/// <summary>
/// Gets a PdfFormXObject from an XPdfForm. Because the returned objects must be unique, always
/// a new instance of PdfFormXObject is created if none exists for the specified form.
/// </summary>
public PdfFormXObject GetForm(XForm form)
{
// If the form already has a PdfFormXObject, return it.
if (form._pdfForm != null)
{
Debug.Assert(form.IsTemplate, "An XPdfForm must not have a PdfFormXObject.");
if (ReferenceEquals(form._pdfForm.Owner, Owner))
{
return(form._pdfForm);
}
//throw new InvalidOperationException("Because of a current limitation of PDFsharp an XPdfForm object can be used only within one single PdfDocument.");
// Dispose PdfFromXObject when document has changed
form._pdfForm = null;
}
XPdfForm pdfForm = form as XPdfForm;
if (pdfForm != null)
{
// Is the external PDF file from which is imported already known for the current document?
Selector selector = new Selector(form);
PdfImportedObjectTable importedObjectTable;
if (!_forms.TryGetValue(selector, out importedObjectTable))
{
// No: Get the external document from the form and create ImportedObjectTable.
PdfDocument doc = pdfForm.ExternalDocument;
importedObjectTable = new PdfImportedObjectTable(Owner, doc);
_forms[selector] = importedObjectTable;
}
PdfFormXObject xObject = importedObjectTable.GetXObject(pdfForm.PageNumber);
if (xObject == null)
{
xObject = new PdfFormXObject(Owner, importedObjectTable, pdfForm);
importedObjectTable.SetXObject(pdfForm.PageNumber, xObject);
}
return(xObject);
}
Debug.Assert(form.GetType() == typeof(XForm));
form._pdfForm = new PdfFormXObject(Owner, form);
return(form._pdfForm);
}