小编And*_*sen的帖子

我有以下小部件：

class OutsiderButton extends StatelessWidget {

  final Function onPressed;
  final Icon icon;
  final OutsiderButtonPosition position;

  OutsiderButton({this.onPressed, @required this.icon, this.position});

  @override
  Widget build(BuildContext context) {
    return new Stack(fit: StackFit.loose, alignment: Alignment.center, children: [
      new CustomPaint(
        painter: new _OutsiderShape(position: position),
        size: Size(60.0, 60.0),
        isComplex: false,
      ),
      OutlineButton(
        borderSide: BorderSide(width: 1.0, color: Colors.white),
        color: AppThemeColors.accentColor,
        shape: new CircleBorder(),
        child: new Padding(
          padding: const EdgeInsets.all(6.0),
          child: icon,
        ),
        onPressed: onPressed,
      )
    ]);
  }
}

它用于CustomPainter绘制背景。我需要它CustomPainter来绘制阴影，但是每次单击小部件时，阴影都会重新绘制并变得越来越强。这是CustomPainter：

class _OutsiderShape extends …

在Android中,当一个Activity被销毁时,我应该删除所有的侦听器

ref.addAuthStateListener(listener);
ref.addListenerForSingleValueEvent(listener);
ref.addChildEventListener(listener);
ref.addValueEventListener(listener);

使用ref.removeEventListener(listener)或它们会被自动销毁？

我知道因为FirebaseRecyclerAdapter我们可以cleanup()用来做这项工作.除了监听器和适配器之外还有其他需要清理的对象吗？