Platform Conforming Widgets for Flutter

platty

Flutter makes no attempt to provide familiar widgets for a specific platform (unlike React Native, ionic, and other cross platform tooling). This has enormous benefits to unified rendering on all platforms, maximum flexibility, and eliminating a whole class of bugs and testing done for each platform. While this is great, many scenarios we want our apps to look and feel like an Android or iOS app. Platty allows you to render iOS (Cupertino) and Android (Material) like widgets with minimal effort and maximum control in a unified API.

No more checking for platform inside render blocks to render a CupertinoButton or FlatButton, let platty do the logic for you! Want to use bottom tabs in your app that resolve to platform specific UI? No problem!

Getting Started

Use platty to unify render-specific APIs for you. The library utilizes the BuildContext theming APIs to propagate platform
information into the Widgets.

By default, all widgets conform to the default TargetPlatform. It looks up the Theme.of(context).platform for its default.
Also, all widgets provide a renderPlatform prop that allows you to choose which one to render (if you wish).

Replace MaterialApp and CupertinoApp with PlatformApp:

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return PlatformApp(
      title: 'Flutter Demo',
      // specify our app theme here. We do the leg work of bridging it to Cupertino.
      unifiedTheme: ThemeData(
            primarySwatch: Colors.lightBlue,
            bottomAppBarColor: Colors.red,
          ),
      home: ExamplePage(),
    );
  }
}

Dart

PlatformApp unifies all of the same properties between MaterialApp and CupertinoApp to allow both instances of widgets in the hiearchy and
switching styling based on platform.

Now you replace widgets that are included in this library with their "P" counterparts:

Button/CupertinoButton -> PButton




Source

FlatButton/CupertinoButton -> PFlatButton

Source

AppBar/CupertinoNavigationBar -> PNavigationBar




Source

SliverAppBar/CupertinoSliverNavigationBar -> PSliverNavigationBar

Slider/CupertinoSlider -> PSlider

Source

Switch/CupertinoSwitch -> PSwitch

Source

Scaffold/CupertinoScaffold -> PScaffold

CircularProgressIndicator/CupertinoActivityIndicator -> PActivityIndicator

Source

BackButton/CupertinoNavigationBarBackButton -> PBackButton

AlertDialog/CupertinoAlertDialog -> PAlertDialog

Source

Properties Specific to a platform have a prefix

Any widgets that have ios-only or android-only counterparts, they are prefixed to android/ios accordingly:

For example PButton, androidShape applies to RaisedButton.shape property. It does not exist on a CupertinoButton.
However CupertinoButton has a borderRadius and pressedOpacity. Those two props become iosBorderRadius and iosPressedOpacity.

Helpers

This library bundles a few standard functions to easily return code that is unique for each platform. Instead of checking
and switching on the result of Theme.of(context).targetPlatform, utilize the following methods:

Specific Platform Instance

To have a specific P-Widget utilize a specific platform theme only, such as Material or Cupertino, you can wrap
it in a PTheme instance:

PTheme(
  data: PThemeData(
    platform: TargetPlatform.android,  // or iOS
    child: child,
  ),
);

Dart

Or, more simply, utilize helper method:

PTheme.ios(child);
PTheme.android(child);

Dart

Also, all P-widgets and methods allow you to override the PTheme with a renderPlatformparameter in their constructor
or calling method:

PButton("Hello Android", 
  renderPlatform: TargetPlatform.Android,
)

Dart

This will swap the rendering over to Material widgets for this specific widget.

Note: Wrapping a widget with the PTheme will propagate that instance down the widget hierarchy and is thus preferred than
manually specifying the renderPlatform for each individual widget.

Creating Your Own Platform-Adapting Widgets

We can extend upon the logic included in this library to build our own, powerful platform-adapting widgets.
Included in the library is the PlatformAdaptingWidget base class, which inherits from StatelessWidget.

class SamplePlatformWidget extends PlatformAdaptingWidget {
  final Color color;

  SamplePlatformWidget({Key key, @required this.color, TargetPlatform renderPlatform}) // should allow consumers to choose TargetPlatform
      : super(key: key, renderPlatform: renderPlatform);

  /// Render a material widget here. Most Material widgets require a Material Theme instance above it.
  @override
  get renderMaterial => (BuildContext context) {
        return BackButton(
          color: color,
        );
      };

  /// Render a cupertino widget here.
  @override
  get renderCupertino => (BuildContext context) {
        return CupertinoNavigationBarBackButton(
          color: color,
        );
      };
  
  /// Render a fuchsia widget here. (defaults to material)
    @override
    get renderFuchsia => (BuildContext context) {
          return BackButton(
            color: color,
          );
        };
}

Dart

Platform-specific logic

This library comes with a few standard ways to implement behavior based on platform.
You can utilize platformWrap, which allows you to specify a child, and on 1 or all platforms, wrap it
with another widget:

platformWrap(
      context,
      child: PButton(
        padding: EdgeInsets.all(0.0),
        child: Text(title),
        color: Colors.red,
        onPressed: () {
          Navigator.push(context, PlatformRoute.of(context, builder: page));
        },
      ),
      renderCupertino: (context, child) => Padding(
            padding: EdgeInsets.only(bottom: 8.0),
            child: child,
          ),
    );

Dart

You can specify any of renderCupertino, renderMaterial, or renderFuschia (or none).
Any render methods not specified default to the child.

Also, platformSelect is a helper that enables returning different objects based on platform in a unified way.
In our PlatformAdaptingWidget, we utilize it to return a different widget based on platform. You can use it to return any
return type based on platform:

Column(
  children: [
    platformSelect(context, 
      renderMaterial: (context) => Text("I am android"),
      renderCupertino: (context) => Text("I am iOS"),
      renderFuchsia: (context) => Text("I am FUCHSIA")) 
  ],
),

Dart

renderMaterial and renderCupertino are required. renderFuchsia defaults to material.

or you can return a non-widget too:

Column(
  children: [
    Text(platformSelect(context, 
      renderMaterial: (context) => "I am android"),
      renderCupertino: (context) => "I am iOS",
      renderFuchsia: (context) => "I am FUCHSIA")) 
  ],
),

GitHub

fuzz-productions/platty

261

Platform-adapting flutter widgets. — Read More

Latest commit to the master branch on 1-3-2019

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