[image_picker] Add limit parameter to pickMultiImage and pickMultipleMedia to ios and Android

[pdenert]

Adds limit parameter to MediaOptions and MultiImagePickerOptions and supports its use on iOS and Android. The limit argument defines how many images or media files can be select.

Fixes: flutter/flutter#85772

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I read and followed the relevant style guides and ran the auto-formatter. (Unlike the flutter/flutter repo, the flutter/packages repo does use dart format.)
• I signed the CLA.
• The title of the PR starts with the name of the package surrounded by square brackets, e.g. [shared_preferences]
• I linked to at least one issue that this PR fixes in the description above.
• I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy, or this PR is exempt from version changes.
• I updated CHANGELOG.md to add a description of the change, following repository CHANGELOG style.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is test-exempt.
• All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.

[tarrinneal]

Seems like a solid change once the method deprecation is changed. Thanks for putting this together, and let me know if you need any help/guidance with anything!

This isn't a full review, I'll double back around once these changes are made.

[ditman]

I think that this PR could be much simplified if it were: "add a new parameter to MultiImagePickerOptions, and then use it in iOS and Android". For example, the web package wouldn't need any changes, because it doesn't care about the new parameter of that object at all.

There's a lot of extra code because this is updating a bunch of deprecated methods (as @tarrinneal mentioned in his review above!), which... we might be even able to delete...

[pdenert]

I've cleaned up packages which remain unchanged.
I've removed limit from deprecated methods.
I've updated iOS and Android implementations

[ditman]

Thanks for reverting the web package @pdenert!

I checked the web APIs again and there's nothing new to limit the number of files that the user selects (as in: disable file selection once the user selects limit files).

We could count how many they've selected and throw an exception, or discard extras if they've picked too many, but that's probably confusing, and can be implemented on the application layer too.

[pdenert]

We could count how many they've selected and throw an exception, or discard extras if they've picked too many, but that's probably confusing, and can be implemented on the application layer too.

Yeah, I feel the same way. If we can't limit choice on the UI side, then it's better to do nothing.

[pdenert]

@tarrinneal do you mind look at this again?

[vashworth]

The iOS side looks good, however, the usage of pickMultiImageWithMaxSize and makeWithMaxSize within image_picker_ios/example/ios/RunnerTests/ImagePickerPluginTests.m will need to be updated to use new parameter.

Also, additional tests should be added to test the new limit parameter correctly sets the maxImageCount. I've included an example you can use below. You should also add ones where the limit is nil.

Test example

- (void)testPickMultiImageWithLimit {
  FLTImagePickerPlugin *plugin = [[FLTImagePickerPlugin alloc] init];
  [plugin pickMultiImageWithMaxSize:[[FLTMaxSize alloc] init]
                            quality:nil
                       fullMetadata:NO
                              limit:@(2)
                         completion:^(NSArray<NSString *> *_Nullable result,
                                      FlutterError *_Nullable error){
                         }];
  XCTAssertEqual(plugin.callContext.maxImageCount, 2);
}

- (void)testPickMediaWithLimitAllowsMultiple {
  FLTImagePickerPlugin *plugin = [[FLTImagePickerPlugin alloc] init];
  FLTMediaSelectionOptions *mediaSelectionOptions =
      [FLTMediaSelectionOptions makeWithMaxSize:[FLTMaxSize makeWithWidth:@(100) height:@(200)]
                                   imageQuality:nil
                            requestFullMetadata:NO
                                  allowMultiple:YES
                                          limit:@(2)];

  [plugin pickMediaWithMediaSelectionOptions:mediaSelectionOptions
                                  completion:^(NSArray<NSString *> *_Nullable result,
                                               FlutterError *_Nullable error){
                                  }];

  XCTAssertEqual(plugin.callContext.maxImageCount, 2);
}

- (void)testPickMediaWithLimitMultipleNotAllowed {
  FLTImagePickerPlugin *plugin = [[FLTImagePickerPlugin alloc] init];
  FLTMediaSelectionOptions *mediaSelectionOptions =
      [FLTMediaSelectionOptions makeWithMaxSize:[FLTMaxSize makeWithWidth:@(100) height:@(200)]
                                   imageQuality:nil
                            requestFullMetadata:NO
                                  allowMultiple:NO
                                          limit:@(2)];

  [plugin pickMediaWithMediaSelectionOptions:mediaSelectionOptions
                                  completion:^(NSArray<NSString *> *_Nullable result,
                                               FlutterError *_Nullable error){
                                  }];

  XCTAssertEqual(plugin.callContext.maxImageCount, 1);
}

[pdenert]

@vashworth thanks for the test examples. I've also added tests for variants where the limit is nil

[vashworth]

The test Linux repo_checks is failing on formatting issues:
https://logs.chromium.org/logs/flutter/buildbucket/cr-buildbucket/8754354673776286193/+/u/Run_package_tests/format/stdout

Looks like a number of files need to be formatted: https://github.com/flutter/packages/blob/main/script/tool/README.md#format-code

[pdenert]

@tarrinneal may you look at this soon?

[tarrinneal]

Thanks for putting in the time and effort on this pr.

(and sorry for the delays in approval)