When designing user-friendly Flutter applications, developers often use widgets like DraggableScrollableSheet and showBottomSheet to offer dynamic and engaging user experiences. However, one common challenge many Flutter developers encounter is the disabled background interaction that arises when combining these two powerful widgets.
In this post, we’ll provide a clear understanding of the DraggableScrollableSheet and showBottomSheet widgets, discuss why background interaction is disabled when combining these widgets, and most importantly—showcase a practical, step-by-step solution allowing easy background interactions.
What is DraggableScrollableSheet and showBottomSheet?
Understanding DraggableScrollableSheet
The DraggableScrollableSheet widget offers a sheet of content that the user can drag upward or downward. It provides a flexible and interactive UI element in Flutter apps, ideal for contexts where you might want to provide additional information progressively. Examples of usage include maps (where more details slide up from the bottom), product cards in e-commerce apps, or even settings panels.
The key advantage here is that the user has complete control over how much information they want to view, enhancing UX significantly.
Understanding showBottomSheet
The showBottomSheet widget, on the other hand, displays a persistent bottom sheet at the bottom of your app screen. It is different from modal bottom sheets since it is not modal, meaning users can continue interacting with the parent UI while the bottom sheet is visible. This widget is often used to display additional details about items without fully interrupting user flow, such as extra details on a warning message, secondary actions, or quick-access toolbars.
How These Widgets Are Used in Flutter Applications
Flutter developers commonly use DraggableScrollableSheet and showBottomSheet to build interactive, accessible, and streamline experiences. This combination lets users swipe up sheets for additional functions while still preserving screen context.
However, developers frequently encounter a common usability issue when pairing both widgets together: interaction with the background content becomes disabled.
The Problem: Background Interaction Disabled
When using the DraggableScrollableSheet along with a BottomSheet in Flutter, typically one unintended effect arises—users find they can’t click, scroll, or interact with any elements behind the draggable sheet.
Instead, the primary background becomes unreachable, and users must first close or dismiss the sheet to regain interaction with the underlying UI elements. While this can be useful in certain contexts (when you want users to focus entirely on the visible content), it often creates a less intuitive user experience.
Why This Happens and How It Affects UX
This behavior occurs primarily because the default approach when combining bottom sheets relies on the modal barrier, resulting in disabled background interactions by design.
From a UX standpoint, it detracts from the user experience in scenarios where you’d ideally want a kind of transparent interaction. It becomes especially problematic in use cases like interactive maps, music apps, streaming apps, or any context where both the sheet and background interactions are anticipated simultaneously.
Hence, it’s critical to find a solution to enable background interaction effectively when combining these valuable widgets.
Solution: Enabling Background Interaction
To resolve this limitation, we need to explicitly enable background interactions while presenting a draggable scrollable bottom sheet in Flutter applications.
Below is a practical solution and step-by-step process to ensure both draggable scrollable functionality and seamless background interactions.
Code Snippet for Enabling Background Interaction
Here’s an easy-to-understand Flutter code snippet demonstrating how to implement background interaction effectively while displaying a DraggableScrollableSheet using showBottomSheet.
// Function to show bottom sheet with DraggableScrollableSheet
void showCustomDraggableScrollableSheet(BuildContext context) {
Scaffold.of(context).showBottomSheet(
(context) => DraggableScrollableSheet(
initialChildSize: 0.3,
minChildSize: 0.2,
maxChildSize: 0.8,
builder: (context, scrollController) {
return Container(
decoration: BoxDecoration(
color: Colors.white,
borderRadius: BorderRadius.vertical(top: Radius.circular(20)),
boxShadow: [
BoxShadow(
color: Colors.black12,
blurRadius: 10,
),
],
),
child: ListView.builder(
controller: scrollController,
itemCount: 50,
itemBuilder: (context, index) => ListTile(title: Text("Item $index")),
),
);
},
),
backgroundColor: Colors.transparent, // Transparent allows background interaction
);
}
Steps to Implement the Solution in Flutter
Follow these easy steps to successfully integrate transparent background interaction:
1: Create a Flutter scaffold with a body containing interactive elements such as Buttons, text fields, etc.
2: Implement the provided method in your Dart file, as shown above.
3: Invoke this method within desired events (button tap or gesture), ensure that the parent widget has a properly set Scaffold context.
The key element in this solution is making sure that no modal barrier or opaque color hinders background elements. Setting the backgroundColor parameter to transparent allows users to seamlessly interact with the content behind your draggable scrollable sheet.
Explanation of How the Solution Works
The above solution works by taking advantage of Flutter’s mechanism behind showBottomSheet. By explicitly setting the bottom sheet’s backgroundColor parameter to transparent, Flutter no longer blocks underlying interactive elements. The draggable scrollable content renders above the current screen thus allowing input events to pass through to the background UI when outside the sheet area.
This method provides a simple, elegant way to ensure smooth UX transitions while offering the rich interactivity of the scrollable sheet itself.
FAQs About DraggableScrollableSheet and showBottomSheet
What is the purpose of DraggableScrollableSheet and showBottomSheet in Flutter?
Flutter developers commonly use these widgets to display incremental information or persistent content at the bottom of the UI. These widgets provide enhanced user interaction and improve app performance by displaying content adaptively.
Why is background interaction typically disabled when combining DraggableScrollableSheet and showBottomSheet?
By default, Flutter’s UI widgets like bottom sheets add modal barriers that prevent interaction with elements behind. This is designed to direct user attention exclusively toward presented content but impacts user interaction significantly when background interaction is desired.
How does the provided solution enable background interaction effectively?
The solution specifically sets the background color of the bottom sheet to transparent. This prevents adding an opaque modal barrier behind the DraggableScrollableSheet, thus re-enabling background interaction.
Are there any limitations to enabling background interaction using this solution?
While the provided solution significantly improves user experience, one limitation might occur: confused views if you have overly complex UIs. Background interactions can potentially confuse users who expect full control within one visible content area only. Always assess and confirm this solution is appropriate for your users and their expectations.
Conclusion: Enhancing Flutter UX with DraggableScrollableSheet & showBottomSheet
We’ve explored the challenge Flutter developers face when implementing DraggableScrollableSheet alongside showBottomSheet widgets—loss of background interaction negatively impacting UX.
Thankfully, the solution we’ve covered is straightforward and effective. By setting your BottomSheet’s background to transparent you can re-enable intuitive background interaction, creating seamless user experiences.
Always remember, usability and user experience are fundamental when implementing interactive widgets. Evaluating your app context, use-case scenarios, and carefully examining user expectations helps tremendously in ensuring your Flutter apps offer both usability and delightful interaction.
Got questions or need more tailored insights on building interactive Flutter apps? Feel free to explore the Official Flutter Documentation or reach out in comments below. Happy coding!
