How to avoid scrolling listview when scrolling in map within listview

Issue

I have a ListView, at the top of which I have a map, I want the map to scroll out of view when the ListView is scrolled, but I also want the user to be able to interact with the map. So scrolling should only happen when the user scrolls on the other ListView widgets and not when they scroll on the map, then I want the gesture to be applied directly to the map. Currently though, when the user scrolls on the map, it scrolls the whole ListView.

I have tried the other suggestion that I have come across on here In Flutter, how can a child widget prevent the scrolling of its scrollable parent? I added a GestureDetector as suggested in the answer to the post above wrapping the map container in the sample below, however this just blocked scrolling of both the ListView and the Map when scrolling on the map. Video link https://imgur.com/SeCRzUC

Here is the widget that is returned by my build method. This code depends on the google_maps_flutter plugin.

Container(
  height: MediaQuery.of(context).size.height,
  child:
  ListView.builder(
    itemCount: 12 + 1,
    itemBuilder: (context, index) {
      if (index == 0) return GestureDetector(
        onVerticalDragUpdate: (_){},
        child: Container(
          height: MediaQuery.of(context).size.height / 2,
          child: GoogleMap(initialCameraPosition: initalPosition),
        ),
      );
      else return ListTile(title: Text("$index"),);
    }
  )
),

I had hoped the map would capture gestures but it doesn't, the listview which contains it captures all. Could anyone suggest how I could force all gestures for this item in the list to be passed directly to the map, and still have the list scroll when other items in the list are scrolled?

Solution

The accepted answer (Eset Mehmet's answer was marked as excepted as of time of writing) is way to complicated and in my case it did not even work! It provided left-to-right scrolling, panning, and scaling, however top-to-bottom scrolling still scrolled the ListView.

A real solution is very simple, since GoogleMap by default has those gesture detectors. You must just specify that gesture detection must be prioritized by GoogleMap and not ListView. This is achieved by giving GoogleMap object an EagerGestureRecognizer in the following way for example.

ListView(
  children: <Widget>[
    Text('a'),
    Text('b'),
    GoogleMap(
      ...,
      gestureRecognizers: {
        Factory<OneSequenceGestureRecognizer>(
          () => EagerGestureRecognizer(),
        ),
      },
    ),
  ],
)

In this way, all gestures that happen on or over the GoogleMap object will be prioritized by GoogleMap instead of any other widget.

Answered By - campovski