add beginning of Dart-specific MediaPipe implementation

mediapipe/dart/mediapipe/.gitignore

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+# https://dart.dev/guides/libraries/private-files
+# Created by `dart pub`
+.dart_tool/
+
+# Avoid committing pubspec.lock for library packages; see
+# https://dart.dev/guides/libraries/private-files#pubspeclock.
+pubspec.lock

mediapipe/dart/mediapipe/CHANGELOG.md

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+## 1.0.0
+
+- Initial version.

mediapipe/dart/mediapipe/README.md

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+<!-- 
+This README describes the package. If you publish this package to pub.dev,
+this README's contents appear on the landing page for your package.
+
+For information about how to write a good package README, see the guide for
+[writing package pages](https://dart.dev/guides/libraries/writing-package-pages). 
+
+For general information about developing packages, see the Dart guide for
+[creating packages](https://dart.dev/guides/libraries/create-library-packages)
+and the Flutter guide for
+[developing packages and plugins](https://flutter.dev/developing-packages). 
+-->
+
+TODO: Put a short description of the package here that helps potential users
+know whether this package might be useful for them.
+
+## Features
+
+TODO: List what your package can do. Maybe include images, gifs, or videos.
+
+## Getting started
+
+TODO: List prerequisites and provide or point to information on how to
+start using the package.
+
+## Usage
+
+TODO: Include short and useful examples for package users. Add longer examples
+to `/example` folder. 
+
+```dart
+const like = 'sample';
+```
+
+## Additional information
+
+TODO: Tell users more about the package: where to find more information, how to 
+contribute to the package, how to file issues, what response they can expect 
+from the package authors, and more.

mediapipe/dart/mediapipe/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

mediapipe/dart/mediapipe/lib/generated/README.md

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+To generate protocol buffers for Dart (in this folder), navigate to the `dart_builder` directory and run:
+
+```
+$ dart bin/dart_builder.dart
+```

mediapipe/dart/mediapipe/lib/mediapipe.dart

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+library mediapipe;
+
+export 'src/tasks/tasks.dart';

mediapipe/dart/mediapipe/lib/src/tasks/core/base_options.dart

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+import 'dart:io' as io;
+import 'dart:typed_data';
+import 'package:path/path.dart' as path;
+import 'package:protobuf/protobuf.dart' as $pb;
+
+import '../../../generated/mediapipe/calculators/calculators.dart';
+import '../../../generated/mediapipe/tasks/tasks.dart' as tasks_pb;
+
+/// Class to extend in task-specific *Options classes. Funnels the three
+/// [BaseOptions] attributes into their own object.
+abstract class TaskOptions {
+  TaskOptions({this.modelAssetBuffer, this.modelAssetPath, this.delegate})
+      : baseOptions = BaseOptions(
+          delegate: delegate,
+          modelAssetBuffer: modelAssetBuffer,
+          modelAssetPath: modelAssetPath,
+        );
+
+  final Uint8List? modelAssetBuffer;
+  final String? modelAssetPath;
+  final Delegate? delegate;
+
+  final BaseOptions baseOptions;
+
+  $pb.GeneratedMessage toProto();
+
+  /// In proto2 syntax, extensions are unique IDs, suitable for keys in a hash
+  /// map, which power the Extensions pattern for protos to house arbitrary
+  /// extended data.
+  ///
+  /// In proto3, this pattern is replaced with the [Any] protobuf, as the
+  /// convention for setting the unique identifiers surpassed the maximum upper
+  /// bound of 29 bits as allocated in the protobuf spec.
+  $pb.Extension get ext;
+}
+
+final class BaseOptions {
+  BaseOptions({this.modelAssetBuffer, this.modelAssetPath, this.delegate});
+
+  /// The model asset file contents as bytes;
+  Uint8List? modelAssetBuffer;
+
+  /// Path to the model asset file.
+  String? modelAssetPath;
+
+  /// Acceleration strategy to use. GPU support is currently limited to
+  /// Ubuntu platform.
+  Delegate? delegate;
+
+  /// See also: https://source.corp.google.com/piper///depot/google3/third_party/mediapipe/tasks/python/core/base_options.py;l=63-89;rcl=548857458
+  tasks_pb.BaseOptions toProto() {
+    String? absModelPath =
+        modelAssetPath != null ? path.absolute(modelAssetPath!) : null;
+
+    if (!io.Platform.isLinux && delegate == Delegate.gpu) {
+      throw Exception(
+        'GPU Delegate is not yet supported for ${io.Platform.operatingSystem}',
+      );
+    }
+    tasks_pb.Acceleration? acceleration;
+    if (delegate == Delegate.cpu) {
+      acceleration = tasks_pb.Acceleration.create()
+        ..tflite = InferenceCalculatorOptions_Delegate_TfLite.create();
+    }
+
+    final modelAsset = tasks_pb.ExternalFile.create();
+    if (absModelPath != null) {
+      modelAsset.fileName = absModelPath;
+    }
+    if (modelAssetBuffer != null) {
+      modelAsset.fileContent = modelAssetBuffer!;
+    }
+
+    final options = tasks_pb.BaseOptions.create()..modelAsset = modelAsset;
+    if (acceleration != null) {
+      options.acceleration = acceleration;
+    }
+    return options;
+  }
+}
+
+/// Hardware location to perform the given task.
+enum Delegate { cpu, gpu }

mediapipe/dart/mediapipe/lib/src/tasks/core/core.dart

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+export 'base_options.dart';
+export 'task_info.dart';
+export 'task_runner.dart';

mediapipe/dart/mediapipe/lib/src/tasks/core/task_info.dart

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+import 'package:mediapipe/generated/mediapipe/calculators/calculators.dart';
+
+import '../../../generated/mediapipe/framework/framework.dart';
+import '../tasks.dart';
+
+class TaskInfo<T extends TaskOptions> {
+  TaskInfo({
+    required this.taskGraph,
+    required this.inputStreams,
+    required this.outputStreams,
+    required this.taskOptions,
+  });
+  String taskGraph;
+  List<String> inputStreams;
+  List<String> outputStreams;
+  T taskOptions;
+
+  CalculatorGraphConfig generateGraphConfig({
+    bool enableFlowLimiting = false,
+  }) {
+    assert(inputStreams.isNotEmpty, 'TaskInfo.inputStreams must be non-empty');
+    assert(
+      outputStreams.isNotEmpty,
+      'TaskInfo.outputStreams must be non-empty',
+    );
+
+    FlowLimiterCalculatorOptions.ext;
+    final taskSubgraphOptions = CalculatorOptions();
+    taskSubgraphOptions.addExtension(taskOptions.ext, taskOptions.toProto());
+
+    if (!enableFlowLimiting) {
+      return CalculatorGraphConfig.create()
+        ..node.add(
+          CalculatorGraphConfig_Node.create()
+            ..calculator = taskGraph
+            ..inputStream.addAll(inputStreams)
+            ..outputStream.addAll(outputStreams)
+            ..options = taskSubgraphOptions,
+        );
+    }
+
+    // When a FlowLimiterCalculator is inserted to lower the overall graph
+    // latency, the task doesn't guarantee that each input must have the
+    // corresponding output.
+    final taskSubgraphInputs =
+        inputStreams.map<String>(_addStreamNamePrefix).toList();
+    String finishedStream = 'FINISHED: ${_stripTagIndex(outputStreams.first)}';
+
+    final flowLimiterOptions = CalculatorOptions.create();
+    flowLimiterOptions.setExtension(
+      FlowLimiterCalculatorOptions.ext,
+      FlowLimiterCalculatorOptions.create()
+        ..maxInFlight = 1
+        ..maxInQueue = 1,
+    );
+
+    final flowLimiter = CalculatorGraphConfig_Node.create()
+      ..calculator = 'FlowLimiterCalculator'
+      ..inputStreamInfo.add(
+        InputStreamInfo.create()
+          ..tagIndex = 'FINISHED'
+          ..backEdge = true,
+      )
+      ..inputStream.addAll(inputStreams.map<String>(_stripTagIndex).toList())
+      ..inputStream.add(finishedStream)
+      ..outputStream.addAll(
+        taskSubgraphInputs.map<String>(_stripTagIndex).toList(),
+      )
+      ..options = flowLimiterOptions;
+
+    final config = CalculatorGraphConfig.create()
+      ..node.add(
+        CalculatorGraphConfig_Node.create()
+          ..calculator = taskGraph
+          ..inputStream.addAll(taskSubgraphInputs)
+          ..outputStream.addAll(outputStreams)
+          ..options = taskSubgraphOptions,
+      )
+      ..node.add(flowLimiter)
+      ..inputStream.addAll(inputStreams)
+      ..outputStream.addAll(outputStreams);
+    return config;
+  }
+}
+
+String _stripTagIndex(String tagIndexName) => tagIndexName.split(':').last;
+String _addStreamNamePrefix(String tagIndexName) {
+  final split = tagIndexName.split(':');
+  split.last = 'trottled_${split.last}';
+  return split.join(':');
+}

mediapipe/dart/mediapipe/lib/src/tasks/core/task_runner.dart

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+import '../../../generated/mediapipe/framework/calculator.pb.dart';
+
+// TODO: Wrap C++ TaskRunner with this, similarly to this Python wrapper:
+// https://source.corp.google.com/piper///depot/google3/third_party/mediapipe/python/framework_bindings.cc?q=python%20framework_bindings.cc
+class TaskRunner {
+  TaskRunner(this.graphConfig);
+
+  final CalculatorGraphConfig graphConfig;
+
+  // TODO: Actually decode this line for correct parameter type:
+  // https://source.corp.google.com/piper///depot/google3/third_party/mediapipe/tasks/python/text/text_classifier.py;l=181
+  Map<String, Packet> process(Map<String, Object> data) => {};
+}
+
+// TODO: Wrap C++ Packet with this, similarly to this Python wrapper:
+// https://source.corp.google.com/piper///depot/google3/third_party/mediapipe/python/pybind/packet.h
+class Packet {}

mediapipe/dart/mediapipe/lib/src/tasks/tasks.dart

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+export 'core/core.dart';
+export 'text/text.dart';

mediapipe/dart/mediapipe/lib/src/tasks/text/text.dart

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+export 'text_classifier.dart';

mediapipe/dart/mediapipe/lib/src/tasks/text/text_classifier.dart

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+import 'package:protobuf/protobuf.dart' as $pb;
+import '../../../generated/mediapipe/tasks/tasks.dart' as tasks_pb;
+import '../tasks.dart';
+
+class TextClassifier {
+  /// Primary constructor for [TextClassifier].
+  TextClassifier(this.options)
+      : _taskInfo = TaskInfo(
+          taskGraph: taskGraphName,
+          inputStreams: <String>['$textTag:$textInStreamName'],
+          outputStreams: <String>[
+            '$classificationsTag:$classificationsStreamName'
+          ],
+          taskOptions: options,
+        ) {
+    _taskRunner = TaskRunner(_taskInfo.generateGraphConfig());
+  }
+
+  /// Shortcut constructor which only accepts a local path to the model.
+  factory TextClassifier.fromAssetPath(String assetPath) => TextClassifier(
+        TextClassifierOptions(modelAssetPath: assetPath),
+      );
+
+  /// Configuration options for this [TextClassifier].
+  final TextClassifierOptions options;
+  final TaskInfo _taskInfo;
+
+  TaskRunner get taskRunner => _taskRunner!;
+  TaskRunner? _taskRunner;
+
+  static const classificationsStreamName = 'classifications_out';
+  static const classificationsTag = 'CLASSIFICATIONS';
+  static const textTag = 'TEXT';
+  static const textInStreamName = 'text_in';
+  static const taskGraphName =
+      'mediapipe.tasks.text.text_classifier.TextClassifierGraph';
+
+  /// Performs classification on the input `text`.
+  Future<tasks_pb.ClassificationResult> classify(String text) async {
+    // TODO: Actually decode this line to correctly fill up this map parameter
+    // https://source.corp.google.com/piper///depot/google3/third_party/mediapipe/tasks/python/text/text_classifier.py;l=181
+    final outputPackets = taskRunner.process({});
+
+    // TODO: Obviously this is not real
+    return tasks_pb.ClassificationResult.create();
+  }
+}
+
+class TextClassifierOptions extends TaskOptions {
+  TextClassifierOptions({
+    this.displayNamesLocale,
+    this.maxResults,
+    this.scoreThreshold,
+    this.categoryAllowlist,
+    this.categoryDenylist,
+    super.modelAssetBuffer,
+    super.modelAssetPath,
+    super.delegate,
+  });
+
+  /// The locale to use for display names specified through the TFLite Model
+  /// Metadata.
+  String? displayNamesLocale;
+
+  /// The maximum number of top-scored classification results to return.
+  int? maxResults;
+
+  /// Overrides the ones provided in the model metadata. Results below this
+  /// value are rejected.
+  double? scoreThreshold;
+
+  /// Allowlist of category names. If non-empty, classification results whose
+  /// category name is not in this set will be discarded. Duplicate or unknown
+  /// category names are ignored. Mutually exclusive with `categoryDenylist`.
+  List<String>? categoryAllowlist;
+
+  /// Denylist of category names. If non-empty, classification results whose
+  /// category name is in this set will be discarded. Duplicate or unknown
+  /// category names are ignored. Mutually exclusive with `categoryAllowList`.
+  List<String>? categoryDenylist;
+
+  @override
+  $pb.Extension get ext => tasks_pb.TextClassifierGraphOptions.ext;
+
+  @override
+  tasks_pb.TextClassifierGraphOptions toProto() {
+    final classifierOptions = tasks_pb.ClassifierOptions.create();
+    if (displayNamesLocale != null) {
+      classifierOptions.displayNamesLocale = displayNamesLocale!;
+    }
+    if (maxResults != null) {
+      classifierOptions.maxResults = maxResults!;
+    }
+    if (scoreThreshold != null) {
+      classifierOptions.scoreThreshold = scoreThreshold!;
+    }
+    if (categoryAllowlist != null) {
+      classifierOptions.categoryAllowlist.addAll(categoryAllowlist!);
+    }
+    if (categoryDenylist != null) {
+      classifierOptions.categoryDenylist.addAll(categoryDenylist!);
+    }
+
+    return tasks_pb.TextClassifierGraphOptions.create()
+      ..baseOptions = baseOptions.toProto()
+      ..classifierOptions = classifierOptions;
+  }
+}

mediapipe/dart/mediapipe/pubspec.yaml

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+name: mediapipe
+description: Flutter plugin for Google's MediaPipe.
+version: 1.0.0
+# repository: https://github.com/my_org/my_repo
+environment:
+  sdk: ^3.1.0-149.0.dev
+
+# Add regular dependencies here.
+dependencies:
+  fixnum: ^1.1.0
+  path: ^1.8.3
+  protobuf: ^3.0.0
+
+dev_dependencies:
+  lints: ^2.0.0
+  test: ^1.21.0