harmony 鸿蒙拍照

2023-06-24
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拍照

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。

导入image接口。创建拍照输出流的SurfaceId以及拍照输出的数据，都需要用到系统提供的image接口能力，导入image接口的方法如下。

   import image from '@ohos.multimedia.image';
   import camera from '@ohos.multimedia.camera';
   import { BusinessError } from '@ohos.base';

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，与拍照输出流相关联，获取拍照输出流的数据。

   async function getImageReceiverSurfaceId(): Promise<string|undefined> {
     let photoSurfaceId: string|undefined = undefined;
     let receiver: image.ImageReceiver = image.createImageReceiver(640, 480, 4, 8);
     console.info('before ImageReceiver check');
     if (receiver !== undefined) {
       console.info('ImageReceiver is ok');
       photoSurfaceId = await receiver.getReceivingSurfaceId();
       console.info(`ImageReceived id: ${JSON.stringify(photoSurfaceId)}`);
     } else {
       console.info('ImageReceiver is not ok');
     }
     return photoSurfaceId;
   }

创建拍照输出流。

通过CameraOutputCapability类中的photoProfiles()方法，可获取当前设备支持的拍照输出流，通过createPhotoOutput()方法传入支持的某一个输出流及步骤一获取的SurfaceId创建拍照输出流。

   function getPhotoOutput(cameraManager: camera.CameraManager, cameraOutputCapability: camera.CameraOutputCapability, photoSurfaceId: string): camera.PhotoOutput|undefined {
     let photoProfilesArray: Array<camera.Profile> = cameraOutputCapability.photoProfiles;
     if (!photoProfilesArray) {
       console.error("createOutput photoProfilesArray == null||undefined");
     }
     let photoOutput: camera.PhotoOutput|undefined = undefined;
     try {
       photoOutput = cameraManager.createPhotoOutput(photoProfilesArray[0], photoSurfaceId);
     } catch (error) {
       let err = error as BusinessError;
       console.error(`Failed to createPhotoOutput. error: ${JSON.stringify(err)}`);
     }
     return photoOutput;
   }

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。

   function configuringSession(captureSession: camera.CaptureSession): void {
     // 判断设备是否支持闪光灯
     let flashStatus: boolean = false;
     try {
       flashStatus = captureSession.hasFlash();
     } catch (error) {
       let err = error as BusinessError;
       console.error(`Failed to hasFlash. error: ${JSON.stringify(err)}`);
     }
     console.info(`Promise returned with the flash light support status: ${flashStatus}`);
     if (flashStatus) {
       // 判断是否支持自动闪光灯模式
       let flashModeStatus: boolean = false;
       try {
         let status: boolean = captureSession.isFlashModeSupported(camera.FlashMode.FLASH_MODE_AUTO);
         flashModeStatus = status;
       } catch (error) {
         let err = error as BusinessError;
         console.error(`Failed to check whether the flash mode is supported. error: ${JSON.stringify(err)}`);
       }
       if (flashModeStatus) {
         // 设置自动闪光灯模式
         try {
           captureSession.setFlashMode(camera.FlashMode.FLASH_MODE_AUTO);
         } catch (error) {
           let err = error as BusinessError;
           console.error(`Failed to set the flash mode. error: ${JSON.stringify(err)}`);
         }
       }
     }
     // 判断是否支持连续自动变焦模式
     let focusModeStatus: boolean = false;
     try {
       let status: boolean = captureSession.isFocusModeSupported(camera.FocusMode.FOCUS_MODE_CONTINUOUS_AUTO);
       focusModeStatus = status;
     } catch (error) {
       let err = error as BusinessError;
       console.error(`Failed to check whether the focus mode is supported. error: ${JSON.stringify(err)}`);
     }
     if (focusModeStatus) {
       // 设置连续自动变焦模式
       try {
         captureSession.setFocusMode(camera.FocusMode.FOCUS_MODE_CONTINUOUS_AUTO);
       } catch (error) {
         let err = error as BusinessError;
         console.error(`Failed to set the focus mode. error: ${JSON.stringify(err)}`);
       }
     }
     // 获取相机支持的可变焦距比范围
     let zoomRatioRange: Array<number> = [];
     try {
       zoomRatioRange = captureSession.getZoomRatioRange();
     } catch (error) {
       let err = error as BusinessError;
       console.error(`Failed to get the zoom ratio range. error: ${JSON.stringify(err)}`);
     }
     if (zoomRatioRange.length <= 0 ) {
       return;
     }
     // 设置可变焦距比
     try {
       captureSession.setZoomRatio(zoomRatioRange[0]);
     } catch (error) {
       let err = error as BusinessError;
       console.error(`Failed to set the zoom ratio value. error: ${JSON.stringify(err)}`);
     }
   }

触发拍照。

通过photoOutput类的capture()方法，执行拍照任务。该方法有两个参数，第一个参数为拍照设置参数的setting，setting中可以设置照片的质量和旋转角度，第二参数为回调函数。

   function capture(captureLocation: camera.Location, photoOutput: camera.PhotoOutput): void {
     let settings: camera.PhotoCaptureSetting = {
       quality: camera.QualityLevel.QUALITY_LEVEL_HIGH,  // 设置图片质量高
       rotation: camera.ImageRotation.ROTATION_0,  // 设置图片旋转角度0
       location: captureLocation,  // 设置图片地理位置
       mirror: false  // 设置镜像使能开关(默认关)
     };
     photoOutput.capture(settings, (err: BusinessError) => {
       if (err) {
         console.error(`Failed to capture the photo. error: ${JSON.stringify(err)}`);
         return;
       }
       console.info('Callback invoked to indicate the photo capture request success.');
     });
   }

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captureStart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，该事件返回此次拍照的captureId。

  function onPhotoOutputCaptureStart(photoOutput: camera.PhotoOutput): void {
    photoOutput.on('captureStart', (err: BusinessError, captureId: number) => {
      console.info(`photo capture stated, captureId : ${captureId}`);
    });
  }

通过注册固定的captureEnd回调函数获取监听拍照结束结果，photoOutput创建成功时即可监听，该事件返回结果为拍照完全结束后的相关信息CaptureEndInfo。

  function onPhotoOutputCaptureEnd(photoOutput: camera.PhotoOutput): void {
    photoOutput.on('captureEnd', (err: BusinessError, captureEndInfo: camera.CaptureEndInfo) => {
      console.info(`photo capture end, captureId : ${captureEndInfo.captureId}`);
      console.info(`frameCount : ${captureEndInfo.frameCount}`);
    });
  }

通过注册固定的error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CameraErrorCode。

  function onPhotoOutputError(photoOutput: camera.PhotoOutput): void {
    photoOutput.on('error', (error: BusinessError) => {
      console.info(`Photo output error code: ${error.code}`);
    });
  }