鸿蒙AI功能开发【拍照识别文字】

拍照识别文字

介绍

本示例通过使用@ohos.multimedia.camera (相机管理)和textRecognition（文字识别）接口来实现识别提取照片内文字的功能。

效果预览

使用说明

1.点击界面下方圆形文字识别图标，弹出文字识别结果信息界面，显示当前照片的文字识别结果；

2.点击除了弹窗外的空白区域，弹窗关闭，返回主页。

具体实现

本实例完成AI文字识别的功能模块主要封装在CameraModel，源码参考:[CameraModel.ets]。

/** Copyright (c) 2023 Huawei Device Co., Ltd.* Licensed under the Apache License, Version 2.0 (the "License");* you may not use this file except in compliance with the License.* You may obtain a copy of the License at**     http://www.apache.org/licenses/LICENSE-2.0** Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS,* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.* See the License for the specific language governing permissions and* limitations under the License.*/
import { BusinessError } from '@kit.BasicServicesKit';
import { camera } from '@kit.CameraKit';
import { common } from '@kit.AbilityKit';
import { image } from '@kit.ImageKit';
import { textRecognition } from '@kit.CoreVisionKit';
import Logger from './Logger';
import CommonConstants from '../constants/CommonConstants';const TAG: string = '[CameraModel]';export default class Camera {private cameraMgr: camera.CameraManager | undefined = undefined;private cameraDevice: camera.CameraDevice | undefined = undefined;private capability: camera.CameraOutputCapability | undefined = undefined;private cameraInput: camera.CameraInput | undefined = undefined;public previewOutput: camera.PreviewOutput | undefined = undefined;private receiver: image.ImageReceiver | undefined = undefined;private photoSurfaceId: string | undefined = undefined;private photoOutput: camera.PhotoOutput | undefined = undefined;public captureSession: camera.PhotoSession | undefined = undefined;public result: string = '';private imgReceive: Function | undefined = undefined;async initCamera(surfaceId: string): Promise<void> {this.cameraMgr = camera.getCameraManager(getContext(this) as common.UIAbilityContext);let cameraArray = this.getCameraDevices(this.cameraMgr);this.cameraDevice = cameraArray[CommonConstants.INPUT_DEVICE_INDEX];this.cameraInput = this.getCameraInput(this.cameraDevice, this.cameraMgr) as camera.CameraInput;await this.cameraInput.open();this.capability = this.cameraMgr.getSupportedOutputCapability(this.cameraDevice, camera.SceneMode.NORMAL_PHOTO);this.previewOutput = this.getPreviewOutput(this.cameraMgr, this.capability, surfaceId) as camera.PreviewOutput;this.photoOutput = this.getPhotoOutput(this.cameraMgr, this.capability) as camera.PhotoOutput;this.photoOutput.on('photoAvailable', (errCode: BusinessError, photo: camera.Photo): void => {let imageObj = photo.main;imageObj.getComponent(image.ComponentType.JPEG,async (errCode: BusinessError, component: image.Component)=> {if (errCode || component === undefined) {return;}let buffer: ArrayBuffer;buffer = component.byteBufferthis.result = await this.recognizeImage(buffer);})})// Session Initthis.captureSession = this.getCaptureSession(this.cameraMgr) as camera.PhotoSession;this.beginConfig(this.captureSession);this.startSession(this.captureSession, this.cameraInput, this.previewOutput, this.photoOutput);}async takePicture() {this.result = '';this.photoOutput!.capture();}async recognizeImage(buffer: ArrayBuffer): Promise<string> {let imageResource = image.createImageSource(buffer);let pixelMapInstance = await imageResource.createPixelMap();let visionInfo: textRecognition.VisionInfo = {pixelMap: pixelMapInstance};let textConfiguration: textRecognition.TextRecognitionConfiguration = {isDirectionDetectionSupported: true};let recognitionString: string = '';if (canIUse("SystemCapability.AI.OCR.TextRecognition")) {await textRecognition.recognizeText(visionInfo, textConfiguration).then((TextRecognitionResult) => {if (TextRecognitionResult.value === '') {let context = getContext(this) as common.UIAbilityContextrecognitionString = context.resourceManager.getStringSync($r('app.string.unrecognizable').id);} else {recognitionString = TextRecognitionResult.value;}})pixelMapInstance.release();imageResource.release();} else {let context = getContext(this) as common.UIAbilityContextrecognitionString = context.resourceManager.getStringSync($r('app.string.Device_not_support').id);Logger.error(TAG, `device not support`);}return recognitionString;}async releaseCamera(): Promise<void> {if (this.cameraInput) {await this.cameraInput.close();Logger.info(TAG, 'cameraInput release');}if (this.previewOutput) {await this.previewOutput.release();Logger.info(TAG, 'previewOutput release');}if (this.receiver) {await this.receiver.release();Logger.info(TAG, 'receiver release');}if (this.photoOutput) {await this.photoOutput.release();Logger.info(TAG, 'photoOutput release');}if (this.captureSession) {await this.captureSession.release();Logger.info(TAG, 'captureSession release');this.captureSession = undefined;}this.imgReceive = undefined;}getCameraDevices(cameraManager: camera.CameraManager): Array<camera.CameraDevice> {let cameraArray: Array<camera.CameraDevice> = cameraManager.getSupportedCameras();if (cameraArray != undefined && cameraArray.length > 0) {return cameraArray;} else {Logger.error(TAG, `getSupportedCameras faild`);return [];}}getCameraInput(cameraDevice: camera.CameraDevice, cameraManager: camera.CameraManager): camera.CameraInput | undefined {let cameraInput: camera.CameraInput | undefined = undefined;cameraInput = cameraManager.createCameraInput(cameraDevice);return cameraInput;}getPreviewOutput(cameraManager: camera.CameraManager, cameraOutputCapability: camera.CameraOutputCapability,surfaceId: string): camera.PreviewOutput | undefined {let previewProfilesArray: Array<camera.Profile> = cameraOutputCapability.previewProfiles;let previewOutput: camera.PreviewOutput | undefined = undefined;previewOutput = cameraManager.createPreviewOutput(previewProfilesArray[CommonConstants.OUTPUT_DEVICE_INDEX], surfaceId);return previewOutput;}async getImageReceiverSurfaceId(receiver: image.ImageReceiver): Promise<string | undefined> {let photoSurfaceId: string | undefined = undefined;if (receiver !== undefined) {photoSurfaceId = await receiver.getReceivingSurfaceId();Logger.info(TAG, `getReceivingSurfaceId success`);}return photoSurfaceId;}getPhotoOutput(cameraManager: camera.CameraManager, cameraOutputCapability: camera.CameraOutputCapability): camera.PhotoOutput | undefined {let photoProfilesArray: Array<camera.Profile> = cameraOutputCapability.photoProfiles;Logger.info(TAG, JSON.stringify(photoProfilesArray));if (!photoProfilesArray) {Logger.info(TAG, `createOutput photoProfilesArray == null || undefined`);}let photoOutput: camera.PhotoOutput | undefined = undefined;try {photoOutput = cameraManager.createPhotoOutput(photoProfilesArray[CommonConstants.OUTPUT_DEVICE_INDEX]);} catch (error) {Logger.error(TAG, `Failed to createPhotoOutput. error: ${JSON.stringify(error as BusinessError)}`);}return photoOutput;}getCaptureSession(cameraManager: camera.CameraManager): camera.PhotoSession | undefined {let captureSession: camera.PhotoSession | undefined = undefined;try {captureSession = cameraManager.createSession(1) as camera.PhotoSession;} catch (error) {Logger.error(TAG, `Failed to create the CaptureSession instance. error: ${JSON.stringify(error as BusinessError)}`);}return captureSession;}beginConfig(captureSession: camera.PhotoSession): void {try {captureSession.beginConfig();Logger.info(TAG, 'captureSession beginConfig')} catch (error) {Logger.error(TAG, `Failed to beginConfig. error: ${JSON.stringify(error as BusinessError)}`);}}async startSession(captureSession: camera.PhotoSession, cameraInput: camera.CameraInput, previewOutput:camera.PreviewOutput, photoOutput: camera.PhotoOutput): Promise<void> {captureSession.addInput(cameraInput);captureSession.addOutput(previewOutput);captureSession.addOutput(photoOutput);await captureSession.commitConfig().then(() => {Logger.info(TAG, 'Promise returned to captureSession the session start success.')}).catch((err: BusinessError) => {Logger.info(TAG, 'captureSession error')Logger.info(TAG, JSON.stringify(err))});await captureSession.start().then(() => {Logger.info(TAG, 'Promise returned to indicate the session start success.')}).catch((err: BusinessError) => {Logger.info(TAG, JSON.stringify(err))})}
}