title: Enlarge the center of an Android gradient drawable
body: <p>I created an <a href="https://developer.android.com/reference/android/graphics/drawable/GradientDrawable.html" rel="noreferrer">Android gradient drawable</a> where the top and bottom are black and the center is transparent:</p>
  
  <pre><code>&lt;shape xmlns:android="http://schemas.android.com/apk/res/android"
      android:shape="rectangle" &gt;
  
      &lt;gradient
          android:startColor="@android:color/black"
          android:centerColor="@android:color/transparent"
          android:endColor="@android:color/black"
          android:angle="90"/&gt;
  &lt;/shape&gt;
  </code></pre>
  
  <p>The rendered gradient looks like this:</p>
  
  <p><a href="https://i.stack.imgur.com/vShj1.png" rel="noreferrer"><img src="https://i.stack.imgur.com/vShj1.png" alt="gradient image"></a></p>
  
  <p>As you can see, the black parts spread to most of the screen. I want the black to show only on a small portion of the top and bottom. Is there a way I can make the transparent center larger, or make the top and bottom black stripes smaller?</p>
  
  <p>I tried playing around with some of the other XML attributes mentioned in the linked <code>GradientDrawable</code> documentation, yet none of them seem to make and difference.</p>