เพิ่มข้อความลงในไฟล์ PDF ผ่าน C#

var inputFile = Path.Combine(dataDir, "sample.pdf");
var outputFile = Path.Combine(dataDir, "sample_out.pdf");
var pdfDocument = new Aspose.Pdf.Document(inputFile);
var page = pdfDocument.Pages[1];

var textFragment = new Aspose.Pdf.Text.TextFragment("Lorem ipsum")
{
    Position = new Aspose.Pdf.Text.Position(100, 600)
};
        
textFragment.TextState.FontSize = 12;
textFragment.TextState.Font = Aspose.Pdf.Text.FontRepository.FindFont("TimesNewRoman");
textFragment.TextState.BackgroundColor = Aspose.Pdf.Color.LightGray;
textFragment.TextState.ForegroundColor = Aspose.Pdf.Color.Red;

var textBuilder = new Aspose.Pdf.Text.TextBuilder(page);
textBuilder.AppendText(textFragment);
pdfDocument.Save(outputFile);