception of the main asset entry. If the main asset entry doesnât correspond to a real file, then the asset with the lowest resolution is used as the fallback for devices with device pixel ratios below that resolution. The entry should still be included in the pubspec.yaml manifest, however. For example, it's valid to declare `assets/image.png` as an asset even if only `assets/3x/image.png` exists on disk. This fix restores older behavior of including a main asset as a variant of itself in the manifest if it exists. This fix also includes a non-user-visible behavior change: * `"dpr"` is no longer a required field in the asset manifest's underlying structure. For the main asset entry, we do not include `"dpr"`. It makes less sense for the tool to decide what the default target dpr for an image should be. This should be left to the framework. https://dart.googlesource.com/external/github.com/flutter/flutter/+/759ebef689e73158904f7b8112adb5ce15c38bad
Monorepo is:
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
Flutter's instructions for building the engine are at Compiling the engine
They can be followed closely, with a few changes:
goma_ctl ensure_start is sufficient.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 $(command -v gclient))/.cipd_bin goma_ctl ensure_start pushd engine/src flutter/tools/gn --goma --no-prebuilt-dart-sdk --unoptimized --full-dart-sdk autoninja -C out/host_debug_unopt popd
The Flutter commands used to build and run apps will use the locally built Flutter engine and Dart SDK, instead of the one downloaded by the Flutter tool, if the --local-engine option is provided.
For example, to build and run the Flutter spinning square sample on the web platform,
MONOREPO_PATH=$PWD cd flutter/examples/layers flutter --local-engine=host_debug_unopt \ -d chrome run widgets/spinning_square.dart cd $MONOREPO_PATH
To build for desktop, specify the desktop platform device in flutter run as -d macos or -d linux or -d windows. You may also need to run the command
flutter create --platforms=windows,macos,linux
on existing apps, such as sample apps. New apps created with flutter create already include these support files. Details of desktop support are at Desktop Support for Flutter
Tests in the Flutter source tree can be run with the flutter test command, run in the directory of a package containing tests. For example:
MONOREPO_PATH=$PWD cd flutter/packages/flutter flutter test --local-engine=host_debug_unopt cd $MONOREPO_PATH
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.gclient sync needs to be run in an administrator session, because some installed dependencies create symlinks.