Introduction

Have you ever found yourself in the situation of doing some async processing your screen and wanting to prevent the user from interacting with the screen while the application is loading? If so, this package was made just for you.

Basic Usage

The most simple usage is just wrap the widget that you want an overlay on LoaderOverlay. Default loader will be shown.

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: LoaderOverlay(
        child: MyHomePage(title: 'Flutter Demo Home Page'),
      ),
    );
  }
}

This simple step will already configure the loader overlay for use.

After that configuration you can just call:

context.loaderOverlay.show();

This will show the overlay with the default loading indicator. The default loading configured is to just show a centered CircularProgressIndicator

To hide the overlay (after the async processing, for example), just call:

context.loaderOverlay.hide();

You can check if overlay is visible:

final isVisible = context.loaderOverlay.visible;

*Note: You will always need the context to show or hide the loader overlay

Basic Usage on Navigation

To use this package with named routes you can just wrap your MaterialApp with GlobalLoaderOverlay. This widget has all the features of LoaderOverlay but it is provided for all the routes of the app.

@override
Widget build(BuildContext context) {
  return GlobalLoaderOverlay(
    child: MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Flutter Demo',
      theme: ThemeData(primarySwatch: Colors.teal, fontFamily: 'Baloo'),
      initialRoute: '/',
      routes: {
        '/': (context) => Page1(),
        '/page2': (context) => Page2(),
      },
    ),
  );
}

Customization

Your overlay loader widget can be any widget you want. For example you can import the package flutter_spinkit and customise your widget like this. To do that just pass your widget to overlayWidget and set useDefaultLoading to false.

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: LoaderOverlay(
        useDefaultLoading: false,
        overlayWidgetBuilder: (_) { //ignored progress for the moment
          return Center(
            child: SpinKitCubeGrid(
              color: Colors.red,
              size: 50.0,
            ),
          );
        },
        child: MyHomePage(title: 'Flutter Demo Home Page'),
      ),
    );
  }
}

Another customisation you can do is configure the color and opacity of the overlay. The default opacity is grey with 0.4 opacity, but you can change it with the overlayColor: Colors.yellow.withValues(alpha: 0.8).

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: LoaderOverlay(
        useDefaultLoading: false,
        overlayWidgetBuilder: (_) { //ignored progress for the moment
          return Center(
            child: SpinKitCubeGrid(
              color: Colors.red,
              size: 50.0,
            ),
          );
        },
        overlayColor: Colors.yellow.withValues(alpha: 0.8),
        child: MyHomePage(title: 'Flutter Demo Home Page'),
      ),
    );
  }
}

This is a much opaque yellow overlay:

You may want to have several different loaders in your app. In this case just pass any widget to the loaderOverlay.show:

class ReconnectingOverlay extends StatelessWidget {
  String? progress;

  ReconnectingOverlay(this.progress);

  @override
  Widget build(BuildContext context) =>
      Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            CircularProgressIndicator(),
            SizedBox(height: 12),
            Text(
              'Reconnecting...',
            ),
            SizedBox(height: 12),
            Text(
              progress ?? '',
            ),
          ],
        ),
      );
}

context.loaderOverlay.show(
  widgetBuilder: (progress) {
    return ReconnectingOverlay(
      progress != null ? progress as String : null,
    );
  },
);

If you pass widget to context.loaderOverlay.show, then defaultLoader and widgetOverlay will be ignored;

Progress

If you want to show some progress while the loader overlay is visible, you can do it with the context.loaderOverlay.show(progress: 'Doing progress #0',) for an initial progress, and with context.loaderOverlay.progress('Doing progress #1'); every time the progress need to change. Both this methods pass the progress to the current widgetBuilder on every call.

Setting up the builder to use the progress

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: LoaderOverlay(
        useDefaultLoading: false,
        overlayWidgetBuilder: (dynamic? progress) {
          return Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              SpinKitCubeGrid(
                color: Colors.red,
                size: 50.0,
              ),
              SizedBox(
                height: 50,
              ),
              if (progress != null) Text(progress)
            ],
          );
        },
        child: MyHomePage(title: 'Flutter Demo Home Page'),
      ),
    );
  }
}

Once the builder is configured, you can call it and update the progress by calling:

context.loaderOverlay.show(
  progress: 'Doing progress #0',
);

await Future.delayed(Duration(seconds: 1));
context.loaderOverlay.progress('Doing progress #1');
await Future.delayed(Duration(seconds: 1));
context.loaderOverlay.progress('Doing progress #2');
await Future.delayed(Duration(seconds: 1));
context.loaderOverlay.progress('Doing progress #3');
await Future.delayed(Duration(seconds: 1));

if (_isLoaderVisible) {
  context.loaderOverlay.hide();
}

This will have as result:

You can also remove by complete the overlayColor (set to transparent), set the useDefaultLoading to false, and use a fully personalized overlayWidgetBuilder to make your own 100% customizable overlay.

    LoaderOverlay(
      overlayColor: Colors.transparent,
      useDefaultLoading: false,
      overlayWidgetBuilder: (progress) {
        return BackdropFilter(
          filter: ImageFilter.blur(
            sigmaX: 4.5,
            sigmaY: 4.5,
          ),
          child: Center(
            child: Container(
              width: 100,
              height: 100,
              color: Colors.purple,
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  CircularProgressIndicator(),
                  Text(
                    'Doing stuff... bip...bup',
                    textAlign: TextAlign.center,
                  )
                ],
              ),
            ),
          ),
        );
      },
    )

Breaking changes

1 - Since version 3.0.0 the overlay widget's got changed by a builder to manage the progress.

Before:

      LoaderOverlay(
        //...
        useDefaultLoading: false,
        overlayWidget: Center(
          child: SpinKitCubeGrid(
            color: Colors.red,
            size: 50.0,
          ),
        ),
        //...      
      )

After:

      LoaderOverlay(
        //...
        useDefaultLoading: false,
        overlayWidgetBuilder: (_) {
          return Center(
            child: SpinKitCubeGrid(
              color: Colors.red,
              size: 50.0,
            ),
          );
        },
        //...
      )

2 - overlayOpacity was removed. Now use the opacity direct in the overlayColor

Before:

      LoaderOverlay(
        //...
        overlayColor: Colors.black,
        overlayOpacity: 0.8,
        //...
      )

After:

      LoaderOverlay(
        //...
        overlayColor: Colors.black.withValues(alpha: 0.8),
        //...
      )

Animation

By default, the overlay does not animate in or out. You can enable animations by passing the appropriate parameters to LoaderOverlay. Internally, an AnimatedSwitcher is used to manage animations, so the parameters are passed directly to the AnimatedSwitcher. By specifying a duration and reverseDuration, the overlay will animate in and out using a fade (the default transition used by AnimatedSwitcher). You can also pass curves, a transition builder and a layout builder for further customisation.

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: LoaderOverlay(
        duration: const Duration(milliseconds: 250),
        reverseDuration: const Duration(milliseconds: 250),
        // switchInCurve,
        // switchOutCurve,
        // transitionBuilder,
        // layoutBuilder,
        child: MyHomePage(title: 'Flutter Demo Home Page'),
      ),
    );
  }
}

Todo

• Tests

Suggestions & Bugs

For any suggestions or bug report please head to issue tracker.