Image Receiver (C/C++)
You can use the ImageReceiver APIs 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 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 enable debugging, add the permissions to the src\main\module.json5 file of the DevEco Studio project. For details about the fields in the configuration file, see module.json5 Configuration File.
"requestPermissions":[
{
"name" : "ohos.permission.CAMERA"
}
]
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 '@ohos.multimedia.image' 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 '@ohos.multimedia.image' import abilityAccessCtrl from '@ohos.abilityAccessCtrl' import camera from '@ohos.multimedia.camera' @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]) let previewProfiles: Array<camera.Profile> = profiles.previewProfiles; if (previewProfiles.length <= 0) { return; } let profileObj = previewProfiles[0]; this.receiver = image.createImageReceiver(profileObj.size.width, 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 a camera. await cameraInput.open(); // Create a session. let captureSession : camera.CaptureSession = cameraManager.createCaptureSession(); // Configure the session. captureSession.beginConfig(); // Add a CameraInput instance to the session. captureSession.addInput(cameraInput); // Add the preview stream to the session. captureSession.addOutput(previewOutput); // Commit the configuration. await captureSession.commitConfig(); // Start the session. await captureSession.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 API Reference.
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;
}