Render signatures on PDF using PdfSharp

Added functionality to render captured signatures onto a PDF document using the PdfSharp library. Introduced a new `_signatures` field to store signature data and updated `OnInitializedAsync` to fetch and process signatures. Implemented the `DrawSignaturesOnPdf` method to overlay signature images, separator lines, and signer details (name, position, place, date) onto the PDF. Added a helper method `DataUrlToBytes` for decoding Base64-encoded signature images. Defined constants for layout and styling to ensure consistent rendering. Updated `Dispose` to clean up resources.

EnvelopeGenerator.Server/EnvelopeGenerator.Server/Components/Pages/EnvelopeReceiverReportSignedPage.razor

@@ -92,6 +92,7 @@
     string? _errorMessage;
     ClaimsPrincipal? _receiverUser;
     EnvelopeGenerator.Application.Common.Dto.EnvelopeReceiver.EnvelopeReceiverDto? _envelopeReceiver;
+    IReadOnlyList<SignatureDto> _signatures = [];
     XtraReport? _report;
     SignatureCaptureDto? _sig;
 
@@ -130,6 +131,11 @@
             }
 
             _envelopeReceiver = await PageDataService.GetEnvelopeReceiverAsync(EnvelopeKey);
+            _signatures       = await PageDataService.GetSignaturesAsync(_receiverUser);
+
+            // Burn signature image + info onto PDF via PdfSharp
+            if (_sig is not null && _signatures.Count > 0)
+                pdfBytes = DrawSignaturesOnPdf(pdfBytes, _signatures, _sig);
 
             var report = new XtraReport
             {
@@ -176,4 +182,109 @@
     {
         _report?.Dispose();
     }
+
+    // ----- PDF signature rendering -----
+
+    /// <summary>
+    /// Uses PdfSharp to burn the captured signature onto the PDF at each signature field.
+    /// Layout per field (top-left origin, Y down, units = PDF points):
+    ///   [top 65%]  signature image
+    ///   [separator line]
+    ///   [bottom 35%] FullName (bold) / Position (optional) / Place, Date
+    /// </summary>
+    static byte[] DrawSignaturesOnPdf(
+        byte[] pdfBytes,
+        IReadOnlyList<SignatureDto> signatures,
+        SignatureCaptureDto sig)
+    {
+        var imgBytes = DataUrlToBytes(sig.DataUrl);
+        if (imgBytes is not { Length: > 0 }) return pdfBytes;
+
+        using var inputMs  = new System.IO.MemoryStream(pdfBytes);
+        using var outputMs = new System.IO.MemoryStream();
+
+        var document = PdfSharp.Pdf.IO.PdfReader.Open(
+            inputMs, PdfSharp.Pdf.IO.PdfDocumentOpenMode.Modify);
+
+        const double sigW = 1.77 * 72;   // 127.44 pt
+        const double sigH = 1.96 * 72;   // 141.12 pt
+        const double imgRatio  = 0.60;   // top 60% = image
+        const double textRatio = 0.38;   // bottom 38% = text  (2% padding)
+
+        var black     = PdfSharp.Drawing.XColor.FromArgb(255, 20,  20,  20);
+        var darkGray  = PdfSharp.Drawing.XColor.FromArgb(255, 80,  80,  80);
+        var lineColor = PdfSharp.Drawing.XColor.FromArgb(180, 100, 100, 120);
+
+        var fontBold   = new PdfSharp.Drawing.XFont("Arial", 7.5, PdfSharp.Drawing.XFontStyleEx.Bold);
+        var fontNormal = new PdfSharp.Drawing.XFont("Arial", 6.5, PdfSharp.Drawing.XFontStyleEx.Regular);
+        var linePen    = new PdfSharp.Drawing.XPen(lineColor, 0.5);
+
+        var fmtLeft = new PdfSharp.Drawing.XStringFormat
+        {
+            Alignment     = PdfSharp.Drawing.XStringAlignment.Near,
+            LineAlignment = PdfSharp.Drawing.XLineAlignment.Near,
+        };
+
+        var date = DateTime.Now.ToString("dd.MM.yyyy");
+
+        foreach (var field in signatures)
+        {
+            int pageIndex = field.Page - 1;
+            if (pageIndex < 0 || pageIndex >= document.PageCount) continue;
+
+            var page = document.Pages[pageIndex];
+
+            using var gfx = PdfSharp.Drawing.XGraphics.FromPdfPage(page);
+
+            double x = field.X;
+            double y = field.Y;
+
+            // --- Image area ---
+            double imgH    = sigH * imgRatio;
+            var    imgRect = new PdfSharp.Drawing.XRect(x, y, sigW, imgH);
+
+            using var imgStream = new System.IO.MemoryStream(imgBytes);
+            var xImg = PdfSharp.Drawing.XImage.FromStream(imgStream);
+            gfx.DrawImage(xImg, imgRect);
+
+            // --- Separator line ---
+            double lineY = y + imgH + sigH * 0.01;
+            gfx.DrawLine(linePen, x + 2, lineY, x + sigW - 2, lineY);
+
+            // --- Text area ---
+            double textY    = lineY + 2;
+            double textH    = sigH * textRatio;
+            double lineH    = textH / 3.5;  // max 3 text rows
+            double padding  = 3;
+
+            // Row 1: FullName (bold)
+            var nameRect = new PdfSharp.Drawing.XRect(x + padding, textY, sigW - padding * 2, lineH);
+            gfx.DrawString(sig.FullName, fontBold, new PdfSharp.Drawing.XSolidBrush(black), nameRect, fmtLeft);
+
+            // Row 2: Position (optional)
+            double row2Y = textY + lineH;
+            if (!string.IsNullOrWhiteSpace(sig.Position))
+            {
+                var posRect = new PdfSharp.Drawing.XRect(x + padding, row2Y, sigW - padding * 2, lineH);
+                gfx.DrawString(sig.Position, fontNormal, new PdfSharp.Drawing.XSolidBrush(darkGray), posRect, fmtLeft);
+                row2Y += lineH;
+            }
+
+            // Row 3 (or 2 if no position): Place, Date
+            var placeDate = $"{sig.Place}, {date}";
+            var dateRect  = new PdfSharp.Drawing.XRect(x + padding, row2Y, sigW - padding * 2, lineH);
+            gfx.DrawString(placeDate, fontNormal, new PdfSharp.Drawing.XSolidBrush(darkGray), dateRect, fmtLeft);
+        }
+
+        document.Save(outputMs);
+        return outputMs.ToArray();
+    }
+
+    static byte[]? DataUrlToBytes(string? dataUrl)
+    {
+        if (string.IsNullOrWhiteSpace(dataUrl)) return null;
+        var comma = dataUrl.IndexOf(',');
+        if (comma < 0) return null;
+        return Convert.FromBase64String(dataUrl[(comma + 1)..]);
+    }
 }