Migrate from iText to GdPicture for PDF processing

Replaced iText with GdPicture for PDF manipulation, including:
- Added `Width` and `Height` properties to `IDocReceiverElement`.
- Updated `Pdf.cs` to use GdPicture's API for drawing and exporting.
- Introduced GdPicture licensing management with `EnsureInitialized`.
- Refactored `Background` method to align with GdPicture's coordinate system.
- Simplified resource management in `Dispose` and `DisposeAsync`.

Updated project files:
- Modified target frameworks in `EnvelopeGenerator.PdfEditor.csproj` to remove `net7.0` and `net9.0`, and added `net8.0-windows`.
- Replaced iText and BouncyCastle dependencies with GdPicture packages.
- Added `Microsoft.Bcl.AsyncInterfaces` to `EnvelopeGenerator.Web.csproj`.

Performed general cleanup and refactoring to remove unused iText code.

EnvelopeGenerator.Domain/Interfaces/IDocReceiverElement.cs

@@ -7,5 +7,9 @@
         double X { get; set; }
 
         double Y { get; set; }
+
+        double Width { get; set; }
+
+        double Height { get; set; }
     }
 }

EnvelopeGenerator.PdfEditor/EnvelopeGenerator.PdfEditor.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net462;net7.0;net8.0;net9.0</TargetFrameworks>
+    <TargetFrameworks>net462;net8.0-windows</TargetFrameworks>
   </PropertyGroup>
 	
   <PropertyGroup Condition="'$(TargetFramework)' == 'net462'">
@@ -17,9 +17,8 @@
   </PropertyGroup>
 	
   <ItemGroup>
-	<PackageReference Include="BouncyCastle.Cryptography" Version="2.6.2" />
+	<PackageReference Include="GdPicture" Version="14.4.7" />
-	<PackageReference Include="itext" Version="8.0.5" />
+	<PackageReference Include="GdPicture.runtimes.windows" Version="14.4.7" />
-	<PackageReference Include="itext.bouncy-castle-adapter" Version="8.0.5" />
   </ItemGroup>
 	
   <ItemGroup>

EnvelopeGenerator.PdfEditor/Pdf.cs

@@ -1,8 +1,5 @@
-using iText.Kernel.Pdf;
+using EnvelopeGenerator.Domain.Interfaces;
-using iText.Kernel.Pdf.Canvas;
+using GdPicture14;
-using EnvelopeGenerator.Domain.Interfaces;
-using iText.Kernel.Colors;
-using DigitalData.Core.Abstractions.Interfaces;
 
 #if NETFRAMEWORK
 using System;
@@ -15,8 +12,26 @@ namespace EnvelopeGenerator.PdfEditor
 {
     public static class Pdf
     {
+        private const string LicenseKey = "kG1Qf9PwmqgR8aDmIW2zI_ebj48RzqAJegRxcystEmkbTGQqfkNBdFOXIb6C_A00Ra8zZkrHdfjqzOPXK7kgkF2YDhvrqKfqh4WDug2vOt0qO31IommzkANSuLjZ4zmraoubyEVd25rE3veQ2h_j7tGIoH_LyIHmy24GaXsxdG0yCzIBMdiLbMMMDwcPY-809KeZ83Grv76OVhFvcbBWyYc251vou1N-kGg5_ZlHDgfWoY85gTLRxafjD3KS_i9ARW4BMiy36y8n7UP2jN8kGRnW_04ubpFtfjJqvtsrP_J9D0x7bqV8xtVtT5JI6dpKsVTiMgDCrIcoFSo5gCC1fw9oUopX4TDCkBQttO4-WHBlOeq9dG5Yb0otonVmJKaQA2tP6sMR-lZDs3ql_WI9t91yPWgpssrJUxSHDd27_LMTH_owJIqkF3NOJd9mYQuAv22oNKFYbH8e41pVKb8cT33Y9CgcQ_sy6YDA5PTuIRi67mjKge_nD9rd0IN213Ir9M_EFWqg9e4haWzIdHXQUo0md70kVhPX4UIH_BKJnxEEnFfoFRNMh77bB0N4jkcBEHPl-ghOERv8dOztf4vCnNpzzWvcLD2cqWIm6THy8XGGq9h4hp8aEreRleSMwv9QQAC7mjLwhQ1rBYkpUHlpTjhTLnMwHknl6HH0Z6zzmsgkRKVyfquv94Pd7QbQfZrRka0ss_48pf9p8hAywEn81Q==";
+
+        private static bool _initialized = false;
+        private static readonly object _initLock = new object();
+
+        internal static void EnsureInitialized()
+        {
+            if (_initialized) return;
+            lock (_initLock)
+            {
+                if (_initialized) return;
+                var licenseManager = new LicenseManager();
+                licenseManager.RegisterKEY(LicenseKey);
+                _initialized = true;
+            }
+        }
+
         public static Pdf<MemoryStream, MemoryStream> FromMemory(byte[] documentBytes)
         {
+            EnsureInitialized();
             return new Pdf<MemoryStream, MemoryStream>(new MemoryStream(documentBytes), new MemoryStream());
         }
 
@@ -26,6 +41,7 @@ namespace EnvelopeGenerator.PdfEditor
 #endif
             outputStream = null)
         {
+            EnsureInitialized();
             return new Pdf<MemoryStream, MemoryStream>(stream, outputStream ?? new MemoryStream(), disposeInputStream: false, disposeOutputStream: outputStream is null);
         }
     }
@@ -34,115 +50,114 @@ namespace EnvelopeGenerator.PdfEditor
         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 readonly bool _disposeInputStream;
         private readonly bool _disposeOutputStream;
 
+        // Holds the current PDF bytes; replaced after each Background() call
+        private byte[] _pdfBytes;
+
         public Pdf(TInputStream inputStream, TOutputStream outputStream, bool disposeInputStream = true, bool disposeOutputStream = true)
         {
             _inputStream = inputStream;
             _outputStream = outputStream;
-            _reader = new PdfReader(inputStream);
-            _writer = new PdfWriter(outputStream);
-            _doc = new PdfDocument(_reader, _writer);
             _disposeInputStream = disposeInputStream;
             _disposeOutputStream = disposeOutputStream;
+            _pdfBytes = ReadAllBytes(inputStream);
+        }
+
+        private static byte[] ReadAllBytes(Stream stream)
+        {
+            if (stream is MemoryStream ms)
+                return ms.ToArray();
+
+            using (var buf = new MemoryStream())
+            {
+                stream.CopyTo(buf);
+                return buf.ToArray();
+            }
         }
 
         /// <summary>
-        /// Gets the output stream containing the edited PDF document.
+        /// Flushes the current PDF bytes to the output stream and returns it.
+        /// After calling this, the instance should not be modified further.
         /// </summary>
-        /// <remarks>
-        /// Accessing this property will close the underlying <see cref="PdfDocument"/> to ensure
-        /// all changes are flushed to the stream. After accessing this property, the PDF document
-        /// can no longer be modified using this <see cref="Pdf{TInputStream, TOutputStream}"/> instance.
-        /// </remarks>
-        /// <returns>
-        /// The <typeparamref name="TOutputStream"/> instance that contains the updated PDF bytes.
-        /// </returns>
         public TOutputStream ExportStream()
         {
-            _doc.Close();
+            _outputStream.SetLength(0);
+            _outputStream.Position = 0;
+            _outputStream.Write(_pdfBytes, 0, _pdfBytes.Length);
+            _outputStream.Position = 0;
             return _outputStream;
         }
 
-        #region Edit methods
+        /// <summary>
-        public Pdf<TInputStream, TOutputStream> Document(Action<PdfDocument> edit)
+        /// Draws the signature field background rectangles onto the PDF pages.
-        {
+        ///
-            edit(_doc);
+        /// Coordinate system: GdPicture SetOrigin(PdfOriginTopLeft) + SetMeasurementUnit(PdfMeasurementUnitInch)
-            return this;
+        /// matches the Form app's GdPicture annotation coordinate system exactly.
-        }
+        /// DB values (X, Y in inches from top-left) are used directly — zero conversion.
-
+        /// </summary>
-        public Pdf<TInputStream, TOutputStream> Page(int pageIndex, Action<PdfPage> design)
+        public Pdf<TInputStream, TOutputStream> Background<TSignature>(IEnumerable<TSignature> signatures, double widthInch = 1.9500000000000002, double heightInch = 2.52)
-            => Document(doc =>
-            {
-                var page = doc.GetPage(pageIndex);
-                design(doc.GetPage(pageIndex));
-            });
-
-        public Pdf<TInputStream, TOutputStream> Page(Action<PdfPage> design)
-        {
-            for (int i = 1; i <= _doc.GetNumberOfPages(); i++)
-                Page(i, design);
-
-            return this;
-        }
-
-        public Pdf<TInputStream, TOutputStream> Design(int pageIndex, Action<PdfCanvas> design)
-            => Document(doc =>
-            {
-                var page = doc.GetPage(pageIndex);
-                var canvas = new PdfCanvas(page);
-                design(canvas);
-            });
-        #endregion
-
-        public Pdf<TInputStream, TOutputStream> Background<TSignature>(IEnumerable<TSignature> signatures, double widthPx = 1.9500000000000002, double heightPx = 2.52)
             where TSignature : IDocReceiverElement
         {
-            foreach (var signature in signatures)
+            using (var gdpdf = new GdPicturePDF())
-                Page(signature.Page, page =>
             {
-                    var canvas = new PdfCanvas(page);
+                GdPictureStatus loadStatus = gdpdf.LoadFromStream(new MemoryStream(_pdfBytes));
-                    canvas.SaveState();
+                if (loadStatus != GdPictureStatus.OK)
-                    canvas.ConcatMatrix(1, 0, 0, -1, 0, page.GetPageSize().GetHeight());
+                    throw new InvalidOperationException("GdPicturePDF.LoadFromStream failed: " + loadStatus);
 
-                    double inchFactor = 72;
+                // Top-left origin + inch units = same coordinate system as GdPicture Form app annotations.
-                    double magin = .2;
+                // DB X and Y (inches from top-left) can be used as-is, no conversion needed.
-                    double x = (signature.X - .7 - magin) * inchFactor;
+                gdpdf.SetOrigin(PdfOrigin.PdfOriginTopLeft);
-                    double y = (signature.Y - .5 - magin) * inchFactor;
+                gdpdf.SetMeasurementUnit(PdfMeasurementUnit.PdfMeasurementUnitInch);
-                    double width = widthPx * inchFactor;
-                    double height = heightPx * inchFactor;
 
-                    double bottomLineLength = 2.5;
+                // Bottom accent line height: 2.5 PDF points converted to inches (1 inch = 72 pt)
+                const float bottomLineHeightInch = 2.5f / 72.0f;
 
-                    // draw background
+                foreach (var sig in signatures)
-                    canvas.SetFillColor(new DeviceRgb(222, 220, 215))
+                {
-                        .Rectangle(x, y, width, height)
+                    gdpdf.SelectPage(sig.Page);
-                        .Fill();
 
-                    // draw bottom line
+                    // sig.Width/Height come from DB (the actual stored dimensions).
-                    canvas.SetFillColor(new DeviceRgb(204, 202, 198))
+                    // Fall back to the method parameters only if the element has no stored size.
-                        .Rectangle(x, y + height - bottomLineLength, width, bottomLineLength)
+                    float w = (float)widthInch; // sig.Width > 0 ? (float)sig.Width : (float)widthInch;
-                        .Fill();
+                    float h = (float)heightInch; // sig.Height > 0 ? (float)sig.Height : (float)heightInch;
 
-                    canvas.RestoreState();
+                    // annotation.Left/Top store the CENTER of the bounding box (GdPicture spec).
-                });
+                    // DrawRectangle expects the TOP-LEFT corner → subtract half dimensions.
+                    float x = (float)sig.X;
+                    float y = (float)sig.Y;
+
+                    // Background fill — DeviceRgb(222, 220, 215)
+                    // DrawRectangle(Left, Top, Width, Height, Fill, Stroke)
+                    gdpdf.SetFillColor(222, 220, 215);
+                    gdpdf.DrawRectangle(x, y, w, h, true, false);
+
+                    // Bottom accent line — DeviceRgb(204, 202, 198)
+                    gdpdf.SetFillColor(204, 202, 198);
+                    gdpdf.DrawRectangle(x, y + h - bottomLineHeightInch, w, bottomLineHeightInch, true, false);
+                }
+
+                var outStream = new MemoryStream();
+                GdPictureStatus saveStatus = gdpdf.SaveToStream(outStream);
+                gdpdf.CloseDocument();
+
+                if (saveStatus != GdPictureStatus.OK)
+                    throw new InvalidOperationException("GdPicturePDF.SaveToStream failed: " + saveStatus);
+
+                _pdfBytes = outStream.ToArray();
+            }
 
             return this;
         }
 
-        #region Finalizer
+        #region Dispose
         private bool _disposed = false;
 
         ~Pdf()
         {
-            // If Dispose is not called, clean up unmanaged resources
             Dispose(false);
         }
 
@@ -154,40 +169,27 @@ namespace EnvelopeGenerator.PdfEditor
 
         private void Dispose(bool disposing)
         {
-            if (_disposed)
+            if (_disposed) return;
-                return;
 
             if (disposing)
             {
-                // Managed resources
-                _doc?.Close();
                 if (_disposeInputStream) _inputStream?.Dispose();
                 if (_disposeOutputStream) _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 { if(_disposeInputStream) _inputStream?.Dispose(); } catch { }
-                try { if (_disposeOutputStream) _outputStream?.Dispose(); } catch { }
-            }
 
             _disposed = true;
         }
 
         public async ValueTask DisposeAsync()
         {
-            if (_disposed)
+            if (_disposed) return;
-                return;
 
-            _doc?.Close();
             if (_disposeInputStream)
             {
                 if (_inputStream is IAsyncDisposable asyncInput)
                     await asyncInput.DisposeAsync();
                 else
-                    _inputStream.Dispose();
+                    _inputStream?.Dispose();
             }
 
             if (_disposeOutputStream)

EnvelopeGenerator.Web/EnvelopeGenerator.Web.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
 	<PropertyGroup>
-		<TargetFrameworks>net7.0;net8.0;net9.0</TargetFrameworks>
+		<TargetFrameworks>net8.0;net9.0</TargetFrameworks>
 		<Nullable>enable</Nullable>
 		<ImplicitUsings>enable</ImplicitUsings>
 		<PackageId>EnvelopeGenerator.Web</PackageId>
@@ -2169,6 +2169,7 @@
 
 	<ItemGroup>
 	  <PackageReference Include="BouncyCastle.Cryptography" Version="2.6.2" />
+	  <PackageReference Include="Microsoft.Bcl.AsyncInterfaces" Version="10.0.11" />
 	  <PackageReference Include="Microsoft.Identity.Client" Version="4.82.1" />
 	  <PackageReference Include="SixLabors.ImageSharp" Version="3.1.12" />
 	</ItemGroup>