title: How to do widget slide down animation in flutter?
body: <p>I want to do a <code>slide-down</code> animation for a widget. I've seen a lot of examples from the internet but nothing meets my requirements. Here is what I need. Below is a custom widget I made. </p>
  
  <pre><code>Widget Toast(String content, ToastType type) {
    return Column(
      children: &lt;Widget&gt;[
        Padding(
          padding: const EdgeInsets.all(50),
          child: Card(
            elevation: 10,
            shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(5)),
            color: ToastColors[type.index],
            child: Padding(
              padding: const EdgeInsets.only(left: 15, right: 20, top: 10, bottom: 10),
              child: Row(
                mainAxisSize: MainAxisSize.min,
                children: &lt;Widget&gt;[
                  ToastIcons[type.index],
                  SizedBox(
                    width: 15,
                  ),
                  Flexible(
                    child: Text(
                      content,
                      style: TextStyle(
                        color: Colors.white,
                        fontWeight: FontWeight.w400,
                      ),
                    ),
                  ),
                ],
              ),
            ),
          ),
        ),
      ],
    );
  }
  </code></pre>
  
  <p>It's a toast layout. I want this to be accessible from anywhere within the app. That's why I've created separate <code>dart</code> file for this.</p>
  
  <p><strong>What I want?</strong>
  When the widget is shown, I want the toast layout to slide down. I don't want to loop or reverse the animation. After the animation is completed, the widget must stay still in the end position.</p>