拍照(C/C++)

拍照是相机的最重要功能之一，拍照模块基于相机复杂的逻辑，为了保证用户拍出的照片质量，在中间步骤可以设置分辨率、闪光灯、焦距、照片质量及旋转角度等信息。

开发步骤

详细的API说明请参考Camera API参考。

  1. 导入NDK接口，接口中提供了相机相关的属性和方法，导入方法如下。

     // 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。

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

  3. 获取SurfaceId。

    通过image的createImageReceiver()方法创建ImageReceiver实例，再通过实例的getReceivingSurfaceId()方法获取SurfaceId。

  4. 创建拍照输出流。

    根据传入的SurfaceId，通过OH_CameraManager_GetSupportedCameraOutputCapability()方法，可获取当前设备支持的拍照输出流，通过OH_CameraManager_CreatePhotoOutput()方法传入支持的某一个输出流及步骤3获取的SurfaceId创建拍照输出流。

     NDKCamera::NDKCamera(char *str)
 {
     Camera_Manager* cameraManager = nullptr;
     Camera_Device* cameras = nullptr;
     Camera_OutputCapability* cameraOutputCapability = nullptr;
     Camera_PhotoOutput* photoOutput = nullptr;
     Camera_CaptureSession* captureSession = nullptr;
     const Camera_Profile* photoProfile = nullptr;
     uint32_t size = 0;
     uint32_t cameraDeviceIndex = 0;
     char* photoSurfaceId = str;
     Camera_ErrorCode ret = OH_Camera_GetCameraManager(&cameraManager);
     if (cameraManager == nullptr || ret != CAMERA_OK) {
         OH_LOG_ERROR(LOG_APP, "OH_Camera_GetCameraManager failed.");
     }
     ret = OH_CameraManager_GetSupportedCameras(cameraManager, &cameras, &size);
     if (cameras == nullptr || size < 0 || ret != CAMERA_OK) {
         OH_LOG_ERROR(LOG_APP, "OH_CameraManager_GetSupportedCameras failed.");
     }
     ret = OH_CameraManager_GetSupportedCameraOutputCapability(cameraManager, &cameras[cameraDeviceIndex], &cameraOutputCapability);
     if (cameraOutputCapability == nullptr || ret != CAMERA_OK) {
         OH_LOG_ERROR(LOG_APP, "GetSupportedCameraOutputCapability failed.");
     }
     photoProfile = cameraOutputCapability->photoProfiles[0];
     if (photoProfile == nullptr) {
         OH_LOG_ERROR(LOG_APP, "Get photoProfiles failed.");
     }
     ret = OH_CameraManager_CreatePhotoOutput(cameraManager, photoProfile, photoSurfaceId, &photoOutput);
     if (photoOutput == nullptr || ret != CAMERA_OK) {
         OH_LOG_ERROR(LOG_APP, "OH_CameraManager_CreatePhotoOutput failed.");
     }
 }

  5. 参数配置。

    配置相机的参数可以调整拍照的一些功能，包括闪光灯、变焦、焦距等。

     // 判断设备是否支持闪光灯
 Camera_FlashMode flashMode = FLASH_MODE_AUTO;
 bool hasFlash = false;
 ret = OH_CameraManager_CreateCaptureSession(cameraManager, &captureSession);
 if (captureSession == nullptr || ret != CAMERA_OK) {
     OH_LOG_ERROR(LOG_APP, "OH_CameraManager_CreateCaptureSession failed.");
 }
 ret = OH_CaptureSession_HasFlash(captureSession, &hasFlash);
 if (ret != CAMERA_OK) {
     OH_LOG_ERROR(LOG_APP, "OH_CaptureSession_HasFlash failed.");
 }
 if (hasFlash) {
     OH_LOG_INFO(LOG_APP, "hasFlash success");
 } else {
     OH_LOG_ERROR(LOG_APP, "hasFlash fail");
 }
 // 检测闪光灯模式是否支持
 bool isSupported = false;
 ret = OH_CaptureSession_IsFlashModeSupported(captureSession, flashMode, &isSupported);
 if (ret != CAMERA_OK) {
     OH_LOG_ERROR(LOG_APP, "OH_CaptureSession_IsFlashModeSupported failed.");
 }
 if (isSupported) {
     OH_LOG_INFO(LOG_APP, "isFlashModeSupported success");
     // 设置闪光灯模式
     ret = OH_CaptureSession_SetFlashMode(captureSession, flashMode);
     if (ret == CAMERA_OK) {
         OH_LOG_INFO(LOG_APP, "OH_CaptureSession_SetFlashMode success.");
     } else {
         OH_LOG_ERROR(LOG_APP, "OH_CaptureSession_SetFlashMode failed. %{public}d ", ret);
     }
     // 获取当前设备的闪光灯模式
     ret = OH_CaptureSession_GetFlashMode(captureSession, &flashMode);
     if (ret == CAMERA_OK) {
         OH_LOG_INFO(LOG_APP, "OH_CaptureSession_GetFlashMode success. flashMode：%{public}d ", flashMode);
     } else {
         OH_LOG_ERROR(LOG_APP, "OH_CaptureSession_GetFlashMode failed. %d ", ret);
     }
 } else {
     OH_LOG_ERROR(LOG_APP, "isFlashModeSupported fail");
 }

 // 判断是否支持连续自动变焦模式
 Camera_FocusMode focusMode = FOCUS_MODE_CONTINUOUS_AUTO;
 bool isFocusModeSupported = false;
 ret = OH_CaptureSession_IsFocusModeSupported(captureSession, focusMode, &isFocusModeSupported);
 if (ret != CAMERA_OK) {
     OH_LOG_ERROR(LOG_APP, "OH_CaptureSession_IsFocusModeSupported failed.");
 }
 if (isFocusModeSupported) {
     OH_LOG_INFO(LOG_APP, "isFocusModeSupported success");
     ret = OH_CaptureSession_SetFocusMode(captureSession, focusMode);
     if (ret != CAMERA_OK) {
         OH_LOG_ERROR(LOG_APP, "OH_CaptureSession_SetFocusMode failed. %{public}d ", ret);
     }
     ret = OH_CaptureSession_GetFocusMode(captureSession, &focusMode);
     if (ret == CAMERA_OK) {
         OH_LOG_INFO(LOG_APP, "OH_CaptureSession_GetFocusMode success. focusMode%{public}d ", focusMode);
     } else {
         OH_LOG_ERROR(LOG_APP, "OH_CaptureSession_GetFocusMode failed. %d ", ret);
     }
 } else {
     OH_LOG_ERROR(LOG_APP, "isFocusModeSupported fail");
 }

 // 获取相机支持的可变焦距比范围
 float minZoom;
 float maxZoom;
 ret = OH_CaptureSession_GetZoomRatioRange(captureSession, &minZoom, &maxZoom);
 if (ret != CAMERA_OK) {
     OH_LOG_ERROR(LOG_APP, "OH_CaptureSession_GetZoomRatioRange failed.");
 } else {
     OH_LOG_INFO(LOG_APP, "OH_CaptureSession_GetZoomRatioRange success. minZoom: %{public}f, maxZoom:%{public}f",
         minZoom, maxZoom);
 }
 // 设置变焦
 ret = OH_CaptureSession_SetZoomRatio(captureSession, maxZoom);
 if (ret == CAMERA_OK) {
     OH_LOG_INFO(LOG_APP, "OH_CaptureSession_SetZoomRatio success.");
 } else {
     OH_LOG_ERROR(LOG_APP, "OH_CaptureSession_SetZoomRatio failed. %{public}d ", ret);
 }
 // 获取当前设备的变焦值
 ret = OH_CaptureSession_GetZoomRatio(captureSession, &maxZoom);
 if (ret == CAMERA_OK) {
     OH_LOG_INFO(LOG_APP, "OH_CaptureSession_GetZoomRatio success. zoom：%{public}f ", maxZoom);
 } else {
     OH_LOG_ERROR(LOG_APP, "OH_CaptureSession_GetZoomRatio failed. %{public}d ", ret);
 }

  6. 触发拍照。

    通过OH_PhotoOutput_Capture()方法，执行拍照任务。

     ret = OH_PhotoOutput_Capture(photoOutput);
 if (ret == CAMERA_OK) {
     OH_LOG_INFO(LOG_APP, "OH_PhotoOutput_Capture success ");
 } else {
     OH_LOG_ERROR(LOG_APP, "OH_PhotoOutput_Capture failed. %d ", ret);
 }

状态监听

在相机应用开发过程中，可以随时监听拍照输出流状态，包括拍照流开始、拍照帧的开始与结束、拍照输出流的错误。

  • 通过注册固定的onFrameStart回调函数获取监听拍照开始结果，photoOutput创建成功时即可监听，拍照第一次曝光时触发。

      ret = OH_PhotoOutput_RegisterCallback(photoOutput, GetPhotoOutputListener());
  if (ret != CAMERA_OK) {
      OH_LOG_ERROR(LOG_APP, "OH_PhotoOutput_RegisterCallback failed.");
  }

      void PhotoOutputOnFrameStart(Camera_PhotoOutput* photoOutput)
  {
      OH_LOG_INFO(LOG_APP, "PhotoOutputOnFrameStart");
  }
  void PhotoOutputOnFrameShutter(Camera_PhotoOutput* photoOutput, Camera_FrameShutterInfo* info)
  {
      OH_LOG_INFO(LOG_APP, "PhotoOutputOnFrameShutter");
  }
  PhotoOutput_Callbacks* GetPhotoOutputListener()
  {
      static PhotoOutput_Callbacks photoOutputListener = {
          .onFrameStart = PhotoOutputOnFrameStart,
          .onFrameShutter = PhotoOutputOnFrameShutter,
          .onFrameEnd = PhotoOutputOnFrameEnd,
          .onError = PhotoOutputOnError
      };
      return &photoOutputListener;
  }

  • 通过注册固定的onFrameEnd回调函数获取监听拍照结束结果，photoOutput创建成功时即可监听。

      void PhotoOutputOnFrameEnd(Camera_PhotoOutput* photoOutput, int32_t frameCount)
  {
      OH_LOG_INFO(LOG_APP, "PhotoOutput frameCount = %{public}d", frameCount);
  }

  • 通过注册固定的onError回调函数获取监听拍照输出流的错误结果。callback返回拍照输出接口使用错误时的对应错误码，错误码类型参见Camera_ErrorCode。

      void PhotoOutputOnError(Camera_PhotoOutput* photoOutput, Camera_ErrorCode errorCode)
  {
      OH_LOG_INFO(LOG_APP, "PhotoOutput errorCode = %{public}d", errorCode);
  }