micha_core 0.1.0

micha_core: ^0.1.0 copied to clipboard

Extensions and widgets that are missing in Flutter's SDK.

Features #

• Declarative extensions to avoid loops and imperative logic.
• Useful widgets, like a Gap widget to avoid the use of Padding.

Usage #

Separate items of collections #

Need to add some items between existing items of a List or Iterable? Use collection.separated(separator):

[1, 2, 3].separated(0); // [1, 0, 2, 0, 3]

Are these separators dependent on preceding and succeeding items? Use collection.separatedBy((before, after) => separator):

[1, 2, 3].separatedBy((before, after) => before + after); // [1, 3, 2, 5, 3]

Enum values byNameOrNull #

In dart, you can find enum values by their names, like:

enum TestEnum { one, two, three }

TestEnum.values.byName('two');

But what if that value does not exist? Dart will throw an ArgumentError. Use byNameOrNull to receive null instead:

TestEnum.values.byValueOrNull('four');

Gap #

We often require some small space between widgets. Flutter's widget catalog has limited options:

• Flutter's Spacer takes up all available space, which is often more than we want.
• Flutter's Padding unfortunately needs to be wrapped around widgets, adding boilerplate, while also being hard to read inside of lists.
• The best that Flutter offers is a SizedBox with a specified width or height.
  However, this still has some problems: We need to set either width or height, depending on whether the SizedBox is placed inside a Row or Column.
  We also need to repeat the same constant pixel size all throughout the application.

Instead, consider using a Gap:

Column(
  children: [
    Text('first'),
    Gap(),
    Text('second'),
  ],
);

Gap takes up a fixed space in both directions.
It takes 16 pixels by default, but can be configured using the GapThemeData theme extension or its constructor parameters.
When you need a little more or less space relative to the configured theme, create a Gap with a scale factor, like Gap(scale: 2) or Gap(scale: 0.5) respectivly. You can also add to, subtract from, multiply or devide a Gap to scale it, e.g. Gap() * 2.

ThemedText #

Avoid accessing ThemeData manually to set a themed textStyle. Use a ThemedText widget instead:

ThemedText.headlineMedium('Some headline');

AsyncBuilder #

Using Flutter's FutureBuilder requires a lot of imperative boilerplate.
You need to explicitly catch loading, error and no-data states while also keeping the Future in state.
If you do this: FutureBuilder(future: load(), builder: ...);, then FutureBuilder will call load() whenever your widget rebuilds.

As an alternative, AsyncBuilder offers a declarative API:

AsyncBuilder(
  createFuture: () => Future.delayed(
    const Duration(seconds: 1),
    () => 'some data',
  ),
  builder: (context, data) => Text(data),
);

AsyncBuilder only reloads when its key changes. You can also customize initialData and change the look of loading, no-data and error states, which each have sensible defaults.

Spinner #

Spinner is essentially a slightly improved SpinningProgressIndicator.
It is always centered, can be given a fixed size, its strokeWidth is a bit more narrow and it all can be themed using SpinnerThemeData.
It is also the default loading indicator used by AsyncBuilder.