25-7-28-2

lib/controller/functions/digit_obsecur_formate.dart

@@ -0,0 +1,42 @@
+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);
+  }
+}