Export Annotation Data from PDFs in C# .NET

XMP annotations can be stored in one of the following ways:

  • XML file

  • Stream object

  • Base64-encoded string

To export XMP annotations from the currently opened file in the AnnotationManager object, use the SaveAnnotationsToXMP method for XML files and Stream objects, and the SaveAnnotationsToXMPBase64 method for the encoded string.

In the following example, the XMP annotations from a template image are applied to another image:

using AnnotationManager annotationManager = new AnnotationManager();
// Load the template image to the `AnnotationManager` object.
annotationManager.InitFromFile(@"C:\temp\template.jpg");
// Save the annotations from the template image to an XML file.
annotationManager.SaveAnnotationsToXMP(@"C:\temp\annotTemplate.xml");
// Load the source image to the `AnnotationManager` object.
annotationManager.InitFromFile(@"C:\temp\source.jpg");
// Load the XML file with the annotations to the `AnnotationManager` object.
annotationManager.LoadAnnotationsFromXMP(@"C:\temp\annotTemplate.xml");
// Flatten the annotations into the image.
annotationManager.BurnAnnotationsToPage(false);
// Save the image to a file.
annotationManager.SaveDocumentToJPEG(@"C:\temp\output.jpg", 100);
Using annotationManager As AnnotationManager = New AnnotationManager()
    ' Load the template image to the `AnnotationManager` object.
    annotationManager.InitFromFile("C:\temp\template.jpg")
    ' Save the annotations from the template image to an XML file.
    annotationManager.SaveAnnotationsToXMP("C:\temp\annotTemplate.xml")
    ' Load the source image to the `AnnotationManager` object.
    annotationManager.InitFromFile("C:\temp\source.jpg")
    ' Load the XML file with the annotations to the `AnnotationManager` object.
    annotationManager.LoadAnnotationsFromXMP("C:\temp\annotTemplate.xml")
    ' Flatten the annotations into the image.
    annotationManager.BurnAnnotationsToPage(False)
    ' Save the image to a file.
    annotationManager.SaveDocumentToJPEG("C:\temp\output.jpg", 100)
End Using
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To export data from a PDF annotation, follow these steps:

  1. Create a GdPicturePDF object.

  2. Load the PDF file with the LoadFromFile method.

  3. Loop through all PDF pages.

  4. Select the PDF page from where to get the annotation data with the SelectPage method.

  5. Get the total number of annotations in the PDF document with the GetAnnotationCount method.

  6. Loop through all annotations.

  7. Use a method to get the annotation data and save it to a variable. For more information, refer to the guide on getting PDF annotation properties.

The following code example gets the index number, type, and contents of all annotations and saves them to a CSV file:

using GdPicturePDF gdpicturePDF = new GdPicturePDF();
gdpicturePDF.LoadFromFile(@"C:\temp\source.pdf");
// Create a `StringBuilder` variable to store data.
StringBuilder data = new StringBuilder();
// Add headers to the first line.
String[] headers = { "Index", "Annotation Type", "Contents", "Page" };
data.AppendLine(string.Join(";", headers));
// Get the number of pages.
int pageCount = gdpicturePDF.GetPageCount();
// Loop through all pages.
for(int page = 1; page <= pageCount; page++)
{
    // Select a PDF page.
    gdpicturePDF.SelectPage(page);
    int annotCount = gdpicturePDF.GetAnnotationCount();
    // Loop through all annotations.
    for (int i = 0; i < annotCount; i++)
    {
        // Get the current annotation type.
        string annotType = gdpicturePDF.GetAnnotationSubType(i);
        // Get the current annotation contents.
        string annotContents = gdpicturePDF.GetAnnotationContents(i);
        // Add a new line to the `StringBuilder` with the annotation data.
        String[] newLine = { i.ToString(), annotType.ToString(),
            annotContents.ToString(), page.ToString() };
        data.AppendLine(string.Join(";", newLine));
    }
}
// Save the collected data to a CSV file.
String formData = @"C:\temp\output.csv";
File.AppendAllText(formData, data.ToString());
Using gdpicturePDF As GdPicturePDF = New GdPicturePDF()
    gdpicturePDF.LoadFromFile("C:\temp\source.pdf")
    ' Create a `StringBuilder` variable to store data.
    Dim data As StringBuilder = New StringBuilder()
    ' Add headers to the first line.
    Dim headers = {"Index", "Annotation Type", "Contents", "Page"}
    data.AppendLine(String.Join(";", headers))
    ' Get the number of pages.
    Dim pageCount As Integer = gdpicturePDF.GetPageCount()
    ' Loop through all pages.
    For page = 1 To pageCount
        ' Select a PDF page.
        gdpicturePDF.SelectPage(page)
        Dim annotCount As Integer = gdpicturePDF.GetAnnotationCount()
        ' Loop through all annotations.
        For i = 0 To annotCount - 1
            ' Get the current annotation type.
            Dim annotType As String = gdpicturePDF.GetAnnotationSubType(i)
            ' Get the current annotation contents.
            Dim annotContents As String = gdpicturePDF.GetAnnotationContents(i)
            ' Add a new line to the `StringBuilder` with the annotation data.
            Dim newLine As String() = {i.ToString(), annotType.ToString(), annotContents.ToString(), page.ToString()}
            data.AppendLine(String.Join(";", newLine))
        Next
    Next
    ' Save the collected data to a CSV file.
    Dim formData = "C:\temp\output.csv"
    File.AppendAllText(formData, data.ToString())
End Using
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