1. 插件必须渲染好,

final RenderBox box = globalKey.currentContext.findRenderObject();final size = box.size;final topLeftPosition = box.localToGlobal(Offset.zero);return topLeftPosition.dy;

　　

2. 可以通过context.size获取当前控件的尺寸和位置offset信息

下面是示例，通过contex.size.height可以拿到child控件的高度

 

class HeightReporter extends StatelessWidget {  final Widget child;  HeightReporter({this.child});  @override  Widget build(BuildContext context) {    return new GestureDetector(      child: child,      onTap: () {        print('Height is ${context.size.height}');      },    );  }