Add utility to collect headers from google/mediapipe

.flutter-mediapipe-root

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+// Used to normalize the paths of commands.
+// The contents of this file do not matter.

packages/build_cmd/.gitignore

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+# https://dart.dev/guides/libraries/private-files
+# Created by `dart pub`
+.dart_tool/

packages/build_cmd/CHANGELOG.md

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+## 1.0.0
+
+- Initial version.

packages/build_cmd/README.md

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+A sample command-line application with an entrypoint in `bin/`, library code
+in `lib/`, and example unit test in `test/`.

packages/build_cmd/analysis_options.yaml

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+# This file configures the static analysis results for your project (errors,
+# warnings, and lints).
+#
+# This enables the 'recommended' set of lints from `package:lints`.
+# This set helps identify many issues that may lead to problems when running
+# or consuming Dart code, and enforces writing Dart using a single, idiomatic
+# style and format.
+#
+# If you want a smaller set of lints you can change this to specify
+# 'package:lints/core.yaml'. These are just the most critical lints
+# (the recommended set includes the core lints).
+# The core lints are also what is used by pub.dev for scoring packages.
+
+include: package:lints/recommended.yaml
+
+# Uncomment the following section to specify additional rules.
+
+# linter:
+#   rules:
+#     - camel_case_types
+
+# analyzer:
+#   exclude:
+#     - path/to/excluded/files/**
+
+# For more information about the core and recommended set of lints, see
+# https://dart.dev/go/core-lints
+
+# For additional information about configuring this file, see
+# https://dart.dev/guides/language/analysis-options

packages/build_cmd/bin/main.dart

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+import 'package:args/command_runner.dart';
+import 'package:build/sync_headers.dart';
+
+final runner = CommandRunner(
+  'build',
+  'Performs build operations for google/flutter-mediapipe that '
+      'depend on contents in this repository',
+)..addCommand(SyncHeadersCommand());
+
+void main(List<String> arguments) => runner.run(arguments);

packages/build_cmd/lib/repo_finder.dart

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+import 'dart:io' as io;
+import 'package:args/args.dart';
+import 'package:args/command_runner.dart';
+import 'package:path/path.dart' as path;
+import 'package:io/ansi.dart';
+
+/// Mixin to help [Command] subclasses locate both `google/mediapipe` and
+/// the root of `google/flutter-mediapipe` (this repository).
+///
+/// The primary methods are [findFlutterMediaPipeRoot] and [findMediaPipeRoot].
+///
+/// By default, the root for `google/flutter-mediapipe` is determined by the
+/// firest ancestor directory which contains a `.flutter-mediapipe-root` file
+/// (whose contents are irrelevant), and the root of `google/mediapipe` is
+/// expected to be a sibling of that. However, the `--source` flag can overwrite
+/// this expectation and specify an absolute path where to find `google/mediapipe`.
+///
+/// Note that it is not possible to override the method of locating the root of
+/// `google/flutter-mediapipe`.
+mixin RepoFinderMixin on Command {
+  /// Name of the file which, when found, indicates the root of this repository.
+  static String sentinelFileName = '.flutter-mediapipe-root';
+
+  void addSourceOption(ArgParser argParser) {
+    argParser.addOption(
+      'source',
+      abbr: 's',
+      help: 'The location of google/mediapipe. Defaults to being '
+          'adjacent to google/flutter-mediapipe.',
+    );
+  }
+
+  /// Looks upward for the root of the `google/mediapipe` repository. This assumes
+  /// the `dart build` command is executed from within said repository. If it is
+  /// not executed from within, then this searching algorithm will reach the root
+  /// of the file system, log the error, and exit.
+  io.Directory findFlutterMediaPipeRoot() {
+    final placesChecked = <io.Directory>[];
+    io.Directory dir = io.Directory(path.current);
+    while (true) {
+      if (_isFlutterMediaPipeRoot(dir)) {
+        return dir;
+      }
+      placesChecked.add(dir);
+      dir = dir.parent;
+      if (dir.parent.path == dir.path) {
+        io.stderr.writeln(
+          wrapWith(
+            'Failed to find google/flutter-mediapipe root directory. '
+            'Did you execute this command from within the repository?\n'
+            'Looked in:',
+            [red],
+          ),
+        );
+        io.stderr.writeln(
+          wrapWith(
+            placesChecked
+                .map<String>((dir) => ' - ${dir.absolute.path}')
+                .toList()
+                .join('\n'),
+            [red],
+          ),
+        );
+        io.exit(1);
+      }
+    }
+  }
+
+  /// Finds the `google/mediapipe` checkout where artifacts built in this
+  /// repository should be sourced. By default, this command assumes the two
+  /// repositories are siblings on the file system, but the `--source` flag
+  /// allows for this assumption to be overridden.
+  io.Directory findMediaPipeRoot(
+    io.Directory flutterMediaPipeDir,
+    String? source,
+  ) {
+    final mediaPipeDirectory = io.Directory(
+      source ??
+          path.joinAll([flutterMediaPipeDir.parent.absolute.path, 'mediapipe']),
+    );
+
+    if (!mediaPipeDirectory.existsSync()) {
+      io.stderr.writeln(
+        'Could not find ${mediaPipeDirectory.absolute.path}. '
+        'Folder does not exist.',
+      );
+      io.exit(1);
+    }
+    return mediaPipeDirectory;
+  }
+
+  /// Looks for the sentinel file of this repository's root directory. This allows
+  /// the `dart build` command to be run from various locations within the
+  /// `google/mediapipe` repository and still correctly set paths for all of its
+  /// operations.
+  bool _isFlutterMediaPipeRoot(io.Directory dir) {
+    return io.File(
+      path.joinAll(
+        [dir.absolute.path, sentinelFileName],
+      ),
+    ).existsSync();
+  }
+}

packages/build_cmd/lib/sync_headers.dart

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+import 'dart:convert';
+import 'dart:io' as io;
+import 'package:args/command_runner.dart';
+import 'package:build/repo_finder.dart';
+import 'package:io/ansi.dart';
+import 'package:path/path.dart' as path;
+import 'package:process/process.dart';
+
+/// Relative header paths (in both repositories)
+final containers = 'mediapipe/tasks/c/components/containers';
+final processors = 'mediapipe/tasks/c/components/processors';
+final core = 'mediapipe/tasks/c/core';
+final tc = 'mediapipe/tasks/c/text/text_classifier';
+
+/// google/flutter-mediapipe package paths
+final corePackage = 'packages/mediapipe-core/third_party';
+final textPackage = 'packages/mediapipe-task-text/third_party';
+
+/// First string is its relative location in both repositories,
+/// Second string is its package location in `google/flutter-mediapipe`,
+/// Third string is the file name
+/// Fourth param is an optional function to modify the file
+List<(String, String, String, Function(io.File)?)> headerPaths = [
+  (containers, corePackage, 'category.h', null),
+  (containers, corePackage, 'classification_result.h', null),
+  (core, corePackage, 'base_options.h', null),
+  (processors, corePackage, 'classifier_options.h', null),
+  (tc, textPackage, 'text_classifier.h', relativeIncludes),
+];
+
+/// Command to copy all necessary C header files into this repository.
+///
+/// Pulls a list of hard-coded header files out of various destinations within
+/// the google/mediapipe repository and places them in the same paths within
+/// this repository. The only major change between their orientation within the
+/// source repository (google/mediapipe) and their orientation here is that
+/// shared header files are placed in `mediapipe-core` here, and no such
+/// distinction exists in the source. This also implies rewriting the import
+/// paths within these files to match, as their old relative positioning is
+/// disrupted by the move.
+class SyncHeadersCommand extends Command with RepoFinderMixin {
+  @override
+  String description = 'Syncs header files to google/flutter-mediapipe';
+  @override
+  String name = 'headers';
+
+  SyncHeadersCommand() {
+    argParser.addFlag(
+      'overwrite',
+      abbr: 'o',
+      defaultsTo: true,
+      help: 'If true, will overwrite existing header files '
+          'at destination locations.',
+    );
+    addSourceOption(argParser);
+  }
+
+  @override
+  Future<void> run() async {
+    final io.Directory flutterMediaPipeDirectory = findFlutterMediaPipeRoot();
+    final io.Directory mediaPipeDirectory = findMediaPipeRoot(
+      flutterMediaPipeDirectory,
+      argResults!['source'],
+    );
+
+    final config = Options(
+      allowOverwrite: argResults!['overwrite'],
+      mediaPipeDir: mediaPipeDirectory,
+      flutterMediaPipeDir: flutterMediaPipeDirectory,
+    );
+
+    await copyHeaders(config);
+  }
+
+  /// Central method that does the work of actually moving the files into the
+  /// local repository and rewriting their relative import statements within
+  /// the files themselves.
+  Future<void> copyHeaders(Options config) async {
+    final mgr = LocalProcessManager();
+    for (final tup in headerPaths) {
+      final headerFile = io.File(path.joinAll(
+        [config.mediaPipeDir.absolute.path, tup.$1, tup.$3],
+      ));
+      if (!headerFile.existsSync()) {
+        io.stderr.writeln(
+          'Expected to find ${headerFile.path}, but '
+          'file does not exist.',
+        );
+        io.exit(1);
+      }
+      final destinationPath = path.joinAll(
+        [config.flutterMediaPipeDir.absolute.path, tup.$2, tup.$1, tup.$3],
+      );
+      final destinationFile = io.File(destinationPath);
+      if (destinationFile.existsSync() && !config.allowOverwrite) {
+        io.stdout.writeAll(
+          [
+            'Warning: Not overwriting existing file at $destinationPath\n',
+            wrapWith('Skipping ${tup.$3}.\n', [cyan]),
+          ],
+        );
+        continue;
+      }
+
+      // MediaPipe header files often come from deeply nested locations, and new
+      // header files could require new folders. Thus, create any missing folders.
+      ensureFolders(io.File(destinationPath));
+
+      final process = await mgr.start(['cp', headerFile.path, destinationPath]);
+      int processExitCode = await process.exitCode;
+      if (processExitCode != 0) {
+        final processStdErr = utf8.decoder.convert(
+            (await process.stderr.toList())
+                .fold<List<int>>([], (arr, el) => arr..addAll(el)));
+        io.stderr.write(wrapWith(processStdErr, [red]));
+
+        final processStdOut = utf8.decoder.convert(
+            (await process.stdout.toList())
+                .fold<List<int>>([], (arr, el) => arr..addAll(el)));
+        io.stderr.write(wrapWith(processStdOut, [red]));
+        io.exit(processExitCode);
+      } else {
+        io.stderr.writeln(wrapWith('Copied ${tup.$3}', [green]));
+      }
+
+      // Call the final modification function, if supplied
+      if (tup.$4 != null) {
+        tup.$4!.call(destinationFile);
+      }
+    }
+  }
+
+  /// Builds any missing folders between the file and the root of the repository
+  void ensureFolders(io.File file) {
+    io.Directory parent = file.parent;
+    List<io.Directory> dirsToCreate = [];
+    while (!parent.existsSync()) {
+      dirsToCreate.add(parent);
+      parent = parent.parent;
+    }
+    for (io.Directory dir in dirsToCreate.reversed) {
+      dir.createSync();
+    }
+  }
+}
+
+class Options {
+  const Options({
+    required this.allowOverwrite,
+    required this.mediaPipeDir,
+    required this.flutterMediaPipeDir,
+  });
+
+  final bool allowOverwrite;
+  final io.Directory mediaPipeDir;
+  final io.Directory flutterMediaPipeDir;
+}
+
+void relativeIncludes(io.File textClassifierHeader) {
+  assert(textClassifierHeader.path.endsWith('text_classifier.h'));
+  String contents = textClassifierHeader.readAsStringSync();
+
+  Map<String, String> rewrites = {
+    'mediapipe/tasks/c/components/containers/classification_result.h':
+        '../../../../../../../mediapipe-core/third_party/mediapipe/tasks/c/components/containers/classification_result.h',
+    'mediapipe/tasks/c/components/processors/classifier_options.h':
+        '../../../../../../../mediapipe-core/third_party/mediapipe/tasks/c/components/processors/classifier_options.h',
+    'mediapipe/tasks/c/core/base_options.h':
+        '../../../../../../../mediapipe-core/third_party/mediapipe/tasks/c/core/base_options.h',
+  };
+
+  for (final rewrite in rewrites.entries) {
+    contents = contents.replaceAll(rewrite.key, rewrite.value);
+  }
+  textClassifierHeader.writeAsStringSync(contents);
+}

packages/build_cmd/pubspec.yaml

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+name: build
+description: Performs build operations for google/flutter-mediapipe that depend
+  on contents in this repository.
+version: 1.0.0
+# repository: https://github.com/my_org/my_repo
+environment:
+  sdk: ^3.2.0-162.0.dev
+
+# Add regular dependencies here.
+dependencies:
+  args: ^2.4.2
+  io: ^1.0.4
+  logging: ^1.2.0
+  path: ^1.8.0
+  process: ^5.0.0
+
+dev_dependencies:
+  ffigen: ^9.0.1
+  lints: ^2.1.0
+  test: ^1.24.0