You can design the signature appearance in a completely custom manner by retrieving the PdfFormXObject
Layer 2 and drawing on it:
PdfSigner signer = ...
PdfSignatureAppearance appearance = signer.getSignatureAppearance();
PdfFormXObject layer2 = appearance.getLayer2();
try (Canvas layer2Canvas = new Canvas(layer2, signer.getDocument())) {
[... design your signature appearance on layer2Canvas ...]
}
If you don't want to do that, though, iText designs it itself hardly leaving you any options.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…