How do I get a C# WebBrowser control to show jpeg

问题:

Does anyone know in .Net 2.0 - .Net 3.5 how to load a jpeg into a System.Windows.Forms.WebControl as a byte-array and with the right mimetypes set so it will show?

Something like:

webBrowser1.DocumentStream = new MemoryStream(File.ReadAllBytes("mypic.jpg"));
webBrowser1.DocumentType = "application/jpeg";

The webBrowser1.DocumentType seems to be read only, so I do not know how to do this. In general I want to be able to load any kind of filesource with a mimetype defined into the browser to show it.

Solutions with writing temp files are not good ones. Currently I have solved it with having a little local webserver socket listener that delivers the jpeg I ask for with the right mimetype.

UPDATE: Since someone deleted a answer-my-own question where I had info that others could use, I will add it as an update instead. (to those who delete that way, please update the questions with the important info).

Sample solution in C# here that works perfectly: http://www.codeproject.com/KB/aspnet/AspxProtocol.aspx

回答1:

You have to implement an async pluggable protocol, e.g. IClassFactory, IInternetProtocol... Then you use CoInternetGetSession to register your protocol. When IE calls your implementation, you can serve your image data from memory/provide mime type.

It's a bit tedious, but doable. Look at IInternetProtocol and pluggable protocols documentation on MSDN.

回答2:

You cannot do it. You cannot stuff images into Microsoft's web-browser control.

The limitation comes from the IWebBrowser control itself, which .NET wraps up.

回答3:

If you want a total hack, try having your stream be the HTML file that only shows your picture. You lose your image byte stream and will have to write the image to disk.

回答4:

I do not know whether the WebBrowser .NET control supports this, but RFC2397 defines how to use inline images. Using this and a XHTML snippet created on-the-fly, you could possibly assign the image without the need to write it to a file.

Image someImage = Image.FromFile("mypic.jpg");

// Firstly, get the image as a base64 encoded string
ImageConverter imageConverter = new ImageConverter();
byte[] buffer = (byte[])imageConverter.ConvertTo(someImage, typeof(byte[]));
string base64 = Convert.ToBase64String(buffer, Base64FormattingOptions.InsertLineBreaks);

// Then, dynamically create some XHTML for this (as this is just a sample, minimalistic XHTML :D)
string html = "<img src=\"data:image/" . someImage.RawFormat.ToString() . ";base64, " . $base64 . "\">";

// And put it into some stream
using (StreamWriter streamWriter = new StreamWriter(new MemoryStream()))
{
    streamWriter.Write(html);
    streamWriter.Flush();
    webBrowser.DocumentStream = streamWriter.BaseStream;
    webBrowser.DocumentType = "text/html";
}

No idea whether this solution is elegant, but I guess it is not. My excuse for not being sure is that it is late at night. :)

References:

• RFC2397
• Image to base64 encoded string

回答5:

IE only support 32KB for inline images in base64 encoding, so not a good solution.

回答6:

Try the res: protocol.

I haven't tried it with a .net dll but this post says it should work. Even if it does require a C++ dll it's much simpler to use as far as coding goes.

I've created a post that show you how here that shows you how to create the resource script and use the res: protocol correctly.