title: How to scroll only down direction in flutter?
body: <p>I have a Pageview scroll which can be scrolled in up and down direction. Can i make it to scroll only downwards once scrolled down cannot go up . I googled but i haven't found anything useful</p>
  <p><strong>Update :</strong></p>
  <pre><code>class _ScrollDownOnlyState extends State&lt;ScrollDownOnly&gt; {
    bool checkDir = false;
    @override
    Widget build(BuildContext context) {
      return Scaffold(
        appBar: AppBar(
          title: Text(&quot;Down scroll&quot;),
        ),
        body: PageView.builder(
          scrollDirection: Axis.vertical,
          physics: checkDir ? const NeverScrollableScrollPhysics() : const AlwaysScrollableScrollPhysics(),
          itemBuilder: (context, index) {
            print(&quot;checl $checkDir&quot;);
            return GestureDetector(
              onPanUpdate: (details) {
                print(details.delta.dy);
                if (details.delta.dy &gt; 0) {
                  setState(() {
                    checkDir = true;
                  });
                }
                if (details.delta.dy &lt; 0) {
                  // set your var
                  setState(() {
                    checkDir = false;
                  });
                }
              },
              child: Container(
                margin: EdgeInsets.only(top: 20),
                color: Colors.pink,
                child: Center(
                  child: Text(
                    &quot;${index + 1}&quot;,
                    style: TextStyle(color: Colors.white, fontSize: 30),
                  ),
                ),
              ),
            );
          },
          itemCount: 50,
        ),
      );
    }
  }
  </code></pre>