formatEditUpdate method

@override TextEditingValue formatEditUpdate(TextEditingValue oldValue, TextEditingValue newValue)

Called when text is being typed or cut/copy/pasted in the EditableText.

You can override the resulting text based on the previous text value and the incoming new text value.

When formatters are chained, oldValue reflects the initial value of TextEditingValue at the beginning of the chain.

Implementation

@override
TextEditingValue formatEditUpdate(
  TextEditingValue oldValue,
  TextEditingValue newValue,
) {
  // Only handle the input if it's a number (remove commas and symbols)
  String newText = newValue.text.replaceAll(RegExp(r'[^0-9]'), '');

  if (newText.isNotEmpty) {
    // Parse the value and format it as currency
    final parsedValue = double.tryParse(newText);
    if (parsedValue != null) {
      newText =
          _currencyFormat.format(parsedValue).replaceAll('₦', '').trim();
    }
  }

  // Ensure the cursor stays in the right place
  return newValue.copyWith(
    text: newText,
    selection: TextSelection.collapsed(offset: newText.length),
  );
}