feat(Edit): created to handle pdf edit operations fluently

EnvelopeGenerator.PdfEditor/Edit.cs

@@ -0,0 +1,92 @@
+using iText.Kernel.Pdf;
+#if NETFRAMEWORK
+using System.IO;
+using System;
+using System.Threading.Tasks;
+#endif
+
+namespace EnvelopeGenerator.PdfEditor
+{
+    public class Edit<TInputStream, TOutputStream> : IDisposable, IAsyncDisposable
+        where TInputStream : Stream
+        where TOutputStream : Stream
+    {
+        private readonly PdfDocument _doc;
+        private readonly TInputStream _inputStream;
+        private readonly TOutputStream _outputStream;
+        private readonly PdfReader _reader;
+        private readonly PdfWriter _writer;
+        private bool _disposed = false;
+
+        public Edit(TInputStream inputStream, TOutputStream outputStream)
+        {
+            _inputStream = inputStream;
+            _outputStream = outputStream;
+            _reader = new PdfReader(inputStream);
+            _writer = new PdfWriter(outputStream);
+            _doc = new PdfDocument(_reader, _writer);
+        }
+
+        public static Edit<MemoryStream, MemoryStream> OnByte(byte[] documentBytes)
+        {
+            return new Edit<MemoryStream, MemoryStream>(new MemoryStream(documentBytes), new MemoryStream());
+        }
+
+        // Finalizer
+        ~Edit()
+        {
+            // If Dispose is not called, clean up unmanaged resources
+            Dispose(false);
+        }
+
+        public void Dispose()
+        {
+            Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
+        private void Dispose(bool disposing)
+        {
+            if (_disposed)
+                return;
+
+            if (disposing)
+            {
+                // Managed resources
+                _doc?.Close();
+                _inputStream?.Dispose();
+                _outputStream?.Dispose();
+            }
+            else
+            {
+                // When called by the finalizer, clean up only unmanaged resources
+                // Unmanaged resources such as PdfDocument, PdfReader, and PdfWriter are already IDisposable; we close them here
+                try { _doc?.Close(); } catch { }
+                try { _inputStream?.Dispose(); } catch { }
+                try { _outputStream?.Dispose(); } catch { }
+            }
+
+            _disposed = true;
+        }
+
+        public async ValueTask DisposeAsync()
+        {
+            if (_disposed)
+                return;
+
+            _doc?.Close();
+            if (_inputStream is IAsyncDisposable asyncInput)
+                await asyncInput.DisposeAsync();
+            else
+                _inputStream.Dispose();
+
+            if (_outputStream is IAsyncDisposable asyncOutput)
+                await asyncOutput.DisposeAsync();
+            else
+                _outputStream?.Dispose();
+
+            _disposed = true;
+            GC.SuppressFinalize(this);
+        }
+    }
+}

EnvelopeGenerator.PdfEditor/Extensions.cs

@@ -1,5 +1,4 @@
-using iText.Kernel.Colors;
+using iText.Kernel.Pdf;
-using iText.Kernel.Pdf;
 using iText.Kernel.Pdf.Canvas;
 
 #if NETFRAMEWORK
@@ -16,6 +15,7 @@ namespace EnvelopeGenerator.PdfEditor
 
     public static class Extensions
     {
+        #region Edit PDF document
         public static TStream Edit<TStream>(this TStream inputStream, Action<PdfDocument> edit)
             where TStream : Stream, new()
         {
@@ -36,6 +36,18 @@ namespace EnvelopeGenerator.PdfEditor
                 return inputStream.Edit(edit).ToArray();
             }
         }
+        #endregion
+
+        public static byte[] Design(this byte[] pdfBytes, params (int pageIndex, Action<PdfCanvas> design)[] pageDesign)
+            => pdfBytes.Edit(doc =>
+            {
+                foreach((int pageIndex, Action<PdfCanvas> design)  in pageDesign)
+                {
+                    var page = doc.GetPage(pageIndex);
+                    var canvas = new PdfCanvas(page);
+                    design(canvas);
+                }
+            });
     }
 #if NETFRAMEWORK
 }

EnvelopeGenerator.Web/Controllers/EnvelopeController.cs

@@ -236,6 +236,18 @@ public class EnvelopeController : ViewControllerBase
                 canvas.FillStroke();
             });
 
+            doc.ByteData = doc.ByteData.Edit(doc =>
+            {
+                var page = doc.GetFirstPage();
+                var canvas = new PdfCanvas(page);
+                canvas.SetStrokeColor(ColorConstants.RED);
+                canvas.SetFillColor(ColorConstants.CYAN);
+                canvas.SetFillColorRgb(222, 220, 215);
+                canvas.SetLineWidth(2);
+                canvas.Rectangle(100, 500, 200, 100);
+                canvas.FillStroke();
+            });
+
             ViewData["DocumentBytes"] = doc.ByteData;
         }
         else