从Android Web视图启动QR扫描仪，并使用Xamarin返回扫描结果

Question

I have this Xamarin application that launches a QR scanner when a button is clicked. 我有这个Xamarin应用程序，当单击一个按钮时，它会启动QR扫描仪。 This button click is handled in Javascript. 该按钮单击使用Java语言处理。 When the button is clicked, below C# code gets called. 单击该按钮时，将调用下面的C＃代码。 This supposed to launch the QR scanner and once the value is scanned, the scanned value is returned to a Javascript function. 这应该启动QR扫描仪，并且一旦扫描了值，扫描的值将返回到Javascript函数。 But as soon as the button to scan QR code is clicked, web view app gets to the background but camera is not launched to scan the QR code. 但是，一旦单击扫描QR码的按钮，Web视图应用程序即会进入后台，但不会启动相机来扫描QR码。

 public class QRScannerJSInterface : Java.Lang.Object
    {
        QRScanner qrScanner;
        WebView webView;

        public QRScannerJSInterface(WebView webView)
        {
            this.webView = webView;
            qrScanner = new QRScanner();
        }

        [Export]
        [JavascriptInterface]
        public void ScanQR()
        {
            String result = qrScanner.ScanQR();
            var js = string.Format("getQRValue('{0}');", result);
            webView.LoadUrl("javascript:" + js);
            //call the Javascript method here with "result" as its parameter to get the scanned value
        }

Below is how the main activity calls this class. 以下是主要活动如何调用此类。

        webView = FindViewById<WebView>(Resource.Id.webView);
        webView.Settings.JavaScriptEnabled = true;
        webView.Settings.AllowFileAccessFromFileURLs = true;
        webView.Settings.AllowUniversalAccessFromFileURLs = true;
        webView.Settings.AllowFileAccess = true;
        webView.AddJavascriptInterface(new QRScannerJSInterface(webView),"CSharpQRInterface");

Below is the QRScanner code. 以下是QRScanner代码。

class QRScanner
    {
        MobileBarcodeScanner scanner;

        public QRScanner()
        {
            scanner = new MobileBarcodeScanner();
        }

        public String ScanQR()
        {
            scanner.UseCustomOverlay = false;
            scanner.TopText = "Scanning for barcode";
            Task<ZXing.Result> result = scanner.Scan();
            return result.ToString();
        }
    }

What am I doing wrong here? 我在这里做错了什么？ Any help would be much appreciated. 任何帮助将非常感激。

Answer 1

Below is working solution. 下面是工作解决方案。 Please note scanner async Scan changes. 请注意扫描仪异步扫描更改。 before you would get Task into your js file, you need to await for result. 在将Task放入js文件之前，您需要等待结果。

Asset scannerPage.html 资产扫描器

<html>
<head>
    <title></title>

    <script type='text/javascript'>

        function getQRValue(result) {
    };

        function scan() {
            CSharpQRInterface.ScanQR();
        };


    </script>

</head>
<body style="background-color:powderblue;">
    <button type="button" onclick="scan()">Click Me!</button>
</body>
</html>

MainActivity 主要活动

public class MainActivity : Activity
    {
        WebView webView;

        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            MobileBarcodeScanner.Initialize(Application);

            // Set our view from the "main" layout resource
            SetContentView(Resource.Layout.Main);

            webView = FindViewById<WebView>(Resource.Id.webView);
            webView.Settings.JavaScriptEnabled = true;
            webView.Settings.AllowFileAccessFromFileURLs = true;
            webView.Settings.AllowUniversalAccessFromFileURLs = true;
            webView.Settings.AllowFileAccess = true;
            webView.AddJavascriptInterface(new QRScannerJSInterface(webView), "CSharpQRInterface");
            webView.LoadUrl("file:///android_asset/scannerPage.html");

        }

Scanner interface 扫描仪界面

public class QRScannerJSInterface : Java.Lang.Object
    {
        QRScanner qrScanner;
        WebView webView;

        public QRScannerJSInterface(WebView webView)
        {
            this.webView = webView;
            qrScanner = new QRScanner();
        }

        [Export("ScanQR")]
        public void ScanQR()
        {
            qrScanner.ScanQR()
                .ContinueWith((t) =>
                {
                    //var js = string.Format("getQRValue('{0}');", t.Result);
                    //webView.LoadUrl("javascript:" + js);
                    //call the Javascript method here with "result" as its parameter to get the scanned value
                    if (t.Status == TaskStatus.RanToCompletion)
                        webView.LoadUrl(@"javascript:getQRValue('" + t.Result + "')");
                });
        }
    }

Scanner class 扫描仪类

class QRScanner
    {
        MobileBarcodeScanner scanner;

        public QRScanner()
        {
            scanner = new MobileBarcodeScanner();
        }

        public async Task<string> ScanQR()
        {
            scanner.UseCustomOverlay = false;
            scanner.TopText = "Scanning for barcode";
            var result = await scanner.Scan();
            return result.ToString();
        }
    }

从Android Web视图启动QR扫描仪，并使用Xamarin返回扫描结果

问题描述

1 个解决方案

解决方案1
3 已采纳 2016-10-27 16:30:09

从Android Web视图启动QR扫描仪，并使用Xamarin返回扫描结果

问题描述

1 个解决方案

解决方案1 3 已采纳 2016-10-27 16:30:09

解决方案1
3 已采纳 2016-10-27 16:30:09