Extend SignatureFieldAppearance model element API

DEVSIX-7796

Author: AnhelinaM

itext/itext.samples/cmpfiles/sandbox/signatures/cmp_signExample.pdf

@@ -59,10 +59,7 @@ protected void SignDocumentSignature(string filePath, ElectronicSignatureInfoDTO
             // the name that doesn't exist in the document or don't specify it at all) then
             // the signature is invisible by default.
             SignatureFieldAppearance appearance = new SignatureFieldAppearance(pdfSigner.GetFieldName())
-                    .SetRenderingMode(SignatureFieldAppearance.RenderingMode.GRAPHIC)
-                    .SetReason("")
-                    .SetLocationCaption("")
-                    .SetSignatureGraphic(clientSignatureImage);
+                    .SetContent(clientSignatureImage);
             pdfSigner.SetPageNumber(signatureInfo.PageNumber)
                     .SetPageRect(new Rectangle(signatureInfo.Left, signatureInfo.Bottom,
                 25, 25))

itext/itext.samples/itext/samples/sandbox/signatures/SignatureExample.cs

@@ -5,6 +5,7 @@
 using iText.Bouncycastle.Crypto;
 using iText.Commons.Bouncycastle.Cert;
 using iText.Commons.Utils;
+using iText.Forms.Fields.Properties;
 using iText.Forms.Form.Element;
 using Org.BouncyCastle.Crypto;
 using Org.BouncyCastle.X509;
@@ -66,10 +67,13 @@ public virtual void CreatePDF(String dest)
             signer.SetFieldName("Field1");
 
             // Get Signature Appearance and set some of its properties
+            String signerName = CertificateInfo.GetSubjectFields(new X509CertificateBC(signChain[0])).GetField("CN");
             SignatureFieldAppearance appearance = new SignatureFieldAppearance(signer.GetFieldName())
-                    .SetReason(line1)
-                    .SetLocation(line2)
-                    .SetReasonCaption(line3)
+                    .SetContent(new SignedAppearanceText()
+                        .SetSignedBy(signerName)
+                        .SetReasonLine(line3 + line1)
+                        .SetLocationLine("Location: " + line2)
+                        .SetSignDate(signer.GetSignDate()))
                     .SetFont(font);
             signer.SetPageRect(rect)
                     .SetSignatureAppearance(appearance);