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1# 图片接收
2<!--Kit: Image Kit-->
3<!--Subsystem: Multimedia-->
4<!--Owner: @aulight02-->
5<!--Designer: @liyang_bryan-->
6<!--Tester: @xchaosioda-->
7<!--Adviser: @zengyawen-->
8
9> **说明：**
10>
11> 当前开发指导使用的接口为[Image](../../reference/apis-image-kit/capi-image.md)模块下的C API，可完成图片编解码，图片接收器，处理图像数据等功能。这部分API在API 11之前发布，在后续的版本不再增加新功能，**不再推荐使用**。<br>
12> 开发者可使用[Image_NativeModule](../../reference/apis-image-kit/capi-image-nativemodule.md)模块下的C API，不仅提供上述图片框架基础功能，还可以完成多图编解码等新特性，相关开发指导请参考[图片开发指导(C/C++)](image-source-c.md)节点下的内容。这部分API从API 12开始支持，并将持续演进，**推荐开发者使用**。<br>
13> 两套C API不建议同时使用，在部分场景下存在不兼容的问题。
14
15图片接收类，用于获取组件surface id，接收最新的图片和读取下一张图片，以及释放ImageReceiver实例。
16
17## 开发步骤
18
19### 添加依赖
20
21在进行应用开发之前，开发者需要打开native工程的src/main/cpp/CMakeLists.txt，在target_link_libraries依赖中添加libace_napi.z.so、libimage_ndk.z.so、libimage_receiver_ndk.z.so、libnative_image.so以及日志依赖libhilog_ndk.z.so。
22
23```txt
24target_link_libraries(entry PUBLIC libace_napi.z.so libhilog_ndk.z.so libimage_ndk.z.so libimage_receiver_ndk.z.so libnative_image.so)
25```
26
27### 添加接口映射
28
29打开src/main/cpp/hello.cpp文件，在Init函数中添加接口映射如下：
30
31```c++
32EXTERN_C_START
33static napi_value Init(napi_env env, napi_value exports)
34{
35    napi_property_descriptor desc[] = {
36        { "createFromReceiver", nullptr, createFromReceiver, nullptr, nullptr, nullptr, napi_default, nullptr },
37    };
38
39    napi_define_properties(env, exports, sizeof(desc) / sizeof(desc[0]), desc);
40    return exports;
41}
42EXTERN_C_END
43```
44
45### 添加权限申请
46
47此处通过camera图片获取输入数据，需要申请权限ohos.permission.CAMERA，申请方式请参考[向用户申请授权](../../security/AccessToken/request-user-authorization.md)。
48
49### JS侧调用
50
511. 打开src\main\cpp\types\libentry\index.d.ts（其中libentry根据工程名生成），导入如下引用文件：
52
53    ```js
54    import { image } from '@kit.ImageKit';
55
56    export const createFromReceiver: (a: image.ImageReceiver) => image.Image;
57    ```
58
592. 打开src\main\ets\pages\index.ets，导入"libentry.so（根据工程名生成）"，调用Native接口，传入JS的资源对象。示例如下：
60
61    ```js
62    import testNapi from 'libentry.so';
63    import { image } from '@kit.ImageKit';
64    import { common, abilityAccessCtrl } from '@kit.AbilityKit';
65    import { camera } from '@kit.CameraKit';
66
67    @Entry
68    @Component
69    struct Index {
70      private receiver: image.ImageReceiver | undefined = undefined;
71      func (){
72         let context = this.getUIContext().getHostContext() as common.UIAbilityContext;
73         abilityAccessCtrl.createAtManager().requestPermissionsFromUser(context,['ohos.permission.CAMERA']).then(async () => {
74            let cameraManager = await camera.getCameraManager(context);
75            // 获取支持的相机设备对象。
76            let cameraDevices: Array<camera.CameraDevice> = cameraManager.getSupportedCameras();
77            if (cameraDevices.length <= 0) {
78            return;
79            }
80            // 获取对应相机设备的profiles。
81            let profiles: camera.CameraOutputCapability = cameraManager.getSupportedOutputCapability(cameraDevices[0], camera.SceneMode.NORMAL_PHOTO);
82            let previewProfiles: Array<camera.Profile> = profiles.previewProfiles;
83            if (previewProfiles.length <= 0) {
84            return;
85            }
86            let profileObj = previewProfiles[0];
87            this.receiver = image.createImageReceiver({width:profileObj.size.width, height:profileObj.size.height}, image.ImageFormat.JPEG, 8);
88            let receiverSurfaceId: string = await this.receiver.getReceivingSurfaceId();
89            // 创建预览流输出对象。
90            let previewOutput: camera.PreviewOutput = cameraManager.createPreviewOutput(profileObj,receiverSurfaceId);
91            let cameraInput : camera.CameraInput = cameraManager.createCameraInput(cameraDevices[0]);
92            // 打开相机。
93            await cameraInput.open();
94            // 会话流程。
95            let session : camera.PhotoSession = cameraManager.createSession(camera.SceneMode.NORMAL_PHOTO) as camera.PhotoSession;
96            // 配置会话。
97            session.beginConfig();
98            // 把cameraInput加入到会话。
99            session.addInput(cameraInput);
100            // 把预览流加入到会话。
101            session.addOutput(previewOutput);
102            // 提交配置信息。
103            await session.commitConfig();
104            // 会话开始。
105            await session.start();
106
107            this.receiver.on('imageArrival', () => {
108               let img : image.Image = testNapi.createFromReceiver(this.receiver);
109               img.release();
110            })
111
112         });
113      }
114
115      build() {
116         Row() {
117            Column() {
118            Button("start")
119               .width(100)
120               .height(100)
121               .onClick(() => {
122                  console.info("button click in");
123                  if (this.receiver == undefined) {
124                     this.func();
125                  }
126               })
127            }
128            .width('100%')
129         }
130         .height('100%')
131      }
132    }
133    ```
134
135### Native接口调用
136
137具体接口说明请参考[API文档](../../reference/apis-image-kit/capi-image.md)。
138
139在hello.cpp文件中获取JS的资源对象，并转为Native的资源对象，即可调用Native接口，调用方式示例代码如下：
140
141**添加引用文件**
142
143```c++
144#include <multimedia/image_framework/image_mdk.h>
145#include <multimedia/image_framework/image_receiver_mdk.h>
146#include <malloc.h>
147#include <hilog/log.h>
148
149static napi_value createFromReceiver(napi_env env, napi_callback_info info)
150{
151   size_t argc = 1;
152   napi_value args[2] = {nullptr};
153   napi_get_cb_info(env, info, &argc, args , nullptr, nullptr);
154   napi_valuetype valuetype0;
155   napi_typeof(env, args[0], &valuetype0);
156   napi_ref reference;
157   napi_create_reference(env, args[0], 1 ,&reference);
158   napi_value imgReceiver_js;
159   napi_get_reference_value(env, reference, &imgReceiver_js);
160
161   ImageReceiverNative * imgReceiver_c = OH_Image_Receiver_InitImageReceiverNative(env, imgReceiver_js);
162
163   int32_t capacity;
164   OH_Image_Receiver_GetCapacity(imgReceiver_c, &capacity);
165   OH_LOG_Print(LOG_APP, LOG_INFO, 0xFF00, "[receiver]", "capacity: %{public}d", capacity);
166   int32_t format;
167   OH_Image_Receiver_GetFormat(imgReceiver_c, &format);
168   OH_LOG_Print(LOG_APP, LOG_INFO, 0xFF00, "[receiver]", "format: %{public}d", format);
169   char * surfaceId = static_cast<char *>(malloc(sizeof(char)));
170   OH_Image_Receiver_GetReceivingSurfaceId(imgReceiver_c, surfaceId, sizeof(char));
171   OH_LOG_Print(LOG_APP, LOG_INFO, 0xFF00, "[receiver]", "surfaceId: %{public}c", surfaceId[0]);
172   OhosImageSize size;
173   OH_Image_Receiver_GetSize(imgReceiver_c, &size);
174   OH_LOG_Print(LOG_APP, LOG_INFO, 0xFF00, "[receiver]", "OH_Image_Receiver_GetSize  width: %{public}d, height:%{public}d", size.width, size.height);
175
176   int32_t ret;
177   napi_value nextImage;
178   // 或调用 OH_Image_Receiver_ReadNextImage(imgReceiver_c, &nextImage);
179   ret = OH_Image_Receiver_ReadLatestImage(imgReceiver_c, &nextImage);
180
181   ImageNative * nextImage_native = OH_Image_InitImageNative(env, nextImage);
182
183   OhosImageSize imageSize;
184   OH_Image_Size(nextImage_native, &imageSize);
185   OH_LOG_Print(LOG_APP, LOG_INFO, 0xFF00, "[receiver]", "OH_Image_Size  width: %{public}d, height:%{public}d", imageSize.width, imageSize.height);
186
187   OhosImageComponent imgComponent;
188   ret = OH_Image_GetComponent(nextImage_native, 4, &imgComponent); // 4=jpeg
189
190   uint8_t *img_buffer = imgComponent.byteBuffer;
191
192   ret = OH_Image_Release(nextImage_native);
193   ret = OH_Image_Receiver_Release(imgReceiver_c);
194   return nextImage;
195}
196```
197