StringDotLengthLimiterTextInputFormatter class

StringDotLengthLimiterTextInputFormatter is a TextInputFormatter that limits text by String.length, not user-perceived characters (grapheme clusters).

The important detail is that it counts with String.length, but when it cuts text, it walks user-visible characters (with the characters package), so it does not split an emoji or combined character in half.

Use StringDotLengthLimiterTextInputFormatter when the allowed length of some text is based on Dart's String.length, such as when a server, database, or file format has that same limit.

This is different from Flutter's native LengthLimitingTextInputFormatter, which counts user-visible characters using the characters package, not String.length. Because of that, Flutter's formatter may result in text that does not really fit the limit of String.length, and may even allow text that exceeds that limit. For example, if the limit is 10, Flutter's formatter may allow 10 emojis, which can be more than 10 characters in String.length. This can cause issues if you are trying to enforce a limit based on String.length, such as when a server or database has that same limit.

Note, when using StringDotLengthLimiterTextInputFormatter you should not show the normal character count to the user in the UI, because what the user sees is not the real limit.

Inheritance

Constructors

StringDotLengthLimiterTextInputFormatter(int? maxLength)
Creates a formatter that prevents the insertion of more characters than a limit. The maxLength must be null, -1 or greater than zero. If it is null or -1, then no limit is enforced.

Properties

hashCode → int
The hash code for this object.
no setterinherited
maxLength → int?
The limit on the number of String.length characters that this formatter will allow. The value must be null or greater than zero. If it is null or -1, then no limit is enforced.
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited

Methods

formatEditUpdate(TextEditingValue oldValue, TextEditingValue newValue) → TextEditingValue
Called when text is being typed or cut/copy/pasted in the EditableText.
override
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toString() → String
A string representation of this object.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited

Static Methods

truncate(TextEditingValue value, int maxLength) → TextEditingValue
Truncate the given TextEditingValue to maxLength using String.length (not user-perceived characters).
truncateString(String value, int maxLength) → String
Truncate the given String to maxLength using String.length (not user-perceived characters).