How to set the color based on dark / light theme?

Question

I want to set a dark and a light color scheme and use it as a background color of containers.

Here is my code:

Container(
  padding: const EdgeInsets.all(kDefaultPadding),
  //change required here:
  decoration: const BoxDecoration(color: kDarkColor),
  child: ... ,
)

Answer 1

In your root file (main.dart) your entry point of the app is located. In general, you have a class MyApp which returns a MaterialApp widget. This out-of-the-box widget from the Flutter SDK lets you define your app´s theme. Here you can define the theme.

In your Container, you can assign the color directly via the color parameter. To refer to your theme data do this: Theme.of(context).backgroundColor for example.

Answer 2

You can use platformBrightness from MediaQuery.

final isDarkTheme = MediaQuery.of(context).platformBrightness == Brightness.dark;

  Container(
    padding: const EdgeInsets.all(kDefaultPadding),
    //change required here
    decoration: const BoxDecoration(color: isDarkTheme? kDarkColor: kLightColor),
    child: Column(
    // ...
  ),

Also see how to implement dark mode in flutter