PDF sticky Annotations using C#

The following code snippet also work with Aspose.PDF.Drawing library.

Add Watermark Annotation

A watermark annotation shall be used to represent graphics that shall be printed at a fixed size and position on a page, regardless of the dimensions of the printed page.

You can add Watermark Text using WatermarkAnnotation at a specific position of the PDF page. The opacity of Watermark can also be controlled by using opacity property.

Please check the following code snippet to add WatermarkAnnotation.

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void AddWatermarkAnnotation()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Annotations();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "source.pdf"))
    {
        // Load Page object to add Annotation
        var page = document.Pages[1];

        // Create Watermark Annotation
        var wa = new Aspose.Pdf.Annotations.WatermarkAnnotation(page, new Aspose.Pdf.Rectangle(100, 500, 400, 600));

        // Add annotation into Annotation collection of Page
        page.Annotations.Add(wa);

        // Create TextState for Font settings
        var ts = new Aspose.Pdf.Text.TextState();
        ts.ForegroundColor = Aspose.Pdf.Color.Blue;
        ts.Font = Aspose.Pdf.Text.FontRepository.FindFont("Times New Roman");
        ts.FontSize = 32;

        // Set opacity level of Annotation Text
        wa.Opacity = 0.5;

        // Add Text in Annotation
        wa.SetTextAndState(new string[] { "HELLO", "Line 1", "Line 2" }, ts);

        // Save PDF document
        document.Save(dataDir + "AddWatermarkAnnotation_out.pdf");
    }
}

Add Reference of a single Image multiple times in a PDF Document

Sometimes we have a requirement to use same image multiple times in a PDF document. Adding a new instance increases the resultant PDF document. We have added a new method XImageCollection.Add(XImage) in Aspose.PDF for .NET 17.1.0. This method allows to add reference to the same PDF object as original image that optimize the PDF Document size.

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void AddWatermarkAnnotationWithImage()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Annotations();

    // Define the rectangle for the image
    var imageRectangle = new Aspose.Pdf.Rectangle(0, 0, 30, 15);

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "input.pdf"))
    {
        // Open the image stream
        using (var imageStream = File.Open(dataDir + "icon.png", FileMode.Open))
        {
            XImage image = null;

            // Iterate through each page in the document
            foreach (Page page in document.Pages)
            {
                // Create a Watermark Annotation
                var annotation = new Aspose.Pdf.Annotations.WatermarkAnnotation(page, page.Rect);
                XForm form = annotation.Appearance["N"];
                form.BBox = page.Rect;

                string name;

                // Add the image to the form resources if it hasn't been added yet
                if (image == null)
                {
                    name = form.Resources.Images.Add(imageStream);
                    image = form.Resources.Images[name];
                }
                else
                {
                    name = form.Resources.Images.Add(image);
                }

                // Add operators to the form contents to place the image
                form.Contents.Add(new Aspose.Pdf.Operators.GSave());
                form.Contents.Add(new Aspose.Pdf.Operators.ConcatenateMatrix(new Aspose.Pdf.Matrix(imageRectangle.Width, 0, 0, imageRectangle.Height, 0, 0)));
                form.Contents.Add(new Aspose.Pdf.Operators.Do(name));
                form.Contents.Add(new Aspose.Pdf.Operators.GRestore());

                // Add the annotation to the page
                page.Annotations.Add(annotation, false);

                // Adjust the image rectangle size for the next iteration
                imageRectangle = new Aspose.Pdf.Rectangle(0, 0, imageRectangle.Width * 1.01, imageRectangle.Height * 1.01);
            }
        }

        // Save PDF document
        document.Save(dataDir + "AddWatermarkAnnotationWithImage_out.pdf");
    }
}