WebBrowser Control - No CSS applied

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I need to host an online payment gateway in a Browser control in Framework 4.5 and have come across the problem where the CSS is not appli

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悲&欢浪女

2021-01-23 19:09

Usually, implementing FEATURE_BROWSER_EMULATION resolves issues like this, but you mentioned you already did that. I could share a test app if you like to try it with your own HTML+CSS.

using Microsoft.Win32;
using System;
using System.Diagnostics;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WbTest
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            SetBrowserFeatureControl();
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            DoNavigationAsync().ContinueWith(_ =>
            {
                MessageBox.Show("Navigation complete!");
            }, TaskScheduler.FromCurrentSynchronizationContext());
        }

        private async Task DoNavigationAsync()
        {
            TaskCompletionSource<bool> documentCompleteTcs = null;

            WebBrowserDocumentCompletedEventHandler handler = delegate 
            {
                if (documentCompleteTcs.Task.IsCompleted)
                    return;
                documentCompleteTcs.SetResult(true);
            };

            documentCompleteTcs = new TaskCompletionSource<bool>();
            this.wb.DocumentCompleted += handler;

            // could do this.wb.Navigate(url) here 
            this.wb.DocumentText = "<!DOCTYPE html><head><meta http-equiv='X-UA-Compatible' content='IE=edge'/></head>"+
                "<body><input size=50 type='text' placeholder='HTML5 if this placeholder is visible'/></body>";

            await documentCompleteTcs.Task;
            this.wb.DocumentCompleted -= handler;

            dynamic document = this.wb.Document.DomDocument;
            dynamic navigator = document.parentWindow.navigator;
            var info =
                "\n navigator.userAgent: " + navigator.userAgent +
                "\n navigator.appName: " + navigator.appName +
                "\n document.documentMode: " + document.documentMode +
                "\n document.compatMode: " + document.compatMode;

            MessageBox.Show(info);
        }

        private static void SetBrowserFeatureControl()
        {
            // http://msdn.microsoft.com/en-us/library/ee330720(v=vs.85).aspx

            // WebBrowser Feature Control settings are per-process
            var fileName = System.IO.Path.GetFileName(Process.GetCurrentProcess().MainModule.FileName);

            // make the control is not running inside Visual Studio Designer
            if (String.Compare(fileName, "devenv.exe", true) == 0 || String.Compare(fileName, "XDesProc.exe", true) == 0)
                return;

            SetBrowserFeatureControlKey("FEATURE_BROWSER_EMULATION", fileName, GetBrowserEmulationMode()); 
        }

        private static void SetBrowserFeatureControlKey(string feature, string appName, uint value)
        {
            using (var key = Registry.CurrentUser.CreateSubKey(
                String.Concat(@"Software\Microsoft\Internet Explorer\Main\FeatureControl\", feature),
                RegistryKeyPermissionCheck.ReadWriteSubTree))
            {
                key.SetValue(appName, (UInt32)value, RegistryValueKind.DWord);
            }
        }

        private static UInt32 GetBrowserEmulationMode()
        {
            int browserVersion = 7;
            using (var ieKey = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\Internet Explorer",
                RegistryKeyPermissionCheck.ReadSubTree,
                System.Security.AccessControl.RegistryRights.QueryValues))
            {
                var version = ieKey.GetValue("svcVersion");
                if (null == version)
                {
                    version = ieKey.GetValue("Version");
                    if (null == version)
                        throw new ApplicationException("Microsoft Internet Explorer is required!");
                }
                int.TryParse(version.ToString().Split('.')[0], out browserVersion);
            }

            // Internet Explorer 10. Webpages containing standards-based !DOCTYPE directives are displayed in IE10 Standards mode. Default value for Internet Explorer 10.
            UInt32 mode = 10000; 

            switch (browserVersion)
            {
                case 7:
                    // Webpages containing standards-based !DOCTYPE directives are displayed in IE7 Standards mode. Default value for applications hosting the WebBrowser Control.
                    mode = 7000;                     
                    break;
                case 8:
                    // Webpages containing standards-based !DOCTYPE directives are displayed in IE8 mode. Default value for Internet Explorer 8
                    mode = 8000; 
                    break;
                case 9:
                    // Internet Explorer 9. Webpages containing standards-based !DOCTYPE directives are displayed in IE9 mode. Default value for Internet Explorer 9.
                    mode = 9000; 
                    break;
                default:
                    // use IE10 mode by default
                    break;
            }

            return mode;
        }
    }
}

First, try it as is, you should see something like this:

enter image description here

Note documentMode and compatMode values, these correspond to HTML5 standard mode. Then try it with your HTML, see if they stay the same.

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