Resize leading widget in flutter AppBar - flutter

Question

I am making a custom AppBar that has a larger height than the typical AppBar. I would like to resize the leading widget/icon as well, and take advantage of the automaticallyImplyLeading default behaviors (so the menu icons and back icons are automatically implemented).
This is the solution I thought I would implement:
class AppAppBar extends PreferredSize{
AppAppBar(String title) : super(
preferredSize: Size.fromHeight(56.0),
child: AppBar(
centerTitle: true,
title: Text(title, style: textStyle)
)) {
(child as AppBar).leading =
SizedBox(width: 30.0, height: 30.0, child: (child as AppBar).leading);
}
static const textStyle = TextStyle(fontSize: 32.0);
}
But of course this won't work because (child as AppBar).leading is final.
So in the AppBar below (text size made dramatically larger for illustration purposes), I would like to make the automatically added hamburger icon larger in comparison.
What do you think? Are there solutions for this or should I give up on the automatic icons and add them myself?
Edit: Added an image to show what I mean

Answer 1

You cant because it is a predefined widget.
You can work around it with a Row widget:
Scaffold(
key:_scaffoldKey,
drawer: Drawer(),
appBar: AppBar(
automaticallyImplyLeading: false
title: Row(
mainAxisAlignment: MainAxisAlignment.start,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
SizedBox(
height: 20, // Your Height
width: 20, // Your width
child: IconButton( // Your drawer Icon
onPressed: () => _scaffoldKey.currentState.openDrawer()),
icon: Icon(Icons.arrow_back, color: Colors.white),
),)
// Your widgets here
],
),
),
)
You need the Key to open the drawer with _scaffoldKey.currentState.openDrawer().
automaticallyImplyLeading: false will prevent the default drawer Icon.

Answer 2

A simple example to demonstrate Raffi Jonas answer
AppBar(
automaticallyImplyLeading: false,
title: Row(
children: [
Expanded(
child: Text('One'),
),
Center(
child: Text('Two'),
),
Expanded(
child: Align(
alignment: Alignment.centerRight,
child: Text('Three'),
),
),
],
),
),

Answer 3

The leading Widget width of AppBar in Flutter can be resized using the leadingWidth property.
For Example :
AppBar(
title: const Text('Title'),
leadingWidth: 50,
leading: Container()
)

Answer 4

What you want is a custom app bar in Flutter. Most people try giving their own widgets in the title argument of an AppBar. But let me show you how to properly do it.
#override
Widget build(BuildContext context) => Scaffold(
appBar: _appBar(),
body: _body(),
);
//Custom AppBar
_appBar() => PreferredSize(
//kToolBarHeight: Default size used by all AppBar widgets in Flutter.
//MediaQuery...: viewPadding.top is StatusBar area. viewPadding.bottom is iPhone bottom bar.
preferredSize: PreferredSize.fromHeight(kToolBarHeight + MediaQuery.of(context).viewPadding.top),
child: Container(
child: Row(
//This will spread Row content evenly across the screen.
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
//Leading Widget
Icon(Icons.home),
//Title
Text("Hello World!"),
//Trailing Widget / Actions
Icon(Icons.home),
],
),
),
);
Widget _body() => Container(
color: Colors.blue,
);

Answer 5

You can set a margin for height or width.
AppBar(
leading: Container(
margin: EdgeInsets.symmetric(vertical: 15),
child: IconButton(
icon: Icon(CupertinoIcons.chevron_left),
onPressed: () {},
),
),

Answer 6

To use a custom appBar leading button, here is the code.
appBar: AppBar(
title: Text('hello'),
// automaticallyImplyLeading: false,
elevation: 0,
leadingWidth: 58,
actions: [
ProfileBar(),
],
leading: Container(
width: 14,
//color: Colors.yellow,
child: Row( // <--- Using row to avoid force resizing of leading
children: [
Padding( // <--- Padding to make it look more nicer
padding: const EdgeInsets.only(left: 24.0),
child: GestureDetector(
onTap: () {
Navigator.of(context).pop();
},
child: SvgPicture.asset( // <-- Using SvgPicture package
'assets/svg/icons/backbtn.svg',
width: 24,
height: 24,
),
),
),
],
),
),
),