OpenHarmony Camera开发指导（三）：相机设备输入输出（ArkTS）

相机应用可通过创建相机输入流调用并控制相机设备，创建不同类型的输出流，进而实现预览、拍照、录像等基础功能。

开发步骤

在创建相机设备输入之前需要先完成相机设备管理，详细开发步骤可参考上一篇文章。

创建相机输入流

通过cameraManager类的createCameraInput方法创建相机输入流，监听相机输入流错误事件并打开相机

import { camera } from '@kit.CameraKit';
import { BusinessError } from '@kit.BasicServicesKit';

async function createInput(cameraDevice: camera.CameraDevice, cameraManager: camera.CameraManager): Promise<camera.CameraInput | undefined> {
  // 创建相机输入流。
  let cameraInput: camera.CameraInput | undefined = undefined;
  try {
    cameraInput = cameraManager.createCameraInput(cameraDevice);
  } catch (error) {
    let err = error as BusinessError;
    console.error(`The createCameraInput call failed. error code: ${err.code}`);
  }
  if (cameraInput === undefined) {
    return undefined;
  }
  // 监听cameraInput错误信息。
  cameraInput.on('error', cameraDevice, (error: BusinessError) => {
    console.error(`Camera input error code: ${error.code}`);
  });
  // 打开相机。
  await cameraInput.open();
  return cameraInput;
}

获取相机支持的模式列表

调用getSupportedSceneModes方法，获取当前相机设备支持的所有模式列表SceneMode数组

function getSupportedSceneMode(cameraDevice: camera.CameraDevice, cameraManager: camera.CameraManager): Array<camera.SceneMode> {
  // 获取相机设备支持的模式列表
  let sceneModeArray: Array<camera.SceneMode> = cameraManager.getSupportedSceneModes(cameraDevice);
  if (sceneModeArray != undefined && sceneModeArray.length > 0) {
    for (let index = 0; index < sceneModeArray.length; index++) {
      console.info('Camera SceneMode : ' + sceneModeArray[index]);  
  }
    return sceneModeArray;
  } else {
      console.error("cameraManager.getSupportedSceneModes error");
      return [];
  }
}

相机支持的模式包括NORMAL_PHOTO（普通拍照模式）、NORMAL_VIDEO（普通录像模式）和SECURE_PHOTO（安全相机模式）。

获取相机支持的输出流

获取当前相机设备支持的所有输出流：通过getSupportedOutputCapability方法，获取当前相机设备支持的所有输出流，如预览流、拍照流、录像流等。输入CameraDevice和SceneMode，获取CameraOutputCapability相机输出能力，不同输出流的能力保存在CameraOutputCapability中的各个profile字段中

async function getSupportedOutputCapability(cameraDevice: camera.CameraDevice, cameraManager: camera.CameraManager, sceneMode: camera.SceneMode): Promise<camera.CameraOutputCapability | undefined> {
   // 获取相机设备支持的输出流能力。
   let cameraOutputCapability: camera.CameraOutputCapability = cameraManager.getSupportedOutputCapability(cameraDevice, sceneMode);
   if (!cameraOutputCapability) {
     console.error("cameraManager.getSupportedOutputCapability error");
     return undefined;
   }
   console.info("outputCapability: " + JSON.stringify(cameraOutputCapability));
   
   // previewProfiles属性为获取当前设备支持的预览输出流。
   let previewProfilesArray: Array<camera.Profile> = cameraOutputCapability.previewProfiles;
   if (!previewProfilesArray) {
     console.error("getSupportedOutputCapability previewProfilesArray == null || undefined");
   }
   //photoProfiles属性为获取当前设备支持的拍照输出流。
   let photoProfilesArray: Array<camera.Profile> = cameraOutputCapability.photoProfiles;
   if (!photoProfilesArray) {
     console.error("getSupportedOutputCapability photoProfilesArray == null || undefined");
   }
   //videoProfiles属性为获取当前设备支持的录像输出流。
   let videoProfilesArray: Array<camera.VideoProfile> = cameraOutputCapability.videoProfiles;
   if (!videoProfilesArray) {
     console.error("getSupportedOutputCapability videoProfilesArray == null || undefined");
   }
   //supportedMetadataObjectTypes属性为获取当前设备支持的metadata流类型信息集合，目前只定义了FACE_DETECTION用于人脸检测的metadata类型
   let metadataObjectTypesArray: Array<camera.MetadataObjectType> = cameraOutputCapability.supportedMetadataObjectTypes;
   if (!metadataObjectTypesArray) {
     console.error("getSupportedOutputCapability metadataObjectTypesArray== null || undefined");
   }
   return cameraOutputCapability;
} 

创建相机输出流

根据用户需求创建不同类型的输出流

//创建预览流
function createPreviewOutput(cameraManager: camera.CameraManager, cameraOutputCapability: camera.CameraOutputCapability, surfaceId: string): camera.PreviewOutput | undefined {
  let previewProfilesArray: Array<camera.Profile> = cameraOutputCapability.previewProfiles;
  let previewOutput: camera.PreviewOutput | undefined = undefined;
  try {
    previewOutput = cameraManager.createPreviewOutput(previewProfilesArray[0], surfaceId);
  } catch (error) {
    let err = error as BusinessError;
    console.error(`The createPreviewOutput call failed. error code: ${err.code}`);
  }
  return previewOutput;
}
 
// 创建拍照流
function createPhotoOutput(cameraManager: camera.CameraManager, cameraOutputCapability: camera.CameraOutputCapability): camera.PhotoOutput | undefined {
  let photoProfilesArray: Array<camera.Profile> = cameraOutputCapability.photoProfiles;
  let photoOutput: camera.PhotoOutput | undefined = undefined;
  try {
    photoOutput = cameraManager.createPhotoOutput(photoProfilesArray[0]);
  } catch (error) {
    let err = error as BusinessError;
    console.error(`The createPhotoOutput call failed. error code: ${err.code}`);
  }
  return photoOutput;
}

//创建录像流
function createVideoOutput(cameraOutputCapability: camera.CameraOutputCapability, cameraManager: camera.CameraManager, surfaceId: string): camera.VideoOutput | undefined {
  let videoProfilesArray: Array<camera.VideoProfile> = cameraOutputCapability.videoProfiles;
  let videoOutput: camera.VideoOutput | undefined = undefined;
  try {
    videoOutput = cameraManager.createVideoOutput(videoProfilesArray[0], surfaceId);
  } catch (error) {
    let err = error as BusinessError;
    console.error(`The createVideoOutput call failed. error code: ${err.code}`);
  }
  return videoOutput;
}

API参考

createCameraInput

createCameraInput(camera: CameraDevice): CameraInput

使用CameraDevice对象创建CameraInput实例，同步返回结果。
参数CameraDevice对象，通过 CameraManager.getSupportedCameras 接口获取。

createCameraInput(position: CameraPosition, type: CameraType): CameraInput

根据相机位置和类型创建CameraInput实例，同步返回结果。

getSupportedSceneModes

getSupportedSceneModes(camera: CameraDevice): Array<SceneMode>

enum SceneMode {
    NORMAL_PHOTO = 1,   // 普通拍照模式
    NORMAL_VIDEO = 2,   // 普通录像模式
    SECURE_PHOTO = 12,  // 安全相机模式
    ...                 // 其余模式为system api，如人像、夜景、专业拍照模式等
}

getSupportedOutputCapability

getSupportedOutputCapability(camera: CameraDevice, mode: SceneMode): CameraOutputCapability

interface CameraOutputCapability {
    readonly previewProfiles: Array<Profile>;
    readonly photoProfiles: Array<Profile>;
    readonly videoProfiles: Array<VideoProfile>;
    readonly depthProfiles: Array<DepthProfile>; //深度数据配置信息，systemapi
    readonly supportedMetadataObjectTypes: Array<MetadataObjectType>;
  }

查询相机设备在某种模式下支持的输出能力，同步返回结果