原理介绍

鸿蒙系统的文字和提取主要是使用基础视觉服务下图是相关介绍

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本文主要是使用基础视觉服务的的textRecognition方法，识别图片中的文字。

功能实现

1. 配置页面的布局，并添加点击事件

   Image(this.chooseImage)
           .objectFit(ImageFit.Fill)
           .height('60%')
    
         Text(this.dataValues)
           .copyOption(CopyOptions.LocalDevice)
           .height('15%')
           .margin(10)
           .width('60%')
    
         Button('选择图片')
           .type(ButtonType.Capsule)
           .fontColor(Color.White)
           .alignSelf(ItemAlign.Center)
           .width('80%')
           .margin(10)
           .onClick(() => {
             // 拉起图库，获取图片资源
             this.selectImage();
           })
    
         Button('开始识别')
           .type(ButtonType.Capsule)
           .fontColor(Color.White)
           .alignSelf(ItemAlign.Center)
           .width('80%')
           .margin(10)
           .onClick(async () => {
             this.textRecognitionTest();
           })复制
   

2. 通过图库获取图片资源

   private openPhoto(): Promise<string> {
       return new Promise<string>((resolve) => {
         let photoPicker: photoAccessHelper.PhotoViewPicker = new photoAccessHelper.PhotoViewPicker();
         photoPicker.select({
           MIMEType: photoAccessHelper.PhotoViewMIMETypes.IMAGE_TYPE,
           maxSelectNumber: 1
         }).then((res: photoAccessHelper.PhotoSelectResult) => {
           resolve(res.photoUris[0]);
         }).catch((err: BusinessError) => {
           hilog.error(0x0000, 'OCRDemo', `Failed to get photo image uri. Code：${err.code}，message：${err.message}`);
           resolve('');
         })
       })
     }复制
   

3. 将图片资源转换为需要的格式（PixelMap）

   private loadImage(name: string) {
       setTimeout(async () => {
         let fileSource = await fileIo.open(name, fileIo.OpenMode.READ_ONLY);
         this.imageSource = image.createImageSource(fileSource.fd);
         this.chooseImage = await this.imageSource.createPixelMap();
       }, 100)
     }复制
   

4. 初始化相关资源

     //初始化textRecognition
     async aboutToAppear(): Promise<void> {
       const initResult = await textRecognition.init();
       hilog.info(0x0000, 'OCRDemo', `OCR service initialization result:${initResult}`);
     }
    
     //释放方法textRecognition
     async aboutToDisappear(): Promise<void> {
       await textRecognition.release();
       hilog.info(0x0000, 'OCRDemo', 'OCR service released successfully');
     }
    
     private async selectImage() {
       let uri = await this.openPhoto();
       if (uri === undefined) {
         hilog.error(0x0000, 'OCRDemo', "Failed to get uri.");
         return;
       }
       this.loadImage(uri);
     }复制
   

5. 调用textRecognition的recognizeText方法识别文字，并处理识别结果

   private textRecognitionTest() {
       if (!this.chooseImage) {
         return;
       }
       // 实例化VisionInfo对象，并传入待检测图片的PixelMap
       let visionInfo: textRecognition.VisionInfo = {
         pixelMap: this.chooseImage
       };
       //配置通用文本识别的配置项TextRecognitionConfiguration，用于配置是否支持朝向检测。
       let textConfiguration: textRecognition.TextRecognitionConfiguration = {
         isDirectionDetectionSupported: false
       };
       textRecognition.recognizeText(visionInfo, textConfiguration)
         .then((data: textRecognition.TextRecognitionResult) => {
           // 识别成功，获取对应的结果
           let recognitionString = JSON.stringify(data);
           hilog.info(0x0000, 'OCRDemo', `Succeeded in recognizing text：${recognitionString}`);
           // 将结果更新到Text中显示
           this.dataValues = data.value;
         })
         .catch((error: BusinessError) => {
           hilog.error(0x0000, 'OCRDemo', `Failed to recognize text. Code: ${error.code}, message: ${error.message}`);
           this.dataValues = `Error: ${error.message}`;
         });
     }