Transform comma to period if the locale forces commas on the keyboard

lib/components/IPField.dart

@@ -50,10 +50,69 @@ class IPField extends StatelessWidget {
           maxLength: ipOnly ? 15 : null,
           maxLengthEnforced: ipOnly ? true : false,
           inputFormatters: ipOnly
-              ? [WhitelistingTextInputFormatter(RegExp(r'[\d\.]+'))]
+              ? [IPTextInputFormatter()]
               : [WhitelistingTextInputFormatter(RegExp(r'[^\s]+'))],
           textInputAction: this.textInputAction,
           placeholder: help,
         ));
   }
 }
+
+class IPTextInputFormatter extends TextInputFormatter {
+  final Pattern whitelistedPattern = RegExp(r'[\d\.,]+');
+
+  @override
+  TextEditingValue formatEditUpdate(TextEditingValue oldValue, TextEditingValue newValue) {
+    return _selectionAwareTextManipulation(
+      newValue,
+      (String substring) {
+        return whitelistedPattern
+            .allMatches(substring)
+            .map<String>((Match match) => match.group(0))
+            .join().replaceAll(RegExp(r','), '.');
+      },
+    );
+  }
+}
+
+TextEditingValue _selectionAwareTextManipulation(
+    TextEditingValue value,
+    String substringManipulation(String substring),
+    ) {
+  final int selectionStartIndex = value.selection.start;
+  final int selectionEndIndex = value.selection.end;
+  String manipulatedText;
+  TextSelection manipulatedSelection;
+  if (selectionStartIndex < 0 || selectionEndIndex < 0) {
+    manipulatedText = substringManipulation(value.text);
+  } else {
+    final String beforeSelection = substringManipulation(
+        value.text.substring(0, selectionStartIndex)
+    );
+    final String inSelection = substringManipulation(
+        value.text.substring(selectionStartIndex, selectionEndIndex)
+    );
+    final String afterSelection = substringManipulation(
+        value.text.substring(selectionEndIndex)
+    );
+    manipulatedText = beforeSelection + inSelection + afterSelection;
+    if (value.selection.baseOffset > value.selection.extentOffset) {
+      manipulatedSelection = value.selection.copyWith(
+        baseOffset: beforeSelection.length + inSelection.length,
+        extentOffset: beforeSelection.length,
+      );
+    } else {
+      manipulatedSelection = value.selection.copyWith(
+        baseOffset: beforeSelection.length,
+        extentOffset: beforeSelection.length + inSelection.length,
+      );
+    }
+  }
+  return TextEditingValue(
+    text: manipulatedText,
+    selection: manipulatedSelection ?? const TextSelection.collapsed(offset: -1),
+    composing: manipulatedText == value.text
+        ? value.composing
+        : TextRange.empty,
+  );
+}