title: Approaches for position-based animation using TextBlocks and Canvas controls
body: <p>I'm writing an app that simulates a news ticker. I chose WPF for its animation support, which is very nice, but I'm running into some questions about positioning.</p>
  
  <p>I'm starting out with moving a TextBlock on a Canvas from the right edge of the screen to the left edge. I'm using a Storyboard tied to the <code>Canvas.Left</code> property of the <code>TextBlock</code>, and a <code>DoubleAnimation</code>.</p>
  
  <p>How do I determine the correct values of the <strong>From</strong> and <strong>To</strong> values of the <code>DoubleAnimation</code> such that the text starts with its left edge at the right edge of the form and ends with its right edge at the left edge of the form? Do I need to use <code>Measure()</code> and the <code>ActualWidth</code> properties to determine this? Perhaps there's some other class I should use for the animation?</p>