Flutter: programmatically cause darkTheme to be used - flutter

Question

In Flutter, you can set a dark theme to be used, which will be used if certain contexts (e.g. Dark Mode is set on Android Q). Is there a recommended way to allow that to be overridden programmatically; e.g, in response to a user preference?
I guess this could be done at the very top level of the app:
MaterialApp(
theme: ThemeData.light(),
darkTheme: ThemeData.dark(),
themeMode: fromSomeState,
)
However, I'd also like to be able switch on whether or not the app is in dark mode programmatically at various points in the app (e.g. for image selection):
MediaQuery.of(context).platformBrightness == Brightness.dark;
I could try and update the MediaQueryData to override platformBrightness as well, but that can only be done inside MaterialApp, which seems awkward.
Is there a better pattern for doing this kind of thing?

Answer 1

You can check out dynamic_theme
How to use
Just add Dynamic Theme as the parent of your MaterialApp
DynamicTheme(
defaultBrightness: Brightness.light,
data: (brightness) => new ThemeData(
primarySwatch: Colors.indigo,
brightness: brightness,
),
themedWidgetBuilder: (context, theme) {
return new MaterialApp(
.......
);
}
)
Get the currentBrightness using
DynamicTheme.of(context).brightness;
And Set it using
DynamicTheme.of(context).setBrightness(Theme.of(context).brightness == Brightness.dark? Brightness.light: Brightness.dark);
You can read more about it or create your own, check this medium Post
Edited
You can check the current OS theme using
MediaQuery.of(context).platformBrightness;
And set the theme accordingly.