WoltModalSheet is designed to revolutionize the use of Flutter modal sheets. Built with Wolt-grade design quality and used extensively in Wolt products, this UI component offers a visually appealing and user-friendly modal sheet with multiple pages, motion animation for page transitions, and scrollable content within each page.
Traverse through numerous pages within a single sheet.
Greater flexibility with scrollable content per page, accommodating large content effortlessly.
The modal sheet adjusts to fit all screen sizes, appearing as a dialog on larger screens and as a bottom sheet on smaller screens, guided by user-specified conditions.
Engage users with dynamic motion animation for page transitions and scrolling.
| Pagination | Scrolling |
|---|---|
 |
 |
The library showcases examples of both imperative and declarative navigation patterns to display modal sheet on screen.
User input can dynamically shape the modal sheet's page list.
Pages in the Wolt Modal Sheet offer a customizable look and the page components
are provided with an instance of WoltModalSheetPage class. The API provides a
way
to manage the state among the page components to be used with popular libraries
such as Bloc and Provider
Each element within the WoltModalSheet has a role to play, offering context, navigational assistance, and explicit action prompts to the user. By understanding these elements and their roles, you can fully harness the power of WoltModalSheet and create an intuitive and engaging user experience.
The structure is organized across layers on the z-axis:
By employing these various layers, you can create an interactive and visually
appealing interface that resonates with users. Each layer contributes to the
overall coherence of the page, serving a specific purpose and enhancing the
overall user experience.
The navigation bar has a transparent background, and resides at the top of the sheet, situated directly above the top bar on the z-axis. It includes two specific widgets: the leading and the trailing. The leading widget usually functions as the back button, enabling users to navigate to the previous page. The trailing widget often serves as the close button, utilized to close the modal sheet. Together, these widgets provide clear and intuitive navigational control, differentiating themselves from the top bar by focusing specifically on directional navigation within the interface.
The Top Bar sits above the main content layer and below the navigation
bar layer. It aids users in grasping the context by displaying an optional
title. In scenarios where sheets are filled with content requiring scrolling,
the top bar becomes visible as the user scrolls, causing the page title
replaced. At this point, the top bar adopts a 'sticky' position at the top,
guaranteeing consistent visibility. Its design is flexible, with an option
to remain hidden or always visible regardless of the scroll position. The
navigation bar widgets overlay above the top bar, and the top bar title is
symmetrically framed between the leading and trailing navigation bar widgets.
The Top Bar design is flexible, when hasTopBarLayer is set to false, the
top bar and the topBarTitle will be hidden. If
isTopBarLayerAlwaysVisible set to true, the top bar will be always visible
regardless of the scroll position.
The Sticky Action Bar (SAB) guides the user towards the next step. Anchored to the bottom of the view, the SAB elevates above the content with an optional gentle gradient. This position guarantees that the action remains visible, subtly hinting to the user that there is more content to be explored below the fold by scrolling.
An optional Hero Image can be positioned at the top of the main content. This element immediately grabs the user's attention, effectively conveying the primary theme or message of the content.
An optional page title above the main content provides users with a quick understanding of what to expect from the page. As the user scrolls, this title becomes hidden, at which point the top bar title continues to serve this context-providing purpose.
The main content delivers information according to the user need. It can be scrollable to handle larger content. The content is built lazily to improve the performance.
Here is an example that shows all the modal sheet elements in use:
To use this plugin, add wolt_modal_sheet as a dependency in your pubspec.yaml file.
This package has 4 example projects.
The example app demonstrates how to display a two-pages modal sheet that can be customized for dark and light themes using WoltModalSheetThemeData theme extension.
Widget build(BuildContext context) {
final pageIndexNotifier = ValueNotifier(0);
WoltModalSheetPage page1(BuildContext modalSheetContext, TextTheme textTheme) {
return WoltModalSheetPage.withSingleChild(
hasSabGradient: false,
stickyActionBar: Padding(
padding: const EdgeInsets.all(_pagePadding),
child: Column(
children: [
ElevatedButton(
onPressed: () => Navigator.of(modalSheetContext).pop(),
child: const SizedBox(
height: _buttonHeight,
width: double.infinity,
child: Center(child: Text('Cancel')),
),
),
const SizedBox(height: 8),
ElevatedButton(
onPressed: () => pageIndexNotifier.value = pageIndexNotifier.value + 1,
child: const SizedBox(
height: _buttonHeight,
width: double.infinity,
child: Center(child: Text('Next page')),
),
),
],
),
),
topBarTitle: Text('Pagination', style: textTheme.titleSmall),
isTopBarLayerAlwaysVisible: true,
trailingNavBarWidget: IconButton(
padding: const EdgeInsets.all(_pagePadding),
icon: const Icon(Icons.close),
onPressed: Navigator.of(modalSheetContext).pop,
),
child: const Padding(
padding: EdgeInsets.fromLTRB(
_pagePadding,
_pagePadding,
_pagePadding,
_bottomPaddingForButton,
),
child: Text(
'''
Pagination involves a sequence of screens the user navigates sequentially. We chose a lateral motion for these transitions. When proceeding forward, the next screen emerges from the right; moving backward, the screen reverts to its original position. We felt that sliding the next screen entirely from the right could be overly distracting. As a result, we decided to move and fade in the next page using 30% of the modal side.
''',
)),
);
}
WoltModalSheetPage page2(BuildContext modalSheetContext, TextTheme textTheme) {
return WoltModalSheetPage.withCustomSliverList(
stickyActionBar: Padding(
padding:
const EdgeInsets.fromLTRB(_pagePadding, _pagePadding / 4, _pagePadding, _pagePadding),
child: ElevatedButton(
onPressed: () {
Navigator.of(modalSheetContext).pop();
pageIndexNotifier.value = 0;
},
child: const SizedBox(
height: _buttonHeight,
width: double.infinity,
child: Center(child: Text('Close')),
),
),
),
pageTitle: Padding(
padding: const EdgeInsets.symmetric(horizontal: _pagePadding),
child: Text(
'Material Colors',
style: textTheme.headlineMedium!.copyWith(fontWeight: FontWeight.bold),
),
),
heroImage: Image(
image: AssetImage(
'lib/assets/images/material_colors_hero${_isLightTheme ? '_light' : '_dark'}.png',
),
fit: BoxFit.cover,
),
leadingNavBarWidget: IconButton(
padding: const EdgeInsets.all(_pagePadding),
icon: const Icon(Icons.arrow_back_rounded),
onPressed: () => pageIndexNotifier.value = pageIndexNotifier.value - 1,
),
trailingNavBarWidget: IconButton(
padding: const EdgeInsets.all(_pagePadding),
icon: const Icon(Icons.close),
onPressed: () {
Navigator.of(modalSheetContext).pop();
pageIndexNotifier.value = 0;
},
),
sliverList: SliverList(
delegate: SliverChildBuilderDelegate(
(_, index) => ColorTile(color: allMaterialColors[index]),
childCount: allMaterialColors.length,
),
),
);
}
return MaterialApp(
themeMode: _isLightTheme ? ThemeMode.light : ThemeMode.dark,
theme: ThemeData.light(useMaterial3: true).copyWith(
extensions: const <ThemeExtension>[
WoltModalSheetThemeData(
heroImageHeight: _heroImageHeight,
topBarShadowColor: _lightThemeShadowColor,
modalBarrierColor: Colors.black54,
),
],
),
darkTheme: ThemeData.dark(useMaterial3: true).copyWith(
extensions: const <ThemeExtension>[
WoltModalSheetThemeData(
topBarShadowColor: _darkThemeShadowColor,
modalBarrierColor: Colors.white12,
sabGradientColor: _darkSabGradientColor,
dialogShape: BeveledRectangleBorder(),
bottomSheetShape: BeveledRectangleBorder(),
),
],
),
home: Scaffold(
body: Builder(
builder: (context) {
return Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
const Text('Light Theme'),
Padding(
padding: const EdgeInsets.all(_pagePadding),
child: Switch(
value: !_isLightTheme,
onChanged: (_) => setState(() => _isLightTheme = !_isLightTheme),
),
),
const Text('Dark Theme'),
],
),
ElevatedButton(
onPressed: () {
WoltModalSheet.show<void>(
pageIndexNotifier: pageIndexNotifier,
context: context,
pageListBuilder: (modalSheetContext) {
final textTheme = Theme.of(context).textTheme;
return [
page1(modalSheetContext, textTheme),
page2(modalSheetContext, textTheme),
];
},
modalTypeBuilder: (context) {
final size = MediaQuery.of(context).size.width;
if (size < _pageBreakpoint) {
return WoltModalType.bottomSheet;
} else {
return WoltModalType.dialog;
}
},
onModalDismissedWithBarrierTap: () {
debugPrint('Closed modal sheet with barrier tap');
Navigator.of(context).pop();
pageIndexNotifier.value = 0;
},
maxDialogWidth: 560,
minDialogWidth: 400,
minPageHeight: 0.0,
maxPageHeight: 0.9,
);
},
child: const SizedBox(
height: _buttonHeight,
width: _buttonWidth,
child: Center(child: Text('Show Modal Sheet')),
),
),
],
);
},
),
),
);
}The code snippet above produces the following:
The playground app demonstrates how to imperatively show the modal sheet. The purpose of this module is to play and experiment with various use cases. These use cases include:
- A page with forced max height independent of its content.
- A page with a hero image
- A page with a list whose items are lazily built.
- A page with an auto-focused text field.
- A page without a page title nor a top bar.
The playground_navigator2 has the same content with the playground app but the modal sheet is shown using Navigator 2.0 (Router API) in a declarative way.
Finally, the coffee_maker app demonstrates how to manage the state among the page components with an opinionated use of the Provider state management library.
The code snippet demonstrates how to decorate the modal sheet with a change notifier provider so that the page components can be rebuilt according to the current state:
void _onCoffeeOrderSelectedInAddWaterState(BuildContext context,
String coffeeOrderId) {
final model = context.read<StoreOnlineViewModel>();
final pageIndexNotifier = ValueNotifier(0);
WoltModalSheet.show(
pageIndexNotifier: pageIndexNotifier,
context: context,
decorator: (child) {
return ChangeNotifierProvider<StoreOnlineViewModel>.value(
value: model,
builder: (_, __) => child,
);
},
pageListBuilderNotifier: AddWaterModalPageBuilder.build(
coffeeOrderId: coffeeOrderId,
goToPreviousPage: () =>
pageIndexNotifier.value = pageIndexNotifier.value - 1,
goToNextPage: () => pageIndexNotifier.value = pageIndexNotifier.value + 1,
),
modalTypeBuilder: _modalTypeBuilder,
);
}
- Design Philosophy: Dive into the creative thought process behind WoltModalSheet's functionality in our blog post . Explore how we tackled the design challenges to create an intuitive and responsive experience.
- Insights from FlutterCon'23 talk: We delved into both the design and developmental facets of this package at the FlutterCon'23 conference. Catch the enlightening recording of his talk to understand the nuances.