A11Y issue - MaterialPinField/PinInput: semanticHint is hardcoded and cannot be overridden

[epentesi]

Summary

PinInput (and by extension MaterialPinField) exposes a semanticLabel parameter that allows consumers to customize the accessibility label announced by screen readers. However, the semanticHint is hardcoded inside _PinInputState.build() and there is no way to override it.

Current behaviour

The hint is always computed as:

final semanticHint = filledCount < widget.length
    ? 'Enter ${widget.length - filledCount} more ${widget.length - filledCount == 1 ? 'digit' : 'digits'}'
    : 'PIN complete';

This string is English-only and cannot be replaced, so apps that:

• support multiple languages / localisation,
• use a custom terminology (e.g. "characters" instead of "digits"),
• or simply want to provide context-specific guidance,

have no way to customize the accessibility hint without forking the package.

Expected behavior

A semanticHint parameter (or a semanticHintBuilder) should be available on both PinInput and MaterialPinField, consistent with how semanticLabel is already handled.

Additional context

semanticLabel is already overridable in both widgets (see material_pin_field.dart line 81 and pin_input.dart line 97), so this change would simply extend the same pattern to semanticHint.