// Delete image:
imageHelper.DeleteImage(imageInfos[0]);

// Extract images:
int index = 0;
foreach (PdfImageInfo info in imageInfos)
{
    info.Image.Save(outputFile_I + string.Format("Image-{0}.png", index));
    index++;
}

// Replace image:
PdfImage image = PdfImage.FromFile(TestUtil.DataPath + "ImgFiles/E-iceblue logo.png");
imageHelper.ReplaceImage(imageInfos[0], image);

// Compress images:
foreach (PdfPageBase page in doc.Pages)
{
    foreach (PdfImageInfo info in imageHelper.GetImagesInfo(page))
    {
        bool success = info.TryCompressImage();
    }
}

PdfDocument doc = new PdfDocument();
doc.LoadFromFile(input);
PdfPageBase pdfPageBase = doc.Pages[0];
PdfTextFinder finder = new PdfTextFinder(pdfPageBase);
finder.Options.Strategy = PdfTextStrategy.Simple;

PdfDocument doc = new PdfDocument();
PdfPageBase page = doc.Pages.Add();
string text = "Please add the code picture BehindText=true to set the picture behind text";
PdfSolidBrush solidBrush = new PdfSolidBrush (new PdfRGBColor(Color.Black));
PdfStringFormat format = new PdfStringFormat():
format.HorizontalScalingFactor = 80;
PdfFont font = new PdfFont(PdfFontFamily.TimesRoman, 14f, PdfFontStyle.Regular);
PdfGraphicsState state = page.Canvas.Save();
page.Canvas.DrawString(text, font, solidBrush, 0, 0, format);
page.Canvas.Restore(state):
doc.SaveToFile(outputFile);
doc.Close();

PdfDocument doc = new PdfDocument();
doc.LoadFromFile(inputFile);
doc.ConvertOptions.ApplyPermissionsOptions(true);
StringBuilder sb = new StringBuilder();
    foreach (FileFormat type in Enum.GetValues(typeof(FileFormat)))
        {
            try
                {
                    if (type.ToString().Equals("PDF"))
                    {
                        doc.SaveToFile(outputFile_P, type);
                    }
                    else
                    {
                        doc.SaveToFile(outputFile, type);
                    }
                }
                catch (Exception ex)
                {
                    sb.AppendLine("save to： "+ type +"  :"+ ex.Message);
                }
            }
File.AppendAllText(outputFile,sb.ToString());
doc.Dispose();

bool value = PdfDocument.IsPasswordProtected("1.pdf"); 

pdf.PrintSettings.SelectMultiPageLayout(2,2,false,Spire.Pdf.Print.PdfMultiPageOrder.Horizontal, marginValue)

PdfDocument pdf1 = new PdfDocument(inputFile_1);
PdfDocument pdf2 = new PdfDocument(inputFile_2);
PdfComparer compare = new PdfComparer(pdf1, pdf2);
compare.Options.SetPageRanges(0, pdf1.Pages.Count - 1, 0, pdf2.Pages.Count - 1);
compare.Compare(outputFile);

PdfDocument doc = new PdfDocument();
//Add a new page
PdfPageBase page = doc.Pages.Add();
PdfGrid grid = new PdfGrid();
grid.Columns.Add(1);
PdfGridRow headerRow1 = grid.Headers.Add(1)[0];
//HEADER WITHOUT UNCICODE SUPPORT BUT VALID WORD FONT
headerRow1.Style.Font = new PdfTrueTypeFont(new Font("Arial", 11f, FontStyle.Regular), true);
headerRow1.Cells[0].Value = "Spire.PDF for .NET";
headerRow1.Cells[0].StringFormat = new PdfStringFormat(PdfTextAlignment.Center, PdfVerticalAlignment.Middle);
grid.Draw(page, new PointF(0, 10));
//Save the document to stream
MemoryStream stream = new MemoryStream();
doc.SaveToStream(stream, FileFormat.PDF);
stream.Position = 0L;
PdfToWordConverter converter = new PdfToWordConverter(stream);
converter.SaveToDocx(@"out.docx");

PdfDocument doc = new PdfDocument();
doc.LoadFromFile(@"in.pdf");           
PdfSecurityPolicy securityPolicy = new PdfPasswordSecurityPolicy(userPassword, ownerPassword);
securityPolicy.EncryptMetadata = false;
securityPolicy.EncryptionAlgorithm = PdfEncryptionAlgorithm.AES_128;
securityPolicy.DocumentPrivilege = PdfDocumentPrivilege.AllowAll;
securityPolicy.DocumentPrivilege.AllowPrint = false;
doc.Encrypt(securityPolicy);
doc.SaveToFile(@"out.pdf");

PdfDocument doc = new PdfDocument();
PdfPageBase page = doc.Pages.Add(PdfPageSize.A4, new PdfMargins(20));
page.SetTabOrder(TabOrder.Structure);
PdfTaggedContent taggedContent = new PdfTaggedContent(doc);
taggedContent.SetLanguage("en-US");
taggedContent.SetTitle("test");
taggedContent.SetPdfUA1Identification();
PdfTrueTypeFont font = new PdfTrueTypeFont(new System.Drawing.Font("Times New Roman", 14), true);
PdfSolidBrush brush = new PdfSolidBrush(Color.Black);
PdfStructureElement document = taggedContent.StructureTreeRoot.AppendChildElement(PdfStandardStructTypes.Document);
PdfStructureElement heading1 = document.AppendChildElement(PdfStandardStructTypes.HeadingLevel1);
heading1.BeginMarkedContent(page);
string headingText = "What is a Tagged PDF?";
page.Canvas.DrawString(headingText, font, brush, new PointF(0, 0));
heading1.EndMarkedContent(page);
PdfStructureElement paragraph = document.AppendChildElement(PdfStandardStructTypes.Paragraph);
paragraph.BeginMarkedContent(page);
string paragraphText = ""Tagged PDF" doesn’t seem like a life-changing term. But for some, it is. For people who are " +
    "blind or have low vision and use assistive technology (such as screen readers and connected Braille displays) to " +
    "access information, an untagged PDF means they are missing out on information contained in the document because assistive " +
    "technology cannot "read" untagged PDFs.  Digital accessibility has opened up so many avenues to information that were once " +
    "closed to people with visual disabilities, but PDFs often get left out of the equation.";
RectangleF rect = new RectangleF(0, 30, page.Canvas.ClientSize.Width, page.Canvas.ClientSize.Height);
page.Canvas.DrawString(paragraphText, font, brush, rect);
paragraph.EndMarkedContent(page);
PdfStructureElement figure = document.AppendChildElement(PdfStandardStructTypes.Figure);
figure.BeginMarkedContent(page);
PdfImage image = PdfImage.FromFile(TestUtil.DataPath + "ImgFiles/Bug_3938.png");
page.Canvas.DrawImage(image, new PointF(0, 150));
figure.EndMarkedContent(page);

PdfStructureElement table = document.AppendChildElement(PdfStandardStructTypes.Table);
PdfTable pdfTable = new PdfTable();
pdfTable.Style.DefaultStyle.Font = font;
System.Data.DataTable dataTable = new System.Data.DataTable();
dataTable.Columns.Add("Name");
dataTable.Columns.Add("Age");
dataTable.Columns.Add("Sex");
dataTable.Rows.Add(new string[] { "John", "22", "Male" });
dataTable.Rows.Add(new string[] { "Katty", "25", "Female" });
pdfTable.DataSource = dataTable;
pdfTable.Style.ShowHeader = true;
pdfTable.StructureElement = table;
pdfTable.Draw(page.Canvas, new PointF(0, 280), 300f);

doc.SaveToFile("1.pdf");
doc.Dispose();

PdfDocument myPdf = new PdfDocument("test.pdf");
PdfPageBase page = myPdf .Pages[0];
PdfDestination dest = new PdfDestination(page, new PointF(-40f, -40f));
dest.Mode = PdfDestinationMode.FitV; 
PdfGoToAction gotoaction = new PdfGoToAction(dest);
myPdf.AfterOpenAction = gotoaction;
myPdf.ViewerPreferences.PageMode = PdfPageMode.UseOutlines;
myPdf.SaveToFile("FitBH.pdf");
myPdf.Close();