Cannot get HTML source of browser web page, async to sync problem

Question

Visual Studio 2017, Windows 10, .NET Framework 4.8, CefSharp WinForms 83.4.20, platform target x64

Created new very simple CefSharp Windows Forms application. I cannot get the html source of the web page. I think I have looked at every CefSharp and async to sync question on StackOverflow - have tried so many solutions - my head has turned to mush. This is the first question I looked at - I have the same problem.

Get HTML source code from CefSharp web browser

'browser.ViewSource();' does pop up a notepad with the source of the webpage. But when I try to get a string with the source code - the task never seems to run. The task that runs to get the web page source says ---> Status = WaitingForActivation ---> and never returns with the source.

I have tried the async to sync conversion - probably ten different ways. None work. One StackOverflow solution suggested the Application.DoEvents() - so I even tried that.

Hope someone has some ideas. This browser seems to have a ton of potential - but I need to get the web page source html.

using System;
using System.Threading.Tasks;
using System.Windows.Forms;
using CefSharp;
using CefSharp.WinForms;
using System.Diagnostics;
namespace Test1
{
    public partial class Form1 : Form
    {
        public ChromiumWebBrowser browser;
        public Form1()
        {
            InitializeComponent();
            InitBrowser();
        }
        private void Form1_Load(object sender, EventArgs e)
        {
        }
        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            browser.Dispose();
            Cef.Shutdown();
        }
        private void exitToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }
        public void InitBrowser()
        {
            Cef.Initialize(new CefSettings());
            browser = new ChromiumWebBrowser("https://google.com/");
            this.Controls.Add(browser);
            browser.Dock = DockStyle.Fill;
            browser.FrameLoadEnd += OnWebBrowserFrameLoadEnded;
        }
        void OnWebBrowserFrameLoadEnded(object sender, FrameLoadEndEventArgs e)
        {
            ChromiumWebBrowser BrowserSender = (ChromiumWebBrowser)sender;
            if (this.InvokeRequired)
            {
                this.Invoke(new MethodInvoker(() => { WebBrowserFrameLoadEnded(BrowserSender, e); }));
            }
            else
            {
                WebBrowserFrameLoadEnded(BrowserSender, e);
            }
        }
        void WebBrowserFrameLoadEnded(ChromiumWebBrowser BrowserSender, FrameLoadEndEventArgs e)
        {
            string html1 = null;
            Task<String> taskString1;

            if (e.Frame.IsMain)
            {
                //browser.ViewSource();
                taskString1 = Task.Run(() => GetBrowserSource(browser));
                while (taskString1.Status != TaskStatus.RanToCompletion)
                {
                    Application.DoEvents();
                    System.Threading.Thread.Sleep(100);
                }
                html1 = taskString1.Result;
                Debug.WriteLine("");
            }
        }

        async Task<string> GetBrowserSource(ChromiumWebBrowser Browser)
        {
            return await Browser.GetMainFrame().GetSourceAsync();
        }
    }
}

my app.config

<?xml version="1.0" encoding="utf-8"?>
<configuration>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.8"/>
    </startup>
</configuration>

my packages.config

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="cef.redist.x64" version="83.4.2" targetFramework="net452" />
  <package id="cef.redist.x86" version="83.4.2" targetFramework="net452" />
  <package id="CefSharp.Common" version="83.4.20" targetFramework="net452" />
  <package id="CefSharp.WinForms" version="83.4.20" targetFramework="net452" />
</packages>

Answer 1

Looks like a deadlock. That's a proper async/await usage problem.

private async void WebBrowserFrameLoadEnded(ChromiumWebBrowser BrowserSender, FrameLoadEndEventArgs e)
{
    if (e.Frame.IsMain)
    {
        string html1 = await GetBrowserSource(BrowserSender);
        Debug.WriteLine(html1);
    }
}

But why not simply do this?

private async void OnWebBrowserFrameLoadEnded(object sender, FrameLoadEndEventArgs e)
{
    if (e.Frame.IsMain)
    {
        ChromiumWebBrowser browserSender = (ChromiumWebBrowser)sender;
        string html = await browserSender.GetMainFrame().GetSourceAsync();
        Debug.WriteLine(html);
    }
}

Note that Application.DoEvents() isn't safe to use.