Text annotation is frequently used in PDF for creating a comment or explaining more about an item. Using Spire.PDF you can create a text mark-up annotation, edit an existing annotation and delete specified or all annotations. This article is aimed to demonstrate how to modify and format an existing text annotation in a PDF document.
Test File:

Changes we want to make:
- Modify the annotation text.
- Change the color of the annotation icon.
- Fix the annotation flag including its position, color, and type.
Code Snippet
Step 1: Create a new PDF document and load the test file.
PdfDocument pdf = new PdfDocument("test.pdf");
Step 2: Get the annotation from the document.
PdfAnnotation annotation = pdf.Pages[0].Annotations[0];
Step 3: Set the text, border, color of the annotation and lock the annotation flag.
annotation.Text = "Revised annotation"; annotation.Border = new PdfAnnotationBorder(0.75f); annotation.Color = new PdfRGBColor(Color.White); annotation.Flags = PdfAnnotationFlags.Locked;
Step 4: Save and launch the file.
pdf.SaveToFile("result.pdf");
Process.Start("result.pdf");
Target Effect:

Full Code:
[C#]
using Spire.Pdf;
using Spire.Pdf.Annotations;
using Spire.Pdf.Graphics;
using System.Diagnostics;
using System.Drawing;
namespace ModifyAndFormatAnnotation
{
class Program
{
static void Main(string[] args)
{
PdfDocument pdf = new PdfDocument("test.pdf");
PdfAnnotation annotation = pdf.Pages[0].Annotations[0];
annotation.Text = "Revised annotation";
annotation.Border = new PdfAnnotationBorder(0.75f);
annotation.Color = new PdfRGBColor(Color.White);
annotation.Flags = PdfAnnotationFlags.Locked;
pdf.SaveToFile("result.pdf");
Process.Start("result.pdf");
}
}
}
[VB.NET]
Imports Spire.Pdf
Imports Spire.Pdf.Annotations
Imports Spire.Pdf.Graphics
Imports System.Diagnostics
Imports System.Drawing
Namespace ModifyAndFormatAnnotation
Class Program
Private Shared Sub Main(args As String())
Dim pdf As New PdfDocument("test.pdf")
Dim annotation As PdfAnnotation = pdf.Pages(0).Annotations(0)
annotation.Text = "Revised annotation"
annotation.Border = New PdfAnnotationBorder(0.75F)
annotation.Color = New PdfRGBColor(Color.White)
annotation.Flags = PdfAnnotationFlags.Locked
pdf.SaveToFile("result.pdf")
Process.Start("result.pdf")
End Sub
End Class
End Namespace
