ion</a> in the <a href="dart-ui/Window/onBeginFrame.html">Window.onBeginFrame</a> callback is exactly the
<code>Duration(microseconds: timestampInMicroseconds(FramePhase.buildStart))</code>.</p>
<p>The build finishes when <a href="dart-ui/Window/render.html">Window.render</a> is called.</p>
<p>To ensure smooth animations of X fps, this should not exceed 1000/X
milliseconds.That's about 16ms for 60fps, and 8ms for 120fps.</p>
        </section>
                <section class="summary source-code" id="source"