harmony 鸿蒙Device Input Management (C/C++)

2025-06-12
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Device Input Management (C/C++)

Before developing a camera application, request permissions by following the instructions provided in Requesting Camera Development Permissions.

A camera application invokes and controls a camera device to perform basic operations such as preview, photo capture, and video recording.

How to Develop

Read Camera for the API reference.

Import the NDK.

   // Include the NDK header files.
   #include "hilog/log.h"
   #include "ohcamera/camera.h"
   #include "ohcamera/camera_input.h"
   #include "ohcamera/capture_session.h"
   #include "ohcamera/photo_output.h"
   #include "ohcamera/preview_output.h"
   #include "ohcamera/video_output.h"
   #include "ohcamera/camera_manager.h"

Link the dynamic library in the CMake script.

   target_link_libraries(entry PUBLIC
       libace_napi.z.so
       libohcamera.so
       libhilog_ndk.z.so
   )

Call OH_CameraManager_CreateCameraInput() to obtain a cameraInput object. “`c++ // Listen for camera input errors. void OnCameraInputError(const Camera_Input* cameraInput, Camera_ErrorCode errorCode) { OH_LOG_INFO(LOG_APP, “OnCameraInput errorCode: %{public}d”, errorCode); }

CameraInput_Callbacks* GetCameraInputListener(void) { static CameraInput_Callbacks cameraInputCallbacks = { .onError = OnCameraInputError }; return &cameraInputCallbacks; }

   ```c++
   // Listen for camera status information.
   void CameraManagerStatusCallback(Camera_Manager* cameraManager, Camera_StatusInfo* status)
   {
       OH_LOG_INFO(LOG_APP, "CameraManagerStatusCallback is called");
   }

   CameraManager_Callbacks* GetCameraManagerListener()
   {
       static CameraManager_Callbacks cameraManagerListener = {
           .onCameraStatus = CameraManagerStatusCallback
       };
       return &cameraManagerListener;
   }

   void CreateAndOpenCamera()
   {
       Camera_Manager* cameraManager = nullptr;
       Camera_Input* cameraInput = nullptr;
       Camera_Device* cameras = nullptr;
       uint32_t size = 0;
       uint32_t cameraDeviceIndex = 0;
       // Create a CameraManager object.
       Camera_ErrorCode ret = OH_Camera_GetCameraManager(&cameraManager);
       if (cameraManager == nullptr||ret != CAMERA_OK) {
           OH_LOG_ERROR(LOG_APP, "OH_Camera_GetCameraManager failed.");
           return;
       }
       // Listen for camera status changes.
       ret = OH_CameraManager_RegisterCallback(cameraManager, GetCameraManagerListener());
       if (ret != CAMERA_OK) {
           OH_LOG_ERROR(LOG_APP, "OH_CameraManager_RegisterCallback failed.");
       }
       // Obtain the camera list.
        ret = OH_CameraManager_GetSupportedCameras(cameraManager, &cameras, &size);
        if (cameras == nullptr||size < 0||ret != CAMERA_OK) {
            OH_LOG_ERROR(LOG_APP, "OH_CameraManager_GetSupportedCameras failed.");
            return;
        }
       // Create a camera input stream.
       ret = OH_CameraManager_CreateCameraInput(cameraManager, &cameras[cameraDeviceIndex], &cameraInput);
       if (cameraInput == nullptr||ret != CAMERA_OK) {
           OH_LOG_ERROR(LOG_APP, "OH_CameraManager_CreateCameraInput failed.");
           return;
       }
       ret = OH_CameraInput_RegisterCallback(cameraInput, GetCameraInputListener());
       if (ret != CAMERA_OK) {
           OH_LOG_ERROR(LOG_APP, "OH_CameraInput_RegisterCallback failed.");
       }
       // Open a camera.
       ret = OH_CameraInput_Open(cameraInput);
       if (ret != CAMERA_OK) {
           OH_LOG_ERROR(LOG_APP, "OH_CameraInput_open failed.");
           return;
       }
   }

NOTE

Before any camera device input, you must complete camera management by following the instructions provided in Camera Device Management.

Call OH_CameraManager_GetSupportedSceneModes() to obtain the list of scene modes supported by the current camera device. The list stores all the Camera_SceneModes supported by the camera device.

   bool IsSupportedSceneMode(Camera_Device camera, Camera_SceneMode sceneMode)
   {
       Camera_SceneMode* sceneModes = nullptr;
       uint32_t sceneModeSize = 0;
       Camera_ErrorCode ret = OH_CameraManager_GetSupportedSceneModes(&camera, &sceneModes, &sceneModeSize);
       if (sceneModes == nullptr||ret != CAMERA_OK) {
           OH_LOG_ERROR(LOG_APP, "OH_CameraManager_GetSupportedSceneModes failed.");
           return false;
       }
       for (int index = 0; index < sceneModeSize; index++) {
           OH_LOG_INFO(LOG_APP, "scene mode = %{public}u ", sceneModes[index]);    // Obtain the specified scene mode.
           if (sceneModes[index] == sceneMode) {
               return true;
           }
       }
       return false;
   }

Call OH_CameraManager_GetSupportedCameraOutputCapabilityWithSceneMode() to obtain all output streams supported by the current device, such as preview streams and photo streams. The output streams supported are the value of each profile field under CameraOutputCapability. Different types of output streams must be added based on the value of Camera_SceneMode specified by the camera device.

   Camera_OutputCapability* GetSupportedCameraOutputCapability(Camera_Manager* cameraManager, Camera_Device &camera)
   {
       Camera_OutputCapability* cameraOutputCapability = nullptr;
       // The following sample code checks whether the NORMAL_PHOTO mode is supported by the camera.
       bool isSupported = IsSupportedSceneMode(camera, Camera_SceneMode::NORMAL_PHOTO);
       if (!isSupported) {
           OH_LOG_ERROR(LOG_APP, "NORMAL_PHOTO is not supported.");
           return cameraOutputCapability;
       }
       // Obtain the output stream capability supported by the camera.
       const Camera_Profile* previewProfile = nullptr;
       const Camera_Profile* photoProfile = nullptr;
       Camera_ErrorCode ret = OH_CameraManager_GetSupportedCameraOutputCapabilityWithSceneMode(cameraManager, &camera,
           Camera_SceneMode::NORMAL_PHOTO, &cameraOutputCapability);
       if (cameraOutputCapability == nullptr||ret != CAMERA_OK) {
           OH_LOG_ERROR(LOG_APP, "OH_CameraManager_GetSupportedCameraOutputCapability failed.");
           return cameraOutputCapability;
       }
       // The following uses the NORMAL_PHOTO mode as an example. You need to add the preview stream and photo stream.
       if (cameraOutputCapability->previewProfiles == nullptr) {
           OH_LOG_ERROR(LOG_APP, "previewProfiles == null");
       } else {
           // Select an appropriate preview resolution from previewProfiles of cameraOutputCapability.
           previewProfile = cameraOutputCapability->previewProfiles[0];
       }
       if (cameraOutputCapability->photoProfiles == nullptr) {
           OH_LOG_ERROR(LOG_APP, "photoProfiles == null");
       } else {
           // Select an appropriate photo resolution from photoProfiles of cameraOutputCapability.
           photoProfile = cameraOutputCapability->photoProfiles[0];
       }
       return cameraOutputCapability;
   }