react native 手势绘图

项目新增一个业务需求，需要用户可以通过手势进行签名，然后去研究了下react native的ART，最后搞出来个这个东西。

import React, { Component } from "react"
import {
    View，
    ART,
    PanResponder,
    Dimensions
} from "react-native"

let {
    Surface,
    Shape,
    Path
} = ART;
let {
    height: deviceHeight,
    width: deviceWidth
} = Dimensions.get('window');
let path;

class Draw extends Component {

	state = {
		coordinates: [] // 线路
	}	

	componentWillMount() {
        this._panResponder = PanResponder.create({
            onStartShouldSetPanResponder: this._handleStartShouldSetPanResponder,
            onMoveShouldSetPanResponder: this._handleMoveShouldSetPanResponder,
            onPanResponderGrant: this._handlePanResponderGrant,
            onPanResponderMove: this._onPanResponderMove,
            onPanResponderRelease: this._handlePanResponderEnd,
            onPanResponderTerminate: this._handlePanResponderEnd,
        });
    }

	_handleStartShouldSetPanResponder = (e, gestureState) => {
		// 响应触摸
        return true;
    }

    _handleMoveShouldSetPanResponder = (e, gestureState) => {
    	// 响应移动
        return true;
    }


    _handlePanResponderGrant = (e, gestureState) => {
    	//  响应移动操作
        let coordinates = this.state.coordinates.concat([{
            x: e.nativeEvent.locationX,
            y: e.nativeEvent.locationY,
        }])
        this.setState({ coordinates })
    }

    _onPanResponderMove = (e, gestureState) => {
    	// 最近一次的移动距离
        let coordinates = this.state.coordinates.concat([{
            x: e.nativeEvent.locationX,
            y: e.nativeEvent.locationY,
        }])
        this.setState({ coordinates })
    }

    _handlePanResponderEnd = () => {
    	// 结束触摸
    }
	render() {
       path = Path()
       this.state.coordinates.forEach(item => {
       	   // ios获取的x,y有时候为0，android正常，这里需要处理一下
           if (item.x && item.y) {
               if (item.move) 
                   path.moveTo(item.x, item.y)
               else
                   path.lineTo(item.x, item.y)
           }
       })
		
		return 
			
                
                    
                
            
		
	}

}