!5094 ImageReciver使用指导

Merge pull request !5094 from 张晓波/master

zh-cn/application-dev/media/image.md

@@ -258,16 +258,42 @@ imagePackerApi.packing(imageSourceApi, packOpts)
              
 //编码完成，释放imagepacker
  imagePackerApi.release();
- 
+
 //用于获取imagesource信息
 imageSourceApi.getImageInfo(imageInfo => {
      console.info('TC_045 imageInfo');
      expect(imageInfo !== null).assertTrue();
      done();
    })
-   
+
 //用于更新增量数据
 imageSourceIncrementalSApi.updateData(array, false, 0, 10,(error,data )=> {})
 
 ```
 
+### ImageReceiver的使用
+
+示例场景：camera作为客户端将拍照数据传给服务端
+
+```js
+public async init(surfaceId: any) {
+
+  //服务端代码，创建ImageReceiver
+  var receiver = image.createImageReceiver(8 * 1024, 8, image.ImageFormat.JPEG, 1);
+
+  //获取Surface ID
+  var surfaceId = await receiver.getReceivingSurfaceId();
+
+  //注册Surface的监听，在suface的buffer准备好后触发
+  receiver.on('imageArrival', () => {
+    //去获取Surface中最新的buffer
+    receiver.readNextImage((err, img) => {
+	    img.getComponent(4, (err, componet) => {
+			//消费componet.byteBuffer，例如：将buffer内容保存成图片。
+		})
+	})
+  })
+
+  //调用Camera方法将surfaceId传递给Camera。camera会通过surfaceId获取surface，并生产出surface buffer。
+}
+```
\ No newline at end of file