Parallax Scroll Effect in Flutter: Elevate Your App’s User Experience

Ashish Sharma
Nerd For Tech
Published in
4 min readOct 11, 2023

Parallax scrolling is a technique that can creating an illusion of depth and movement in your flutter design, this effect can captivate users and make your app more engaging. In this post, we’ll delve into the world of parallax scroll effects in Flutter, learning how to implement them step by step.

Understanding the Parallax Effect

Let’s start with the basics. Parallax scrolling is like that cool illusion where different objects seem to move at different speeds or in different directions. It adds depth and interactivity to your Flutter app, creating a visually engaging user experience.

Think of it as your app’s way of saying, “Hey, I’m not just any app; I’m the app that dances with your scroll.”

Implementaion

1. Setting Up Your Flutter Environment

Ensure you have a working Flutter project set up before you begin.

2. Create a List

In your Flutter app, you first need a list of items to display in your ListView. This can be a list of images, text, or any widget you want to apply the parallax effect to. For instance, if you’re creating a captivating image gallery, your list should contain images you want to scroll with that wow-factor.

Here’s a snippet of how you can create a simple list in Flutter:

/// This is your screen where you want to display list
class HotelListScreen extends StatefulWidget {
const HotelListScreen({super.key});

@override
State createState() => _HotelListScreenState();
}

class _HotelListScreenState extends State<HotelListScreen> {
final hotelImages = [
/// images' path
];

@override
Widget build(BuildContext context) {
return ListView.builder(
itemBuilder: (context, index) => Padding(
padding: const EdgeInsets.all(8.0),
child: ParallaxImage(
imagePath: hotelImages[index],
),
),
itemCount: hotelImages.length,
);
}
}
/// This is the widget which will be used for that wow animation.
/// Feel free to customise it accordingly...
class ParallaxImage extends StatelessWidget {
ParallaxImage({super.key, required this.imagePath});

final GlobalKey _backgroundImageKey = GlobalKey();
final String imagePath;

@override
Widget build(BuildContext context) {
return ClipRRect(
// Create rounded corners for the image
borderRadius: BorderRadius.circular(20.0),
child: AspectRatio(
// Define the aspect ratio for the image

aspectRatio: 16 / 9,
child: Flow(
delegate: ParallaxFlowDelegate(
/// Access the scrollable widget
scrollable: Scrollable.of(context),

// Context of the list item
listItemContext: context,

// Pass the background image key
backgroundImageKey: _backgroundImageKey,
),
// Apply anti-aliasing to the clipping
clipBehavior: Clip.antiAlias,
children: [
Image.asset(
imagePath,
// Use the provided key for this image
key: _backgroundImageKey,
fit: BoxFit.cover, // Set the image to cover the available space
),
],
),
),
);
}
}

What is _backgroundImageKey?

The _backgroundImageKey is a GlobalKey used to uniquely identify and reference a widget within a widget tree. In this specific code, it is employed for several key purposes:

A. Identifying the Image Widget: The _backgroundImageKey is associated with the Image.asset widget that loads an image from the provided imagePath. By assigning the same key to this widget, it enables the ParallaxFlowDelegate to locate and reference this particular image.

B. Synchronization with ParallaxFlowDelegate: The ParallaxFlowDelegate widget within the Flow widget uses the _backgroundImageKey to paint the background image with the desired parallax effect. It inspects the image's position and uses this key to understand which image to manipulate.

3. Create a Parallax Flow Delegate

Experiment with different settings to achieve the desired parallax effect. Enhance the user experience without overwhelming it.

Below is a code for flow Delegate:

Vertical flow delegate for parallax effect

Conclusion:

With the ParallaxImage widget, you've entered the world of parallax scrolling in Flutter. Whether you're looking to add depth to images, create captivating headers, or simply enhance the user experience, parallax effects offer a dynamic way to engage your audience.

Flutter gives you the power to explore new dimensions in app design. The parallax effect is a delightful addition to your toolkit, and with some creativity, it can breathe life into your apps like never before. So go ahead, experiment with this technique, and turn your Flutter app into a parallax playground!

Let me know your thoughts and share your parallax creations. Happy Fluttering!

That’s it for this article! I hope you enjoyed it and leave a few claps if you did. Follow me for more Flutter articles and comment for any feedback you might have about this article.

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Ashish Sharma
Nerd For Tech

TheFlutterist: Teaching Flutter in the most playful way possible. Join me in the land of widgets and hot reloads! http://flutterist.in/