harmony 鸿蒙Using Image_NativeModule to Receive Images

2025-06-12
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Using Image_NativeModule to Receive Images

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. For details about the sample code of camera preview implemented with the use of the camera API, see Secondary Processing of Preview Streams (C/C++).

How to Develop

Adding Dependencies

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

target_link_libraries(entry PUBLIC libhilog_ndk.z.so libohimage.so libimage_receiver.so libnative_image.so)

Calling the Native APIs

For details about the APIs, see Image_NativeModule.

Create a native C++ application in DevEco Studio. The project created by default contains the index.ets file, and a hello.cpp or napi_init.cpp file is generated in the entry\src\main\cpp directory. In this example, the generated file is hello.cpp. Implement the C APIs in hello.cpp. Refer to the sample code below.

#include <hilog/log.h>
#include <multimedia/image_framework/image/image_native.h>
#include <multimedia/image_framework/image/image_receiver_native.h>

#undef LOG_DOMAIN
#define LOG_DOMAIN 0x3200

#undef LOG_TAG
#define LOG_TAG "MY_TAG"

#define IMAGE_WIDTH 320
#define IMAGE_HEIGHT 480
#define IMAGE_CAPACITY 2

static void OnCallback(OH_ImageReceiverNative *receiver)
{
    // Callback for processing the received image data.
    OH_LOG_INFO(LOG_APP, "ImageReceiverNativeCTest buffer avaliable.");

    // Read the next image object of OH_ImageReceiverNative.
    OH_ImageNative* image = nullptr;
    errCode = OH_ImageReceiverNative_ReadNextImage(receiver, &image); 
    // You can also call OH_ImageReceiverNative_ReadLatestImage to obtain image data.
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImageReceiverNativeCTest get image receiver next image failed, errCode: %{public}d.", errCode);
        OH_ImageReceiverOptions_Release(options);
        OH_ImageReceiverNative_Release(receiver);
        return;
    }

    // The application processes the image data.
    // ...

    // Release the OH_ImageNative instance.
    errCode = OH_ImageNative_Release(image);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImageReceiverNativeCTest release image native failed, errCode: %{public}d.", errCode);
    }
}

static OH_ImageReceiverNative* receiver = nullptr;

static void ImageReceiverNativeCTest()
{
    // Create an OH_ImageReceiverOptions instance.
    OH_ImageReceiverOptions* options = nullptr;
    Image_ErrorCode errCode = OH_ImageReceiverOptions_Create(&options);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImageReceiverNativeCTest create image receiver options failed, errCode: %{public}d.", errCode);
        return;
    }

    Image_Size imgSize;
    imgSize.width = IMAGE_WIDTH;
    imgSize.height = IMAGE_HEIGHT;

    // Set the size attribute of OH_ImageReceiverOptions.
    errCode = OH_ImageReceiverOptions_SetSize(options, imgSize);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImageReceiverNativeCTest set image receiver options size failed, errCode: %{public}d.", errCode);
        OH_ImageReceiverOptions_Release(options);
        return;
    }

    // Set the capacity attribute of OH_ImageReceiverOptions.
    errCode = OH_ImageReceiverOptions_SetCapacity(options, IMAGE_CAPACITY);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImageReceiverNativeCTest set image receiver options capacity failed, errCode: %{public}d.", errCode);
        OH_ImageReceiverOptions_Release(options);
        return;
    }

    // Read the size attribute of OH_ImageReceiverOptions.
    Image_Size imgSizeRead;
    errCode = OH_ImageReceiverOptions_GetSize(options, &imgSizeRead);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImageReceiverNativeCTest get image receiver options size failed, errCode: %{public}d.", errCode);
        OH_ImageReceiverOptions_Release(options);
        return;
    }

    // Check whether the size read is the same as the size set.
    if (imgSizeRead.width != IMAGE_WIDTH||imgSizeRead.height != IMAGE_HEIGHT) {
        OH_LOG_ERROR(LOG_APP, "ImageReceiverNativeCTest get image receiver options size failed, width: %{public}d, height: %{public}d.", imgSizeRead.width, imgSizeRead.height);
        OH_ImageReceiverOptions_Release(options);
        return;
    }

    // Read the capacity attribute of OH_ImageReceiverOptions.
    int32_t capacity = 0;
    errCode = OH_ImageReceiverOptions_GetCapacity(options, &capacity);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImageReceiverNativeCTest get image receiver options capacity failed, errCode: %{public}d.", errCode);
        OH_ImageReceiverOptions_Release(options);
        return;
    }

    // Check whether the capacity read is the same as the capacity set.
    if (capacity != IMAGE_CAPACITY) {
        OH_LOG_ERROR(LOG_APP, "ImageReceiverNativeCTest get image receiver options capacity failed, capacity: %{public}d.", capacity);
        OH_ImageReceiverOptions_Release(options);
        return;
    }

    // Create an OH_ImageReceiverNative instance.
    errCode = OH_ImageReceiverNative_Create(options, &receiver);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImageReceiverNativeCTest create image receiver failed, errCode: %{public}d.", errCode);
        OH_ImageReceiverOptions_Release(options);
        return;
    }

    // Register a callback event. Each time a new image is received, the callback event is triggered.
    uint64_t surfaceID = 0;
    errCode = OH_ImageReceiverNative_On(receiver, OnCallback);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImageReceiverNativeCTest image receiver on failed, errCode: %{public}d.", errCode);
        OH_ImageReceiverOptions_Release(options);
        OH_ImageReceiverNative_Release(receiver);
        return;
    }

    // Read the surface ID attribute of OH_ImageReceiverNative.
    uint64_t surfaceID = 0;
    errCode = OH_ImageReceiverNative_GetReceivingSurfaceId(receiver, &surfaceID);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImageReceiverNativeCTest get image receiver surfaceID failed, errCode: %{public}d.", errCode);
        OH_ImageReceiverOptions_Release(options);
        OH_ImageReceiverNative_Release(receiver);
        return;
    }
    OH_LOG_INFO(LOG_APP, "ImageReceiverNativeCTest get image receiver surfaceID: %{public}llu.", surfaceID);

    // Read the size attribute of OH_ImageReceiverNative.
    errCode = OH_ImageReceiverNative_GetSize(receiver, &imgSizeRead);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImageReceiverNativeCTest get image receiver size failed, errCode: %{public}d.", errCode);
        OH_ImageReceiverOptions_Release(options);
        OH_ImageReceiverNative_Release(receiver);
        return;
    }
    OH_LOG_INFO(LOG_APP, "ImageReceiverNativeCTest get image receiver size: width = %{public}d, height = %{public}d.", imgSizeRead.width, imgSizeRead.height);

    // Read the capacity attribute of OH_ImageReceiverNative.
    errCode = OH_ImageReceiverNative_GetCapacity(receiver, &capacity);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImageReceiverNativeCTest get image receiver capacity failed, errCode: %{public}d.", errCode);
        OH_ImageReceiverOptions_Release(options);
        OH_ImageReceiverNative_Release(receiver);
        return;
    }
    OH_LOG_INFO(LOG_APP, "ImageReceiverNativeCTest get image receiver capacity: %{public}d.", capacity);

    // Release the OH_ImageReceiverOptions instance.
    errCode = OH_ImageReceiverOptions_Release(options);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImageReceiverNativeCTest release image receiver options failed, errCode: %{public}d.", errCode);
    }
}

// Release ImageReceiverNative resources at a proper time.
static void ImaggReceiverRelease()
{
    // Unregister the callback event registered by calling OH_ImageReceiverNative_On.
    errCode = OH_ImageReceiverNative_Off(receiver);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImageReceiverNativeCTest image receiver off failed, errCode: %{public}d.", errCode);
    }

    // Release the OH_ImageReceiverOptions instance.
    errCode = OH_ImageReceiverNative_Release(receiver);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImageReceiverNativeCTest release image receiver failed, errCode: %{public}d.", errCode);
    }
}