实现圆形绘制接口

components/Circle.js

+import React, {PropTypes, Component} from 'react'
+import {requireNativeComponent, View, PixelRatio} from 'react-native'
+import {CoordinatePropType} from './PropTypes'
+
+class Circle extends Component {
+  static propTypes = {
+    ...View.propTypes,
+
+    /**
+     * 圆点
+     */
+    center: CoordinatePropType,
+
+    /**
+     * 半径（米）
+     */
+    radius: PropTypes.number,
+
+    strokeWidth: PropTypes.number,
+    strokeColor: PropTypes.string,
+    fillColor: PropTypes.string,
+    zIndex: PropTypes.number,
+  }
+
+  render() {
+    const props = {
+      ...this.props,
+      strokeWidth: PixelRatio.getPixelSizeForLayoutSize(this.props.strokeWidth),
+    }
+    return <AMapCircle {...props}/>
+  }
+}
+
+AMapCircle = requireNativeComponent('AMapCircle', Circle)
+
+export default Circle