lerpFrom method Null safety
- Decoration? a,
- double t
Linearly interpolates from another Decoration (which may be of a
different class) to this.
When implementing this method in subclasses, return null if this class
cannot interpolate from a. In that case, lerp will try a's lerpTo
method instead.
Supporting interpolating from null is recommended as the Decoration.lerp method uses this as a fallback when two classes can't interpolate between each other.
The t argument represents position on the timeline, with 0.0 meaning
that the interpolation has not started, returning a (or something
equivalent to a), 1.0 meaning that the interpolation has finished,
returning this (or something equivalent to this), and values in
between meaning that the interpolation is at the relevant point on the
timeline between a and this. The interpolation can be extrapolated
beyond 0.0 and 1.0, so negative values and values greater than 1.0 are
valid (and can easily be generated by curves such as
Curves.elasticInOut).
Values for t are usually obtained from an Animation<double>, such as
an AnimationController.
Instead of calling this directly, use Decoration.lerp.
Implementation
@override
FlutterLogoDecoration? lerpFrom(Decoration? a, double t) {
assert(debugAssertIsValid());
if (a == null || a is FlutterLogoDecoration) {
assert(a == null || a.debugAssertIsValid());
return FlutterLogoDecoration.lerp(a as FlutterLogoDecoration?, this, t);
}
return super.lerpFrom(a, t) as FlutterLogoDecoration?;
}