How to Develop an Internet Explorer Extension Using C# and Visual Studio?

Create an Internet Explorer extension

Prerequisites:

• Familiar with Visual Studio and .NET development
• Learn about COM interfaces (optional, but helpful)

Steps:

1. Create a class library project: In Visual Studio, create a new C# class library project named "InternetExplorerExtension".

2. Add References: Add references to the "Interop.SHDocVw" and "Microsoft.mshtml" assemblies.

3. Define the BHO class: Create a class named "WordHighlighterBHO" and implement the following interface:

   • IObjectWithSite (used to manage browser objects)
   • IOleCommandTarget (used to handle menu item commands)

4. Handling the document completion event: Implement the "OnDocumentComplete" method, which traverses the DOM and uses JavaScript to highlight occurrences of a specific word (e.g., "browser").

5. Add menu item: Define a menu item command to open the add-in's configuration form.

6. Persistent data: Save configuration options (such as text to highlight) to the registry for persistence.

7. Register BHO: Use the "RegisterBHO" method to register the add-in to the system.

8. Compile and install: Build the solution and make sure to configure the "post-build" event to register the assembly in the GAC.

Additional notes for IE11:

• Make sure Visual Studio is running as administrator for post-build registration.
• If the "MSHTML" assembly is not already registered in the system, add it to the project references.

Sample code:

<code class="language-csharp">namespace InternetExplorerExtension
{
    public class WordHighlighterBHO : IObjectWithSite, IOleCommandTarget
    {
        // ...
        public void OnDocumentComplete(object pDisp, ref object URL)
        {
            // ...
        }
        // ...
        public int Exec(IntPtr pguidCmdGroup, uint nCmdID, uint nCmdexecopt, IntPtr pvaIn, IntPtr pvaOut)
        {
            // ...
            // 从命令栏访问文档。
            var document = browser.Document as IHTMLDocument2;
            var window = document.parentWindow;
            var result = window.execScript(@"alert('您现在可以配置要高亮的文本...');");

            var form = new HighlighterOptionsForm();
            form.InputText = TextToHighlight;
            if (form.ShowDialog() != DialogResult.Cancel)
            {
                TextToHighlight = form.InputText;
                SaveOptions();
            }
            // ...
            return 0;
        }
        // ...
        public static void RegisterBHO(Type type)
        {
            string guid = type.GUID.ToString("B");

            // ...
        }
        // ...
    }
}</code>

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