XML Layout for Flutter

Flutterappworld

3 years ago

XML Layout for Flutter. Brings Angular’s style to Flutter!

Imagine that you can do this :

<Container width="50 | widthPercent"
           height="50 | heightPercent"
           color="blue"
           :text="'Hello world!'"
           :opacity=".9"
           :center
           :if="ctrl.textVisible | behavior" />

Instead of this:

    final size = MediaQuery.of(context).size;
    final __widget = StreamBuilder(
      initialData: ctrl.textVisible.value,
      stream: ctrl.textVisible,
      builder: (BuildContext context, snapshot) {
        if (snapshot.data) {
          return Opacity(
            opacity: .9,
            child: Center(
              child: Container(
                color: Colors.blue,
                height: (size.height * 50) / 100.0,
                width: (size.width * 50) / 100.0,
                child: Text(
                  'Hello world!'
                )
              )
            )
          );
        }
        else {
          return Container(width: 0, height: 0);
        }
      }
    );
    return __widget;

Which is about 20 lines of code, and if you just updated the :text property to use a stream variable :text="ctrl.myTextStream | stream" that will add another 4 lines of code for the StreamBuilder.

Extension features:

Separates UI code (widget and widget’s state) from the business logic.
Brings some Angular’s features like pipes, conditionals…
Provides built-in properties & pipes to make the coding much easier.
Generates localization code depending on json files.
Forms & animation made easy.
Customizable! so developers can add their own properties and modify some features.
Supports Code completion, hover information, Go to Definition, diagnostics and code actions.

Example

Here is a working example

Get Started

Install the extension from vscode marketplace
Create a new flutter project
Install prerequisites packages:
- flutter_xmllayout_helpers
- provider
- flutter_localizations

dependencies:
  flutter:
    sdk: flutter
  flutter_localizations:
    sdk: flutter
  provider: ^3.0.0+1
  flutter_xmllayout_helpers: ^0.0.9

Apply one of the following steps:
- Clear all main.dart content then use fxml_app snippet to create the app.
- Modify main.dart to use MultiProvider from provider package:
  - Register PipeProvider (from flutter_xmllayout_helpers package) as a provider.
  - Register RouteObserver<Route> as a provider (only if you want to use RouteAware events in your widgets’ controllers).

Localization:

Create i18n folder inside lib folder and add JSON files named with locale codes e.g. en.json.
Import i18n/gen/delegate.dart in the main file.
Register AppLocalizationsDelegate() in localizationsDelegates parameter of the MaterialApp.
To use localized text in the UI see Pipes docs.

XML layout:

Create a new folder and name it as your page/widget name e.g. home.
Then create home.xml file inside home folder.
Use fxml_widget snippet to create the starter layout, modify it as you want then save it. the extension will generate a file named home.xml.dart which contains UI code, and home.ctrl.dart file (if not exists) that contains the controller class which is the place you should put your code in (will be generated only if you added controller property).

Example:

<HomePage controller="HomeController" routeAware
    xmlns:cupertino="package:flutter/cupertino.dart">

  <Scaffold>

    <appBar>
      <AppBar>
        <title>
          <Text text="'Home'" />
        </title>
      </AppBar>
    </appBar>

    <body>
      <Column mainAxisAlignment="center" crossAxisAlignment="center">
        <Image :use="asset" source="'assets/my_logo.png'" />
        <Text text="'Hello world!'" />
        <Icon icon="CupertinoIcons.home" />
      </Column>
    </body>
  </Scaffold>
</HomePage>

HomePage (root element) the name of your widget. controller an optional property, the controller name you want to generate. routeAware an optional property, which generates navigation events (didPush(), didPop(), didPushNext() and didPopNext()). xmlns:* an optional property(s) used to import packges and files to be used in HomePage class. (in this example we imported cupertino.dart to use CupertinoIcons).

Controller:

If you added a controller property to your widget then will be generated (if not exists), the file looks like this:

import 'package:flutter/widgets.dart';
import 'home.xml.dart';

class HomeController extends HomeControllerBase {

  //
  // here you can add you own logic and call the variables and methods
  // within the XML file. e.g. <Text text="ctrl.myText" />
  //

  @override
  void didLoad(BuildContext context) {
  }

  @override
  void onBuild(BuildContext context) {
  }

  @override
  void afterFirstBuild(BuildContext context) {
  }

  @override
  void dispose() {
    super.dispose();
  }
}