Unicode C++

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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#include <CkEmailW.h>
#include <CkStringBuilderW.h>

void ChilkatSample(void)
    {
    //  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.

    CkEmailW email;
    email.put_Subject(L"Email with a related style sheet");

    //  Add the text-based related resource first; capture the generated Content-ID.
    const wchar_t *cid = email.addRelatedString(L"styles.css",L"body { color: navy; }",L"utf-8");
    if (email.get_LastMethodSuccess() == false) {
        wprintf(L"%s\n",email.lastErrorText());
        return;
    }

    //  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.
    CkStringBuilderW sbHtml;
    sbHtml.Append(L"<html><head><link rel=\"stylesheet\" href=\"cid:PLACEHOLDER_CID\"/></head><body>Styled content.</body></html>");
    int numReplaced = sbHtml.Replace(L"PLACEHOLDER_CID",cid);
    email.SetHtmlBody(sbHtml.getAsString());

    wprintf(L"Related Content-ID = %s\n",cid);
    wprintf(L"NumRelatedItems = %d\n",email.get_NumRelatedItems());
    }