Flutter - Detect Tap on the Screen that is filled with other Widgets - flutter

Question

I am trying to detect a tap on the screen. I've tried multiple variation of using the GestureDetector but that just leads to the app detecting tap on the child element and not the screen.
Here is the code:
class QQHome extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
theme: ThemeData(
primaryColor: Colors.blueGrey,
),
home: Scaffold(
appBar: AppBar(
centerTitle: true,
title: Text('QuoteQuota'),
),
body: GestureDetector(
onTap: () => print('Tapped'),
child: QQBody(),
),
),
);
}
}
class QQBody extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Center(
child: Text(
'Hello, World!'
),
);
}
}
Output: "tapped" printed when I click "Hello, World!".
Expected Output: "tapped" printed when I click anywhere on the screen with Text in the Center.
How do I do this?

Answer 1

Use GestureDetector's behavior property and pass HitTestBehavior.opaque to it, which recognizes entire screen and detects the tap when you tap anywhere on the screen.
body: GestureDetector(
behavior: HitTestBehavior.opaque,
onTap: () => print('Tapped'),
child: QQBody(),
),
Hope this answers your question.

Answer 2

Like Darshan said, you can trigger Tap by wrapping the body inside a Gesture detector like this...
body: GestureDetector(
behavior: HitTestBehavior.opaque,
onTap: () => print('Tapped'),
child: QQBody(),
),
Also in some cases, you may need to avoid trigger clicking on other widgets while tapping anywhere in body. That can be solved by using IgnorePointer Widget
body: GestureDetector(
behavior: HitTestBehavior.opaque,
onTap: () {
print('This will click');
},
// -------- No Widget below tree will be trigger click.
child: IgnorePointer(
ignoring: ClassLibrary.selected != null ? true : false,
child: TabBarView(
children: [
...

Answer 3

#Darshan is a correct answer but I want to add something to it. I wanted a trigger whenever the screen is touched and onTap only reacts to a tap (no slide). However that behaviour can be achieved bij adding onTapCancel
body: GestureDetector(
behavior: HitTestBehavior.opaque,
onTap: () => print('Tapped'),
onTapCancel: () => print('Touched but not tapped'),
child: QQBody(),
),

Answer 4

Please use below code--
class QQHome extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
theme: ThemeData(
primaryColor: Colors.blueGrey,
),
home: Scaffold(
appBar: AppBar(
centerTitle: true,
title: Text('QuoteQuota'),
),
body: GestureDetector(
onTap: () => print('Tapped'),
child: Container(
height : MediaQuery.of(context).size.height,
width : MediaQuery.of(context).size.width,
),
),
),
);
}
}

Answer 5

You can use Stack: put layers on top of each other.
The good thing about Stack is you can arrange stack order as you want.
If you want to do something as the screen is touched, and do something else if a button on the screen is touched, you can easily do it with stack by putting the button on top of GestureDetector.
The following is your example:
class QQHome extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
theme: ThemeData(
primaryColor: Colors.blueGrey,
),
home: Scaffold(
appBar: AppBar(
centerTitle: true,
title: Text('QuoteQuota'),
),
body: Stack(
// Bottom to Top order
children: <Widget> [
QQBody(),
GestureDetector(
onTap: () => print('Tapped'),
),
]
),
),
);
}
}
class QQBody extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Center(
child: Text(
'Hello, World!'
),
);
}
}