Chapter 1 Understanding InheritedWidget

The InheritedWidget is a powerful tool that often goes underutilized in Flutter applications. Many developers struggle to implement it correctly, which can hinder the app's performance and functionality.

To get started, copy the inherited_state_mixin.dart gist. This mixin provides a well-structured InheritedWidget that can be seamlessly integrated with any State class. By using this mixin, you'll eliminate common pitfalls in the implementation of InheritedWidgets.

Previously, I introduced a similar concept through a free article, but it required the use of my own Flutter framework. The new approach, utilizing a mixin, makes it far more adaptable. This article will showcase an example app to illustrate how to apply this mixin effectively.

In this video titled "InheritedWidget (Flutter Widget of the Week)", you'll find valuable insights into the InheritedWidget's capabilities and best practices.

Section 1.2 The Example App

I've created an example app that demonstrates the mixin in action. Below is a video showcasing the app's startup. The buttons at the bottom labeled 'New Dogs', 'New Cats', 'New Birds', and 'New Foxes' allow users to fetch images from public APIs.

With each button press, three new images of the selected animal are retrieved. The beauty of the InheritedWidget is that it allows for selective rebuilding of widgets. When the InheritedWidget is invoked repeatedly, only the widgets that depend on it are rebuilt, enhancing performance and efficiency.

Let's explore how to implement this mixin. Four key elements in the screenshot below are highlighted, guiding us through the implementation process.

The first element is the mixin, InheritedStateMixin. Attach this mixin to your State class using the with clause to get started. The next highlighted function is initInheritedState(), which is crucial for the functionality of the mixin. This function takes in two parameters: the type of the InheritedWidget and a builder that provides the 'child' widget.

Finally, there's the buildChild() function, which works like any standard build() function in a State object. It returns the necessary 'child' widget for the InheritedWidget.

Chapter 2 Efficient State Management

In the example app, you'll find additional classes, each with its own InheritedWidget, linked to various State objects responsible for displaying images of specific animals.

Each time the InheritedWidget is called, the associated State objects are rebuilt, ensuring that only the relevant parts of the app are updated—demonstrating the true power of using InheritedWidgets correctly.

The second video titled "Flutter State Management using InheritedWidget for Journal App - No Packages" illustrates practical applications of the InheritedWidget in state management.

The images in the app are sourced from the following public APIs:

This example highlights common mistakes in InheritedWidget usage. Often, developers place the InheritedWidget too high in the widget tree, leading to unnecessary rebuilding of the entire app interface. Instead, focus on leveraging InheritedWidgets for selective rebuilding to optimize efficiency.

In short, when using the InheritedStateMixin, you're not just simplifying your build() function; you're also optimizing your setState() function to call the appropriate internal State object containing the InheritedWidget.

Feel free to explore the mixins shared in this article, as they can greatly streamline your Flutter development process. Remember, efficient state management is key to delivering high-performance applications, especially for mobile devices.

Cheers!