getPositionAbove method
Returns the position within the text which is on the line above the given
position.
The position parameter must be relative to the node content.
Primarily used with multi-line or soft-wrapping text.
Can return null which indicates that the position is at the topmost
line in the text already.
Implementation
@override
TextPosition? getPositionAbove(TextPosition position) {
return _getPosition(position, -0.5);
}