Flutter Packages

Flutter packages are pre-built pieces of functionality that can be added to Flutter apps to speed up development and add new features. There are thousands of packages available, covering everything from UI components to network connectivity, storage, and more. In this page, we will explore some basics of Flutter packages.

Syntax

Adding a package to a Flutter project involves adding a dependency to the project's pubspec.yaml file:

dependencies:
  flutter:
    sdk: flutter
  package_name: ^1.0.0

In this example, the package_name package is being added to the project.

Example

An example of using a Flutter package to display a fancy progress dialog might look like this:

import 'package:flutter/material.dart';
import 'package:progress_dialog/progress_dialog.dart';

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  ProgressDialog pr;

  @override
  void initState() {
    super.initState();
    pr = new ProgressDialog(context, type: ProgressDialogType.Normal);
    pr.style(
      message: 'Please wait...',
    );
  }

  void _onButtonPressed() async {
    await pr.show();
    await Future.delayed(Duration(seconds: 3)); // simulate network call
    await pr.hide();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Demo Progress Dialog"),
      ),
      body: Center(
        child: RaisedButton(
          onPressed: _onButtonPressed,
          child: Text("Show Progress Dialog"),
        ),
      ),
    );
  }
}

In this example, the progress_dialog package is being used to display a progress dialog when the user taps a button.

Output

The output of this example is a Flutter app that displays a button. When the button is pressed, a progress dialog is displayed for three seconds, then disappears.

Explanation

The above example demonstrates how to use the progress_dialog package to show a loading indicator in a Flutter app. The package is added to the pubspec.yaml file and then imported in the app using import 'package:progress_dialog/progress_dialog.dart';.

The ProgressDialog object is created in the _MyHomePageState class's initState() method, where its style is set. When the button is pressed, _onButtonPressed() is called, which calls pr.show() to display the progress dialog. After a simulated network call using Future.delayed(), pr.hide() is called to hide the dialog.

Use

Flutter packages can be used in a variety of ways, such as:

• Adding new UI components to an app
• Simplifying common tasks, such as parsing JSON data or accessing device functionality
• Connecting to APIs and other web services
• Adding new functions and utilities to an app

Important Points

• Flutter packages are an essential component of the Flutter ecosystem and can greatly speed up development.
• It's important to choose well-maintained and up-to-date packages that fit the project's needs.
• Developers should consider contributing to the Flutter package community by creating and sharing their own packages.

Summary

Flutter packages provide developers with a wide range of pre-built functionality that can be added to Flutter apps. By adding a dependency line to the project's pubspec.yaml file, developers can quickly take advantage of packages for everything from UI components to web services. Proper use of packages can greatly speed up development and lead to more efficient and effective apps.