43 lines
1.4 KiB
Dart
Executable File
43 lines
1.4 KiB
Dart
Executable File
import 'package:flutter/services.dart';
|
|
|
|
class DigitObscuringFormatter extends TextInputFormatter {
|
|
@override
|
|
TextEditingValue formatEditUpdate(
|
|
TextEditingValue oldValue, TextEditingValue newValue) {
|
|
final maskedText = maskDigits(newValue.text);
|
|
return newValue.copyWith(
|
|
text: maskedText,
|
|
selection: updateCursorPosition(maskedText, newValue.selection));
|
|
}
|
|
|
|
String maskDigits(String text) {
|
|
final totalDigits = text.length;
|
|
final visibleDigits = 4;
|
|
final hiddenDigits = totalDigits - visibleDigits * 2;
|
|
|
|
final firstVisibleDigits = text.substring(0, visibleDigits);
|
|
final lastVisibleDigits = text.substring(totalDigits - visibleDigits);
|
|
|
|
final maskedDigits = List.filled(hiddenDigits, '*').join();
|
|
|
|
return '$firstVisibleDigits$maskedDigits$lastVisibleDigits';
|
|
}
|
|
|
|
TextSelection updateCursorPosition(
|
|
String maskedText, TextSelection currentSelection) {
|
|
final cursorPosition = currentSelection.baseOffset;
|
|
final cursorOffset =
|
|
currentSelection.extentOffset - currentSelection.baseOffset;
|
|
final totalDigits = maskedText.length;
|
|
const visibleDigits = 4;
|
|
final hiddenDigits = totalDigits - visibleDigits * 2;
|
|
|
|
final updatedPosition = cursorPosition <= visibleDigits
|
|
? cursorPosition
|
|
: hiddenDigits + visibleDigits + (cursorPosition - visibleDigits);
|
|
|
|
return TextSelection.collapsed(
|
|
offset: updatedPosition, affinity: currentSelection.affinity);
|
|
}
|
|
}
|