…ine#52943)

…157295)

flutter/engine@de569ba...5eb21d2

2024-10-21 [email protected] [Impeller] Reland: one descriptor pool per frame. (flutter/engine#55960)
2024-10-21 [email protected] Scribe (Android stylus handwriting text input) (flutter/engine#52943)

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Enables the Scribe feature, or Android stylus handwriting text input.


![scribe](https://github.com/flutter/flutter/assets/389558/25a54ae9-9399-4772-8482-913ec7a9b330)

This PR only implements basic handwriting input. Other features will be
done in subsequent PRs:

 * #155948
 * #156018

I created and fixed issue about stylus hovering while working on this:
#148810

Original PR for iOS Scribble, the iOS version of this feature:
#75472
FYI @fbcouch 

~~Depends on flutter/engine#52943 (merged).

Fixes #115607

<details>

<summary>Example code I'm using to test this feature (but any TextField
works)</summary>

```dart
import 'package:flutter/material.dart';
import 'package:flutter/scheduler.dart';
import 'package:flutter/services.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @OverRide
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key});

  @OverRide
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  final FocusNode _focusNode1 = FocusNode();
  final FocusNode _focusNode2 = FocusNode();
  final FocusNode _focusNode3 = FocusNode();
  final TextEditingController _controller3 = TextEditingController(
    text: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.',
  );

  @OverRide
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Scribe demo'),
      ),
      body: Center(
        child: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 74.0),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              TextField(
                focusNode: _focusNode1,
                autofocus: false,
              ),
              TextField(
                focusNode: _focusNode2,
              ),
              TextField(
                focusNode: _focusNode3,
                minLines: 4,
                maxLines: 4,
                controller: _controller3,
              ),
              TextButton(
                onPressed: () {
                  _focusNode1.unfocus();
                  _focusNode2.unfocus();
                  _focusNode3.unfocus();
                },
                child: const Text('Unfocus'),
              ),
              TextButton(
                onPressed: () {
                  _focusNode1.requestFocus();
                  SchedulerBinding.instance.addPostFrameCallback((Duration _) {
                    SystemChannels.textInput.invokeMethod('TextInput.hide');
                  });
                },
                child: const Text('Focus 1'),
              ),
            ],
          ),
        ),
      ),
    );
  }
}
```

</details>

---------

Co-authored-by: Nate Wilson <[email protected]>

The engine API for Android's Scribe stylus handwriting input. Just bare bones handwriting itself, does not support special gestures, which will come in subsequent PR(s).