Request to add Proxy URLs feature to HybridWebView

Description

A core component I've been using to migrate to MAUI is the Proxy URLs API from Eilon/MauiHybridWebView. This feature smoothly replaces our old communication bridge between Javascript and C#. It would be amazing to have this in the MAUI 9 version of HybridWebView.

The HybridWebView control can redirect URL requests to native code, and allow custom responses streams to be set. This allows scenarios such as dynamically generating content, loading content from compressed files like ZIP or SQLite, or loading content from the internet that doesn't support CORS. Eilon/MauiHybridWebView

Public API Changes

The C# side has an event handler to process proxy requests coming from Javascript. The request content is packaged in HybridWebViewProxyEventArgs with the following properties: Property	Type	Description
QueryParams	IDictionary<string, string>	The query string parameters of the request. Note that all values will be strings.
ResponseContentType	string	The content type of the response body. Default: "text/plain"
ResponseStream	Stream	The stream to use as the response body.
Url	string	The full URL that was requested.

myWebView.ProxyRequestReceived += async ((HybridWebViewProxyEventArgs)args) =>
{
    //Use the query string parameters to determine what to do.
    if (args.QueryParams.TryGetValue("myParameter", out var myParameter))
    {
        //Add your logic to determine what to do. 
        if (myParameter == "myValue")
        {
            //Add logic to get your content (e.g. from a database, or generate it).
            //Can be anything that can be turned into a stream.

            //Set the response stream and optionally the content type.
            args.ResponseStream = new MemoryStream(Encoding.UTF8.GetBytes("This is the file content"));
            args.ResponseContentType = "text/plain";
        }
    }
};

Javascript can send data to C# over the proxy url.

var request = window.location.origin + '/proxy?myParameter=' + encodeURIComponent('myValue') + '&secondParameter=foo' ;

fetch(request)
    .then(response => response.text())
    .then(data => console.log(data));

Intended Use-Case

Our .NET app's legacy code communicates between a C# backend and JavaScript frontend over an SSL stream. The Proxy URLs feature in HybridWebView offers a streamlined API that reduces much of this legacy code and preserves core functionality with minimal changes, making it a close fit for our current setup.

I really look forward to seeing this feature in MAUI's HybridWebView. Thank you for considering this request!

dotnet / maui