Refactor Symbol on iOS

lib/extract/extractViewBox.js

@@ -0,0 +1,56 @@
+
+import React, {Component, PropTypes} from 'react';
+import createReactNativeComponentClass from 'react-native/Libraries/Renderer/src/renderers/native/createReactNativeComponentClass';
+import {ViewBoxAttributes} from '../attributes';
+
+const meetOrSliceTypes = {
+    meet: 0,
+    slice: 1,
+    none: 2
+};
+
+const alignEnum = [
+    'xMinYMin', 'xMidYMin', 'xMaxYMin',
+    'xMinYMid', 'xMidYMid', 'xMaxYMid',
+    'xMinYMax', 'xMidYMax', 'xMaxYMax',
+    'none'
+].reduce((prev, name) => {
+    prev[name] = name;
+    return prev;
+}, {});
+
+const spacesRegExp = /\s+/;
+
+export default function (props) {
+    const {viewBox, preserveAspectRatio} = props;
+
+    if (!viewBox) {
+        return null;
+    }
+
+    let params = viewBox.trim().split(spacesRegExp);
+
+    if (params.length === 4 &&  params.every(param => !isNaN(+params))) {
+        console.warn('Invalid `viewBox` prop:' + viewBox);
+        return null;
+    }
+
+    let modes = preserveAspectRatio ? preserveAspectRatio.trim().split(spacesRegExp) : [];
+
+    let meetOrSlice = meetOrSliceTypes[modes[1]] || 0;
+    let align = alignEnum[modes[0]] || 'xMidYMid';
+
+    return {
+        minX: +params[0],
+        minY: +params[1],
+        vbWidth: +params[2],
+        vbHeight: +params[3],
+        align,
+        meetOrSlice
+    }
+}
+
+export {
+    meetOrSliceTypes,
+    alignEnum
+};