title: Determine Scroll Widget height
body: <p>I would like to determine if a 'scrollable' widget indeed needs to scroll. I would ultimately like to show something like 'Scroll for more'. How do I achieve this?</p>
  
  <p>I could use a combination of LayoutBuilder and a ScrollController. However, ScrollController gives me maxScrollExtent and minScrollExtent only after any event - like say for example user trying to scroll</p>
  
  <p>I would like to know during 'build' so that I can determine to show 'Scroll for more' or not depending on the screen dimensions</p>
  
  <pre><code>class _MyHomePageState extends State&lt;MyHomePage&gt; {
    int value = 0;
    String text = 'You have pushed the button 0 times\n';
    @override
    Widget build(BuildContext context) {
      return Scaffold(
        appBar: AppBar(
          title: Text(widget.title),
        ),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: &lt;Widget&gt;[
              Expanded(
                flex: 9,
                child: SingleChildScrollView(
                  child: Text(text),
                ),
              ),
              Expanded(
                flex: 1,
                  child: Text('Scroll for more')),
            ],
          ),
        ),
        floatingActionButton: FloatingActionButton(
          onPressed: () {
            setState(() {
              value += 1;
              text = text + 'You have pushed the button $value times \n';
            });
          },
          tooltip: 'Increment',
          child: Icon(Icons.add),
        ), 
      );
    }
  }
  </code></pre>
  
  <p>I would like to dynamically display </p>
  
  <pre><code>            Text('Scroll for more'),
  
  </code></pre>
  
  <p><strong>only</strong> if the SingleChildScrollView needs to be scrolled to view the entire content. Please note, I am just giving the above code as example. </p>
  
  <p>In my real case, I have a StreamBuilder inside a SingleChildScrollView and I cannot determine how much of data is going to be flowing in from the stream. I also do not have any button or tap or any gesture to access the controller and setState</p>
  
  <p>Thanks in advance for any help</p>