can't open pdf with wpf webbrowser - wpf

Question

I'm trying to create an app to open a local PDF file using web browser in WPF. However the file doesn't open properly, instead displays a grey blank screen. The code works perfectly fine when used to open a HTML file. Please help!
Code: webBrowser1.Navigate(#"file:///C:/Working/sample.pdf");
Note: I have adobe reader installed in my PC, if that is necessary. Is it?

Answer 1

WPF by default uses IE-based WebBrowser. In order to be able to view PDF-files, you must have a plugin installed into IE which can display PDF-files.
In addition to grey background, this is what can happen with a PC where IE doesn't have a PDF-plugin (Acrobat Reader etc) installed:
If you don't want to install plugins, one option to get around this issue is to use Windows 10 APIs to draw the PDF.
Other option is a 3rd party library, like CefSharp. Here's steps for using CefSharp:
First install Nuget CefSharp.WPF
Second, change XAML from the default WebBrowser to:
<wpf:ChromiumWebBrowser Loaded="ChromiumWebBrowser_Loaded" x:Name="Browser"></wpf:ChromiumWebBrowser>
Then create custom resolvers for CefSharp:
public class CustomProtocolSchemeHandler : ResourceHandler
{
public CustomProtocolSchemeHandler()
{
}
public override bool ProcessRequestAsync(IRequest request, ICallback callback)
{
return true;
}
}
public class CustomProtocolSchemeHandlerFactory : ISchemeHandlerFactory
{
public const string SchemeName = "customFileProtocol";
public IResourceHandler Create(IBrowser browser, IFrame frame, string schemeName, IRequest request)
{
return new CustomProtocolSchemeHandler();
}
}
Almost lastly, register the resolvers in App.xaml.cs:
public partial class App : Application
{
protected override void OnLoadCompleted(NavigationEventArgs e)
{
var settings = new CefSettings();
settings.RegisterScheme(new CefCustomScheme
{
SchemeName = CustomProtocolSchemeHandlerFactory.SchemeName,
SchemeHandlerFactory = new CustomProtocolSchemeHandlerFactory(),
IsCSPBypassing = true
});
settings.LogSeverity = LogSeverity.Error;
Cef.Initialize(settings);
}
}
Now everything should work:
More information about using CefSharp: https://www.codeproject.com/Articles/881315/Display-HTML-in-WPF-and-CefSharp-Tutorial-Part

Answer 2

I'll probably add a few changes to #Mikael's code (In case something didn't work out for you)
public class CustomProtocolSchemeHandler : ResourceHandler
{
public CustomProtocolSchemeHandler()
{
}
public override CefSharp.CefReturnValue ProcessRequestAsync(IRequest request, ICallback callback)
{
return CefSharp.CefReturnValue.Continue;
}
}
public class CustomProtocolSchemeHandlerFactory : ISchemeHandlerFactory
{
public const string SchemeName = "customFileProtocol";
public IResourceHandler Create(IBrowser browser, IFrame frame, string schemeName, IRequest request)
{
return new CustomProtocolSchemeHandler();
}
}