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In Euclidean plane geometry, a rectangle is any quadrilateral with four right angles. The term "oblong" is occasionally used to refer to a non-square rectangle. A rectangle with vertices ABCD would be denoted as ABCD. It’s simple for people to draw rectangles in paper. While how about drawing rectangles in PDF document? This section will show you the exact answer. This section will introduce a solution to draw rectangles and set the size and position of rectangles in PDF via a .NET PDF component Spire.PDF for .NET with C#, VB.NET.
In Spire.PDF, there are two classes: Spire.Pdf.Graphics.PdfPen and Spire.Pdf.Granphics.PdfBrush. By using the first class, we can set the color and decide the outline of the PDF rectangle. While the second class can quickly help us fill the rectangles with a color we want. Now let us see this method: Spire.Pdf.PdfPageBase.Canvas.DrawRectangle(PdfPen pen, RectangleF rectangle); There are two parameters passed. One is the PdfPen which I referred above. The other represents the location and size of a rectangle. By calling this method, we can draw rectangles and set their size and position very quickly. Now let us view the rectangles as below picture:
Here we can download Spire.PDF for .NET and install it on system. After adding Spire.Pdf dll, we can draw rectangle in our PDF document as below code:
using System.Drawing;
using Spire.Pdf;
using Spire.Pdf.Graphics;
namespace PDF_rectangles
{
class Program
{
static void Main(string[] args)
{
//create a PDF
PdfDocument pdfDoc = new PdfDocument();
PdfPageBase page = pdfDoc.Pages.Add();
//save graphics state
PdfGraphicsState state = page.Canvas.Save();
//draw rectangles
PdfPen pen = new PdfPen(Color.ForestGreen, 0.1f);
PdfPen pen1 = new PdfPen(Color.Red, 3f);
PdfBrush brush = new PdfSolidBrush(Color.Orange);
page.Canvas.DrawRectangle(pen, new Rectangle(new Point(2, 7), new Size(120, 120)));
page.Canvas.DrawRectangle(pen1, new Rectangle(new Point(350, 7), new Size(160, 120)));
page.Canvas.DrawRectangle(brush, new RectangleF(new Point(158, 7), new SizeF(160, 120)));
//restor graphics
page.Canvas.Restore(state);
pdfDoc.SaveToFile("Rectangles.pdf");
System.Diagnostics.Process.Start("Rectangles.pdf");
}
}
}
Imports System.Drawing
Imports Spire.Pdf
Imports Spire.Pdf.Graphics
Namespace PDF_rectangles
Class Program
Private Shared Sub Main(args As String())
'create a PDF
Dim pdfDoc As New PdfDocument()
Dim page As PdfPageBase = pdfDoc.Pages.Add()
'save graphics state
Dim state As PdfGraphicsState = page.Canvas.Save()
'draw rectangles
Dim pen As New PdfPen(Color.ForestGreen, 0.1F)
Dim pen1 As New PdfPen(Color.Red, 3F)
Dim brush As PdfBrush = New PdfSolidBrush(Color.Orange)
page.Canvas.DrawRectangle(pen, New Rectangle(New Point(2, 7), New Size(120, 120)))
page.Canvas.DrawRectangle(pen1, New Rectangle(New Point(350, 7), New Size(160, 120)))
page.Canvas.DrawRectangle(brush, New RectangleF(New Point(158, 7), New SizeF(160, 120)))
'restor graphics
page.Canvas.Restore(state)
pdfDoc.SaveToFile("Rectangles.pdf")
System.Diagnostics.Process.Start("Rectangles.pdf")
End Sub
End Class
End Namespace
Spire.PDF for .NET is a .NET PDF component that can draw different kinds of shapes in PDF document such as Circles, Arcs. Ellipse and Five-pointed Star.
As PDF documents become increasingly popular in business, ensuring their authenticity has become a key concern. Signing PDFs with a certificate-based signature can protect the content and also let others know who signed or approved the document. In this article, you will learn how to digitally sign PDF with an invisible or a visible signature, and how to remove digital signatures from PDF by using Spire.PDF for .NET.
- Add an Invisible Digital Signature to PDF
- Add a Visible Digital Signature to PDF
- Remove Digital Signatures from PDF
Install Spire.PDF for .NET
To begin with, you need to add the DLL files included in the Spire.PDF for.NET package as references in your .NET project. The DLLs files can be either downloaded from this link or installed via NuGet.
PM> Install-Package Spire.PDF
Add an Invisible Digital Signature to PDF
The following are the steps to add an invisible digital signature to PDF using Spire.PDF for .NET.
- Create a PdfDocument object.
- Load a sample PDF file using PdfDocument.LoadFromFile() method.
- Load a pfx certificate file while initializing the PdfCertificate object.
- Create a PdfSignature object based on the certificate.
- Set the document permissions through the PdfSignature object.
- Save the document to another PDF file using PdfDocument.SaveToFile() method.
- C#
- VB.NET
using Spire.Pdf;
using Spire.Pdf.Security;
namespace AddInvisibleSignature
{
class Program
{
static void Main(string[] args)
{
//Create a PdfDocument object
PdfDocument doc = new PdfDocument();
//Load a sample PDF file
doc.LoadFromFile("C:\\Users\\Administrator\\Desktop\\sample.pdf");
//Load the certificate
PdfCertificate cert = new PdfCertificate("C:\\Users\\Administrator\\Desktop\\MyCertificate.pfx", "e-iceblue");
//Create a PdfSignature object
PdfSignature signature = new PdfSignature(doc, doc.Pages[doc.Pages.Count - 1], cert, "MySignature");
//Set the document permission to forbid changes but allow form fill
signature.DocumentPermissions = PdfCertificationFlags.ForbidChanges Or PdfCertificationFlags.AllowFormFill
//Save to another PDF file
doc.SaveToFile("InvisibleSignature.pdf");
doc.Close();
}
}
}
Add a Visible Digital Signature to PDF
The following are the steps to add a visible digital signature to PDF using Spire.PDF for .NET.
- Create a PdfDocument object.
- Load a sample PDF file using PdfDocument.LoadFromFile() method.
- Load a pfx certificate file while initializing the PdfCertificate object.
- Create a PdfSignature object and specify its position and size on the document.
- Set the signature details including date, name, location, reason, handwritten signature image, and document permissions.
- Save the document to another PDF file using PdfDocument.SaveToFile() method.
- C#
- VB.NET
using System;
using System.Drawing;
using Spire.Pdf;
using Spire.Pdf.Security;
using Spire.Pdf.Graphics;
namespace AddVisibleSignature
{
class Program
{
static void Main(string[] args)
{
//Create a PdfDocument object
PdfDocument doc = new PdfDocument();
//Load a sample PDF file
doc.LoadFromFile("C:\\Users\\Administrator\\Desktop\\sample.pdf");
//Load the certificate
PdfCertificate cert = new PdfCertificate("C:\\Users\\Administrator\\Desktop\\MyCertificate.pfx", "e-iceblue");
//Create a PdfSignature object and specify its position and size
PdfSignature signature = new PdfSignature(doc, doc.Pages[doc.Pages.Count - 1], cert, "MySignature");
RectangleF rectangleF = new RectangleF(doc.Pages[0].ActualSize.Width - 260 - 54, 200, 260, 110);
signature.Bounds = rectangleF;
signature.Certificated = true;
//Set the graphics mode to ImageAndSignDetail
signature.GraphicsMode = GraphicMode.SignImageAndSignDetail;
//Set the signature content
signature.NameLabel = "Signer:";
signature.Name = "Gary";
signature.ContactInfoLabel = "Phone:";
signature.ContactInfo = "0123456";
signature.DateLabel = "Date:";
signature.Date = DateTime.Now;
signature.LocationInfoLabel = "Location:";
signature.LocationInfo = "USA";
signature.ReasonLabel = "Reason:";
signature.Reason = "I am the author";
signature.DistinguishedNameLabel = "DN:";
signature.DistinguishedName = signature.Certificate.IssuerName.Name;
//Set the signature image source
signature.SignImageSource = PdfImage.FromFile("C:\\Users\\Administrator\\Desktop\\handwrittingSignature.png");
//Set the signature font
signature.SignDetailsFont = new PdfTrueTypeFont(new Font("Arial Unicode MS", 12f, FontStyle.Regular));
//Set the document permission to forbid changes but allow form fill
signature.DocumentPermissions = PdfCertificationFlags.ForbidChanges | PdfCertificationFlags.AllowFormFill;
//Save to file
doc.SaveToFile("VisiableSignature.pdf");
doc.Close();
}
}
}
Remove Digital Signatures from PDF
The following are the steps to remove digital signatures from PDF using Spire.PDF for .NET.
- Create a PdfDocument object.
- Get form widgets from the document through PdfDocument.Form property.
- Loop through the widgets and determine if a specific widget is a PdfSignatureFieldWidget.
- Remove the signature widget using PdfFieldCollection.RemoveAt() method.
- Save the document to another PDF file using PdfDocument.SaveToFile() method.
- C#
- VB.NET
using Spire.Pdf;
using Spire.Pdf.Widget;
namespace RemoveSignature
{
class Program
{
static void Main(string[] args)
{
//Create a PdfDocument object
PdfDocument doc = new PdfDocument("C:\\Users\\Administrator\\Desktop\\VisiableSignature.pdf");
//Get form widgets from the document
PdfFormWidget widgets = doc.Form as PdfFormWidget;
//Loop through the widgets
for (int i = 0; i < widgets.FieldsWidget.List.Count; i++)
{
//Get the specific widget
PdfFieldWidget widget = widgets.FieldsWidget.List[i] as PdfFieldWidget;
//Determine if the widget is a PdfSignatureFieldWidget
if (widget is PdfSignatureFieldWidget)
{
//Remove the widget
widgets.FieldsWidget.RemoveAt(i);
}
}
//Save the document to another PDF file
doc.SaveToFile("RemoveSignatures.pdf");
}
}
}
Apply for a Temporary License
If you'd like to remove the evaluation message from the generated documents, or to get rid of the function limitations, please request a 30-day trial license for yourself.
Encrypting PDF is a way people commonly used to protect PDF. Whether for a company or for individual, using PDF encryption to place some certain restrictions is indispensable. In order to make the PDF document available to read but unable to modify by unauthorized users, two passwords are required for an encrypted PDF document: owner password and user password. This section will particularly introduce a simple solution to quickly encrypt PDF with C#, VB.NET via Spire.PDF for .NET.
Spire.PDF for .NET as a .NET PDF component, can encrypt your PDF by owner and user password. Owner password is provided to fully access to PDF file such as reset password and restrictions. While user password allows users to open the document as well as subject to the restrictions placed by owner.
In the encryption solution, an object of the PDFSecurity class which is included in the namespace Spire.PDFDocument.Security is used to set the owner and user password. Please feel free to download Spire.PDF for .NET and load your PDF file and then protect it.
Protect PDF by setting password and specify document restrictions.
Step 1: Set PDF key size by the enum."Spire.Pdf.Security.PdfEncryptionKeySize".Three kinds of key size are available here: Key128Bit, Key256Bit and Key40Bit, you can use any one among the three.
doc.Security.KeySize = PdfEncryptionKeySize.Key256Bit;
doc.Security.KeySize = PdfEncryptionKeySize.Key256Bit
Step 2: Encrypt PDF file by setting owner and user password. The password size you set should not be over the key size.
doc.Security.OwnerPassword = "e-iceblue"; doc.Security.UserPassword = "pdfcomponent";
doc.Security.OwnerPassword = "e-iceblue" doc.Security.UserPassword = "pdfcomponent"
Step 3: Specify access restrictions of user password. There are nine permissions are available in the solution. You can see them as below picture.
doc.Security.Permissions = PdfPermissionsFlags.Print | PdfPermissionsFlags.CopyContent;
doc.Security.Permissions = PdfPermissionsFlags.Print Or PdfPermissionsFlags. CopyContent
After running your project, you will be requested a password when you open this encrypted PDF file. Please look at the effective screenshot below:
