Add limit to image_picker_platform_interface (#6434)

Adds limit parameter to `MediaOptions` and `MultiImagePickerOptions`. The `limit` argument defines how many images or media files can be select.

Only platform interface package changes taken from: #6201

Fixes: [flutter/flutter#85772](flutter/flutter#85772)

Author: pdenert

packages/image_picker/image_picker_platform_interface/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.10.0
+
+* Adds limit parameter to `MediaOptions` and `MultiImagePickerOptions`.
+
 ## 2.9.4
 
 * Updates minimum supported SDK version to Flutter 3.19/Dart 3.3.

packages/image_picker/image_picker_platform_interface/lib/src/method_channel/method_channel_image_picker.dart

@@ -58,6 +58,7 @@ class MethodChannelImagePicker extends ImagePickerPlatform {
     double? maxHeight,
     int? imageQuality,
     bool requestFullMetadata = true,
+    int? limit,
   }) {
     if (imageQuality != null && (imageQuality < 0 || imageQuality > 100)) {
       throw ArgumentError.value(
@@ -79,6 +80,7 @@ class MethodChannelImagePicker extends ImagePickerPlatform {
         'maxHeight': maxHeight,
         'imageQuality': imageQuality,
         'requestFullMetadata': requestFullMetadata,
+        'limit': limit,
       },
     );
   }
@@ -244,6 +246,7 @@ class MethodChannelImagePicker extends ImagePickerPlatform {
       maxHeight: options.imageOptions.maxHeight,
       imageQuality: options.imageOptions.imageQuality,
       requestFullMetadata: options.imageOptions.requestFullMetadata,
+      limit: options.limit,
     );
     if (paths == null) {
       return <XFile>[];
@@ -263,6 +266,7 @@ class MethodChannelImagePicker extends ImagePickerPlatform {
       'maxImageHeight': imageOptions.maxHeight,
       'imageQuality': imageOptions.imageQuality,
       'allowMultiple': options.allowMultiple,
+      'limit': options.limit,
     };
 
     final List<XFile>? paths = await _channel

packages/image_picker/image_picker_platform_interface/lib/src/types/media_options.dart

@@ -13,11 +13,48 @@ class MediaOptions {
   const MediaOptions({
     this.imageOptions = const ImageOptions(),
     required this.allowMultiple,
+    this.limit,
   });
 
+  /// Construct a new MediaOptions instance.
+  ///
+  /// Throws if limit is lower than 2,
+  /// or allowMultiple is false and limit is not null.
+  MediaOptions.createAndValidate({
+    this.imageOptions = const ImageOptions(),
+    required this.allowMultiple,
+    this.limit,
+  }) {
+    _validate(allowMultiple: allowMultiple, limit: limit);
+  }
+
   /// Options that will apply to images upon selection.
   final ImageOptions imageOptions;
 
   /// Whether to allow for selecting multiple media.
   final bool allowMultiple;
+
+  /// The maximum number of images to select.
+  ///
+  /// Default null value means no limit.
+  /// This value may be ignored by platforms that cannot support it.
+  final int? limit;
+
+  /// Validates that all values are within required ranges.
+  ///
+  /// Throws if limit is lower than 2,
+  /// or allowMultiple is false and limit is not null.
+  static void _validate({required bool allowMultiple, int? limit}) {
+    if (!allowMultiple && limit != null) {
+      throw ArgumentError.value(
+        allowMultiple,
+        'allowMultiple',
+        'cannot be false, when limit is not null',
+      );
+    }
+
+    if (limit != null && limit < 2) {
+      throw ArgumentError.value(limit, 'limit', 'cannot be lower then 2');
+    }
+  }
 }

packages/image_picker/image_picker_platform_interface/lib/src/types/multi_image_picker_options.dart

@@ -6,11 +6,37 @@ import 'image_options.dart';
 
 /// Specifies options for picking multiple images from the device's gallery.
 class MultiImagePickerOptions {
-  /// Creates an instance with the given [imageOptions].
+  /// Creates an instance with the given [imageOptions] and [limit].
   const MultiImagePickerOptions({
     this.imageOptions = const ImageOptions(),
+    this.limit,
   });
 
+  /// Creates an instance with the given [imageOptions] and [limit].
+  ///
+  /// Throws if limit is lower than 2.
+  MultiImagePickerOptions.createAndValidate({
+    this.imageOptions = const ImageOptions(),
+    this.limit,
+  }) {
+    _validate(limit: limit);
+  }
+
   /// The image-specific options for picking.
   final ImageOptions imageOptions;
+
+  /// The maximum number of images to select.
+  ///
+  /// Default null value means no limit.
+  /// This value may be ignored by platforms that cannot support it.
+  final int? limit;
+
+  /// Validates that all values are within required ranges.
+  ///
+  /// Throws if limit is lower than 2.
+  static void _validate({int? limit}) {
+    if (limit != null && limit < 2) {
+      throw ArgumentError.value(limit, 'limit', 'cannot be lower then 2');
+    }
+  }
 }

packages/image_picker/image_picker_platform_interface/pubspec.yaml

@@ -4,7 +4,7 @@ repository: https://github.com/flutter/packages/tree/main/packages/image_picker/
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+image_picker%22
 # NOTE: We strongly prefer non-breaking changes, even at the expense of a
 # less-clean API. See https://flutter.dev/go/platform-interface-breaking-changes
-version: 2.9.4
+version: 2.10.0
 
 environment:
   sdk: ^3.3.0

packages/image_picker/image_picker_platform_interface/test/media_options_test.dart

@@ -0,0 +1,54 @@
+// Copyright 2013 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 'package:flutter_test/flutter_test.dart';
+import 'package:image_picker_platform_interface/src/types/types.dart';
+
+void main() {
+  group('MediaOptions', () {
+    test('createAndValidate does not throw when allowMultiple is true', () {
+      expect(
+        () => MediaOptions.createAndValidate(allowMultiple: true),
+        returnsNormally,
+      );
+    });
+    test('createAndValidate does not throw when allowMultiple is false', () {
+      expect(
+        () => MediaOptions.createAndValidate(allowMultiple: false),
+        returnsNormally,
+      );
+    });
+
+    test('createAndValidate does not throw error for correct limit', () {
+      expect(
+        () => MediaOptions.createAndValidate(allowMultiple: true, limit: 2),
+        returnsNormally,
+      );
+    });
+
+    test('createAndValidate throw error for to small limit', () {
+      expect(
+        () => MediaOptions.createAndValidate(allowMultiple: true, limit: 1),
+        throwsArgumentError,
+      );
+      expect(
+        () => MediaOptions.createAndValidate(allowMultiple: true, limit: 0),
+        throwsArgumentError,
+      );
+      expect(
+        () => MediaOptions.createAndValidate(allowMultiple: true, limit: -1),
+        throwsArgumentError,
+      );
+    });
+
+    test(
+        'createAndValidate throw error when allowMultiple is false and has limit',
+        () {
+      expect(
+        () => MediaOptions.createAndValidate(allowMultiple: false, limit: 2),
+        throwsArgumentError,
+      );
+    });
+  });
+}