Invalid document when html contains images and existing headers/footers contain images

[toneb]

Word reports "unreadable content" when document contains header/footer with images and inserted html contains images.

The problem is in duplicated DocProperties.Id: https://github.com/onizet/html2openxml/blob/09d064c3b8824562f23c54881bdba1b144216de8/src/Html2OpenXml/HtmlConverter.cs#L523

Calculation of drawingObjId in above method considers only elements in document body, not other parts of the document.

My workaround is to renumber generated prop ids (but considering elements in other document parts):

// get existing max docProp id
var maxDocPropId = new[] {
    doc.MainDocumentPart!.Document.Body!.Descendants<DocProperties>().Select(x => x.Id?.Value ?? 0),
    doc.MainDocumentPart!.HeaderParts.SelectMany(x => x.Header.Descendants<DocProperties>().Select(x => x.Id?.Value ?? 0)),
    doc.MainDocumentPart!.FooterParts.SelectMany(x => x.Footer.Descendants<DocProperties>().Select(x => x.Id?.Value ?? 0)),
}.SelectMany(x => x).Max();

// convert html to openxml
var converter = new HtmlConverter(doc.MainDocumentPart);
var parsed = converter .Parse(html);

// renumber docProp ids
parsed.SelectMany(x => x.Descendants<DocProperties>()).ToList().ForEach(x => x.Id = ++docPropCopy);

// ... use generated elements ...