Alright, I managed to upgrade the .dll to 4.1.6. I have verified that the
stamper object is not being called in append mode. The signature field is
still not cleared and the field remains signed.
The code has now been changed thusly:
public Boolean ClearSignatureField(string fieldName)
{
try
{
ArrayList list = this.Stamper.AcroFields.GetFieldItem(fieldName);
item.MarkUsed(this.Fields, AcroFields.Item.WRITE_VALUE |
AcroFields.item.WRITE_WIDGET);
int n = item.Size;
for (int k=0; k<n; ++k)
{
ClearSignatureDictionary(item.GetMerged(k));
ClearSignatureDictionary(item.GetWidget(k));
ClearSignatureDictionary(item.GetValue(k));
}
return true;
}
catch(Exception ex)
{
throw new Exception("An Exception has occurred: ", ex);
}
}
private static void ClearSignatureDictionary(PdfDictionary dic)
{
dic.Remove(PdfName.AP);
dic.Remove(PdfName.AS);
dic.Remove(PdfName.V);
dic.Remove(PdfName.DV);
dic.Remove(PdfName.SV);
dic.Remove(PdfName.FF);
dic.Put(PdfName.F, new PdfNumber(PdfAnnotation.FLAGS_PRINT));
}
As you can see, the code now closely more resembles the code updated by
Paulo. The code executes without failure and the field's values are
correctly located. However, the signature field remains signed.
If curious, here is my stamper declaration code:
private void GenerateStamper(bool isAppendMode)
{
bool canCloseReader = false;
if (this.ModifiedStream != null)
{
this.Stamper = new PdfStamper(this.Reader, this.ModifiedStream, '\0',
isAppendMode);
canCloseReader = true;
}
if (canCloseReader)
{
this.Reader.Close();
}
}
isAppendMode is being populated by the value of false during stamper
generation which should be fine.
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