THPDFHTMLImporter.OnResource

Event supplying the external resources referenced by the imported HTML

property OnResource: THPDFHTMLResourceEvent read FOnResource
  write FOnResource;

The unit is HPDFHTMLImport; the handler receives the resource URI and kind (hrkStyleSheet, hrkImage or hrkFont)

Setting Handled to true with Data and ContentType filled in hands over the bytes; leaving it false records a rejected request

Served resources still have to pass the MaxResources, MaxResourceBytes and MaxTotalResourceBytes budgets