位置计算:stageH和imgH的值一样?
let stageDOM = ReactDOM.findDOMNode(this.refs.stage),
stageW = stageDOM.scrollWidth,
stageH = stageDOM.scrollHeight,
//拿到一个imgFigure的大小
let imgFigureDOM = ReactDOM.findDOMNode(this.refs.imgFigure0),
imgW = imgFigureDOM.scrollWidth,
imgH = imgFigureDOM.scrollHeight,