Improve performance by switching method channels to generated pigeon code.

[panmari]

Describe your issue. If applicable, add screenshots to help explain your problem.

See https://pub.dev/packages/pigeon. This would in particular help with performance of #732. Plus it simplifies code by depending on code generation.

Steps to reproduce.

N/A

What is the expected result?

N/A

Did you try our example app?

Yes

Is it reproducible in the example app?

Yes

Reproducible in which OS?

iOS and Android

Flutter/Dart Version?

No response

Plugin Version?

Most recent in tree.

[bensonarafat]

I don't know how this sounds with @fbernaly
If it is okay, I can add the feature

[fbernaly]

@panmari: take this package: https://github.com/flutter-ml/google_ml_kit_flutter/tree/develop/packages/google_mlkit_commons and work on those changes I would like to see how it looks and then we will see if we implement it for the rest of the plugins.

[panmari]

I looked into how much work this is for the image labeling plugin. It's unfortunately a considerable amount of work to get this done, see my (incomplete) attempt at https://github.com/flutter-ml/google_ml_kit_flutter/compare/develop...panmari:Google-Ml-Kit-plugin:pigeon?expand=1.

One of the really nice things: Having multiple instances becomes really easy, because pigeon supports setting a channel suffix:

  factory ImageLabeler({required ImageLabelerOptions options, String identifier = ''}) {
    api = ImageLabelDetectorApi(messageChannelSuffix: identifier);
    api.create(options);
  }

So a lot of the custom logic for handling multiple models at once could be deleted (if I understand the model correctly)