Скачать или смотреть How to Extract CustomScrollView Elements into a Separate Widget in Flutter

Discover how to efficiently extract `CustomScrollView` elements into a separate widget in Flutter, while maintaining the layout functionality.
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This video is based on the question https://stackoverflow.com/q/58718556/ asked by the user 'Alexander' ( https://stackoverflow.com/u/4823692/ ) and on the answer https://stackoverflow.com/a/62698744/ provided by the user 'Jorge Vieira' ( https://stackoverflow.com/u/2831595/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Extract CustomScrollView Elements into a Separate Widget in Flutter

When working with Flutter's powerful CustomScrollView, you may find yourself needing to extract certain elements into a separate widget for better code organization and reusability. This is especially important for maintaining a clean and understandable codebase as your application grows. In this post, we will explore how to extract specific Slivers from a CustomScrollView and nest them within a new widget without losing the desired scrolling effects.

The Problem: Extracting Sliver Elements

Let’s say you have the following CustomScrollView structure:

[[See Video to Reveal this Text or Code Snippet]]

The goal is to refactor this code, specifically extracting the second SliverPersistentHeader (which is pinned) and some additional elements into a new widget called ExtractedWidget. This helps to keep your main UI code clean and more manageable.

The Solution: Creating an Extracted Widget

Step 1: Define the New Extracted Widget

To extract the desired Sliver elements, you can create a new Stateless widget named ExtractedWidget. The challenge is returning the right structure of Slivers because only Sliver widgets are accepted in the slivers list of a CustomScrollView. The correct way to return the sliver is demonstrated below:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Using a Container for Additional Widgets

If you want to include multiple widgets inside the ExtractedWidget, you need a container that can hold them together as a sliver. One common approach is to use SliverToBoxAdapter, which allows embedding standard widgets into a sliver list. Below is an example that demonstrates how to include both Widgets Two and Three into the extracted widget:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Update the CustomScrollView

Once you have created the ExtractedWidget, you can update your original CustomScrollView to include this widget like so:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By following the above steps, you can neatly extract Slivers from your CustomScrollView into a dedicated widget, maintaining the expected functionality of the scrolling UI. This not only improves code clarity but also enhances the reusability of your components. Remember, when including a combination of Slivers and standard widgets, incorporating SliverToBoxAdapter can help you manage that effectively. Happy coding!