PreviewHub

A real-device gallery for your Flutter design system. Preview components, screens, icons, images, fonts, Lottie animations, and Rive files.

Everything is rendered using the same Flutter engine, theme, assets, and runtime configuration used by your application.

No code generation. No build_runner. No custom tooling.

Collections	Dark theme	Widgets

Component	Screen

Requirements

Flutter 3.44 or newer.

PreviewHub keeps dependencies to a minimum and currently uses flutter_svg, http, lottie, and rive. rive ships platform binaries, making it the heaviest dependency.

Install

dependencies:
  preview_hub: ^0.0.4

Use

Push PreviewHubDashboard from anywhere in your app, preferably behind kDebugMode or your own development flag.

import 'package:flutter/foundation.dart';
import 'package:preview_hub/preview_hub.dart';

if (kDebugMode) {
  Navigator.of(context).push(
    MaterialPageRoute<void>(
      builder: (BuildContext context) => const PreviewHubDashboard(
        config: PreviewHubConfig(
          widgets: previewWidgets,
          networkImages: <String>[
            'https://example.com/logo.svg',
          ],
          networkLotties: <String>[
            'https://example.com/loader.json',
          ],
          networkRives: <String>[
            'https://example.com/rating.riv',
          ],
        ),
      ),
    ),
  );
}

Since kDebugMode is a compile-time constant, PreviewHub can be tree-shaken from release builds rather than simply hidden at runtime.

Gating PreviewHub removes its Dart code, but native libraries brought by dependencies such as rive may still be packaged with the application.

Registering widgets

A widget is code rather than an asset, so it cannot be discovered through a manifest. Use WidgetPreview.component for individual components and WidgetPreview.screen for complete screens.

const List<WidgetPreview> previewWidgets = <WidgetPreview>[
  WidgetPreview.component(
    group: 'Buttons',
    title: 'AppButton · primary',
    cases: <WidgetPreviewCase>[
      WidgetPreviewCase(
        label: 'filled · large (52)',
        builder: _primaryLarge,
      ),
      WidgetPreviewCase(
        label: 'disabled',
        builder: _primaryDisabled,
      ),
    ],
  ),
  WidgetPreview.screen(
    group: 'Auth',
    title: 'SignInScreen',
    builder: _signIn,
  ),
];

Widget _primaryLarge(BuildContext context) =>
    AppButton(
      label: 'Continue',
      size: AppButtonSize.large,
      onPressed: () {},
    );

group defines the collapsible heading and title defines the preview name. Components can contain multiple cases, while screens open as full-size previews.

Collections

The landing screen provides global search and recently viewed items for quickly navigating through the gallery.

Collection	Contents
Widgets	Registered components and screens, grouped and searchable.
Icons & Images	SVG, PNG, WebP, JPEG and GIF with dimensions and file size. Icon and image previews support different sizes, backgrounds, and tint.
Fonts	Font families and weights from the font manifest with size previews and a type tester.
Lottie	Bundled and remote JSON animations with duration and frame count.
Rive	Bundled and remote .riv files with artboard and state machine information.
Other	Additional bundled assets such as PDF, JSON, and audio files.

Icons & Images	Fonts

Lottie	Rive

The landing screen also provides an asset size breakdown to visualise the size contribution of each asset type.

Asset size breakdown

Bundled assets are discovered from Flutter's asset and font manifests, so they don't need to be registered manually. Remote assets are validated before being displayed.

Why PreviewHub?

A design system can look different on a real device because of text scale, fonts, pixel density, themes, and runtime behaviour.

PreviewHub puts your design system inside your own app, allowing you to browse and validate components and assets using the real Flutter engine and the same application environment.

Why not IDE previews?

IDE previews are great for individual widgets during development. PreviewHub focuses on browsing an entire design system on a real device, with the same rendering engine, fonts, assets, theme, and runtime behaviour used by your application.

Example

The example/ directory contains a small design system with five components, seven screens, and a real asset set.

cd example
flutter run

License

MIT. See LICENSE.