# Updated Material 3 progress indicators

> The `LinearProgressIndicator` and `CircularProgressIndicator` widgets have been updated to match the Material 3 Design specifications.




:::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.

这些破坏性改动文档的准确性仅限于其发布时对应的版本。
随着时间的推移，文档中描述的方案可能会逐渐失效。
通常情况下，我们不会在每次发布新版本时都对这些文档进行同步更新。

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

[破坏性改动列表](/release/breaking-changes) 
列出了每个版本的文档。

:::


## Summary

The `LinearProgressIndicator` and `CircularProgressIndicator` have
been updated to match the Material 3 Design specifications.

The `LinearProgressIndicator`changes include a gap between
the active and inactive tracks, a stop indicator, and rounded corners.
The `CircularProgressIndicator` changes include a gap between
the active and inactive tracks, and rounded stroke cap.

## Context

The Material 3 Design specifications for the `LinearProgressIndicator` and
`CircularProgressIndicator` were updated in December 2023.

To opt into the 2024 design specifications,
set the `LinearProgressIndicator.year2023` and
`CircularProgressIndicator.year2023` flags to `false`.
This is done to ensure that existing apps aren't affected by
the updated design spec.

## Description of change

The `LinearProgressIndicator` and `CircularProgressIndicator` widgets each
have a `year2023` flag that can be set to `false` to
opt in to the updated design specification.
The default value for the `year2023` flag is `true`, which means that
the progress indicators use the 2023 design spec.

When [`LinearProgressIndicator.year2023`][] is set to `false`,
the progress indicator have gaps between active and inactive tracks,
a stop indicator, and rounded corners.
If the `LinearProgressIndicator` is indeterminate,
the stop indicator isn't shown.

When [`CircularProgressIndicator.year2023`][] is set to `false`,
the progress indicator has a track gap and rounded stroke cap.

## Migration guide

To opt into the updated design spec for the `LinearProgressIndicator`,
set the `year2023` flag to `false`:

```dart highlightLines=2
LinearProgressIndicator(
  year2023: false,
  value: 0.5,
),
```

To update your entire app to use the updated `LinearProgressIndicator` design,
set the `ProgressIndicatorThemeData.year2023` property to `false` in your
`MaterialApp`:

```dart highlightLines=2
return MaterialApp(
  theme: ThemeData(progressIndicatorTheme: const ProgressIndicatorThemeData(year2023: false)),
        // ...
        LinearProgressIndicator(
          year2023: false,
          value: 0.5,
        ),
        // ...
```

To opt into the updated design spec for the `CircularProgressIndicator`,
set the `year2023` flag to `false`:

```dart highlightLines=2
CircularProgressIndicator(
  year2023: false,
  value: 0.5,
),
```

To update your entire app to use the updated `CircularProgressIndicator` design,
set the `ProgressIndicatorThemeData.year2023` property to `false` in your
`MaterialApp`:

```dart highlightLines=2
return MaterialApp(
  theme: ThemeData(progressIndicatorTheme: const ProgressIndicatorThemeData(year2023: false)),
        // ...
        CircularProgressIndicator(
          year2023: false,
          value: 0.5,
        ),
        // ...
```

## Timeline

Landed in version: 3.28.0-0.1.pre<br>
In stable release: 3.29

## References

API documentation:

- [`LinearProgressIndicator`][]
- [`CircularProgressIndicator`][]
- [`LinearProgressIndicator.year2023`][]
- [`CircularProgressIndicator.year2023`][]

Relevant issues:

- [Update both `ProgressIndicator` for Material 3 redesign][]

Relevant PRs:

- [Update Material 3 `LinearProgressIndicator` for new visual style][]
- [Update Material 3 `CircularProgressIndicator` for new visual style][]

[`LinearProgressIndicator`]: https://main-api.flutter-io.cn/flutter/material/LinearProgressIndicator-class.html
[`CircularProgressIndicator`]: https://main-api.flutter-io.cn/flutter/material/CircularProgressIndicator-class.html
[`LinearProgressIndicator.year2023`]: https://main-api.flutter-io.cn/flutter/material/LinearProgressIndicator/year2023.html
[`CircularProgressIndicator.year2023`]: https://main-api.flutter-io.cn/flutter/material/CircularProgressIndicator/year2023.html
[Update both `ProgressIndicator` for Material 3 redesign]: https://github.com/flutter/flutter/issues/141340
[Update Material 3 `LinearProgressIndicator` for new visual style]: https://github.com/flutter/flutter/pull/154817
[Update Material 3 `CircularProgressIndicator` for new visual style]: https://github.com/flutter/flutter/pull/158104