CefSharp custom SchemeHandler

Question

Iam using CefSharp\'s SchemeHandler in order to grab resources from my C# project like .css, .js or .png files using a custom url for

Answer 1

If you simply need to return a string, then you can use ResourceHandler.FromString(html, mimeType). For this you just need to implement the ISchemeHandlerFactory.

https://github.com/cefsharp/CefSharp/blob/cefsharp/47/CefSharp/ResourceHandler.cs#L98

Example reading from a file https://github.com/cefsharp/CefSharp/blob/cefsharp/47/CefSharp.Example/CefSharpSchemeHandlerFactory.cs#L17 which can be translated to reading from a string quite simply.

Answer 2

Since Cefsharp changed a bit in last few months here is an updated and easier way of handling 'file' protocol. I wrote blog post on this matter.

What you want to add is your scheme handler and its factory:

using System;
using System.IO;
using CefSharp;

namespace MyProject.CustomProtocol
{
    public class CustomProtocolSchemeHandler : ResourceHandler
    {
        // Specifies where you bundled app resides.
        // Basically path to your index.html
        private string frontendFolderPath;

        public CustomProtocolSchemeHandler()
        {
            frontendFolderPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "./bundle/");
        }

        // Process request and craft response.
        public override bool ProcessRequestAsync(IRequest request, ICallback callback)
        {
            var uri = new Uri(request.Url);
            var fileName = uri.AbsolutePath;

            var requestedFilePath = frontendFolderPath + fileName;

            if (File.Exists(requestedFilePath))
            {
                byte[] bytes = File.ReadAllBytes(requestedFilePath);
                Stream = new MemoryStream(bytes);

                var fileExtension = Path.GetExtension(fileName);
                MimeType = GetMimeType(fileExtension);

                callback.Continue();
                return true;
            }

            callback.Dispose();
            return false;
        }
    }

    public class CustomProtocolSchemeHandlerFactory : ISchemeHandlerFactory
    {
        public const string SchemeName = "customFileProtocol";

        public IResourceHandler Create(IBrowser browser, IFrame frame, string schemeName, IRequest request)
        {
            return new CustomProtocolSchemeHandler();
        }
    }
}

And then register it before calling Cef.Initialize:

var settings = new CefSettings
{
  BrowserSubprocessPath = GetCefExecutablePath()
};

settings.RegisterScheme(new CefCustomScheme
{
  SchemeName = CustomProtocolSchemeHandlerFactory.SchemeName,
  SchemeHandlerFactory = new CustomProtocolSchemeHandlerFactory()
});