harmony 鸿蒙Image Receiving

2025-06-12
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Image Receiving

You can use the ImageReceiver class to obtain the surface ID of a component, read the latest image or the next image, and release ImageReceiver instances.

How to Develop

Adding Dependencies

Open the src/main/cpp/CMakeLists.txt file of the native project, add libace_napi.z.so, libimage_ndk.z.so, libimage_receiver_ndk.z.so, libnative_image.so, and libhilog_ndk.z.so (on which the native log APIs depend) to the target_link_libraries dependency.

target_link_libraries(entry PUBLIC libace_napi.z.so libhilog_ndk.z.so libimage_ndk.z.so libimage_receiver_ndk.z.so libnative_image.so)

Adding API Mappings

Open the src/main/cpp/hello.cpp file and add the following API mappings to the Init function:

EXTERN_C_START
static napi_value Init(napi_env env, napi_value exports)
{
    napi_property_descriptor desc[] = {
        { "createFromReceiver", nullptr, createFromReceiver, nullptr, nullptr, nullptr, napi_default, nullptr },
    };

    napi_define_properties(env, exports, sizeof(desc) / sizeof(desc[0]), desc);
    return exports;
}
EXTERN_C_END

Requesting Permissions

To obtain input data of an image from a camera, you must request the ohos.permission.CAMERA permission. For details, see Requesting User Authorization.

Calling APIs on the JS Side

Open src\main\cpp\types*libentry*\index.d.ts (where libentry varies according to the project name), and import the following files:
```
import { image } from '@kit.ImageKit';


export const createFromReceiver: (a: image.ImageReceiver) => image.Image;
```

Open src\main\ets\pages\index.ets, import *libentry*.so (where libentry varies according to the project name), call the native APIs, and pass in the JS resource object. The following is an example:

import testNapi from 'libentry.so'
import { image } from '@kit.ImageKit';
import { abilityAccessCtrl } from '@kit.AbilityKit';
import { camera } from '@kit.CameraKit';


@Entry
@Component
struct Index {
  private receiver: image.ImageReceiver|undefined = undefined;
  func (){
     let context = getContext()
     abilityAccessCtrl.createAtManager().requestPermissionsFromUser(context,['ohos.permission.CAMERA']).then(async () => {
        let cameraManager = await camera.getCameraManager(context);
        // Obtain the supported camera devices.
        let cameraDevices: Array<camera.CameraDevice> = cameraManager.getSupportedCameras();
        if (cameraDevices.length <= 0) {
        return;
        }
        // Obtain the profiles of the cameras.
        let profiles: camera.CameraOutputCapability = cameraManager.getSupportedOutputCapability(cameraDevices[0], camera.SceneMode.NORMAL_PHOTO);
        let previewProfiles: Array<camera.Profile> = profiles.previewProfiles;
        if (previewProfiles.length <= 0) {
        return;
        }
        let profileObj = previewProfiles[0];
        this.receiver = image.createImageReceiver({width:profileObj.size.width, height:profileObj.size.height}, image.ImageFormat.JPEG, 8);
        let receiverSurfaceId: string = await this.receiver.getReceivingSurfaceId();
        // Create an output object for the preview stream.
        let previewOutput: camera.PreviewOutput = cameraManager.createPreviewOutput(profileObj,receiverSurfaceId);
        let cameraInput : camera.CameraInput = cameraManager.createCameraInput(cameraDevices[0]);
        // Open the camera.
        await cameraInput.open();
        // Create a session.
        let session : camera.PhotoSession = cameraManager.createSession(camera.SceneMode.NORMAL_PHOTO) as camera.PhotoSession;
        // Configure the session.
        session.beginConfig();
        // Add a CameraInput instance to the session.
        session.addInput(cameraInput);
        // Add the preview stream to the session.
        session.addOutput(previewOutput);
        // Commit the configuration.
        await session.commitConfig();
        // Start the session.
        await session.start();


        this.receiver.on('imageArrival', () => {
           let img : image.Image = testNapi.createFromReceiver(this.receiver);
           img.release();
        })


     });
  }


  build() {
     Row() {
        Column() {
        Button("start")
           .width(100)
           .height(100)
           .onClick(() => {
              console.log("button click in");
              if (this.receiver == undefined) {
                 this.func();
              }
           })
        }
        .width('100%')
     }
     .height('100%')
  }
}

Calling the Native APIs

For details about the APIs, see Image.

Obtain the JS resource object from the hello.cpp file and convert it to a native resource object. Then you can call native APIs.

Adding Reference Files


      #include <multimedia/image_framework/image_mdk.h>
      #include <multimedia/image_framework/image_receiver_mdk.h>
      #include <malloc.h>
      #include <hilog/log.h>

      static napi_value createFromReceiver(napi_env env, napi_callback_info info)
      {
         size_t argc = 1;
         napi_value args[2] = {nullptr};
         napi_get_cb_info(env, info, &argc, args , nullptr, nullptr);
         napi_valuetype valuetype0;
         napi_typeof(env, args[0], &valuetype0);
         napi_ref reference;
         napi_create_reference(env, args[0], 1 ,&reference);
         napi_value imgReceiver_js;
         napi_get_reference_value(env, reference, &imgReceiver_js);
         
         ImageReceiverNative * imgReceiver_c = OH_Image_Receiver_InitImageReceiverNative(env, imgReceiver_js);
   
         int32_t capacity;
         OH_Image_Receiver_GetCapacity(imgReceiver_c, &capacity);
         OH_LOG_Print(LOG_APP, LOG_INFO, 0xFF00, "[receiver]", "capacity: %{public}d", capacity);
         int32_t format;
         OH_Image_Receiver_GetFormat(imgReceiver_c, &format);
         OH_LOG_Print(LOG_APP, LOG_INFO, 0xFF00, "[receiver]", "format: %{public}d", format);
         char * surfaceId = static_cast<char *>(malloc(sizeof(char)));
         OH_Image_Receiver_GetReceivingSurfaceId(imgReceiver_c, surfaceId, sizeof(char));
         OH_LOG_Print(LOG_APP, LOG_INFO, 0xFF00, "[receiver]", "surfaceId: %{public}c", surfaceId[0]);
         OhosImageSize size;
         OH_Image_Receiver_GetSize(imgReceiver_c, &size);
         OH_LOG_Print(LOG_APP, LOG_INFO, 0xFF00, "[receiver]", "OH_Image_Receiver_GetSize  width: %{public}d, height:%{public}d", size.width, size.height);
         
         int32_t ret;
         napi_value nextImage;
         // Alternatively, call OH_Image_Receiver_ReadNextImage(imgReceiver_c, &nextImage).
         ret = OH_Image_Receiver_ReadLatestImage(imgReceiver_c, &nextImage);
         
         ImageNative * nextImage_native = OH_Image_InitImageNative(env, nextImage);

         OhosImageSize imageSize;
         OH_Image_Size(nextImage_native, &imageSize);
         OH_LOG_Print(LOG_APP, LOG_INFO, 0xFF00, "[receiver]", "OH_Image_Size  width: %{public}d, height:%{public}d", imageSize.width, imageSize.height);

         OhosImageComponent imgComponent;
         ret = OH_Image_GetComponent(nextImage_native, 4, &imgComponent); // 4=jpeg
         
         uint8_t *img_buffer = imgComponent.byteBuffer;
         
         ret = OH_Image_Release(nextImage_native);
         ret = OH_Image_Receiver_Release(imgReceiver_c);
         return nextImage;
      }