react-native 图片选择器react-native-image-picker

react-native android端的UI接口属性赶脚都要比ios少很多，图片选择貌似还没有对应官方api。这里使用一个第三的开源库：react-native-image-picker。搬砖记录下：

1. 首先下载这个包包：
   进入工程根目录敲入：
   npm install react-native-image-picker@latest –save
   这里可能会有网络延迟等原因，不能完全下载，可以直接下载zip压缩包，解压之后放到yourProject/node_modules/下面就ok了。

2. 然后在工程中加入以来选项：
   在android/settings.gradle中加入：
   include ‘:react-native-image-picker’
   project(‘:react-native-image-picker’).projectDir = new File(settingsDir,‘../node_modules/react-native-image-picker/android’)
   在android/app/build.gradle中加入:
   dependencies {
   …
   compile project(‘:react-native-image-picker’)
   }

3. 使用：
   声明对像：
   private ImagePickerPackage mImagePicker;

   在MainActivty中添加该module:
   mReactInstanceManager = ReactInstanceManager.builder()
   …
   // register package here
   添加onActivityResult数据：
   @Override
   public void onActivityResult(final int requestCode,final int resultCode,final Intent data) {
   super.onActivityResult(requestCode,resultCode,data);

   // handle onActivityResult
   mImagePicker.handleActivityResult(requestCode,data);

   }

4. 接下来就可以在js中使用该module了
   var UIImagePickerManager = require(‘NativeModules’).UIImagePickerManager;
   一些设置参数：
   var options = {
   title: ‘Select Avatar’,// specify null or empty string to remove the title
   cancelButtonTitle: ‘Cancel’,
   takePhotoButtonTitle: ‘Take Photo…’,// specify null or empty string to remove this button
   chooseFromLibraryButtonTitle: ‘Choose from Library…’,// specify null or empty string to remove this button
   customButtons: {
   ‘Choose Photo from Facebook’: ‘fb’,// [Button Text] : [String returned upon selection]
   },
   maxWidth: 100,
   maxHeight: 100,
   quality: 0.2,
   allowsEditing: false,// Built in iOS functionality to resize/reposition the image
   noData: false,// Disables the base64 data field from being generated (greatly improves performance on large photos)
   storageOptions: { // if this key is provided,the image will get saved in the documents directory (rather than a temporary directory)
   skipBackup: true,// image will NOT be backed up to icloud
   path: ‘images’ // will save image at /Documents/images rather than the root
   }
   };
   选择开启摄像头：
   // Launch Camera:
   UIImagePickerManager.launchCamera(options,(didCancel,response) => {
   // Same code as in above section!
   });
   直接在文件中选取图片：
   // Open Image Library:
   UIImagePickerManager.launchImageLibrary(options,response) => {
   // Same code as in above section!
   });

其实这个第三方包是一个好的学习react-native的demo，可以根据其构建思路写自己的native modules，这样在js中就能够调用本地组件、接口，可以极大地丰富hybird app。

下一篇，继续自定义module的实现。