Show/Hide Drop down menu on hover Flutter for web

Question

I'm trying to achieve drop down menu as on this site https://www.mapbox.com/mapbox-gljs

Screenshot: What I want?

So far I have used PopupMenuButton to show the drop down. But I am unable to figure out:

• How would I change the layout of the PopupMenuButton dropdown list
• How to show/hide on mouse hover. I have tried using onHover of InkWell and MouseRegion but that doesn't Hide the menu once the mouse is not over the button.

Screenshot: Where I stand

Code

return PopupMenuButton(
  offset: Offset(0, 60),
  elevation: 4.0,
  child: Container(
    decoration: BoxDecoration(
      border:
          tabBarProviders.currentIndex == i
              ? Border(
                  bottom: BorderSide(
                    width: 3.0,
                    color: kRedPrimaryColor,
                  ),
                )
              : Border(),
    ),
    padding: const EdgeInsets.all(8.0),
    child: Row(
      children: [
        Text(
          _actionBtns[i],
          style: TextStyle(
              fontWeight: FontWeight.bold),
        ),
        Icon(Icons.arrow_drop_down),
      ],
    ),
  ),
  onSelected: (value) {
    if (value == "WATERPROOFING") {
      tabBarProviders.currentIndex = 3;
    }
  },
  itemBuilder: (context) =>
      _waterProofingDropDown
          .map((e) => PopupMenuItem(
              value: e, child: Text(e)))
          .toList(),
);

Answer 1

Here is the demo code for your problem

import 'package:flutter/material.dart';
void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  OverlayState? overlayState;
  OverlayEntry? overlayEntry;
  OverlayEntry? overlayEntry2;
  bool showOverlay = false;
  int index = 0;
  List<Widget> widgets = [
    Container(
      height: 40, 
      width: 60, 
      color: Colors.transparent
      ),
    Container(
      height: 40, 
      width: 60, 
      color: Colors.transparent
      ),
    Container(
      height: 300, 
      width: 300, 
      color: Colors.green,
      child: TextButton(
      child: Text('Click Me'), 
      onPressed: (){
        print('Clicked');
        },
        ),
        ),
    Container(
      height: 300, 
      width: 300, 
      color: Colors.black,
       child: TextButton(child: Text('Click Me'), 
      onPressed: (){
        print('Clicked');
        },
        ),
        ),
  ];
  final layerLink = LayerLink();
  final textButtonFocusNode = FocusNode();
  final textButtonFocusNode1 = FocusNode();
  

  void _showOverlay(BuildContext context, int index) async {
    overlayState = Overlay.of(context)!;
   
    overlayEntry = OverlayEntry(
        maintainState: true,
        builder: (context) {
          return Positioned(
            left:index==0?  MediaQuery.of(context).size.width * 0.43 : MediaQuery.of(context).size.width *  0.5,
            top: MediaQuery.of(context).size.height * 0.09,
            child: TextButton(
              onPressed: () {},
              onHover: (val) {
                if (val && showOverlay) {
                  if (index == 0) {
                    textButtonFocusNode.requestFocus();
                  } else if (index == 1) {
                    textButtonFocusNode1.requestFocus();
                  }
                } else {
                  if (index == 0) {
                    textButtonFocusNode.unfocus();
                  } else if (index == 1) {
                    textButtonFocusNode1.unfocus();
                  }
                }
              },
              child: widgets[index],
            ),
          );
        });
      overlayEntry2 = OverlayEntry(
        maintainState: true,
        builder: (context) {
          return Positioned(
            left:index==0?  MediaQuery.of(context).size.width * 0.43 : MediaQuery.of(context).size.width *  0.5,
            top: MediaQuery.of(context).size.height * 0.13,
            child: TextButton(
              onPressed: () {},
              onHover: (val) {
                if (val && showOverlay) {
                  if (index == 0) {
                    textButtonFocusNode.requestFocus();
                  } else if (index == 1) {
                    textButtonFocusNode1.requestFocus();
                  }
                } else {
                  if (index == 0) {
                    textButtonFocusNode.unfocus();
                  } else if (index == 1) {
                    textButtonFocusNode1.unfocus();
                  }
                }
              },
              child: widgets[index+2],
            ),
          );
        });

    // overlayState!.insert(overlayEntry!);
    overlayState!.insertAll([overlayEntry!, overlayEntry2!]);
  }

  void removeOverlay() {
    overlayEntry!.remove();
    overlayEntry2!.remove();
  }

  @override
  void initState() {
    super.initState();
    textButtonFocusNode.addListener(() {
      if (textButtonFocusNode.hasFocus) {
        _showOverlay(context, 0);
      } else {
        removeOverlay();
      }
    });
    textButtonFocusNode1.addListener(() {
      if (textButtonFocusNode1.hasFocus) {
        _showOverlay(context, 1);
      } else {
        removeOverlay();
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Container(
        height: 100,
        child: Row(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            TextButton(
              focusNode: textButtonFocusNode,
              onHover: (val) {
                if (val) {
                  textButtonFocusNode.requestFocus();
                  showOverlay = true;
                }
              },
              onPressed: () {},
              child: const Text('Hover'),
            ),
            TextButton(
              focusNode: textButtonFocusNode1,
              onHover: (val) {
                if (val) {
                  textButtonFocusNode1.requestFocus();
                  showOverlay = true;
                }
              },
              onPressed: () {},
              child: const Text('Hover'),
            ),
          ],
        ),
      ),
    );
  }
}