feat: #494 - added OCR for packaging (#497)

New files:
* `OcrPackagingResult.dart`: Result from OCR applied to packaging.
* `OcrPackagingResult.g.dart`: generated.

Impacted files:
* `OcrPackagingResult.dart`: mere refactoring in order to match the new `OcrPackagingResult` class.
* `openfoodfacts.dart`: new OCR method `extractPackaging`; refactored `extractIngredients` and fixed a bug.

lib/model/OcrIngredientsResult.dart

@@ -3,24 +3,26 @@ import '../interface/JsonObject.dart';
 
 part 'OcrIngredientsResult.g.dart';
 
+/// Result from OCR applied to ingredients.
 @JsonSerializable()
 class OcrIngredientsResult extends JsonObject {
+  const OcrIngredientsResult({
+    this.status,
+    this.ingredientsTextFromImageOrig,
+    this.ingredientsTextFromImage,
+  });
+
+  factory OcrIngredientsResult.fromJson(Map<String, dynamic> json) =>
+      _$OcrIngredientsResultFromJson(json);
+
+  @override
+  Map<String, dynamic> toJson() => _$OcrIngredientsResultToJson(this);
+
   final int? status;
 
   @JsonKey(name: 'ingredients_text_from_image_orig')
   final String? ingredientsTextFromImageOrig;
 
   @JsonKey(name: 'ingredients_text_from_image')
   final String? ingredientsTextFromImage;
-
-  const OcrIngredientsResult(
-      {this.status,
-      this.ingredientsTextFromImageOrig,
-      this.ingredientsTextFromImage});
-
-  factory OcrIngredientsResult.fromJson(Map<String, dynamic> json) =>
-      _$OcrIngredientsResultFromJson(json);
-
-  @override
-  Map<String, dynamic> toJson() => _$OcrIngredientsResultToJson(this);
 }

lib/model/OcrPackagingResult.dart

@@ -0,0 +1,28 @@
+import 'package:json_annotation/json_annotation.dart';
+import '../interface/JsonObject.dart';
+
+part 'OcrPackagingResult.g.dart';
+
+/// Result from OCR applied to packaging.
+@JsonSerializable()
+class OcrPackagingResult extends JsonObject {
+  const OcrPackagingResult({
+    this.status,
+    this.textFromImageOrig,
+    this.textFromImage,
+  });
+
+  factory OcrPackagingResult.fromJson(Map<String, dynamic> json) =>
+      _$OcrPackagingResultFromJson(json);
+
+  @override
+  Map<String, dynamic> toJson() => _$OcrPackagingResultToJson(this);
+
+  final int? status;
+
+  @JsonKey(name: 'packaging_text_from_image_orig')
+  final String? textFromImageOrig;
+
+  @JsonKey(name: 'packaging_text_from_image')
+  final String? textFromImage;
+}

lib/openfoodfacts.dart

@@ -8,6 +8,7 @@ import 'package:http/http.dart';
 import 'package:openfoodfacts/interface/JsonObject.dart';
 import 'package:openfoodfacts/model/KnowledgePanels.dart';
 import 'package:openfoodfacts/model/OcrIngredientsResult.dart';
+import 'package:openfoodfacts/model/OcrPackagingResult.dart';
 import 'package:openfoodfacts/model/OrderedNutrients.dart';
 import 'package:openfoodfacts/model/ProductFreshness.dart';
 import 'package:openfoodfacts/model/ProductImage.dart';
@@ -699,26 +700,54 @@ class OpenFoodAPIClient {
     OcrField ocrField = OcrField.GOOGLE_CLOUD_VISION,
     QueryType? queryType,
   }) async {
-    var ocrUri = UriHelper.getPostUri(
+    final Uri uri = UriHelper.getPostUri(
       path: '/cgi/ingredients.pl',
       queryType: queryType,
     );
-    Map<String, String> queryParameters = <String, String>{
+    final Map<String, String> queryParameters = <String, String>{
       'code': barcode,
       'process_image': '1',
       'id': 'ingredients_${language.code}',
-      'ocr_engine': OcrField.GOOGLE_CLOUD_VISION.key
+      'ocr_engine': ocrField.key
     };
-    Response response = await HttpHelper().doPostRequest(
-      ocrUri,
+    final Response response = await HttpHelper().doPostRequest(
+      uri,
       queryParameters,
       user,
       queryType: queryType,
     );
+    return OcrIngredientsResult.fromJson(
+      json.decode(utf8.decode(response.bodyBytes)) as Map<String, dynamic>,
+    );
+  }
 
-    OcrIngredientsResult result = OcrIngredientsResult.fromJson(
-        json.decode(utf8.decode(response.bodyBytes)));
-    return result;
+  /// Extracts the text from packaging image with OCR.
+  static Future<OcrPackagingResult> extractPackaging(
+    final User user,
+    final String barcode,
+    final OpenFoodFactsLanguage language, {
+    final OcrField ocrField = OcrField.GOOGLE_CLOUD_VISION,
+    final QueryType? queryType,
+  }) async {
+    final Uri uri = UriHelper.getPostUri(
+      path: '/cgi/packaging.pl',
+      queryType: queryType,
+    );
+    final Map<String, String> queryParameters = <String, String>{
+      'code': barcode,
+      'process_image': '1',
+      'id': 'packaging_${language.code}',
+      'ocr_engine': ocrField.key
+    };
+    final Response response = await HttpHelper().doPostRequest(
+      uri,
+      queryParameters,
+      user,
+      queryType: queryType,
+    );
+    return OcrPackagingResult.fromJson(
+      json.decode(utf8.decode(response.bodyBytes)) as Map<String, dynamic>,
+    );
   }
 
   /// Returns suggestions.