timeAt method
The clip's own time at timeline moment t, in seconds — held at the
block's ends.
Implementation
double timeAt(Duration t) {
var into = t - at;
if (into < Duration.zero) into = Duration.zero;
if (into > length) into = length;
var run = reverse ? length - into : into;
return offset.inMicroseconds / 1e6 + run.inMicroseconds / 1e6 * speed;
}