Make TextField read only when the text input is disabled by setting DropdownMenu.requestFocusOnTap to false (#153566)
Fixes [[DropdownMenu] Semantics still reads out "EditBox" when text editing is disabled](https://github.com/flutter/flutter/issues/151686)
### Code sample
<details>
<summary>expand to view the code sample</summary>
```dart
import 'package:flutter/material.dart';
void main() {
runApp(const DropdownMenuExample());
}
enum ColorLabel {
blue('Blue', Colors.blue),
pink('Pink', Colors.pink),
green('Green', Colors.green),
yellow('Orange', Colors.orange),
grey('Grey', Colors.grey);
const ColorLabel(this.label, this.color);
final String label;
final Color color;
}
class DropdownMenuExample extends StatefulWidget {
const DropdownMenuExample({super.key});
@override
State<DropdownMenuExample> createState() => _DropdownMenuExampleState();
}
class _DropdownMenuExampleState extends State<DropdownMenuExample> {
ColorLabel? selectedColor;
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: SafeArea(
child: Padding(
padding: const EdgeInsets.all(16.0),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
spacing: 16.0,
children: <Widget>[
const ExcludeSemantics(child: Text('TexField')),
const TextField(
readOnly: true,
decoration: InputDecoration(
labelText: 'Color',
border: OutlineInputBorder(),
),
),
const ExcludeSemantics(child: Text('DropdownMenu')),
DropdownMenu<ColorLabel>(
requestFocusOnTap: false,
label: const Text('Color'),
dropdownMenuEntries: ColorLabel.values
.map<DropdownMenuEntry<ColorLabel>>((ColorLabel color) {
return DropdownMenuEntry<ColorLabel>(
value: color,
label: color.label,
style: MenuItemButton.styleFrom(
foregroundColor: color.color,
),
);
}).toList(),
),
],
),
),
),
),
);
}
}
```
</details>
### Preview (with Talkback captions)
|Before | After |
| --------------- | --------------- |
| <img src="https://github.com/user-attachments/assets/0d9f79f3-de5d-4c42-adea-3d700464d001" /> | <img src="https://github.com/user-attachments/assets/cf38508e-61f7-43ff-b420-ffe24cc8e28f" /> |
### Before demo
DropdownMenu announces "EditBox" and "double tap to activate" when setting `DropdownMenu.requestFocusOnTap` to `false` shouldn't allow that
https://github.com/user-attachments/assets/f692a4f6-9d6a-4834-8df0-baf6c65fae29
### After demo
When setting `DropdownMenu.requestFocusOnTap` to `false`, the underlying `TextField` gets read only state which changes the semantics to be not editable or focusable and remove"EditBox" and "double tap to activate" announcments
https://github.com/user-attachments/assets/0e14a636-6b81-4535-a5d1-c8f301c4f89e
17ad052792