Recognizing Barcodes in Image Data

Use Cases

This capability can recognize 1D codes, QR codes, and multifunctional codes from NV21 pixel-format images and retrieve information such as the code type, value, position information, and expected image zoom ratio. It can be used to recognize one or multiple barcodes, such as 1D codes and payment codes, on an image.

Flowchart

1. A user sends a barcode recognition request to your atomic service.

2. Your atomic service calls the decodeImage API of Scan Kit to recognize the barcode image.

3. Scan Kit returns the barcode recognition result.

4. Your atomic service sends the barcode scanning result to the user.

API Description

Recognizes a barcode image in the image data and returns the recognition result using a promise. For details about the API, please refer to API Reference.

Development Procedure

The image-based barcode recognition capability can recognize 1D codes, QR codes, and multifunctional codes from NV21 pixel-format images and return information such as the code type, value, position information (coordinates of the upper left and lower right corners of the minimum bounding rectangle of a barcode image, and coordinates of four corner points of the QR code), and expected image zoom ratio.

The following describes how to call the decodeImage API to obtain barcode image information.

1. Import the image-based barcode recognition API module and other relevant API modules. This API module provides parameters and methods for recognizing barcodes in images.

   import { detectBarcode, scanBarcode, scanCore } from '@kit.ScanKit';
   import { BusinessError } from '@kit.BasicServicesKit';
   import { hilog } from '@kit.PerformanceAnalysisKit';

2. Call the decodeImage API to parse image data.

   @Entry
   @Component
   struct DetectImagePage {
     build() {
       Column() {
         Button('Promise with options')
           .backgroundColor('#0D9FFB')
           .fontSize(20)
           .fontColor($r('sys.color.comp_background_list_card'))
           .fontWeight(FontWeight.Normal)
           .align(Alignment.Center)
           .type(ButtonType.Capsule)
           .width('90%')
           .height(40)
           .margin({ top: 5, bottom: 5 })
           .onClick(() => {
             // Define scanning parameters.
             let options: scanBarcode.ScanOptions = {
               scanTypes: [scanCore.ScanType.ALL],
               enableMultiMode: true
             };
             // Obtain the data in NV21 pixel format; for example, read the image data from the resources/rawfile directory.
             this.getUIContext()
               .getHostContext()?.resourceManager
               .getRawFileContent('qrcode_NV21_image_1080X1920.yuv')
               .then((imageData: Uint8Array) => {
                 let byteImage: detectBarcode.ByteImage = {
                   byteBuffer: imageData.buffer,
                   width: 1080,
                   height: 1920,
                   format: detectBarcode.ImageFormat.NV21
                 };
                 try {
                   // Call the image-based barcode recognition API.
                   detectBarcode.decodeImage(byteImage, options).then((data: detectBarcode.DetectResult) => {
                     hilog.info(0x0001, '[Scan Sample]',
                       `Succeeded in getting DetectResult by promise with options, result length: ${data.scanResults.length}, zoomValue: ${data.zoomValue}`);
                   }).catch((err: BusinessError) => {
                     hilog.error(0x0001, '[Scan Sample]',
                       `Failed to get DetectResult by promise with options. Code: ${err.code}, message: ${err.message}`);
                   });
                 } catch (err) {
                   hilog.error(0x0001, '[Scan Sample]',
                     `Failed to detectBarcode. Code: ${err.code}, message: ${err.message}`);
                 }
               })
               .catch((err: BusinessError) => {
                 hilog.error(0x0001, '[Scan Sample]',
                   `Failed to read image. Code: ${err.code}, message: ${err.message}`);
               });
           })
       }
       .width('100%')
       .height('100%')
       .alignItems(HorizontalAlign.Center)
       .justifyContent(FlexAlign.Center)
     }
   }

Emulator-based Development

This capability does not support Emulator-based development currently, and the error message "The capability is not supported on the emulator at this time." will be displayed if you attempt to perform Emulator-based development.