Simple input capitalizer in Dart. You can use it inside InputFormatters in Flutter.

input_capitalizer.dart

import 'package:flutter/services.dart';
import 'package:paynet/common/utils/index.dart';

class InputCapitalizer extends TextInputFormatter {
  @override
  TextEditingValue formatEditUpdate(
      TextEditingValue oldValue, TextEditingValue newValue) {
    int selectionIndex = newValue.selection.end;

    return TextEditingValue(
      text: newValue.text.toUpperCase(),
      selection: TextSelection.collapsed(offset: selectionIndex),
    );
  }
}

Important notice about toUpperCaseMethod:

This function uses the language independent Unicode mapping and thus only works in some languages.

For example, there is a package for Turkish which solves these character issues of toUpperCaseMethod etc.: https://github.com/ahmetaa/turkish