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1# 拍照
2
3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。
4
5## 开发步骤
6
7详细的API说明请参考[Camera API参考](../reference/apis/js-apis-camera.md)。
8
91. 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。
10
11   ```ts
12   import image from '@ohos.multimedia.image';
13   import camera from '@ohos.multimedia.camera';
14   import { BusinessError } from '@ohos.base';
15   ```
16
172. 获取SurfaceId。
18
19   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。
20
21   ```ts
22   async function getImageReceiverSurfaceId(): Promise<string | undefined> {
23     let photoSurfaceId: string | undefined = undefined;
24     let receiver: image.ImageReceiver = image.createImageReceiver(640, 480, 4, 8);
25     console.info('before ImageReceiver check');
26     if (receiver !== undefined) {
27       console.info('ImageReceiver is ok');
28       photoSurfaceId = await receiver.getReceivingSurfaceId();
29       console.info(`ImageReceived id: ${JSON.stringify(photoSurfaceId)}`);
30     } else {
31       console.info('ImageReceiver is not ok');
32     }
33     return photoSurfaceId;
34   }
35   ```
36
373. 创建拍照输出流。
38
39   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。
40
41   ```ts
42   function getPhotoOutput(cameraManager: camera.CameraManager, cameraOutputCapability: camera.CameraOutputCapability, photoSurfaceId: string): camera.PhotoOutput | undefined {
43     let photoProfilesArray: Array<camera.Profile> = cameraOutputCapability.photoProfiles;
44     if (!photoProfilesArray) {
45       console.error("createOutput photoProfilesArray == null || undefined");
46     }
47     let photoOutput: camera.PhotoOutput | undefined;
48     try {
49       photoOutput = cameraManager.createPhotoOutput(photoProfilesArray[0], photoSurfaceId);
50     } catch (error) {
51       let err = error as BusinessError;
52       console.error(`Failed to createPhotoOutput. error: ${JSON.stringify(err)}`);
53     }
54     return photoOutput;
55   }
56   ```
57
584. 参数配置。
59
60   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。
61
62   ```ts
63   function configuringSession(captureSession: camera.CaptureSession): void {
64     // 判断设备是否支持闪光灯
65     let flashStatus: boolean = false;
66     try {
67       flashStatus = captureSession.hasFlash();
68     } catch (error) {
69       let err = error as BusinessError;
70       console.error(`Failed to hasFlash. error: ${JSON.stringify(err)}`);
71     }
72     console.info(`Promise returned with the flash light support status: ${flashStatus}`);
73     if (flashStatus) {
74       // 判断是否支持自动闪光灯模式
75       let flashModeStatus: boolean = false;
76       try {
77         let status: boolean = captureSession.isFlashModeSupported(camera.FlashMode.FLASH_MODE_AUTO);
78         flashModeStatus = status;
79       } catch (error) {
80         let err = error as BusinessError;
81         console.error(`Failed to check whether the flash mode is supported. error: ${JSON.stringify(err)}`);
82       }
83       if (flashModeStatus) {
84         // 设置自动闪光灯模式
85         try {
86           captureSession.setFlashMode(camera.FlashMode.FLASH_MODE_AUTO);
87         } catch (error) {
88           let err = error as BusinessError;
89           console.error(`Failed to set the flash mode. error: ${JSON.stringify(err)}`);
90         }
91       }
92     }
93     // 判断是否支持连续自动变焦模式
94     let focusModeStatus: boolean = false;
95     try {
96       let status: boolean = captureSession.isFocusModeSupported(camera.FocusMode.FOCUS_MODE_CONTINUOUS_AUTO);
97       focusModeStatus = status;
98     } catch (error) {
99       let err = error as BusinessError;
100       console.error(`Failed to check whether the focus mode is supported. error: ${JSON.stringify(err)}`);
101     }
102     if (focusModeStatus) {
103       // 设置连续自动变焦模式
104       try {
105         captureSession.setFocusMode(camera.FocusMode.FOCUS_MODE_CONTINUOUS_AUTO);
106       } catch (error) {
107         let err = error as BusinessError;
108         console.error(`Failed to set the focus mode. error: ${JSON.stringify(err)}`);
109       }
110     }
111     // 获取相机支持的可变焦距比范围
112     let zoomRatioRange: Array<number> = [];
113     try {
114       zoomRatioRange = captureSession.getZoomRatioRange();
115     } catch (error) {
116       let err = error as BusinessError;
117       console.error(`Failed to get the zoom ratio range. error: ${JSON.stringify(err)}`);
118     }
119     if (zoomRatioRange.length <= 0 ) {
120       return;
121     }
122     // 设置可变焦距比
123     try {
124       captureSession.setZoomRatio(zoomRatioRange[0]);
125     } catch (error) {
126       let err = error as BusinessError;
127       console.error(`Failed to set the zoom ratio value. error: ${JSON.stringify(err)}`);
128     }
129   }
130   ```
131
1325. 触发拍照。
133
134   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。
135
136   ```ts
137   function capture(captureLocation: camera.Location, photoOutput: camera.PhotoOutput): void {
138     let settings: camera.PhotoCaptureSetting = {
139       quality: camera.QualityLevel.QUALITY_LEVEL_HIGH,  // 设置图片质量高
140       rotation: camera.ImageRotation.ROTATION_0,  // 设置图片旋转角度0
141       location: captureLocation,  // 设置图片地理位置
142       mirror: false  // 设置镜像使能开关(默认关)
143     };
144     photoOutput.capture(settings, (err: BusinessError) => {
145       if (err) {
146         console.error(`Failed to capture the photo. error: ${JSON.stringify(err)}`);
147         return;
148       }
149       console.info('Callback invoked to indicate the photo capture request success.');
150     });
151   }
152   ```
153
154## 状态监听
155
156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。
157
158- 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。
159
160  ```ts
161  function onPhotoOutputCaptureStart(photoOutput: camera.PhotoOutput): void {
162    photoOutput.on('captureStart', (err: BusinessError, captureId: number) => {
163      console.info(`photo capture stated, captureId : ${captureId}`);
164    });
165  }
166  ```
167
168- 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](../reference/apis/js-apis-camera.md#captureendinfo)。
169
170  ```ts
171  function onPhotoOutputCaptureEnd(photoOutput: camera.PhotoOutput): void {
172    photoOutput.on('captureEnd', (err: BusinessError, captureEndInfo: camera.CaptureEndInfo) => {
173      console.info(`photo capture end, captureId : ${captureEndInfo.captureId}`);
174      console.info(`frameCount : ${captureEndInfo.frameCount}`);
175    });
176  }
177  ```
178
179- 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](../reference/apis/js-apis-camera.md#cameraerrorcode)。
180
181  ```ts
182  function onPhotoOutputError(photoOutput: camera.PhotoOutput): void {
183    photoOutput.on('error', (error: BusinessError) => {
184      console.info(`Photo output error code: ${error.code}`);
185    });
186  }
187  ```
188