react-native-coordinate-measuring.js

class MyComponent extends React.Component {
    render() {
       // <View> will expand to the dimensions of DropZone within it
      return <View ref={view => { this.myComponent = view; }}><DropZone /></View> 
    }
    componentDidMount() {
      this.myComponent.measure((x, f, width, height, px, py) => {
        console.log('MyComponent width is: ' + width)
        console.log('MyComponent height is: ' + height)

        console.log('X offset to parent view: ' + x)
        console.log('Y offset to parent view: ' + y)

        console.log('X offset to page: ' + px)
        console.log('Y offset to page: ' + py)

        this.setState({ x, y })

        // or (depending on your exact needs):
        this.setState({ x: px, y: py })
      })        
    }
}

class MyComponent extends React.Component {
    render() {
       // <View> will expand to the dimensions of DropZone within it
        return <View onLayout={this.measure}><DropZone /></View> 
    }
    measure = ({ nativeEvent: { layout: { x, y, width, height } } }) => {
      this.setState({ x, y});
    }
}