AsyncPageSource.cs

// Copyright © 2010-2015 The CefSharp Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.

using System;
using System.Threading.Tasks;
using CefSharp.OffScreen;

namespace CefSharp.MinimalExample.OffScreen
{
    public class Program
    {
        public static void Main(string[] args)
        {
            const string testUrl = "https://www.google.com/";

            var settings = new CefSettings();
            // Disable GPU in WPF and Offscreen examples until #1634 has been resolved
            settings.SetOffScreenRenderingBestPerformanceArgs();
            settings.WindowlessRenderingEnabled = true;

            //Perform dependency check to make sure all relevant resources are in our output directory.
            Cef.Initialize(settings, shutdownOnProcessExit: false, performDependencyCheck: true);

            var result = Browser(testUrl);

            Console.WriteLine(result);

            // We have to wait for something, otherwise the process will exit too soon.
            Console.ReadKey();

            // Clean up Chromium objects.  You need to call this in your application otherwise
            // you will get a crash when closing.
            Cef.Shutdown();
        }

        private static string Browser(string url)
        {
            var task = BrowseAsync(url);

            task.Wait();

            return task.Result;
        }

        private static async Task<string> BrowseAsync(string url)
        {
            string result;

            var browserSettings = new BrowserSettings { WindowlessFrameRate = 1 };

            using (var browser = new ChromiumWebBrowser(url, browserSettings))
            {
                //Wait for all resources to finish loading
                await LoadPageAsync(browser);

                // Wait awhile for Javascript to finish executing.
                await Task.Delay(2000);

                result = await browser.GetSourceAsync();

                //A little delay to let the browser finish doing it's thing before Disposing
                await Task.Delay(20);
            }

            return result;
        }

        private static Task LoadPageAsync(IWebBrowser browser)
        {
            var tcs = new TaskCompletionSource<bool>();

            EventHandler<LoadingStateChangedEventArgs> handler = null;
            handler = (sender, args) =>
            {
                if (!args.IsLoading)
                {
                    browser.LoadingStateChanged -= handler;
                    //Call TrySetResult on the ThreadPool so any continuation is executed on the ThreadPool
                    Task.Run(delegate { tcs.TrySetResult(true); });
                }
            };

            browser.LoadingStateChanged += handler;
            return tcs.Task;
        }
    }
}