GreenSwamp WebView Control

A cross-platform WebView control for Avalonia UI that provides native web rendering on Windows, macOS, and Linux.

Features

• ✅ Cross-Platform Support: Works on Windows, macOS, and Linux
• ✅ Native Rendering Engines:
  • Windows: WebView2 (Microsoft Edge Chromium) via direct COM interop
  • macOS: WKWebView (WebKit)
  • Linux: WebKitGTK
• ✅ Unified API: Single API across all platforms
• ✅ Pure .NET 8 Implementation: No WinForms or platform-specific SDK dependencies
• ✅ Full Navigation Control: Back, forward, reload, and stop
• ✅ JavaScript Execution: Execute JavaScript code and get results
• ✅ HTML String Support: Load HTML content directly
• ✅ Event Support: Navigation events for tracking page loads

Requirements

Common Requirements

• .NET 8.0 SDK or later
• Avalonia UI 11.x

Platform-Specific Requirements

Windows

• Microsoft Edge WebView2 Runtime
  • Usually pre-installed on Windows 10/11
  • Download from: https://developer.microsoft.com/en-us/microsoft-edge/webview2/

macOS

• macOS 10.13 (High Sierra) or later
• WebKit framework (included with macOS)

Linux

• WebKitGTK 4.0 or later
• Install on Ubuntu/Debian:

  sudo apt-get install libwebkit2gtk-4.0-dev

• Install on Fedora/RHEL:

  sudo dnf install webkit2gtk3-devel

• Install on Arch Linux:

  sudo pacman -S webkit2gtk

Installation

Using the Library in Your Project

1. Add a reference to the GreenSwampWebView project:

   <ItemGroup>
     <ProjectReference Include="path/to/WebViewControl/WebViewControl.csproj" />
   </ItemGroup>

2. Add the namespace to your AXAML file:

   xmlns:gsw="using:GreenSwampWebView"

3. Add the WebView control to your UI:

   <gsw:WebView Name="WebViewControl" Url="https://www.example.com" />

Usage

Basic Usage in AXAML

<Window xmlns="https://github.com/avaloniaui"
        xmlns:gsw="using:GreenSwampWebView"
        x:Class="YourApp.MainWindow">
    
    <gsw:WebView Name="MyWebView"
                 Url="https://www.google.com"
                 NavigationStarting="WebView_NavigationStarting"
                 NavigationCompleted="WebView_NavigationCompleted"
                 NavigationFailed="WebView_NavigationFailed" />
</Window>

Code-Behind Usage

using GreenSwampWebView;

// Navigate to a URL
webView.Navigate("https://www.example.com");

// Navigate to HTML content
webView.NavigateToString("<h1>Hello, WebView!</h1>");

// Navigation controls
webView.GoBack();
webView.GoForward();
webView.Reload();
webView.Stop();

// Check navigation state
bool canGoBack = webView.CanGoBack;
bool canGoForward = webView.CanGoForward;

// Execute JavaScript
string result = await webView.ExecuteScriptAsync("document.title");

Event Handlers

private void WebView_NavigationStarting(object? sender, WebViewNavigationEventArgs e)
{
    Console.WriteLine($"Starting navigation to: {e.Uri}");
}

private void WebView_NavigationCompleted(object? sender, WebViewNavigationEventArgs e)
{
    if (e.IsSuccess)
    {
        Console.WriteLine($"Successfully loaded: {e.Uri}");
    }
}

private void WebView_NavigationFailed(object? sender, WebViewNavigationEventArgs e)
{
    Console.WriteLine($"Navigation failed: {e.ErrorMessage}");
}

API Reference

WebView Control

Properties

• string? Url - Gets or sets the URL to navigate to
• string? Html - Gets or sets the HTML content to display
• bool CanGoBack - Gets whether the WebView can navigate back
• bool CanGoForward - Gets whether the WebView can navigate forward

Methods

• void Navigate(string url) - Navigates to the specified URL
• void NavigateToString(string html) - Loads the specified HTML content
• void GoBack() - Navigates back in history
• void GoForward() - Navigates forward in history
• void Reload() - Reloads the current page
• void Stop() - Stops loading the current page
• Task<string> ExecuteScriptAsync(string script) - Executes JavaScript code

Events

• EventHandler<WebViewNavigationEventArgs> NavigationStarting - Occurs when navigation starts
• EventHandler<WebViewNavigationEventArgs> NavigationCompleted - Occurs when navigation completes
• EventHandler<WebViewNavigationEventArgs> NavigationFailed - Occurs when navigation fails

WebViewNavigationEventArgs

Properties:

• string? Uri - The URI of the navigation
• bool IsSuccess - Whether the navigation was successful
• string? ErrorMessage - Error message if navigation failed
• int StatusCode - HTTP status code

Sample Application

A complete sample application is included in the samples/WebViewDemo directory. To run it:

cd samples/WebViewDemo
dotnet run

The demo application includes:

• URL navigation with address bar
• Back/Forward navigation buttons
• Reload and Stop buttons
• HTML content loading example
• Status bar showing navigation state

Building from Source

# Clone the repository
git clone https://github.com/Principia4834/GreenSwampWebView.git
cd GreenSwampWebView

# Build the solution
dotnet build GS.WebViewControl.sln

# Run the sample
cd samples/WebViewDemo
dotnet run

Architecture

The WebView control uses a platform abstraction pattern:

WebView (Main Control)
    ↓
IWebViewPlatform (Interface)
    ↓
├── WindowsWebView (Windows/WebView2 COM interop)
├── MacOSWebView (macOS/WKWebView)
└── LinuxWebView (Linux/WebKitGTK)

Each platform implementation handles native interop through P/Invoke:

• Windows: Direct COM interop with WebView2 via WebView2Native.cs (no WinForms dependency)
• macOS: Objective-C runtime calls via WKWebViewNative.cs
• Linux: GTK3 and WebKitGTK calls via WebKitGtkNative.cs

This approach ensures zero overhead from unused platforms and builds cleanly on .NET 8 SDK without requiring platform-specific SDKs.

Known Limitations

Windows

• Requires WebView2 Runtime to be installed
• COM threading requirements are handled internally
• Async initialization may cause slight delay on first load

macOS

• JavaScript execution is simplified (async callback not fully implemented)
• Coordinate system differences are handled automatically

Linux

• Requires GTK and WebKitGTK libraries
• JavaScript execution doesn't return results (callback not implemented)
• Best tested on X11; Wayland support may vary

Troubleshooting

Windows: "WebView2 runtime not found"

• Install the WebView2 Runtime from Microsoft's website
• Or include the runtime with your application

Linux: "libwebkit2gtk-4.0.so.37: cannot open shared object file"

• Install WebKitGTK: sudo apt-get install libwebkit2gtk-4.0-37

macOS: WebView not appearing

• Ensure your application has proper window handles
• Check that macOS version is 10.13 or later

General: WebView appears blank

• Check that the URL is valid and accessible
• Verify network connectivity
• Look for errors in the console/debug output

Contributing

Contributions are welcome! Please feel free to submit issues or pull requests.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

• Avalonia UI team for the excellent cross-platform framework
• Microsoft for WebView2
• Apple for WKWebView
• WebKitGTK team for the Linux implementation

References

• Avalonia UI Documentation
• Microsoft WebView2 Documentation
• WebKitGTK Documentation
• WKWebView Documentation