ing.Gradient</code>, the superclass for <code>LinearGradient</code> and
<code>RadialGradient</code>, as used by <code>BoxDecoration</code> et al, which works in
relative coordinates and can create a <a href="dart-ui/Shader-class.html">Shader</a> representing the gradient
for a particular <a href="dart-ui/Rect-class.html">Rect</a> on demand.</li><li><a href="dart-ui/Gradient-class.html">dart:ui.Gradient</a>, the low-level class used when dealing with the
<a href="dart-ui/Paint/shader.html">Paint.shader</a> p