Create an annotation in a PDF using C#
To create an annotation in a PDF document, follow the steps below:
- Create a
GdPicturePDF
object. - Load the PDF file with the
LoadFromFile
method. - Set the origin of the coordinate system with the
SetOrigin
method. This method requires thePDFOrigin
enumeration. - Set the measurement unit with the
SetMeasurementUnit
method to specify the annotation’s dimensions and position. This method uses thePdfMeasurementUnit
enumeration. - Select the PDF page where you want to place the annotation using the
SelectPage
method. - Optional: Specify the font type. For more information, refer to the Font Type section of the guide on adding text to PDFs.
- Add the annotation with any of the following methods:
- Save the PDF document to a file with the
SaveToFile
method.
All methods that create a new annotation return an integer value, which is the annotation’s index. Recommended: Save the annotation index to a variable so that you can later reference that annotation.
using GdPicturePDF gdpicturePDF = new GdPicturePDF();gdpicturePDF.LoadFromFile(@"C:\temp\source.pdf");// Set the origin of the coordinate system.gdpicturePDF.SetOrigin(PdfOrigin.PdfOriginTopLeft);// Set the measurement unit to centimeters.gdpicturePDF.SetMeasurementUnit(PdfMeasurementUnit.PdfMeasurementUnitCentimeter);// Select the first PDF page.gdpicturePDF.SelectPage(1);// Set the text content and determine its size.float fontSize = 16;string fontResName = gdpicturePDF.AddStandardFont(PdfStandardFont.PdfStandardFontHelvetica);string text = "Text annotation example.";float textWidth = gdpicturePDF.GetTextWidth(fontResName, fontSize, text);float textHeight = gdpicturePDF.GetTextHeight(fontResName, fontSize, false);// Add the free text annotation.int annotIndex = gdpicturePDF.AddFreeTextAnnotation(1, 2, textWidth + 0.5f, textHeight + 0.5f, true, "Annotation Example", "Example", text, fontResName, fontSize, 0, 0, 200, 100, 100, 100, 100);gdpicturePDF.SaveToFile(@"C:\temp\output.pdf");
Using gdpicturePDF As GdPicturePDF = New GdPicturePDF() gdpicturePDF.LoadFromFile("C:\temp\source.pdf") ' Set the origin of the coordinate system. gdpicturePDF.SetOrigin(PdfOrigin.PdfOriginTopLeft) ' Set the measurement unit to centimeters. gdpicturePDF.SetMeasurementUnit(PdfMeasurementUnit.PdfMeasurementUnitCentimeter) ' Select the first PDF page. gdpicturePDF.SelectPage(1) ' Set the text content and determine its size. Dim fontSize As Single = 16 Dim fontResName As String = gdpicturePDF.AddStandardFont(PdfStandardFont.PdfStandardFontHelvetica) Dim text = "Text annotation example." Dim textWidth As Single = gdpicturePDF.GetTextWidth(fontResName, fontSize, text) Dim textHeight As Single = gdpicturePDF.GetTextHeight(fontResName, fontSize, False) ' Add the free text annotation. Dim annotIndex As Integer = gdpicturePDF.AddFreeTextAnnotation(1, 2, textWidth + 0.5F, textHeight + 0.5F, True, "Annotation Example", "Example", text, fontResName, fontSize, 0, 0, 200, 100, 100, 100, 100) gdpicturePDF.SaveToFile("C:\temp\output.pdf")End Using
Used methods
Related topics