Tcl

Add a Related File to an HTML Email

Demonstrates the Chilkat Email.AddRelatedFile method, which adds the contents of a local file as a related MIME resource and returns the generated Content-ID. The returned value is the bare Content-ID — no angle brackets and no cid: prefix — so if it returns CID-123@example, the HTML reference is cid:CID-123@example. Because the Content-ID is generated by the call, this example adds the image first, then builds the HTML body in a StringBuilder — using a placeholder in the <img> tag that is replaced with the returned Content-ID — and passes the result to SetHtmlBody.

Background: To embed an image so it displays inside an HTML email (rather than being downloaded from a web server), you add it as a "related" part and reference it from the HTML with a cid: URL that matches the part's Content-ID. Since Chilkat assigns that ID when you add the file, the natural order is: add the related file, capture the returned ID, then build the <img src="cid:..."> reference from it. A StringBuilder makes assembling and updating the HTML convenient.

Chilkat Tcl Downloads

Download Chilkat for Tcl

Tcl


load ./chilkat.dll

#  Demonstrates the AddRelatedFile method, which adds a local file as a related MIME
#  resource (such as an image displayed by an HTML body) and returns the generated
#  Content-ID.  The HTML references the item using cid:<Content-ID>.

set email [new_CkEmail]

CkEmail_put_Subject $email "Email with a related image"

#  Add the image file as a related item first.  The return value is the bare Content-ID
#  (no angle brackets and no "cid:" prefix).
set cid [CkEmail_addRelatedFile $email "qa_data/images/logo.png"]
if {[CkEmail_get_LastMethodSuccess $email] == 0} then {
    puts [CkEmail_lastErrorText $email]
    delete_CkEmail $email
    exit
}

#  Build the HTML body in a StringBuilder, using a placeholder where the image's
#  Content-ID will go.
set sbHtml [new_CkStringBuilder]

CkStringBuilder_Append $sbHtml "<html><body><img src=\"cid:PLACEHOLDER_CID\"/></body></html>"

#  Replace the placeholder with the actual Content-ID returned by AddRelatedFile.
set numReplaced [CkStringBuilder_Replace $sbHtml "PLACEHOLDER_CID" $cid]

#  Set the HTML body from the StringBuilder result.
CkEmail_SetHtmlBody $email [CkStringBuilder_getAsString $sbHtml]

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

#  Note: The path "qa_data/images/logo.png" is a relative local filesystem path,
#  relative to the current working directory of the running application.

delete_CkEmail $email
delete_CkStringBuilder $sbHtml