title: How to get the size of a Composable during runtime?
body: <p>I have as an example the following Composable:</p>
  <pre><code>@Composable
  fun CustomCanvas(
  ) {
     Box(
        Modifier
          .aspectRatio(1.33f)
          .fillMaxWidth())
  } 
  </code></pre>
  <p>How do I know the size of this object after composition?</p>
  <p>Why I want to know:
  I'm trying to resize and place images on a canvas. This requires knowing the size of the canvas. And no, I don't want to hardcode the size of the canvas. How to do this?</p>