only method
Creates an Attribute instance with a custom Alignment or AlignmentDirectional value.
If start
is provided, an AlignmentDirectional is created. Otherwise, an Alignment is created.
Throws an AssertionError if both x
and start
are provided.
Implementation
T only({double? x, double? y, double? start}) {
assert(x == null || start == null,
'Cannot provide both an x and a start parameter.');
return start == null
? builder(Alignment(x ?? 0, y ?? 0))
: builder(AlignmentDirectional(start, y ?? 0));
}