AnimatedWidgets

animated_widgets

Easily add animations on your screen with AnimatedWidgets.

Optimized for MVVM using Bloc, updating the enabled value of the widget will forward or reverse the animation.

Available widgets : TranslationAnimatedWidget, OpacityAnimatedWidget, RotationAnimatedWidget, ScaleAnimatedWidget, SizeAnimatedWidget

For example : add a TranslationAnimatedWidget on a button, then activate it to display it !

TranslationAnimatedWidget(
    enabled: this.displayMyWidget, //update this boolean to forward/reverse the animation
    values: [
        Offset(0, 200), // disabled value value
        Offset(0, 250), //intermediate value
        Offset(0, 0) //enabled value
    ],
    child: /* your widget */
),

or using a tween constructor

RotationAnimatedWidget.tween(
    enabled: this.displayMyWidget, //update this boolean to forward/reverse the animation
    rotationDisabled: Rotation.degrees(z: 0),
    rotationEnabled: Rotation.degrees(z: 90),
    child: /* your widget */
),

Compose

Don't hesitate to compose them

TranslationAnimatedWidget.tween(
    enabled: this.displayMyWidget,
    translationDisabled: Offset(0, 200),
    translationEnabled: Offset(0, 0),
    child:
        OpacityAnimatedWidget.tween(
        enabled: this.displayMyWidget,
        opacityDisabled: 0,
        opacityEnabled: 1,
        child: /* your widget */
    ),
),

Opacity

Example using a Stateful Widget

class _StatefulScreenState extends State<StatefulScreen> {

  // will determine if the opacity animation is launched
  bool _display = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        mainAxisAlignment: MainAxisAlignment.center,
        mainAxisSize: MainAxisSize.max,
        children: [

          //wrap your widget with OpacityAnimatedWidget
          OpacityAnimatedWidget.tween(
            opacityEnabled: 1, //define start value
            opacityDisabled: 0, //and end value
            enabled: _display, //bind with the boolean
            child: Container(
               height: 200,
               width: 200,
               child: FlutterLogo(
                 style: FlutterLogoStyle.stacked,
               ),
            ),
          ),

          RaisedButton(
            color: Colors.blue,
            child: Text(
              _display ? "hide logo" : "display logo",
              style: TextStyle(color: Colors.white),
            ),
            onPressed: () {
              setState(() {

                //will fire the animation
                _display = !_display;

              });
            },
          )
        ],
      ),
    );
  }
}

Translation

Example using bloc pattern

class FirstScreenBloc extends Bloc {
  final _viewState = BehaviorSubject<FirstScreenViewState>.seeded(FirstScreenViewState());
  Observable<FirstScreenViewState> get viewState => _viewState;

  void onClicked() {
    _viewState.add(FirstScreenViewState(buttonVisible: true));
  }

  void onDismissClicked() {
    _viewState.add(FirstScreenViewState(buttonVisible: false));
  }

  @override
  void dispose() {
    _viewState.close();
  }
}

class FirstScreenViewState {
  final bool buttonVisible;

  const FirstScreenViewState({
    this.buttonVisible = false,
  });
}

class FirstScreenView extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final bloc = BlocProvider.of<FirstScreenBloc>(context);

    return StreamBuilder<FirstScreenViewState>(
            stream: bloc.viewState,
            builder: (context, snapshot) {

                final viewState = snapshot.data;

                return Stack(
                  fit: StackFit.expand,
                  children: [
                    _buildInputButton(onClicked: () {
                      bloc.onClicked();
                    }),
                    Positioned(
                      bottom: 20,
                      left: 20,
                      right: 20,

                      child: TranslationAnimatedWidget(
                        enabled: viewState.buttonVisible, //will forward/reverse the animation
                        curve: Curves.easeIn,
                        duration: Duration(seconds: 1),
                        values: [
                          Offset(0, 200),
                          Offset(0, -50),
                          Offset(0, 0),
                        ],
                        child: RaisedButton(
                          onPressed: () {
                            bloc.onDismissClicked();
                          },
                          child: Text("Dismiss"),
                        ),

                      ),
                    ),
                  ],
               );
            }
        );
  }
}

Rotation

RotationAnimatedWidget.tween(
    enabled: enabled,
    rotationDisabled: Rotation.deg(),
    rotationEnabled: Rotation.deg(z: 90, x: 80),
    child: /* your widget */
),

RotationAnimatedWidget.tween(
    enabled: enabled,
    rotation: Rotation.deg(),
    rotationEnabled: Rotation.deg(z: 90, x: 80),
    child: /* your widget */
),

Scale

ScaleAnimatedWidget.tween(
      enabled: this._enabled,
      duration: Duration(milliseconds: 600),
      scaleDisabled: 0.5,
      scaleEnabled: 1,

      //your widget
      child: Container(
        height: 200,
        width: 200,
        child: FlutterLogo(
          style: FlutterLogoStyle.stacked,
        ),
      ),
    ),

Size

SizeAnimatedWidget(
      enabled: this._enabled,
      duration: Duration(milliseconds: 1500),
      values: [Size(100, 100),  Size(100, 150), Size(200, 150), Size(200, 200)],
      curve: Curves.linear,

      //your widget
      child: Container(
        decoration: BoxDecoration(
          border: Border.all(color: Colors.blue)
        ),
        child: FlutterLogo(
          style: FlutterLogoStyle.stacked,
        ),
      ),
    ),

Shake

ShakeAnimatedWidget(
      enabled: this._enabled,
      duration: Duration(milliseconds: 1500),
      shakeAngle: Rotation.deg(z: 40),
      curve: Curves.linear,
      child: FlutterLogo(
        style: FlutterLogoStyle.stacked,
      ),
    ),

Custom Animated

CustomAnimatedWidget(
      enabled: this._enabled,
      duration: Duration(seconds: 3),
      curve: Curves.easeOut,
      builder: (context, percent) { //for custom animation, use builders
        final int displayedDate = (2018 * percent).floor();
        return Text(
              "current year : $displayedDate",
              style: TextStyle(color: Colors.blue),
        );
      },
),

Flutter Package

Animated widget is available at https://pub.dev/packages/animated_widgets

dependencies:
  animated_widgets:

Getting Started with Flutter

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License

Copyright 2019 florent37, Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.