Question 160530 in Flutter Question posted in
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Can Flutter exclude a widget from scrolling in a SingleChildScrollView?

In Flutter I have a SingleChildScrollView with a Column with many Text children.
Besides the Text children there is one HandSignature widget (from this package).

When using your finger to draw onto the signature, it would trigger the scroll of the SingleChildScrollView. Which is why I need to exclude the scrolling behaviour from this widget.

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3

Answers


  1. 0

    Wrap your HandSignature with NotificationListener like this

    child: NotificationListener<ScrollNotification>(
  onNotification: (notification) {
   //do not bubble up the  notification
   return true;
  },
 child: HandSignature()
)
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  2. 0

    Change position of HandSignature to be on AlertDialog

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  3. 0

    Here’s a way to lock and unlock your scroll. Add a bool variable that would be responsible for wether the screen should be scrollable at the moment. change its value when user interacts with signature widget and call setState. If scroll is locked, set scrollPhysics to NeverScrollableScrollPhysics(), otherwise it should be null.
    For simple example I did a button that locks the scroll. You can check this snippet in Dartpad.

    import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: Scaffold(body: ScrollWithLock()),
    );
  }
}

class ScrollWithLock extends StatefulWidget {
  const ScrollWithLock({Key? key}) : super(key: key);

  @override
  State<ScrollWithLock> createState() => _ScrollWithLockState();
}

class _ScrollWithLockState extends State<ScrollWithLock> {
  var isScrollLocked = false;
  @override
  Widget build(BuildContext context) {
    return SingleChildScrollView(
      physics: isScrollLocked ? NeverScrollableScrollPhysics() : null,
      child: Column(children: [
        for (var i = 0; i < 10; i++)
          const Padding(
            padding: EdgeInsets.all(20),
            child: Text('This is scrollable'),
          ),
        ElevatedButton(
          child: SizedBox(
            height: 100,
            width: 200,
            child: Text(isScrollLocked ? 'Locked' : 'Unlocked'),
          ),
          onPressed: () {
            setState(() {
              isScrollLocked = !isScrollLocked;
            });
          },
        ),
        for (var i = 0; i < 10; i++)
          const Padding(
            padding: EdgeInsets.all(20),
            child: Text('This is scrollable'),
          ),
      ]),
    );
  }
}
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