How to make Stack layout scroll-able using SingleChildScrollView? - dart

Question

I am trying to make stack layout scrollable using SingleChildScrollView but it's not scrolling. Is SingleChildScrollView should be used here?
I think I have given enough description to make anyone understand my question. More text here to satisfy StackOverflow's requirement to ask a question. Sorry about this.
Here's example code.
#override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: Container(
child: Center(
child: LayoutBuilder(
builder:
(BuildContext context, BoxConstraints viewportConstraints) {
return SingleChildScrollView(
child: ConstrainedBox(
constraints: BoxConstraints(
minHeight: viewportConstraints.maxHeight,
),
child: IntrinsicHeight(
child: Column(
children: <Widget>[
Container(
// A fixed-height child.
color: Colors.white,
height: 120.0,
),
Expanded(
// A flexible child that will grow to fit the viewport but
// still be at least as big as necessary to fit its contents.
child: Container(
color: Colors.blue,
//height: 120.0,
child: Stack(
children: <Widget>[
Positioned(
top: 0,
left: 0,
right: 0,
child: Container(
color: Colors.red[100],
child: SizedBox(
height: 300,
),
),
),
Positioned(
top: 50,
left: 0,
right: 0,
child: Container(
color: Colors.red[200],
child: SizedBox(
height: 300,
),
),
),
Positioned(
top: 100,
left: 0,
right: 0,
child: Container(
color: Colors.red[300],
child: SizedBox(
height: 300,
),
),
),
Positioned(
top: 150,
left: 0,
right: 0,
child: Container(
color: Colors.green[100],
child: SizedBox(
height: 300,
),
),
),
Positioned(
top: 200,
left: 0,
right: 0,
child: Container(
color: Colors.green[200],
child: SizedBox(
height: 300,
),
),
),
Positioned(
top: 250,
left: 0,
right: 0,
child: Container(
color: Colors.green[300],
child: SizedBox(
height: 300,
),
),
),
Positioned(
top: 300,
left: 0,
right: 0,
child: Container(
color: Colors.yellow[100],
child: SizedBox(
height: 300,
),
),
),
Positioned(
top: 350,
left: 0,
right: 0,
child: Container(
color: Colors.yellow[200],
child: SizedBox(
height: 300,
),
),
),
Positioned(
top: 400,
left: 0,
right: 0,
child: Container(
color: Colors.yellow[300],
child: SizedBox(
height: 300,
),
),
),
],
),
),
),
],
),
),
),
);
},
),
),
),
),
);
}

Answer 1

It depends on what size should the StackView have. For example you can make one of Stack's children not positioned. This child will then affect the size of entire stack view.
SingleChildScrollView(
child: Stack(
children: <Widget>[
Container(
height: 5000,
),
Positioned(
top: 100,
left: 100,
width: 1000,
height: 1000,
child: Container(color: Colors.red),
)
],
),
)

Answer 2

Stack will get the constraints of the biggest child. But if you use Position the constraints of that child are not considered by stack. If you want dynamic height and width for the stack use Margin inside a container instead of position.
To explain more in detail
SingleChildScrollView(
child: Stack(
children: <Widget>[
Container(
height: 500,
),
Positioned(
top: 100,
left: 100,
child: Container(color: Colors.red, height: 1000, width: 1000),
)
],
),
)
In the above case stack will only take 500 as height. Your Container which has 1000 will not be considered.
SingleChildScrollView(
child: Stack(
children: <Widget>[
Container(
height: 500,
),
Container(margin: EdgeInsets.only(top: 100, left: 100, color: Colors.red, height: 1000, width: 1000),
],
),
)
In the above case the height of the container will be used for defining the height of stack. This will also allow for SingleChildScrollView to be scrollable.

Answer 3

Stack(
children: [
Container(
width: 100,
height: 100,
child: Material(
elevation: 8.0,
borderRadius: BorderRadius.circular(10),
child: Text("HELLO")),
),
//please use column and sized box instead of Positioned..
//Then SingleChildScrollView working
//inkwell ontap working perfect
Column(
children: [
SizedBox(height: 100),
Container(
width: 100,
height: 100,
color: Colors.white,
)
])
],
),**

Answer 4

The Stack takes the size of the widest height widget. To fix the problem, you have to calculate the maximum size that your Stack will take. You create an empty Container that has this size. Next you will add the other widgets in the Stack.
Exemple
SingleChildScrollView(
child: Column(
children: [
Stack(
children: [
Container(height: 200), // Max stack size
Container(
alignment: Alignment.topCenter,
height: 150,),
Positioned(
top: 110,
left: 30,
right: 30,
height: 80,
child: Material(
elevation: 8.0,
borderRadius: BorderRadius.circular(10),
child: Text("HELLO")
),
]),// Stack
Container(child: Text("After the stack")),
])// Column
),//SingleChildScrollView

Answer 5

You can put Expanded > SingleChildScrollView > Column
Expanded(
child: SingleChildScrollView(
child: Container(
color: Colors.red,
padding: EdgeInsets.all(20.0),
child: Column(
children: <Widget>[
Text('Red container should be scrollable'),
Container(
width: double.infinity,
height: 700.0,
padding: EdgeInsets.all(10.0),
color: Colors.white.withOpacity(0.7),
child: Text('I will have a column here'),
)
],
),
),
),
),