How do I stretch an image to fit the whole background (100% height x 100% width) in Flutter? : <p>I have an image that doesn't match the aspect ratio of my device's screen. I want to stretch the image so that it fully fills the screen, and I don't want to crop any part of the image.</p>

<p>CSS has the concept of percentages, so I could just set height and width to 100%. But it doesn't seem like Flutter has that concept, and it's bad to just hard code the height and width, so I'm stuck.</p>

<p>Here's what I have (I'm using a Stack since I have something in the foreground of the image):</p>

<pre><code>Widget background = new Container(
  height: // Not sure what to put here!
  width: // Not sure what to put here!
  child: new Image.asset(
    asset.background,
    fit: BoxFit.fill, // I thought this would fill up my Container but it doesn't
  ),
);

return new Stack(
  children: &lt;Widget&gt;[
    background,
    foreground,
  ],
);
</code></pre>
