| commit | 7822accacf2c6de0c9d940664860d671023cae16 | [log] [tgz] |
|---|---|---|
| author | Chinmay Garde <chinmaygarde@google.com> | Wed Mar 26 10:34:14 2025 -0700 |
| committer | dart-internal-monorepo <dart-internal-monorepo@dart-ci-internal.iam.gserviceaccount.com> | Wed Mar 26 11:12:26 2025 -0700 |
| tree | 2e4dc7d24d60b396869bcc10540fb095affcc066 | |
| parent | b7d77b686c7514a7648bfd91d0b5a0ada9528399 [diff] |
[Impeller] libImpeller: Implement APIs for fetching glyph and line metrics. (#165701) This patch adds support in the typography subsystem of the public Impeller API such that users can implement text editing functionality. * Line metrics for a fully laid out paragraph can be retrieved. The metrics contain information about offsets into the original code unit buffer used to create the paragraph. These offsets can be used to implement functionality that edits whole lines. * Glyph information for a specific code unit offset, as well as a coordinate offset relative to the paragraph origin, can be obtained. This information can be used place decorations (like carets), select words surrounding the caret (a hit-test), and edit the source buffer to re-layout the paragraph. * Word boundaries (as specified in Unicode Standard Annex 29) can be retrieved to select and modify paragraph subsets by character, word, and line at caret. Like in Flutter, the code unit buffers are assumed to be arrays of UTF-16 bytes. I'd have preferred this to be UTF-8 because the initial paragraph construction is using UTF-8 bytes. Also, Skia internally seems to work with UTF-8 too but the interfaces are exposed using UTF-16 (presumably for users like Flutter that work with Dart strings that are UTF-16). Exposing additional APIs in txt::Paragraph to back this out seemed onerous. Instead, a UTF-16 assumption for all APIs that retrieve metrics is made (and documented). It stands to reason that paragraphs should be constructable using UTF-16 buffers in the public API too. I'll add that in a subsequent patch as that has little to do with metrics. Fixes https://github.com/flutter/flutter/issues/165509 https://dart.googlesource.com/external/github.com/flutter/flutter/+/39103d9512af2759aa779d670484e848a2b411e8
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.