Delphi ActiveX

Get a Header Attribute of a Related Item

Demonstrates the Chilkat Email.GetRelatedAttr method, which returns a header-field attribute value from a header field of the Nth related item. The first argument is the zero-based related-item index, the second names a header field, and the third names an attribute within it. 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 the name attribute of the related item's Content-Type header.

Background: Related items (inline images, style sheets) are MIME parts whose headers may carry named parameters — for instance Content-Type: image/png; name="logo.png". Because an image is binary, it is loaded into a BinData object (here from a file) and added with AddRelatedBd, rather than being treated as text. GetRelatedAttr then extracts one named attribute from a chosen header of a specific related part, the related-item analogue of GetAttachmentAttr, so you don't have to parse the raw header yourself.

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var
success: Integer;
email: TChilkatEmail;
bdImage: TChilkatBinData;
cid: WideString;
sbHtml: TChilkatStringBuilder;
numReplaced: Integer;
val: WideString;

begin
success := 0;

//  Demonstrates the GetRelatedAttr method, which returns a header-field attribute value
//  from a header field of the Nth related item.  The first argument is the zero-based related-item
//  index, the second is the header field name, and the third is the attribute name.

email := TChilkatEmail.Create(Self);
email.Subject := 'GetRelatedAttr example';

//  Load the image data from a file into a BinData object.
bdImage := TChilkatBinData.Create(Self);
success := bdImage.LoadFile('qa_data/images/logo.png');
if (success = 0) then
  begin
    Memo1.Lines.Add(bdImage.LastErrorText);
    Exit;
  end;

//  Add the image as a related item from the BinData; capture its generated Content-ID.
cid := email.AddRelatedBd('logo.png',bdImage.ControlInterface);
if (email.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(email.LastErrorText);
    Exit;
  end;

//  Reference the related item in the HTML body by its Content-ID.
sbHtml := TChilkatStringBuilder.Create(Self);
sbHtml.Append('<html><body><img src="cid:PLACEHOLDER_CID"/></body></html>');
numReplaced := sbHtml.Replace('PLACEHOLDER_CID',cid);
email.SetHtmlBody(sbHtml.GetAsString());

//  Get the "name" attribute of the related item's Content-Type header (index 0).
val := email.GetRelatedAttr(0,'Content-Type','name');
Memo1.Lines.Add('Related item Content-Type name attribute: ' + val);

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