C++

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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#include <CkEmail.h>
#include <CkBinData.h>
#include <CkStringBuilder.h>

void ChilkatSample(void)
    {
    bool success = false;

    //  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.

    CkEmail email;
    email.put_Subject("GetRelatedContentID example");

    //  Load the image data from a file into a BinData object.
    CkBinData bdImage;
    success = bdImage.LoadFile("qa_data/images/logo.png");
    if (success == false) {
        std::cout << bdImage.lastErrorText() << "\r\n";
        return true;
    }

    //  Add the image as a related item from the BinData; capture its generated Content-ID.
    const char *cid = email.addRelatedBd("logo.png",bdImage);
    if (email.get_LastMethodSuccess() == false) {
        std::cout << email.lastErrorText() << "\r\n";
        return true;
    }

    //  Reference the related item in the HTML body by its Content-ID.
    CkStringBuilder sbHtml;
    sbHtml.Append("<html><body><img src=\"cid:PLACEHOLDER_CID\"/></body></html>");
    int numReplaced = sbHtml.Replace("PLACEHOLDER_CID",cid);
    email.SetHtmlBody(sbHtml.getAsString());

    //  Read the Content-ID of the first related item (index 0).
    const char *cid0 = email.getRelatedContentID(0);
    std::cout << "Related item 0 Content-ID: " << cid0 << "\r\n";

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