# Component theme normalization updates

> `AppBarTheme`, `BottomAppBarTheme` and `InputDecorationTheme` have been normalized to follow Flutter's convention for component themes in the Material library.




:::important
These breaking change docs are accurate, as of the release
under which they are published. Over time, the
workarounds described here might become inaccurate.
We don't, in general, keep these breaking change docs up
to date as of each release.

The [breaking change index file](/release/breaking-changes)
lists the docs created for each release.
:::


## Summary

`AppBarTheme`, `BottomAppBarTheme` and `InputDecorationTheme` were refactored
to conform to Flutter's conventions for component themes.
`AppBarThemeData`, `BottomAppBarThemeData` and `InputDecorationThemeData` were
added to define overrides for the defaults of the component visual properties.
Releases of Flutter continue to normalize component themes like these for
a more consistent theming experience in the material library.

## Migration guide

In `ThemeData`:
- The type of the `appBarTheme` property has been
  changed from `AppBarTheme` to `AppBarThemeData`.
- The type of `bottomAppBarTheme` property has been
  changed from `BottomAppBarTheme` to `BottomAppBarThemeData`.
- The type of `inputDecorationTheme` property has been
  changed from `InputDecorationTheme` to `InputDecorationThemeData`.

The return type of the component theme `xTheme.of()` methods and
`Theme.of().xTheme` have also changed to `xThemeData`.

In `DatePickerThemeData` and `TimePickerThemeData`, the type of the
`inputDecorationTheme` property has been changed from `InputDecorationTheme`
to `InputDecorationThemeData`.

Code before migration:

```dart
final AppBarTheme appBarTheme = Theme.of(context).appBarTheme;
final AppBarTheme appBarTheme = AppBarTheme.of(context);

final BottomAppBarTheme bottomAppBarTheme = Theme.of(context).bottomAppBarTheme;
final BottomAppBarTheme bottomAppBarTheme = BottomAppBarTheme.of(context);

final InputDecorationTheme inputDecorationTheme = Theme.of(context).inputDecorationTheme;
final InputDecorationTheme inputDecorationTheme = InputDecorationTheme.of(context);
final InputDecorationTheme inputDecorationTheme = Theme.of(context).datePickerTheme.inputDecorationTheme;
final InputDecorationTheme inputDecorationTheme = Theme.of(context).timePickerTheme.inputDecorationTheme;
```

```dart
final ThemeData theme = ThemeData(
  appBarTheme: AppBarTheme(),
  bottomAppBarTheme: BottomAppBarTheme(),
  inputDecorationTheme: InputDecorationTheme(),
);

final ThemeData theme = ThemeData().copyWith(
  appBarTheme: AppBarTheme(),
  bottomAppBarTheme: BottomAppBarTheme(),
  inputDecorationTheme: InputDecorationTheme(),
);

const DatePickerThemeData datePickerTheme = DatePickerThemeData(inputDecorationTheme: InputDecorationTheme());
const TimePickerThemeData timePickerTheme = TimePickerThemeData(inputDecorationTheme: InputDecorationTheme());
```

Code after migration:

```dart
final AppBarThemeData appBarTheme = Theme.of(context).appBarTheme;
final AppBarThemeData appBarTheme = AppBarTheme.of(context);

final BottomAppBarThemeData bottomAppBarTheme = Theme.of(context).bottomAppBarTheme;
final BottomAppBarThemeData bottomAppBarTheme = BottomAppBarTheme.of(context);

final InputDecorationThemeData inputDecorationTheme = Theme.of(context).inputDecorationTheme;
final InputDecorationThemeData inputDecorationTheme = InputDecorationTheme.of(context);
final InputDecorationThemeData inputDecorationTheme = Theme.of(context).datePickerTheme.inputDecorationTheme;
final InputDecorationThemeData inputDecorationTheme = Theme.of(context).timePickerTheme.inputDecorationTheme;
```

```dart
final ThemeData theme = ThemeData(
  appBarTheme: AppBarThemeData(),
  bottomAppBarTheme: BottomAppBarThemeData(),
  inputDecorationTheme: InputDecorationThemeData(),
);

final ThemeData theme = ThemeData().copyWith(
  appBarTheme: AppBarThemeData(),
  bottomAppBarTheme: BottomAppBarThemeData(),
  inputDecorationTheme: InputDecorationThemeData(),
);

const DatePickerThemeData datePickerTheme = DatePickerThemeData(inputDecorationTheme: InputDecorationThemeData());
const TimePickerThemeData timePickerTheme = TimePickerThemeData(inputDecorationTheme: InputDecorationThemeData());
```

## Timeline

Landed in version: 3.33.0-1.0.pre through 3.35.0-0.0.pre<br>
Stable release: 3.35

## References

API documentation:

* [`AppBarTheme`][]
* [`BottomAppBarTheme`][]
* [`InputDecorationTheme`][]

Relevant PRs:

* [Normalize ThemeData.appBarTheme][]
* [Normalize ThemeData.bottomAppBarTheme][]
* [Normalize InputDecorationTheme][]
* [Apply normalization to TimePickerThemeData.inputDecorationTheme][]

[`AppBarTheme`]: https://api.flutter.dev/flutter/material/AppBarTheme-class.html
[Normalize ThemeData.appBarTheme]: https://github.com/flutter/flutter/pull/169130
[`BottomAppBarTheme`]: https://api.flutter.dev/flutter/material/BottomAppBarTheme-class.html
[Normalize ThemeData.bottomAppBarTheme]: https://github.com/flutter/flutter/pull/168586
[`InputDecorationTheme`]: https://api.flutter.dev/flutter/material/InputDecorationTheme-class.html
[Normalize InputDecorationTheme]: https://github.com/flutter/flutter/pull/168981
[Apply normalization to TimePickerThemeData.inputDecorationTheme]: https://github.com/flutter/flutter/pull/171584