OpenHarmony开发者论坛

标题: OpenHarmony Flutter扫码功能插件开发 [打印本页]

作者: 深开鸿_石悌君 时间: 7 天前
标题: OpenHarmony Flutter扫码功能插件开发
[md]扫码是手机常用功能，适配fluttertpc_mobile_scanner时发现安卓和OpenHarmony略有差异；解析如下

## 安卓实现方案

安卓插件的扫码基于com.google.mlkit.vision.barcode.BarcodeScanning库实现；

对本地图片进行扫码的核心流程如下

```kotlin
var scanner = BarcodeScanning.getClient() //定义scanner
fun analyzeImage(image: Uri, analyzerCallback: AnalyzerCallback) {
      val inputImage = InputImage.fromFilePath(activity, image)

      scanner.process(inputImage) //调用scanner.process得到扫码结果
         .addOnSuccessListener { barcodes ->
            val barcodeMap = barcodes.map { barcode -> barcode.data }

            if (barcodeMap.isNotEmpty()) {
                  analyzerCallback(barcodeMap)
            } else {
                  analyzerCallback(null)
            }
         }
}
```

通过相机扫码仍然借用图片扫码流程：先调用相机拍照接口得到照片，再调用scanner.process得到扫码结果

## OpenHarmony实现方案

OpenHarmony自带ScanKit，可以方便实现扫码功能

### 图片扫码

图片扫码很简单，使用即可获得扫码结果

```typescript
import { scanCore, scanBarcode, detectBarcode } from '@kit.ScanKit';
analyzeImage(call: MethodCall, result: MethodResult) {
const options: scanBarcode.ScanOptions = {
      scanTypes: [scanCore.ScanType.ALL],
      enableMultiMode: true,
      enableAlbum: true
}

let inputImage: detectBarcode.InputImage = { uri: call.args }
detectBarcode.decode(inputImage, options, (error: BusinessError, scanResult: Array<scanBarcode.ScanResult>) => {
})
}
```

### 相机扫码

相机扫码如果借鉴安卓流程也不是不行，但OpenHarmony提供了customeScan模块，实现更加简单

重点流程如下

```typescript
import { customScan, scanBarcode, scanCore, detectBarcode } from '@kit.ScanKit';
async start(call: MethodCall, result: MethodResult) {
const options: scanBarcode.ScanOptions = {
      scanTypes: scanTypes,
      enableMultiMode: true,
      enableAlbum: true
}
customScan.init(options); //必须先调用

const viewControl: customScan.ViewControl = {
   width: cameraWidth,
   height: cameraHeight,
   surfaceId: this.surfaceId!,
};

customScan.start(viewControl, this.scanCallback, this.frameCallback)
}

//扫码结果的回调
private scanCallback: AsyncCallback<scanBarcode.ScanResult[]> =
async (error: BusinessError, result: scanBarcode.ScanResult[]) => {
//处理扫码结果
}

//扫码时图像的回调
private frameCallback: AsyncCallback<customScan.ScanFrame> =
async (error: BusinessError, frameResult: customScan.ScanFrame) => {

}
```

frameCallback这个回调就比安卓方便多了，不需要调用一堆相机接口得到图像

### 相机图像的转码

frameCallback中返回的图像数据是YUV格式，需要转码成jpg等格式才能正确显示；这里需要用到imageKit系列函数，代码如下

```typescript
private frameCallback: AsyncCallback<customScan.ScanFrame> =
async (error: BusinessError, frameResult: customScan.ScanFrame) => {
let sourcePotions: image.SourceOptions = {
      sourceDensity: 120,
      sourcePixelFormat: image.PixelMapFormat.NV21,
      sourceSize: { height: this.scanHeight, width: this.scanWidth }
}
let imageResource = image.createImageSource(frameResult.byteBuffer, sourcePotions)
let opts: image.InitializationOptions = {
      editable: true,
      pixelFormat: 3,
      size: { height: this.scanHeight, width: this.scanHeight }
}
let pixelMap: image.PixelMap = await imageResource.createPixelMap(opts)
let packer: image.ImagePacker = image.createImagePacker()
let packingOpt: image.PackingOption = { format: "image/jpeg", quality: 100 }
let imgBuffer = await packer.packing(pixelMap, packingOpt);

}
```

### 参考资料

[fluttertpc_mobile_scanner鸿蒙化代码](https://gitee.com/openharmony-sig/fluttertpc_mobile_scanner)

[/md]

欢迎光临 OpenHarmony开发者论坛 (https://forums.openharmony.cn/)