How to use a custom class for decoration? - flutter

Question

I want to use a background image for every page in my Flutter app. Therefore, I want to have a class that I can use to return a BoxDecoration to call it from every new page that I create. For the moment, I'm using a simple global function backgroundImage() that returns a BoxDecoration. Is there a way to have a custom class that I can directly pass to decoration: instead of calling a global function?
BoxDecoration backgroundImage() {
return BoxDecoration(
image: DecorationImage(
image: AssetImage("images/background.png"),
fit: BoxFit.cover,
),
);
}
class HomeScreen extends StatelessWidget{
#override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
decoration: backgroundImage(),
child: null /* add child content here */,
),
);
}
}

Answer 1

It seems to me that what you want is a variable that you can import and re-use. Creating a new class in which you are only going be returning an instance of BoxDecoration with a few custom options is probably overkill. Why not create a separate file, import material, declare a variable with your customisation and use it? Like this example:
Custom decoration file to re-use:
import 'package:flutter/material.dart';
BoxDecoration baseBackgroundDecoration =
BoxDecoration(
image: DecorationImage(
image: AssetImage("images/background.png"),
fit: BoxFit.cover,
),
);
Using it:
import 'custom_decorations.dart';
Using the variable:
Container(
decoration: baseBackgroundDecoration,
),
There's nothing wrong with your original idea though. You wouldn't be using it as a global variable, just a file that you import when you need it, which contains a class with your custom decorations, like this:
import 'package:flutter/material.dart';
class CustomDecorations {
BoxDecoration baseBackgroundDecoration(){
return BoxDecoration(
image: DecorationImage(
image: AssetImage("images/background.png"),
fit: BoxFit.cover,
),
);
}
}
Which you can then just use in one of these ways:
Container(
decoration: CustomDecorations().baseBackgroundDecoration(),
),
Or:
// Declare it
CustomDecorations customDecorations = CustomDecorations();
...
// Use it
Container(
decoration: customDecorations.baseBackgroundDecoration(),
),