fix https://github.com/flutter/flutter/issues/121493
`SegmentedButton` uses `TextButton` for each segments. When we have `MaterialTapTargetSize.padded` for `TextButton`, we make sure the minimum tap target size is 48.0( this value can be adjusted by visual density), even tough the actual button size is smaller. When `SegmentedButton` paints segments by using `MultiChildRenderObjectWidget`, it also includes the tap target size so the button that it actually draws always has the same height as the height of the tap target size.
To fix it, this PR firstly calculate the actual height of a text button in `SegmentedButton` class, then we can get the height delta if there is. Then the the value of (Segmented button render box height - the delta) would be the actual button size that we should see.
For now, we are not able to customize the min, max, fixed size in [`SegmentedButton` style](https://api.flutter.dev/flutter/material/SegmentedButton/style.html). So the standard button height is always 40 and can only be customized by `style.visualDensity` and `style.tapTargetSize`; `SegmentedButton` only simulates the `TextButton` behavior when `TextButton`'s height is its default value.

https://github.com/flutter/flutter/assets/36861262/15ca6034-e6e0-4cc6-8fe3-808b4bd6a920
fixes https://github.com/flutter/flutter/issues/138289
---
SegmentedButtom.styleFrom has been added to the segment button, so there is no longer any need to the button style from the beginning. It works like ElevatedButton.styleFrom only I added selectedForegroundColor, selectedBackgroundColor. In this way, the user will be able to change the color first without checking the MaterialState states. I added tests of the same controls.
#129215 I opened this problem myself, but I was rejected because I handled too many items in a PR. For now, I wrote a structure that only handles MaterialStates instead of users.
old (still avaliable)
<img width="626" alt="image" src="https://github.com/flutter/flutter/assets/65075121/9446b13b-c355-4d20-bda2-c47a23d42d4f">
new (just an option for developer)
<img width="483" alt="image" src="https://github.com/flutter/flutter/assets/65075121/0a645257-4c83-4029-9484-bd746c02265f">
### Code sample
<details>
<summary>expand to view the code sample</summary>
```dart
import 'package:flutter/material.dart';
/// Flutter code sample for [SegmentedButton].
void main() {
runApp(const SegmentedButtonApp());
}
enum Calendar { day, week, month, year }
class SegmentedButtonApp extends StatefulWidget {
const SegmentedButtonApp({super.key});
@override
State<SegmentedButtonApp> createState() => _SegmentedButtonAppState();
}
class _SegmentedButtonAppState extends State<SegmentedButtonApp> {
Calendar calendarView = Calendar.day;
@override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData(useMaterial3: true),
home: Scaffold(
body: Center(
child: SegmentedButton<Calendar>(
style: SegmentedButton.styleFrom(
foregroundColor: Colors.amber,
visualDensity: VisualDensity.comfortable,
),
// style: const ButtonStyle(
// foregroundColor: MaterialStatePropertyAll<Color>(Colors.deepPurple),
// visualDensity: VisualDensity.comfortable,
// ),
segments: const <ButtonSegment<Calendar>>[
ButtonSegment<Calendar>(
value: Calendar.day,
label: Text('Day'),
icon: Icon(Icons.calendar_view_day)),
ButtonSegment<Calendar>(
value: Calendar.week,
label: Text('Week'),
icon: Icon(Icons.calendar_view_week)),
ButtonSegment<Calendar>(
value: Calendar.month,
label: Text('Month'),
icon: Icon(Icons.calendar_view_month)),
ButtonSegment<Calendar>(
value: Calendar.year,
label: Text('Year'),
icon: Icon(Icons.calendar_today)),
],
selected: <Calendar>{calendarView},
onSelectionChanged: (Set<Calendar> newSelection) {
setState(() {
calendarView = newSelection.first;
});
},
),
),
),
);
}
}
```
</details>
Fixes https://github.com/flutter/flutter/issues/135747
Before this change, the render object was storing the `context.canvas` and using it after painting children. If those children were composited (e.g. because of an `Opacity` layer), the canvas it stored was disposed and not valid for use anymore.
Fixes https://github.com/flutter/flutter/issues/59413
This relocates `mock_canvas.dart` and `recording_canvas.dart` from `flutter/test/rendering` to `flutter_test`.
The testing functionality afforded by mock_canvas should be available to everyone, not just the framework. :)
mock_canvas.dart needed a bit of cleanup - things like formatting and super parameters.
Fixes#122250. This PR is to make sure all the MaterialStateProperty defaults are able to correctly resolve different states.
* When a widget is pressed, it is also hovered, so we need to put the `MaterialState.pressed` check before `MaterialState.hovered`.
* When a widget is focused, the widget should still be able to be hovered, so we should check `MaterialState.hovered` before `MaterialState.focused`.
* There are also cases like in _InputDecoratorDefaultsM3, the `MaterialState.disabled` should be checked before `MaterialState.error`.
the order should be disabled, (error), pressed, hovered, focused.