> are usually obtained from an <a href="../../dart-html/Animation-class.html">Animation&lt;double&gt;</a>, such as
an <code>AnimationController</code>.</p>
    </section>
    
    <section class="summary source-code" id="source">
      <h2><span>Implementation</span></h2>
      <pre class="language-dart"><code class="language-dart">static Rect lerp(Rect a, Rect b, double t) {
  assert(t != null);
  if (a == null &amp;&amp; b == null)
    return null;
  if (a == null)
    return Rect.fromLTRB(b.left * t, b.t