# 设备输入(C/C++)

在开发相机应用时，需要先参考开发准备[申请相关权限](camera-preparation.md)。

相机应用通过调用和控制相机设备，完成预览、拍照和录像等基础操作。

## 开发步骤

详细的API说明请参考[Camera API参考](../../reference/apis-camera-kit/_o_h___camera.md)。

1. 导入NDK接口。选择系统提供的NDK接口能力，导入NDK接口的方法如下。

   ```c++
    // 导入NDK接口头文件
    #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"
   ```

2. 在CMake脚本中链接相关动态库。

   ```txt
    target_link_libraries(entry PUBLIC libohcamera.so libhilog_ndk.z.so)
   ```

3. 通过[OH_CameraManager_CreateCameraInput()](../../reference/apis-camera-kit/_o_h___camera.md#oh_cameramanager_createcamerainput)方法，获取cameraInput对象。

   ```c++
   Camera_Manager *cameraManager = nullptr;
   Camera_Input* cameraInput = nullptr;
   Camera_Device* cameras = nullptr;
   Camera_OutputCapability* cameraOutputCapability = nullptr;
   const Camera_Profile* previewProfile = nullptr;
   const Camera_Profile* photoProfile = nullptr;
   uint32_t size = 0;
   uint32_t cameraDeviceIndex = 0;
   // 创建CameraManager对象
   Camera_ErrorCode ret = OH_Camera_GetCameraManager(&cameraManager);
   if (cameraManager == nullptr || ret != CAMERA_OK) {
      OH_LOG_ERROR(LOG_APP, "OH_Camera_GetCameraMananger failed.");
   }
   // 监听相机状态变化
   ret = OH_CameraManager_RegisterCallback(cameraManager, GetCameraManagerListener());
   if (ret != CAMERA_OK) {
      OH_LOG_ERROR(LOG_APP, "OH_CameraManager_RegisterCallback failed.");
   }
   // 获取相机列表
    ret = OH_CameraManager_GetSupportedCameras(cameraManager, &cameras, &size);
    if (cameras == nullptr || size < 0 || ret != CAMERA_OK) {
      OH_LOG_ERROR(LOG_APP, "OH_CameraManager_GetSupportedCameras failed.");
    }
   // 创建相机输入流
   ret = OH_CameraManager_CreateCameraInput(cameraManager, &cameras[cameraDeviceIndex], &cameraInput);
   if (cameraInput == nullptr || ret != CAMERA_OK) {
      OH_LOG_ERROR(LOG_APP, "OH_CameraManager_CreateCameraInput failed.");
   }
   ret == OH_CameraInput_RegisterCallback(cameraInput, GetCameraInputListener());
   if (ret != CAMERA_OK) {
      OH_LOG_ERROR(LOG_APP, "OH_CameraInput_RegisterCallback failed.");
   }
   // 打开相机
   ret = OH_CameraInput_Open(cameraInput);
   if (ret != CAMERA_OK) {
      OH_LOG_ERROR(LOG_APP, "OH_CameraInput_open failed.");
   }
   ```
   ```c++
   // 监听cameraInput错误信息
   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;
   }
   ```

   > **说明：**
   >
   > 在相机设备输入之前需要先完成相机管理，详细开发步骤请参考[相机管理](native-camera-device-management.md)

4. 通过[OH_CameraManager_GetSupportedSceneModes()](../../reference/apis-camera-kit/_o_h___camera.md#oh_cameramanager_getsupportedscenemodes)方法，获获取当前相机设备支持的模式列表，列表中存储了相机设备支持的所有模式[Camera_SceneMode](../../reference/apis-camera-kit/_o_h___camera.md#camera_scenemode)。

   ```c++
   Camera_SceneMode* sceneModes = nullptr;
   uint32_t length = 0;
   uint32_t sceneModeIndex = 0;
   ret = OH_CameraManager_GetSupportedSceneModes(&cameras[cameraDeviceIndex], &sceneModes, &length);
   if (sceneModes == nullptr || ret != CAMERA_OK) {
      OH_LOG_ERROR(LOG_APP, "OH_CameraManager_GetSupportedSceneModes failed.");
   }
   for (int index = 0; index < length; index++) {
      OH_LOG_INFO(LOG_APP, "scene mode = %{public}s ", sceneModes[index]);    // 获取相机指定模式
   }
   ```

5. 通过[OH_CameraManager_GetSupportedCameraOutputCapabilityWithSceneMode()](../../reference/apis-camera-kit/_o_h___camera.md#oh_cameramanager_getsupportedcameraoutputcapabilitywithscenemode)方法，获取当前设备支持的所有输出流，如预览流、拍照流等。输出流在CameraOutputCapability中的各个profile字段中。根据相机设备指定模式[Camera_SceneMode](../../reference/apis-camera-kit/_o_h___camera.md#camera_scenemode)的不同，需要添加不同类型的输出流。


   ```c++
   // 获取相机设备支持的输出流能力
   Camera_OutputCapability* cameraOutputCapability = nullptr;
   const Camera_Profile* previewProfile = nullptr;
   const Camera_Profile* photoProfile = nullptr;
   ret = OH_CameraManager_GetSupportedCameraOutputCapabilityWithSceneMode(cameraManager, &cameras[cameraDeviceIndex], sceneModes[sceneModeIndex]
                                                                  &cameraOutputCapability);
   if (cameraOutputCapability == nullptr || ret != CAMERA_OK) {
      OH_LOG_ERROR(LOG_APP, "OH_CameraManager_GetSupportedCameraOutputCapability failed.");
   }
   // 以NORMAL_PHOTO模式为例，需要添加预览流、拍照流
   if (cameraOutputCapability->previewProfilesSize < 0) {
      OH_LOG_ERROR(LOG_APP, "previewProfilesSize == null");
   }
   previewProfile = cameraOutputCapability->previewProfiles[0];

   if (cameraOutputCapability->photoProfilesSize < 0) {
      OH_LOG_ERROR(LOG_APP, "photoProfilesSize == null");
   }
   photoProfile = cameraOutputCapability->photoProfiles[0];
   ```