Flutter 实现虎牙/斗鱼 弹幕功能

@override
void initState() {
 _animationController =
  AnimationController(duration: widget.duration, vsync: this)
 ..addStatusListener((status){
 if(status == AnimationStatus.completed){
  widget.onComplete('');
 }
 });
 var begin = Offset(-1.0, .0);
 var end = Offset(1.0, .0);
 
 _animation = Tween(begin: begin, end: end).animate(_animationController);
 //开始动画
 _animationController.forward();
 super.initState();
}

@override
 Widget build(BuildContext context) {
 return SlideTransition(
  position: _animation,
  child: widget.child,
 );
 }

_computeTop(int index, double perRowHeight) {
 //第几轮弹幕
 int num = (index / widget.showCount).floor();
 var top;
 top = (index % widget.showCount) * perRowHeight + widget.padding;

 if (num % 2 == 1 && index % widget.showCount != widget.showCount - 1) {
 //第二轮在第一轮2行弹幕中间
 top += perRowHeight / 2;
 }
 if (widget.randomOffset != 0 && top > widget.randomOffset) {
 top += _random.nextInt(widget.randomOffset) * 2 - widget.randomOffset;
 }
 return top;
}

Text(
 text,
 style: TextStyle(color: Colors.white),
);

Text(
 text,
 style: TextStyle(color: Color(0xFFE9A33A)),
)

return Center(
 child: Container(
 padding: EdgeInsets.only(left: 10, right: 10, top: 3, bottom: 3),
 decoration: BoxDecoration(
  color: Colors.red.withOpacity(.8),
  borderRadius: BorderRadius.circular(50)),
 child: Text(
  text,
  style: TextStyle(color: Colors.white),
 ),
 ),
);

return Center(
 child: Container(
 padding: EdgeInsets.only(left: 10, right: 10, top: 3, bottom: 3),
 decoration: BoxDecoration(
  color: Colors.red.withOpacity(.8),
  borderRadius: BorderRadius.circular(50)),
 child: Row(
  mainAxisSize: MainAxisSize.min,
  children: <Widget>[
  Text(
   text,
   style: TextStyle(color: Colors.white),
  ),
  Image.asset('assets/images/timg.jpeg',height: 30,width: 30,),
  Text(
   'x $count',
   style: TextStyle(color: Colors.white, fontSize: 18),
  ),
  ],
 ),
 ),
);