Language Detector task

Makefile

@@ -6,7 +6,7 @@ headers:
 models:
 	cd tool/builder && dart bin/main.dart model -m textclassification
 	cd tool/builder && dart bin/main.dart model -m textembedding
-
+	cd tool/builder && dart bin/main.dart model -m languagedetection
 
 # Runs `ffigen` for all packages
 generate: generate_core generate_text

packages/mediapipe-core/lib/universal_mediapipe_core.dart

@@ -62,7 +62,7 @@ class Classifications extends BaseClassifications {
   });
 
   @override
-  Iterable<BaseCategory> get categories => throw UnimplementedError();
+  Iterable<Category> get categories => throw UnimplementedError();
 
   @override
   int get headIndex => throw UnimplementedError();

packages/mediapipe-core/third_party/mediapipe/tasks/c/components/containers/classification_result.h

@@ -28,7 +28,6 @@ struct Classifications {
   // The array of predicted categories, usually sorted by descending scores,
   // e.g. from high to low probability.
   struct Category* categories;
-
   // The number of elements in the categories array.
   uint32_t categories_count;
 
@@ -58,7 +57,6 @@ struct ClassificationResult {
   // exceed the maximum size that the model can process: to solve this, the
   // input data is split into multiple chunks starting at different timestamps.
   int64_t timestamp_ms;
-
   // Specifies whether the timestamp contains a valid value.
   bool has_timestamp_ms;
 };

packages/mediapipe-core/third_party/mediapipe/tasks/c/components/processors/classifier_options.h

@@ -41,15 +41,13 @@ struct ClassifierOptions {
   // category name is not in this set will be filtered out. Duplicate or unknown
   // category names are ignored. Mutually exclusive with category_denylist.
   const char** category_allowlist;
-
   // The number of elements in the category allowlist.
   uint32_t category_allowlist_count;
 
   // The denylist of category names. If non-empty, detection results whose
   // category name is in this set will be filtered out. Duplicate or unknown
   // category names are ignored. Mutually exclusive with category_allowlist.
   const char** category_denylist;
-
   // The number of elements in the category denylist.
   uint32_t category_denylist_count;
 };

packages/mediapipe-task-text/example/lib/enumerate.dart

@@ -2,12 +2,34 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extension Enumeratable<T> on List<T> {
-  Iterable<S> enumerate<S>(S Function(T, int) fn) sync* {
+extension EnumeratableList<T> on List<T> {
+  /// Invokes the callback on each element of the list, optionally stopping
+  /// after [max] (inclusive) invocations.
+  Iterable<S> enumerate<S>(S Function(T, int) fn, {int? max}) sync* {
     int count = 0;
     while (count < length) {
       yield fn(this[count], count);
       count++;
+
+      if (max != null && count >= max) {
+        return;
+      }
+    }
+  }
+}
+
+extension EnumeratableIterable<T> on Iterable<T> {
+  /// Invokes the callback on each element of the iterable, optionally stopping
+  /// after [max] (inclusive) invocations.
+  Iterable<S> enumerate<S>(S Function(T, int) fn, {int? max}) sync* {
+    int count = 0;
+    for (final T obj in this) {
+      yield fn(obj, count);
+      count++;
+
+      if (max != null && count >= max) {
+        return;
+      }
     }
   }
 }

packages/mediapipe-task-text/example/lib/language_detection_demo.dart

@@ -0,0 +1,158 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:typed_data';
+import 'package:flutter/material.dart';
+import 'package:getwidget/getwidget.dart';
+import 'package:mediapipe_text/mediapipe_text.dart';
+import 'enumerate.dart';
+
+class LanguageDetectionDemo extends StatefulWidget {
+  const LanguageDetectionDemo({super.key, this.detector});
+
+  final LanguageDetector? detector;
+
+  @override
+  State<LanguageDetectionDemo> createState() => _LanguageDetectionDemoState();
+}
+
+class _LanguageDetectionDemoState extends State<LanguageDetectionDemo>
+    with AutomaticKeepAliveClientMixin<LanguageDetectionDemo> {
+  final TextEditingController _controller = TextEditingController();
+  final Completer<LanguageDetector> _completer = Completer<LanguageDetector>();
+  final results = <Widget>[];
+  String? _isProcessing;
+
+  @override
+  void initState() {
+    super.initState();
+    _controller.text = 'Quiero agua, por favor';
+    _initDetector();
+  }
+
+  Future<void> _initDetector() async {
+    if (widget.detector != null) {
+      return _completer.complete(widget.detector!);
+    }
+
+    ByteData? bytes = await DefaultAssetBundle.of(context)
+        .load('assets/language_detector.tflite');
+
+    final detector = LanguageDetector(
+      LanguageDetectorOptions.fromAssetBuffer(
+        bytes.buffer.asUint8List(),
+      ),
+    );
+    _completer.complete(detector);
+    bytes = null;
+  }
+
+  void _prepareForDetection() {
+    setState(() {
+      _isProcessing = _controller.text;
+      results.add(const CircularProgressIndicator.adaptive());
+    });
+  }
+
+  Future<void> _detect() async {
+    _prepareForDetection();
+    _completer.future.then((detector) async {
+      final result = await detector.detect(_controller.text);
+      _showDetectionResults(result);
+      result.dispose();
+    });
+  }
+
+  void _showDetectionResults(LanguageDetectorResult result) {
+    setState(
+      () {
+        results.last = Card(
+          key: Key('prediction-"$_isProcessing" ${results.length}'),
+          margin: const EdgeInsets.all(10),
+          child: Column(
+            children: [
+              Padding(
+                padding: const EdgeInsets.all(10),
+                child: Text(_isProcessing!),
+              ),
+              Padding(
+                padding: const EdgeInsets.all(10.0),
+                child: Wrap(
+                  children: <Widget>[
+                    ...result.predictions
+                        .enumerate<Widget>(
+                          (prediction, index) => _languagePrediction(
+                            prediction,
+                            predictionColors[index],
+                          ),
+                          // Take first 4 because the model spits out dozens of
+                          // astronomically low probability language predictions
+                          max: predictionColors.length,
+                        )
+                        .toList(),
+                  ],
+                ),
+              ),
+            ],
+          ),
+        );
+        _isProcessing = null;
+      },
+    );
+  }
+
+  static final predictionColors = <Color>[
+    Colors.blue[300]!,
+    Colors.orange[300]!,
+    Colors.green[300]!,
+    Colors.red[300]!,
+  ];
+
+  Widget _languagePrediction(LanguagePrediction prediction, Color color) {
+    return Padding(
+      padding: const EdgeInsets.only(right: 8),
+      child: GFButton(
+        onPressed: null,
+        text: '${prediction.languageCode} :: '
+            '${prediction.probability.roundTo(8)}',
+        shape: GFButtonShape.pills,
+        color: color,
+      ),
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    super.build(context);
+    return Scaffold(
+      body: SafeArea(
+        child: Padding(
+          padding: const EdgeInsets.all(16.0),
+          child: SingleChildScrollView(
+            child: Column(
+              children: <Widget>[
+                TextField(controller: _controller),
+                ...results.reversed,
+              ],
+            ),
+          ),
+        ),
+      ),
+      floatingActionButton: FloatingActionButton(
+        onPressed:
+            _isProcessing != null && _controller.text != '' ? null : _detect,
+        child: const Icon(Icons.search),
+      ),
+    );
+  }
+
+  @override
+  bool get wantKeepAlive => true;
+}
+
+extension on double {
+  double roundTo(int decimalPlaces) =>
+      double.parse(toStringAsFixed(decimalPlaces));
+}

packages/mediapipe-task-text/example/lib/main.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'language_detection_demo.dart';
 import 'logging.dart';
 import 'text_classification_demo.dart';
 import 'text_embedding_demo.dart';
@@ -31,7 +32,7 @@ class TextTaskPages extends StatefulWidget {
 class TextTaskPagesState extends State<TextTaskPages> {
   final PageController controller = PageController();
 
-  final titles = <String>['Classify', 'Embed'];
+  final titles = <String>['Classify', 'Embed', 'Detect Languages'];
   int titleIndex = 0;
 
   void switchToPage(int index) {
@@ -61,28 +62,39 @@ class TextTaskPagesState extends State<TextTaskPages> {
         children: const <Widget>[
           TextClassificationDemo(),
           TextEmbeddingDemo(),
+          LanguageDetectionDemo(),
         ],
       ),
-      bottomNavigationBar: ColoredBox(
-        color: Colors.blueGrey,
-        child: Row(
-          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
-          children: <Widget>[
-            TextButton(
-              onPressed: () => switchToPage(0),
-              child: Text(
-                'Classify',
-                style: titleIndex == 0 ? activeTextStyle : inactiveTextStyle,
+      bottomNavigationBar: SizedBox(
+        height: 50,
+        child: ColoredBox(
+          color: Colors.blueGrey,
+          child: Row(
+            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
+            children: <Widget>[
+              TextButton(
+                onPressed: () => switchToPage(0),
+                child: Text(
+                  'Classify',
+                  style: titleIndex == 0 ? activeTextStyle : inactiveTextStyle,
+                ),
               ),
-            ),
-            TextButton(
-              onPressed: () => switchToPage(1),
-              child: Text(
-                'Embed',
-                style: titleIndex == 1 ? activeTextStyle : inactiveTextStyle,
+              TextButton(
+                onPressed: () => switchToPage(1),
+                child: Text(
+                  'Embed',
+                  style: titleIndex == 1 ? activeTextStyle : inactiveTextStyle,
+                ),
               ),
-            ),
-          ],
+              TextButton(
+                onPressed: () => switchToPage(2),
+                child: Text(
+                  'Detect Languages',
+                  style: titleIndex == 2 ? activeTextStyle : inactiveTextStyle,
+                ),
+              ),
+            ],
+          ),
         ),
       ),
     );