Code Comments Error in "flutter/packages/flutter/lib/src/material /navigation_bar.dart" #162592
Description
Flutter version:
Flutter 3.27.3 • channel stable • https://github.com/flutter/flutter.git
Framework • revision c519ee916e (13 days ago) • 2025-01-21 10:32:23 -0800
Engine • revision e672b006cb
Tools • Dart 3.6.1 • DevTools 2.40.2
Comments error:
class NavigationDestination extends StatelessWidget {
...
/// The text label that appears below the icon of this
/// [NavigationDestination].
///
/// The accompanying [Text] widget will use
/// [NavigationBarThemeData.labelTextStyle]. If this are null, the default
/// text style would use [TextTheme.labelSmall] with [ColorScheme.onSurface].
final String label;
...
}
If this are null, the default text style would use [TextTheme.labelSmall] is wrong. Actually, This is right in material2, but wrong in material3. I have dived into _NavigationBarDefaultsM3, I found this:
class _NavigationBarDefaultsM3 extends NavigationBarThemeData {
...
@override
MaterialStateProperty<TextStyle?>? get labelTextStyle {
return MaterialStateProperty.resolveWith((Set<MaterialState> states) {
final TextStyle style = _textTheme.labelMedium!;
return style.apply(
color: states.contains(MaterialState.disabled)
? _colors.onSurfaceVariant.withOpacity(0.38)
: states.contains(MaterialState.selected)
? _colors.onSurface
: _colors.onSurfaceVariant
);
});
}
...
}
The default text style would use [TextTheme.labelMedium] in Material3.
Conclusion
Rectify the comments as below:
/// The text label that appears below the icon of this
/// [NavigationDestination].
///
/// The accompanying [Text] widget will use
/// [NavigationBarThemeData.labelTextStyle]. If this are null, the default
/// text style would use [TextTheme.labelSmall] with [ColorScheme.onSurface]
/// when [ThemeData.useMaterial3] is false, and use [TextTheme.labelMedium]
/// when [ThemeData.useMaterial3] is true.
final String label;