material_defaults 0.1.0

Public, context-aware access to the private Material 3 widget defaults (ButtonStyle, ChipThemeData, InputDecoration...), generated from Flutter's own token data.

material_defaults

Public, context-aware access to the Material 3 default styles that Flutter widgets compute in private classes such as _FilledButtonDefaultsM3 and _InputDecoratorDefaultsM3.

Solves flutter/flutter#130135 ("Expose M3 defaults", labelled would be a good package).

Example app on the iOS simulator: the defaults gallery, and stock widgets next to re-implementations built only from MaterialDefaults (verified pixel-identical by the example's integration test).

Why

Flutter generates each Material 3 component's defaults from the Material Design token database (dev/tools/gen_defaults), but keeps the resulting classes private. So you cannot read "what color is a disabled FilledButton" to build a custom widget that matches Material, or change one property of a theme while keeping every other default.

material_defaults gives you those objects:

final defaults = MaterialDefaults.of(context);

final ButtonStyle filled = defaults.filledButton;
final Color? disabledBg =
    filled.backgroundColor?.resolve(<WidgetState>{WidgetState.disabled});

// Partial override: change only the shape, keep every state-dependent default.
FilledButton(
  style: defaults.filledButton.copyWith(
    shape: const WidgetStatePropertyAll(RoundedRectangleBorder()),
  ),
  onPressed: () {},
  child: const Text('Square'),
);

How the values are made exact

• tool/generate.dart runs the SDK's own gen_defaults templates over the SDK's token JSON (dev/tools/gen_defaults/data) and fails unless every generated block is byte-identical to the block compiled into packages/flutter/lib/src/material. The output is committed in lib/src/generated/ (47 blocks from 39 framework files).
• MaterialDefaults.tokenVersion records the Flutter version the tokens came from (3.41.8), with flutterRevision and tokenDataVersions (6_1_0).
• 214 tests prove equivalence with what the real widgets use, in a light and a dark ColorScheme:
  • instance parity – where the framework exposes its private object (ButtonStyleButton.defaultStyleOf, MenuItemButton.defaultStyleOf, RawChip.defaultProperties, DatePickerTheme.defaults) every property is compared, resolving each WidgetStateProperty for all 256 combinations of 8 widget states;
  • render parity – for every other component the real widget is pumped with the stock theme and with our defaults injected as the component theme, through idle / hover / keyboard-focus / press (or open) states; pixels and render trees must be identical, and a perturbed copy must render differently;
  • source parity – the generated code equals the running framework's.

Install

flutter pub add material_defaults

or add it to pubspec.yaml yourself:

dependencies:
  material_defaults: ^0.1.0

Usage

Call MaterialDefaults.of(context) inside build. Values resolve against the nearest Theme (its ColorScheme and TextTheme).

import 'package:material_defaults/material_defaults.dart';

@override
Widget build(BuildContext context) {
  final defaults = MaterialDefaults.of(context);

  // 1. Read a single default for a given state.
  final Color? hoverOverlay = defaults.filledButton.overlayColor
      ?.resolve(<WidgetState>{WidgetState.hovered});

  // 2. Build a custom widget that matches Material exactly.
  final CardThemeData card = defaults.outlinedCard;
  return Material(
    color: card.color,
    shape: card.shape,
    elevation: card.elevation ?? 0,
    child: const Padding(padding: EdgeInsets.all(16), child: Text('Custom')),
  );
}

Override one property of a component theme while keeping every other default:

Builder(
  builder: (context) {
    final defaults = MaterialDefaults.of(context);
    return Theme(
      data: Theme.of(context).copyWith(
        filledButtonTheme: FilledButtonThemeData(
          style: defaults.filledButton.copyWith(
            shape: const WidgetStatePropertyAll(StadiumBorder()),
          ),
        ),
      ),
      child: child,
    );
  },
);

MaterialDefaults.tokenVersion tells you which Flutter version the values were generated from. See example/ for a full gallery.

What is exposed

Group	Members
Buttons	elevatedButton, filledButton, filledTonalButton, outlinedButton, textButton, iconButton(), filledIconButton(), filledTonalIconButton(), outlinedIconButton() (each with toggleable), menuButton, segmentedButton
FAB	floatingActionButton, smallFloatingActionButton, largeFloatingActionButton, extendedFloatingActionButton({hasIcon})
Surfaces	card, filledCard, outlinedCard, dialog, fullscreenDialog, bottomSheet, snackBar({floating}), banner, divider, listTile, expansionTile
Chips	chip({enabled}), actionChip({enabled, elevated}), filterChip({enabled, selected, elevated}), choiceChip(...), inputChip({enabled, selected})
Inputs	inputDecoration, checkbox, radio, switchTheme, slider, rangeSlider, searchBar, searchView({fullScreen}), datePicker
Navigation	appBar, bottomAppBar, navigationBar, navigationRail, navigationDrawer, drawer, tabBar({isScrollable}), secondaryTabBar({isScrollable}), menu, menuBar, popupMenu
Feedback	badge, linearProgressIndicator, circularProgressIndicator({indeterminate})

Every member returns an ordinary framework object (ButtonStyle, ChipThemeData, InputDecorationThemeData, …): resolve, copyWith, merge and passing it to ThemeData all work. Values are snapshots taken when you call the member, so obtain them in build.

Platform support

Pure Dart/Flutter, no platform code.

Android	iOS	Web	macOS	Windows	Linux
✅	✅	✅	✅	✅	✅

Limitations

• Version-specific. Values are exact for Flutter tokenVersion (3.41.8). The package requires flutter >=3.41.0; on a newer framework whose defaults changed, regenerate with dart run tool/generate.dart --flutter-root <sdk> (the source_parity test fails when the committed code no longer matches the running SDK).
• Material 3 only. With useMaterial3: false widgets use other classes; check appliesToCurrentTheme.
• Not everything is token generated. Tooltip, DropdownMenu, TimePicker (extends a private base class), medium/large SliverAppBar title configs and the year2023: true Slider / progress indicators are hand-written in the framework and are not exposed. slider, rangeSlider and the progress indicator members are the year2023: false defaults.
• Effective values over private values. Where a private class declares a value its widget never reads, the member returns what the widget renders: appBar (toolbarHeight 56, scrolled-under surfaceContainer, surfaceTint tint), banner.elevation 0, fixed snackBar() without shape. dialog matches Dialog/AlertDialog; SimpleDialog titles use titleLarge.
• Setting a theme property can differ from leaving it unset in a few widgets that branch on presence, not value: RawChip disables its InkWell hover color once chipTheme.color is set; SnackBar switches its hit-test behavior when snackBarTheme.insetPadding is set; TabBar adds WidgetState.selected for the selected tab only when resolving its own defaults. Reading and resolving the values is unaffected.

Example app

example/ has a gallery of every member (states grouped by resolved value, colors as swatches), a light/dark and seed switcher, and a Custom tab where a button, card and divider re-implemented from MaterialDefaults sit next to the stock widgets. example/integration_test/app_test.dart runs the real app, walks the whole gallery in light and dark, captures screenshots and asserts the custom widgets are pixel-identical to the stock ones:

cd example
flutter test integration_test -d <device> --dart-define=SHOT_DIR=/tmp/shots

Regenerating

dart run tool/generate.dart            # uses FLUTTER_ROOT or `flutter` on PATH
dart run tool/generate.dart --check    # exit 1 if lib/src/generated is stale

License

MIT © 2026 Manish Kumar Panday. Generated/copied framework code is © The Flutter Authors, BSD-3-Clause (see LICENSE).