Tcl

Add a Related String Resource to an Email

Demonstrates the Chilkat Email.AddRelatedString method, which adds a text-based related MIME resource, such as a style sheet, from an in-memory string and returns the generated Content-ID. The first argument is the MIME resource name, the second is the text content, and the third is the charset used to encode it. Because the Content-ID is generated by the call, this example adds the style sheet first, then builds an HTML body in a StringBuilder that references the style sheet by that cid:, and passes the result to SetHtmlBody.

Background: Related items are not always images loaded from disk — sometimes the resource is text you already have in memory, like a generated CSS style sheet or an SVG. AddRelatedString lets you embed such content directly without writing a temporary file first. As with other related items, it lives in the multipart/related enclosure and is referenced from the HTML by the Content-ID the method returns.

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load ./chilkat.dll

#  Demonstrates the AddRelatedString method, which adds a text-based related MIME resource
#  (such as a style sheet) from an in-memory string and returns the generated Content-ID.
#  The first argument is the resource name, the second is the text content, the third is the charset.

set email [new_CkEmail]

CkEmail_put_Subject $email "Email with a related style sheet"

#  Add the text-based related resource first; capture the generated Content-ID.
set cid [CkEmail_addRelatedString $email "styles.css" "body { color: navy; }" "utf-8"]
if {[CkEmail_get_LastMethodSuccess $email] == 0} then {
    puts [CkEmail_lastErrorText $email]
    delete_CkEmail $email
    exit
}

#  Build the HTML body, referencing the related style sheet by its Content-ID.  A
#  placeholder is used and then replaced with the actual Content-ID.
set sbHtml [new_CkStringBuilder]

CkStringBuilder_Append $sbHtml "<html><head><link rel=\"stylesheet\" href=\"cid:PLACEHOLDER_CID\"/></head><body>Styled content.</body></html>"
set numReplaced [CkStringBuilder_Replace $sbHtml "PLACEHOLDER_CID" $cid]
CkEmail_SetHtmlBody $email [CkStringBuilder_getAsString $sbHtml]

puts "Related Content-ID = $cid"
puts "NumRelatedItems = [CkEmail_get_NumRelatedItems $email]"

delete_CkEmail $email
delete_CkStringBuilder $sbHtml