如何在颤动中为容器设置动画边框

Question

我想用颤动的发光效果为我的容器的边框设置动画，你知道吗？

Answer 1

Below code will animate the width of the border

class Test extends StatefulWidget {
  @override
  _TestState createState() => _TestState();
}

class _TestState extends State<Test> with TickerProviderStateMixin {

  AnimationController _resizableController;

  AnimatedBuilder getContainer() {
    return new AnimatedBuilder(
        animation: _resizableController,
        builder: (context, child) {
          return Container(
            padding: EdgeInsets.all(24),
            child: Text("SAMPLE"),
            decoration: BoxDecoration(
              shape: BoxShape.rectangle,
              borderRadius: BorderRadius.all(Radius.circular(12)),
              border: Border.all(
                  color: Colors.blue, width: _resizableController.value * 10),
            ),
          );
        });
  }

  @override
  void initState() {
    _resizableController = new AnimationController(
      vsync: this,
      duration: new Duration(
        milliseconds: 1000,
      ),
    );
    _resizableController.addStatusListener((animationStatus) {
      switch (animationStatus) {
        case AnimationStatus.completed:
          _resizableController.reverse();
          break;
        case AnimationStatus.dismissed:
          _resizableController.forward();
          break;
        case AnimationStatus.forward:
          break;
        case AnimationStatus.reverse:
          break;
      }
    });
    _resizableController.forward();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        backgroundColor: Colors.white,
        appBar: AppBar(
          title: Text("Test"),
          centerTitle: true,
        ),
        body: Center(child: getContainer()));
  }
}

Answer 2

Thanks to Lakhwinder Singh, I made this code and it does the glowing effect that I asked:

import 'package:flutter/material.dart';

void main()  {
  runApp(new Test());
}

class Test extends StatefulWidget {
  @override
  _TestState createState() => _TestState();
}

class _TestState extends State<Test> with TickerProviderStateMixin {

  AnimationController _resizableController;

  static Color colorVariation(int note){
    if(note <= 1){
      return Colors.blue[50];
    }else if(note>1 && note<=2){
      return Colors.blue[100];
    }else if(note>2 && note<=3){
      return Colors.blue[200];
    }else if(note>3 && note<=4){
      return Colors.blue[300];
    }else if(note>4 && note<=5){
      return Colors.blue[400];
    }else if(note>5 && note<=6){
      return Colors.blue;
    }else if(note>6 && note<=7){
      return Colors.blue[600];
    }else if(note>7 && note<=8){
      return Colors.blue[700];
    }else if(note>8 && note<=9){
      return Colors.blue[800];
    }else if(note>9 && note<=10){
      return Colors.blue[900];
    }
  }

  AnimatedBuilder getContainer() {
    return new AnimatedBuilder(
        animation: _resizableController,
        builder: (context, child) {
          return Container(
            //color: colorVariation((_resizableController.value *100).round()),
            padding: EdgeInsets.all(24),
            child: Text("SAMPLE"),
            decoration: BoxDecoration(
              shape: BoxShape.rectangle,
              borderRadius: BorderRadius.all(Radius.circular(12)),
              border: Border.all(
                  color: colorVariation((_resizableController.value *10).round()), width:10),
            ),
          );
        });
  }

  @override
  void initState() {
    _resizableController = new AnimationController(
      vsync: this,
      duration: new Duration(
        milliseconds: 500,
      ),
    );
    _resizableController.addStatusListener((animationStatus) {
      switch (animationStatus) {
        case AnimationStatus.completed:
          _resizableController.reverse();
          break;
        case AnimationStatus.dismissed:
          _resizableController.forward();
          break;
        case AnimationStatus.forward:
          break;
        case AnimationStatus.reverse:
          break;
      }
    });
    _resizableController.forward();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home:Scaffold(
        backgroundColor: Colors.white,
        body: Center(child: getContainer())));
  }
}

Answer 3

If you use a State Management package in your app such Get, Provider, etc.

You may listen to AnimationContiner with a bool that you have provide

Let's say that you have a bool calls "isEmptyError"

final isEmptyError = false.obs;

Obx(
      () => AnimatedContainer(
        duration: const Duration(seconds: 1),
        curve: Curves.fastOutSlowIn,
        decoration: BoxDecoration(
          border: Border.all(
            color: Get.theme.primaryColor,
            width: 6,
            style: isEmptyError() ? BorderStyle.solid : BorderStyle.none,
          ),
        ),
        child: TextButton(
            style: ButtonStyle(overlayColor: MaterialStateColor.resolveWith((_) => Colors.transparent)),
            child: const Text('Press To Flash'),
            onPressed: () {
              isEmptyError(true);
              Future.delayed(const Duration(milliseconds: 300), () => isEmptyError(false));
              Future.delayed(const Duration(milliseconds: 600), () => isEmptyError(true));
              Future.delayed(const Duration(milliseconds: 900), () => isEmptyError(false));
            },
        ),
      ),
    ),

I hope you manage to solve the issue n I hope this one helps others.