layoutr

A set of succinct Dart/Flutter utilities to help doing responsive layouts with less verbosity.

Why

There are already a ton of layout/UI libraries out there and this is just another one to solve the same problem: responsive layouts.

This package aims to be a single dependecy to handle responsive use-cases in Flutter applications while keeping the verbosity to a minimum, because we know how quickly verbose (reads harder-to-read) we can get with those Widgets.

Usage

Before finding out the package's API, make sure to install this package. With this out of the way, let's get an overview what this package does:

Layout Resolvers

These are the core layout classes that should make the process of handling multiple-layout widgets much less verbose. We can use these resolvers whenever you have a BuildContext (usually in the Widgets build function) available.

Even though the magic should happen inside the abstract LayoutResolver, we need to extend this class to provide our desired Breakpoints. This is intended due to the fact that there is an incredible amount of use-cases available when building any kind of UI - meaning that these breakpoints are completely subjective, based on each project "constraints".

But that's not any reason to not have built-in Layout Resolvers, and these will probably fit the most generic use-cases. To exemplify the resolvers, we can see how the CommonLayout works.

Exemplifying with CommonLayout

---

Before diving into the concepts, you have to make sure to provide a CommonLayout for your widgets. This can be done in multiple different ways, although the easiest is to just wrap your top-most widget in the CommonLayoutWidget:

import 'package:layoutr/common_layout.dart';

// ...
CommonLayoutWidget(
  child: /* My child, possibly a MaterialApp/WidgetsApp */,
);
// ...

Now, CommonLayout is split in 4 breakpoints: desktop, tablet, phone and tinyHardware. A simple usage of returning a responsive Text widget that has both its value and style customized based on the current device's constraints may be done like the below:

import 'package:layoutr/common_layout.dart';

// ...

Widget build(BuildContext context) {
  final layout = context.commonLayout;
  final textTheme = Theme.of(context).textTheme;

  return layout.value(
    desktop: () => Text('Desktop layout', style: textTheme.headline1),
    phone: () => Text('Phone layout', style: textTheme.headline4),
    tinyHardware: () => Text('Tiny Hardware layout', style: textTheme.headline6),
  );
}
// ...

TLDR: all breakpoints don't need to be provided, the layout will automatically find the nearest suitable value for your current breakpoint.

Long version: you can see that there is no tablet supplied to the layout.value, and that is intended to exemplify a common scenario, where we may want to just provide two or three arguments - and that means not all possible scenarios are "covered" - and that's where the resolver comes in handy: if the current breakpoint value is not passed to layout.value, it will fallback to the "nearest" available one, fitting the most suitable layout for your particular value. This "nearest logic" can be confusing, but you can find out more how it works in LayoutResolver.closestValue

Other than layout.value, the CommonLayout provide utilities for simple boolean comparisons:

import 'package:layoutr/common_layout.dart';

// ...

Widget build(BuildContext context) {
  final layout = context.commonLayout;
  const pageTitle = 'Title';

  final myAppBar = layout.isTabletOrSmaller ? AppBar(title: const Text(pageTitle)) : null;

  return Scaffold(
    // We wan't to have an `AppBar` if the current layout is a tablet or smaller
    appBar: myAppBar,
    body: Center(
      child: Column(
        children: [
          // And we wan't to have a custom title `AppBar` if the current layout is a tablet or smaller
          if (layout.isDesktop)
            Text(pageTitle, style: Theme.of(context).textTheme.headline3),
          // ... the rest of the widget
        ],
      ),
    ),
  );
}
// ...

Overriding CommonLayout resolver

---

To override the sizes for each breakpoint, you can provide your own CommonLayout instance:

import 'package:layoutr/common_layout.dart';
// ...
CommonLayoutWidget(
  resolverBuilder: (constraints) => CommonLayout(constraints.maxWidth, desktop: 800, tablet: 520),
  child: /* My child */,
);
// ...

TLDR: your app don't need to necessarily use MaterialApp (or WidgetsApp), just add it above your top-most widget.

Long version: it's probably the best to add the resolver widget above the top-most widget of your tree, because the all built-in widgets use a LayoutBuilder to provide such responsive features, and this may create inconsistencies if they are created in nested widgets, which will only use the parent's BoxConstraints. This could also be useful if you wanted to created a resolver that is not necessarily related to the device's sizes, but I fail to see a useful scenario like this at the moment.

Overriding CommonLayout spacings

---

To override the spacings for each breakpoint, you can provide your own RawSpacings instance:

import 'package:layoutr/common_layout.dart';
// ...
CommonLayoutWidget(
  spacings: const RawSpacings(4, 12, 20, 24, 32, 40, 48, 56, 60),
  child: /* My child */,
);
// ...

While the above will customize all spacings for all breakpoints, it's still not responsive, and that's fine. You may want to use the spacings for the sole benefit of type-safety utilities. Now if you also want them to be responsive, there is a constructor for that:

import 'package:layoutr/common_layout.dart';

// ...
CommonLayoutWidget.withResponsiveSpacings(
  desktopSpacings: RawSpacings(8, 16, 24, 32, 40, 52, 60, 68, 80),
  phoneSpacings: RawSpacings(4, 8, 12, 20, 28, 36, 40, 48, 60),
  child: /* My child */,
);
// ...

Not sure what spacings mean? Check out spacings.

---

Tips:

• we can easily use this package with common libraries like provider (see in example/) and river_pod (see in example/);
• everything explained here is same for all built-in resolvers (like GranularLayout), they just differ in the breakpoints amount/types.

Available Built-in LayoutResolver

---

• CommonLayout: a resolver split in 4 breakpoints: desktop, tablet, phone and tinyHardware. Import this resolver through package:layoutr/common_layout.dart - (see in example/);
• GranularLayout: a resolver split in 6 breakpoints: xxLarge, xLarge, large, medium, small and xSmall. Import this resolver through package:layoutr/granular_layout.dart - (see in example/).

Custom LayoutResolver

---

If the above built-in resolvers don't match the requirements, LayoutResolver can be customized by extending it, taking advantage of the utilities built-in in the abstract class itself. To extend the and implement your custom LayoutResolver, import package:layoutr/layoutr.dart. Check out a custom implementation example in the example/.

Spacings

All spacing features revolve around Spacing enumerator. These are named ranges that should usually fit most use-cases out there in the wild. They are pretty intuitive: xxxSmall, xxSmall, xSmall, small, medium, ... and so on.

Spacings are an additional help for situations where we need type-safety, responsivity, or both. Being more specific:

• type-safety: even if you don't want to use it as a responsive value, you will still benefit from having a type-safe system that will prevent inconsistent spacings, margins and paddings in your application;
• responsivity: the spacings can be customized to one, some or all breakpoints, meaning that you won't have to change anything if you use the Spacing type system.

All built-in LayoutResolver will provide the spacings out-of-the-box, so no need to add anything extra other than your root widget. But this might not be the best for most. If wanted, one could use only this package's feature alone (with SpacingsInheritedWidget), like so:

import 'package:layoutr/layoutr.dart';

// ...
LayoutBuilder(
  builder: (context, constraints) {
    // If we wanted, we could use this spacings type-safety/responsivity without the resolver themselves
    final myCustomSpacings = constraints.maxWidth > 800
        ? RawSpacings(16, 24, 32, 40, 52, 60, 68, 76, 80)
        : RawSpacings(8, 12, 24, 32, 40, 48, 56, 64, 72);

    return SpacingsInheritedWidget(
      spacings: myCustomSpacings,
      child: // ... ,
    );
  },
);
// ...

Alone this can be somewhat useful, but its potential is enhanced with the built-in utilities and resolvers widgets - you can even build your own by extending any BuildContext, Widget or any layout-related element.

An example usage with some of the utilities:

import 'package:layoutr/layoutr.dart';

// SpacingMixin just helps you to call spacings like `smallSpacing`, instead of `Spacing.smallSpacing`, making it
// overall less verbose.
class MyPage extends StatelessWidget with SpacingMixin {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          Text('My page'),
          // Creates a vertical responsive/type-safe spacing
          context.verticalBox(xxxLargeSpacing), 
          Container(
            // Creates a vertical symmetrical insets responsive/type-safe spacing
            margin: context.symmetricInsets(vertical: smallSpacing),
            color: Colors.amber,
            // Wraps this widget in a Padding with all insets to this responsive/type-safe spacing
            child: Placeholder().withAllPadding(context, mediumSpacing),
          ),
        ],
      ),
    );
  }
}

Utilities

• Syntax-sugar for common use-cases, like: deviceWidth and deviceHeight;
• [Helpers] for commonly used elements like EdgeInsets and Padding, using Spacing.

Check out all spacing utilities.

Reference OS Projects

List of open source projects that use this package and can be used as a reference to implement your own use-cases:

WIP

Contributing

Want to contribute? Check it out here.