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MimeKit

MultipartRelated Class

A multipart/related MIME entity.
Inheritance Hierarchy

Namespace:  MimeKit
Assembly:  MimeKit (in MimeKit.dll) Version: 2.2.0
Syntax
C#
public class MultipartRelated : Multipart

The MultipartRelated type exposes the following members.

Constructors
  NameDescription
Public methodMultipartRelated
Initializes a new instance of the MultipartRelated class.
Public methodMultipartRelated(Object)
Initializes a new instance of the MultipartRelated class.
Public methodMultipartRelated(MimeEntityConstructorArgs)
Initializes a new instance of the MultipartRelated class.
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Properties
  NameDescription
Public propertyBoundary
Gets or sets the boundary.
(Inherited from Multipart.)
Public propertyContentBase
Gets or sets the base content URI.
(Inherited from MimeEntity.)
Public propertyContentDisposition
Gets or sets the content disposition.
(Inherited from MimeEntity.)
Public propertyContentId
Gets or sets the content identifier.
(Inherited from MimeEntity.)
Public propertyContentLocation
Gets or sets the content location.
(Inherited from MimeEntity.)
Public propertyContentType
Gets the type of the content.
(Inherited from MimeEntity.)
Public propertyCount
Gets the number of parts in the multipart.
(Inherited from Multipart.)
Public propertyEpilogue
Gets or sets the epilogue.
(Inherited from Multipart.)
Public propertyHeaders
Gets the list of headers.
(Inherited from MimeEntity.)
Public propertyIsAttachment
Gets a value indicating whether this MimePart is an attachment.
(Inherited from MimeEntity.)
Public propertyIsReadOnly
Gets a value indicating whether this instance is read only.
(Inherited from Multipart.)
Public propertyItem
Gets or sets the MimeEntity at the specified index.
(Inherited from Multipart.)
Public propertyPreamble
Gets or sets the preamble.
(Inherited from Multipart.)
Public propertyCode exampleRoot
Gets or sets the root document of the multipart/related part and the appropriate Content-Type parameters.
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Methods
  NameDescription
Public methodAccept
Dispatches to the specific visit method for this MIME entity.
(Overrides MultipartAccept(MimeVisitor).)
Public methodAdd
Adds the specified part.
(Inherited from Multipart.)
Public methodClear
Clears the multipart.
(Inherited from Multipart.)
Public methodContains(Uri)
Checks if the MultipartRelated contains a part matching the specified URI.
Public methodContains(MimeEntity)
Checks if the Multipart contains the specified part.
(Inherited from Multipart.)
Public methodCopyTo
Copies all of the entities in the Multipart to the specified array.
(Inherited from Multipart.)
Public methodEquals
Determines whether the specified object is equal to the current object.
(Inherited from Object.)
Protected methodFinalize
Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.
(Inherited from Object.)
Public methodGetEnumerator
Gets the enumerator for the children of the Multipart.
(Inherited from Multipart.)
Public methodGetHashCode
Serves as the default hash function.
(Inherited from Object.)
Public methodGetType
Gets the Type of the current instance.
(Inherited from Object.)
Public methodCode exampleIndexOf(Uri)
Gets the index of the part matching the specified URI.
Public methodIndexOf(MimeEntity)
Gets the index of the specified part.
(Inherited from Multipart.)
Public methodInsert
Inserts the part at the specified index.
(Inherited from Multipart.)
Protected methodMemberwiseClone
Creates a shallow copy of the current Object.
(Inherited from Object.)
Protected methodOnHeadersChanged
Called when the headers change in some way.
(Inherited from MimeEntity.)
Public methodOpen(Uri)
Opens a stream for reading the decoded content of the MIME part specified by the provided URI.
Public methodOpen(Uri, String, String)
Opens a stream for reading the decoded content of the MIME part specified by the provided URI.
Public methodPrepare
Prepare the MIME entity for transport using the specified encoding constraints.
(Inherited from Multipart.)
Public methodRemove
Removes the specified part.
(Inherited from Multipart.)
Public methodRemoveAt
Removes the part at the specified index.
(Inherited from Multipart.)
Protected methodRemoveHeader
Removes the header.
(Inherited from MimeEntity.)
Protected methodSetHeader(String, Byte)
Sets the header using the raw value.
(Inherited from MimeEntity.)
Protected methodSetHeader(String, String)
Sets the header.
(Inherited from MimeEntity.)
Public methodToString
Returns a String that represents the current MimeEntity.
(Inherited from MimeEntity.)
Protected methodTryInit
Tries to use the given object to initialize the appropriate property.
(Inherited from MimeEntity.)
Public methodWriteTo(Stream, CancellationToken)
Write the MimeEntity to the specified output stream.
(Inherited from MimeEntity.)
Public methodWriteTo(String, CancellationToken)
Writes the MimeEntity to the specified file.
(Inherited from MimeEntity.)
Public methodWriteTo(Stream, Boolean, CancellationToken)
Write the MimeEntity to the specified output stream.
(Inherited from MimeEntity.)
Public methodWriteTo(String, Boolean, CancellationToken)
Write the MimeEntity to the specified file.
(Inherited from MimeEntity.)
Public methodWriteTo(FormatOptions, Stream, CancellationToken)
Write the MimeEntity to the specified output stream.
(Inherited from MimeEntity.)
Public methodWriteTo(FormatOptions, String, CancellationToken)
Write the MimeEntity to the specified file.
(Inherited from MimeEntity.)
Public methodWriteTo(FormatOptions, String, Boolean, CancellationToken)
Write the MimeEntity to the specified file.
(Inherited from MimeEntity.)
Public methodWriteTo(FormatOptions, Stream, Boolean, CancellationToken)
Writes the Multipart to the specified output stream.
(Inherited from Multipart.)
Public methodWriteToAsync(Stream, CancellationToken)
Asynchronously write the MimeEntity to the specified output stream.
(Inherited from MimeEntity.)
Public methodWriteToAsync(String, CancellationToken)
Asynchronously writes the MimeEntity to the specified file.
(Inherited from MimeEntity.)
Public methodWriteToAsync(Stream, Boolean, CancellationToken)
Asynchronously write the MimeEntity to the specified output stream.
(Inherited from MimeEntity.)
Public methodWriteToAsync(String, Boolean, CancellationToken)
Asynchronously write the MimeEntity to the specified file.
(Inherited from MimeEntity.)
Public methodWriteToAsync(FormatOptions, Stream, CancellationToken)
Asynchronously write the MimeEntity to the specified output stream.
(Inherited from MimeEntity.)
Public methodWriteToAsync(FormatOptions, String, CancellationToken)
Asynchronously write the MimeEntity to the specified file.
(Inherited from MimeEntity.)
Public methodWriteToAsync(FormatOptions, String, Boolean, CancellationToken)
Asynchronously write the MimeEntity to the specified file.
(Inherited from MimeEntity.)
Public methodWriteToAsync(FormatOptions, Stream, Boolean, CancellationToken)
Asynchronously writes the Multipart to the specified output stream.
(Inherited from Multipart.)
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Remarks
A multipart/related MIME entity contains, as one might expect, inter-related MIME parts which typically reference each other via URIs based on the Content-Id and/or Content-Location headers.
Examples
C#
/// <summary>
/// Visits a MimeMessage and generates HTML suitable to be rendered by a browser control.
/// </summary>
class HtmlPreviewVisitor : MimeVisitor
{
    List<MultipartRelated> stack = new List<MultipartRelated> ();
    List<MimeEntity> attachments = new List<MimeEntity> ();
    readonly string tempDir;
    string body;

    /// <summary>
    /// Creates a new HtmlPreviewVisitor.
    /// </summary>
    /// <param name="tempDirectory">A temporary directory used for storing image files.</param>
    public HtmlPreviewVisitor (string tempDirectory)
    {
        tempDir = tempDirectory;
    }

    /// <summary>
    /// The list of attachments that were in the MimeMessage.
    /// </summary>
    public IList<MimeEntity> Attachments {
        get { return attachments; }
    }

    /// <summary>
    /// The HTML string that can be set on the BrowserControl.
    /// </summary>
    public string HtmlBody {
        get { return body ?? string.Empty; }
    }

    protected override void VisitMultipartAlternative (MultipartAlternative alternative)
    {
        // walk the multipart/alternative children backwards from greatest level of faithfulness to the least faithful
        for (int i = alternative.Count - 1; i >= 0 && body == null; i--)
            alternative[i].Accept (this);
    }

    protected override void VisitMultipartRelated (MultipartRelated related)
    {
        var root = related.Root;

        // push this multipart/related onto our stack
        stack.Add (related);

        // visit the root document
        root.Accept (this);

        // pop this multipart/related off our stack
        stack.RemoveAt (stack.Count - 1);
    }

    // look up the image based on the img src url within our multipart/related stack
    bool TryGetImage (string url, out MimePart image)
    {
        UriKind kind;
        int index;
        Uri uri;

        if (Uri.IsWellFormedUriString (url, UriKind.Absolute))
            kind = UriKind.Absolute;
        else if (Uri.IsWellFormedUriString (url, UriKind.Relative))
            kind = UriKind.Relative;
        else
            kind = UriKind.RelativeOrAbsolute;

        try {
            uri = new Uri (url, kind);
        } catch {
            image = null;
            return false;
        }

        for (int i = stack.Count - 1; i >= 0; i--) {
            if ((index = stack[i].IndexOf (uri)) == -1)
                continue;

            image = stack[i][index] as MimePart;
            return image != null;
        }

        image = null;

        return false;
    }

    // Save the image to our temp directory and return a "file://" url suitable for
    // the browser control to load.
    // Note: if you'd rather embed the image data into the HTML, you can construct a
    // "data:" url instead.
    string SaveImage (MimePart image, string url)
    {
        string fileName = url.Replace (':', '_').Replace ('\\', '_').Replace ('/', '_');

        string path = Path.Combine (tempDir, fileName);

        if (!File.Exists (path)) {
            using (var output = File.Create (path))
                image.Content.DecodeTo (output);
        }

        return "file://" + path.Replace ('\\', '/');
    }

    // Replaces <img src=...> urls that refer to images embedded within the message with
    // "file://" urls that the browser control will actually be able to load.
    void HtmlTagCallback (HtmlTagContext ctx, HtmlWriter htmlWriter)
    {
        if (ctx.TagId == HtmlTagId.Image && !ctx.IsEndTag && stack.Count > 0) {
            ctx.WriteTag (htmlWriter, false);

            // replace the src attribute with a file:// URL
            foreach (var attribute in ctx.Attributes) {
                if (attribute.Id == HtmlAttributeId.Src) {
                    MimePart image;
                    string url;

                    if (!TryGetImage (attribute.Value, out image)) {
                        htmlWriter.WriteAttribute (attribute);
                        continue;
                    }

                    url = SaveImage (image, attribute.Value);

                    htmlWriter.WriteAttributeName (attribute.Name);
                    htmlWriter.WriteAttributeValue (url);
                } else {
                    htmlWriter.WriteAttribute (attribute);
                }
            }
        } else if (ctx.TagId == HtmlTagId.Body && !ctx.IsEndTag) {
            ctx.WriteTag (htmlWriter, false);

            // add and/or replace oncontextmenu="return false;"
            foreach (var attribute in ctx.Attributes) {
                if (attribute.Name.ToLowerInvariant () == "oncontextmenu")
                    continue;

                htmlWriter.WriteAttribute (attribute);
            }

            htmlWriter.WriteAttribute ("oncontextmenu", "return false;");
        } else {
            // pass the tag through to the output
            ctx.WriteTag (htmlWriter, true);
        }
    }

    protected override void VisitTextPart (TextPart entity)
    {
        TextConverter converter;

        if (body != null) {
            // since we've already found the body, treat this as an attachment
            attachments.Add (entity);
            return;
        }

        if (entity.IsHtml) {
            converter = new HtmlToHtml {
                HtmlTagCallback = HtmlTagCallback
            };
        } else if (entity.IsFlowed) {
            var flowed = new FlowedToHtml ();
            string delsp;

            if (entity.ContentType.Parameters.TryGetValue ("delsp", out delsp))
                flowed.DeleteSpace = delsp.ToLowerInvariant () == "yes";

            converter = flowed;
        } else {
            converter = new TextToHtml ();
        }

        body = converter.Convert (entity.Text);
    }

    protected override void VisitTnefPart (TnefPart entity)
    {
        // extract any attachments in the MS-TNEF part
        attachments.AddRange (entity.ExtractAttachments ());
    }

    protected override void VisitMessagePart (MessagePart entity)
    {
        // treat message/rfc822 parts as attachments
        attachments.Add (entity);
    }

    protected override void VisitMimePart (MimePart entity)
    {
        // realistically, if we've gotten this far, then we can treat this as an attachment
        // even if the IsAttachment property is false.
        attachments.Add (entity);
    }
}
See Also