Question

我有一个示例pdf URL“ http://www.africau.edu/images/default/sample.pdf”。我想显示此pdf文件，并使用Xamarin.Forms在我的移动应用程序中显示。我尝试使用网络视图和一些自定义渲染器，但没有用。

public class PdfViewRenderer : WebViewRenderer
    {
        internal class PdfWebChromeClient : WebChromeClient
        {
            public override bool OnJsAlert(Android.Webkit.WebView view, string url, string message, JsResult result)
            {
                if (message != "PdfViewer_app_scheme:print")
                {
                    return base.OnJsAlert(view, url, message, result);
                }
                using (var printManager = Forms.Context.GetSystemService(Android.Content.Context.PrintService) as PrintManager)
                {
                    printManager?.Print(FileName, new FilePrintDocumentAdapter(FileName, Uri), null);
                }
                return true;
            }
            public string Uri { private get; set; }
            public string FileName { private get; set; }
        }
        protected override void OnElementChanged(ElementChangedEventArgs<WebView> e)
        {
            base.OnElementChanged(e);
            if (e.NewElement == null)
            {
                return;
            }
            var pdfView = Element as PdfView;
            if (pdfView == null)
            {
                return;
            }
            if (string.IsNullOrWhiteSpace(pdfView.Uri) == false)


        {
            Control.SetWebChromeClient(new PdfWebChromeClient
            {
                Uri = pdfView.Uri,
                //FileName = GetFileNameFromUri(pdfView.Uri)
            });
        }
        Control.Settings.AllowFileAccess = true;
        Control.Settings.AllowUniversalAccessFromFileURLs = true;
        LoadFile(pdfView.Uri);
    }
    private static string GetFileNameFromUri(string uri)
    {
        var lastIndexOf = uri?.LastIndexOf("/", StringComparison.InvariantCultureIgnoreCase);
        return lastIndexOf > 0 ? uri.Substring(lastIndexOf.Value, uri.Length - lastIndexOf.Value) : string.Empty;
    }
    protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        base.OnElementPropertyChanged(sender, e);

        if (e.PropertyName != PdfView.UriProperty.PropertyName)
        {
            return;
        }
        var pdfView = Element as PdfView;
        if (pdfView == null)
        {
            return;
        }
        if (string.IsNullOrWhiteSpace(pdfView.Uri) == false)
        {
            Control.SetWebChromeClient(new PdfWebChromeClient
            {
                Uri = pdfView.Uri,
               // FileName = GetFileNameFromUri(pdfView.Uri)
            });
        }
        LoadFile(pdfView.Uri);
    }
    private void LoadFile(string uri)
    {
        if (string.IsNullOrWhiteSpace(uri))
        {
            return;
        }
        //Control.Resources = new Uri(string.Format("ms-appx-web:///Assets/pdfjs/web/viewer.html?file={0}", string.Format("ms-appx-web:///Assets/Content/{0}", WebUtility.UrlEncode(PdfView.Uri))));
        Control.LoadUrl($"file:///android_asset/pdfjs/web/viewer.html?file=file://{uri}");
        //Control.LoadUrl(uri);
        Control.LoadUrl(string.Format("ms-appx-web:///Assets/pdfjs/web/viewer.html?file={0}", string.Format("ms-appx-web:///Assets/Content/{0}", WebUtility.UrlEncode(uri))));
    }
}

Answer 1

您的XAML

<WebView x:Name="Webview"  
             HeightRequest="1000"  
             WidthRequest="1000"              
             VerticalOptions="FillAndExpand"/>

像这样放置您的Webview源

 Webview.Source = "https://docs.google.com/gview?
    embedded=true&url="+"http://www.africau.edu/images/default/sample.pdf";

Answer 2

在Android

[assembly: ExportRenderer(typeof(CustomWebView), typeof(CustomWebViewRenderer))]
namespace DipsDemoXaml.Droid.Renderer

public class CustomWebViewRenderer : WebViewRenderer
{
    public CustomWebViewRenderer(Context context) : base(context)
    { 
    }

    protected override void OnElementChanged(ElementChangedEventArgs<WebView> e)
    {
        base.OnElementChanged(e);

        if (e.NewElement != null)
        {              
            Control.Settings.AllowUniversalAccessFromFileURLs = true;
            Control.Settings.BuiltInZoomControls = true;
            Control.Settings.DisplayZoomControls = true;

        }
        this.Control.SetBackgroundColor(Android.Graphics.Color.Transparent);
    }
    protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        if (e.PropertyName != "Uri") return;
        var customWebView = Element as CustomWebView;
        if (customWebView != null)
        {
            Control.LoadUrl(string.Format("file:///android_asset/pdfjs/web/viewer.html?file={0}", string.Format("file:///android_asset/Content/{0}", WebUtility.UrlEncode(customWebView.Uri))));        
        }
    }

}

}

对于iOS

  [assembly: ExportRenderer(typeof(CustomWebView), typeof(CustomWebViewRenderer))]
 namespace DipsDemoXaml.iOS.Renderes
  {
  public class CustomWebViewRenderer : ViewRenderer<CustomWebView, UIWebView>
 {
    protected override void OnElementChanged(ElementChangedEventArgs<CustomWebView> 
       e)
      {
          base.OnElementChanged(e);

        if (Control == null)
        {
            SetNativeControl(new UIWebView());
        }
        if (e.OldElement != null)
        {
            // Cleanup
        }
        if (e.NewElement != null)
        {
            var customWebView = Element as CustomWebView;
            string fileName = Path.Combine(NSBundle.MainBundle.BundlePath, string.Format("Content/{0}", WebUtility.UrlEncode(customWebView.Uri)));
            Control.LoadRequest(new NSUrlRequest(new NSUrl(fileName, false)));
            Control.ScalesPageToFit = true;
        }

        this.Opaque = false;
        this.BackgroundColor = Color.Transparent.ToUIColor();
    }
}

}

在共享中

   namespace DipsDemoXaml.Custom.Renderer
{
   public class CustomWebView : WebView
   {
    public static readonly BindableProperty UriProperty =



   BindableProperty.Create(nameof(Uri),typeof(string),
    typeof(CustomWebView),default(string)) 
   ;

    public string Uri
    {
        get => (string) GetValue(UriProperty);
        set => SetValue(UriProperty, value);
    }
}

}

在XAML中，您可以像这样呼叫

             <renderer:CustomWebView Uri="{Binding SelectedJournal.Uri}"  />

我认为您的自定义渲染中存在问题您可以在字符串中创建一个新属性（如URI），并且可以调用URI，这是您需要一种访问Android和iOS Webview的方式，您可以为Android和ios，您可以传递一个新的NSUrl来在您的应用程序内部加载pdf

通过网址在移动应用中显示PDF文件

2 个答案: