flutter/dev/tools/gen_defaults
Taha Tesser 9d7d36cfba
Fix Checkbox default visual density to meet Material 3 guidelines (#159081)
Fixes [Compact Visual Density is wrongfully applied to Checkboxes with
`MaterialTapTargetSize.padded` on desktop platforms according to
Material 3 Guidelines](https://github.com/flutter/flutter/issues/156408)

### Description

This PR updates default `Checkbox` visual density to not depend on
`ThemeData.visualDenSity` as it will return `VisualDensity.compact` on
desktop and break Material 3 guidelines for `Checkbox`.

> [!NOTE]  
> This makes a similar fix as
https://github.com/flutter/flutter/pull/110722.

### Code sample

<details>
<summary>expand to view the code sample</summary> 

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

void main() => runApp(const MyApp());

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Center(
          child: Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              ColoredBox(
                color: Colors.amber,
                child: Checkbox(
                  materialTapTargetSize: MaterialTapTargetSize.padded,
                  value: true,
                  onChanged: (bool? value) {},
                ),
              ),
              Container(
                width: 48,
                height: 48,
                color: Colors.red,
                alignment: Alignment.center,
                child: const Text(
                  '48x48px',
                  style: TextStyle(fontSize: 10, color: Colors.white),
                ),
              )
            ],
          ),
        ),
      ),
    );
  }
}
```

</details>


<img width="577" alt="Screenshot 2024-11-18 at 18 02 01"
src="https://github.com/user-attachments/assets/d390c92f-dd62-4c42-b6b7-d4f101078618">



<img width="577" alt="Screenshot 2024-11-18 at 18 01 49"
src="https://github.com/user-attachments/assets/632e8d19-11bf-45c7-9be9-5c4fc308f3ea">


## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [ ] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[Tree Hygiene]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md
2025-01-30 20:03:56 +00:00
..
2024-12-19 20:06:21 +00:00
2024-09-04 00:20:16 +00:00
2025-01-14 05:13:41 +00:00

Token Defaults Generator

Script that generates component theme data defaults based on token data.

Usage

Run this program from the root of the git repository:

dart dev/tools/gen_defaults/bin/gen_defaults.dart [-v]

This updates generated/used_tokens.csv and the various component theme files.

Templates

There is a template file for every component that needs defaults from the token database. These templates are implemented as subclasses of TokenTemplate. This base class provides some utilities and a structure for adding a new block of generated code to the bottom of a given file.

Templates need to override the generate method to provide the generated code block as a string.

See lib/fab_template.dart for an example that generates defaults for the Floating Action Button.

Tokens

Tokens are stored in JSON files in data/, and are sourced from an internal Google database.

template.dart should provide nearly all useful token resolvers (e.g. color, shape, etc.). For special cases in which one shouldn't be defined, use getToken to get the raw token value. The script, through the various revolvers and getToken, validates tokens, keeps track of which tokens are used, and generates generated/used_tokens.csv.