Tcl

Get the Content-ID of a Related Item

Demonstrates the Chilkat Email.GetRelatedContentID method, which returns the Content-ID of a related item (typically an image or style sheet embedded within an HTML email). The index is zero-based. This example loads an image from a file into a BinData object, adds it as a related item with AddRelatedBd (capturing the generated Content-ID and referencing it from the HTML), then reads that Content-ID back.

Background: The Content-ID is the anchor that ties an inline resource to the HTML that displays it: the body references cid: plus the ID, and the matching related part carries that same Content-ID. Because an image is binary, it is loaded into a BinData object (here from a file) and added with AddRelatedBd. Reading the Content-ID back lets a program verify or rewrite those links — for example when relocating embedded images or converting a message for display outside a mail client.

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Tcl


load ./chilkat.dll

set success 0

#  Demonstrates the GetRelatedContentID method, which returns the Content-ID of a related
#  item.  Related items are typically images and style sheets embedded within HTML emails.
#  The index is zero-based.

set email [new_CkEmail]

CkEmail_put_Subject $email "GetRelatedContentID example"

#  Load the image data from a file into a BinData object.
set bdImage [new_CkBinData]

set success [CkBinData_LoadFile $bdImage "qa_data/images/logo.png"]
if {$success == 0} then {
    puts [CkBinData_lastErrorText $bdImage]
    delete_CkEmail $email
    delete_CkBinData $bdImage
    exit
}

#  Add the image as a related item from the BinData; capture its generated Content-ID.
set cid [CkEmail_addRelatedBd $email "logo.png" $bdImage]
if {[CkEmail_get_LastMethodSuccess $email] == 0} then {
    puts [CkEmail_lastErrorText $email]
    delete_CkEmail $email
    delete_CkBinData $bdImage
    exit
}

#  Reference the related item in the HTML body by its Content-ID.
set sbHtml [new_CkStringBuilder]

CkStringBuilder_Append $sbHtml "<html><body><img src=\"cid:PLACEHOLDER_CID\"/></body></html>"
set numReplaced [CkStringBuilder_Replace $sbHtml "PLACEHOLDER_CID" $cid]
CkEmail_SetHtmlBody $email [CkStringBuilder_getAsString $sbHtml]

#  Read the Content-ID of the first related item (index 0).
set cid0 [CkEmail_getRelatedContentID $email 0]
puts "Related item 0 Content-ID: $cid0"

#  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_CkBinData $bdImage
delete_CkStringBuilder $sbHtml