c# - ZXing.Net.Mobile 没有立即开始扫描

Question

我有一个以 ScannerView 作为 MainPage 的页面。当我启动应用程序时，它无法扫描条形码。我必须将另一个页面设置为主页然后导航到扫描仪页面，然后它才能扫描条形码。或者锁定然后解锁手机，然后它就会开始扫描。

App.xaml.cs:

MainPage = new NavigationPage(new ScannerPage());

扫描仪页面.xaml:

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="MyApp.Pages.ScannerPage"
             xmlns:zxing="clr-namespace:ZXing.Net.Mobile.Forms;assembly=ZXing.Net.Mobile.Forms">
    <ContentPage.Content>
        <Grid>
            <zxing:ZXingScannerView x:Name="ScannerView"
                                    IsScanning="True"
                                    IsAnalyzing="True" />
            <zxing:ZXingDefaultOverlay x:Name="ScannerOverlay"
                                       TopText="Hold your phone up to the QR code"
                                       BottomText="Scanning will happen automatically"
                                       ShowFlashButton="True"/>
        </Grid>
    </ContentPage.Content>
</ContentPage>

扫描仪页面.xaml.cs:

public partial class ScannerPage : ContentPage
{
    public ScannerPage ()
    {
        InitializeComponent ();

        ScannerView.Options = new MobileBarcodeScanningOptions
        {
            PossibleFormats = new List<BarcodeFormat>
            {
                BarcodeFormat.DATA_MATRIX,
            },
            TryHarder = true
        };

        ScannerView.OnScanResult += (result) => Device.BeginInvokeOnMainThread(async () =>
        {
            ScannerView.IsAnalyzing = false;
            await DisplayAlert("Scanned", result.Text, "Ok");
            ScannerView.IsAnalyzing = true;
        });
    }
}

Answer 1

我最终以编程方式使用了以下代码:

    public static async Task ScanConnection()
    {
            MobileBarcodeScanningOptions options = new ZXing.Mobile.MobileBarcodeScanningOptions()
                {
                    TryHarder = true,
                    PossibleFormats = new List<ZXing.BarcodeFormat>() { ZXing.BarcodeFormat.QR_CODE }
                };


                MobileBarcodeScanner scanner = new ZXing.Mobile.MobileBarcodeScanner();

                ZXing.Result result = await scanner.Scan(options);

                if (result != null && !string.IsNullOrEmpty(result.Text))
                {
                    ...
                }
    }

您可以从派生页面中重写的 OnAppearing() 方法调用该代码。