maxLines property
The maximum number of lines to show at one time, wrapping if necessary.
This affects the height of the field itself and does not limit the number of lines that can be entered into the field.
If this is 1 (the default), the text will not wrap, but will scroll horizontally instead.
If this is null, there is no limit to the number of lines, and the text container will start with enough vertical space for one line and automatically grow to accommodate additional lines as they are entered, up to the height of its constraints.
If this is not null, the value must be greater than zero, and it will lock the input to the given number of lines and take up enough horizontal space to accommodate that number of lines. Setting minLines as well allows the input to grow and shrink between the indicated range.
Implementation
final int? maxLines;