Spire.PDF Support & FAQs | Resolve PDF Issues with Expert

Q1: How to convert HTML code to PDF?

A : Spire.PDF cannot load a string containing html code. But Spire.Doc can load that and Spire.Doc supports PDF format. So you can use Spire.Doc to do the job. Full code:

string htmlstring = "<!DOCTYPE html><html><body><h1>Header 1</h1><p>First paragraph</p></body></html>";
Document doc = new Document();
Section sec = doc.AddSection();
Paragraph para = sec.AddParagraph();

//add html code to document
para.AppendHTML(htmlstring);

//save document as PDF format
doc.SaveToFile("result.pdf", FileFormat.PDF);

Q2: How to embed another table in a cell of a table?

A : Table is a simpler grid. In grid, you can manipulate each cell, set different style for each cell and embed another grid. So you can use grid to do the job. Full code:

PdfDocument document = new PdfDocument();
PdfPageBase page = document.Pages.Add(PdfPageSize.A4);

PdfGrid grid = new PdfGrid();
grid.Columns.Add(1);
grid.Columns[0].Width = page.Canvas.ClientSize.Width;
PdfGridRow row0 = grid.Rows.Add();
row0.Cells[0].Value = "This is the first row.";
row0.Cells[0].StringFormat = new PdfStringFormat(PdfTextAlignment.Center, PdfVerticalAlignment.Middle);
PdfGridRow row1 = grid.Rows.Add();
PdfLayoutResult result=grid.Draw(page, new PointF(0, 20));

PdfGrid grid2 = new PdfGrid();
grid2.Columns.Add(2);
PdfGridRow newrow = grid2.Rows.Add();
grid2.Columns[0].Width = grid.Columns[0].Width / 2;
grid2.Columns[1].Width = grid.Columns[0].Width / 2;
newrow.Cells[0].Value = "This is row two column one.";
newrow.Cells[0].StringFormat = new PdfStringFormat(PdfTextAlignment.Center, PdfVerticalAlignment.Middle);
newrow.Cells[1].Value = "This is row two column two.";
newrow.Cells[1].StringFormat = new PdfStringFormat(PdfTextAlignment.Center, PdfVerticalAlignment.Middle);

//assign grid2 to row1
row1.Cells[0].Value = grid2;

//drwa grid2
result = grid2.Draw(page, new PointF(0, result.Bounds.Location.Y + result.Bounds.Height));
document.SaveToFile("result.pdf");

Q3: How to merge cells in grid?

A : Spire.PDF provides you properties called RowSpan and ColumnSpan to merge cells. Full code:

PdfDocument doc = new PdfDocument();
PdfPageBase page = doc.Pages.Add();

PdfGrid grid = new PdfGrid();
grid.Columns.Add(5);
float width = page.Canvas.ClientSize.Width - (grid.Columns.Count + 1);
for (int i = 0; i < grid.Columns.Count; i++)
{
    grid.Columns[i].Width = width * 0.20f;
}
PdfGridRow row0 = grid.Rows.Add();
PdfGridRow row1 = grid.Rows.Add();

row0.Style.Font = new PdfTrueTypeFont(new Font("Arial", 16f, FontStyle.Bold), true);
row1.Style.Font = new PdfTrueTypeFont(new Font("Arial", 16f, FontStyle.Italic), true);

row0.Cells[0].Value = "Corporation";

//merge with the downside cell
row0.Cells[0].RowSpan = 2;

row0.Cells[1].Value = "B&K Undersea Photo";
row0.Cells[1].StringFormat = new PdfStringFormat(PdfTextAlignment.Center, PdfVerticalAlignment.Middle);

//merge with the right cell
row0.Cells[1].ColumnSpan = 3;

row0.Cells[4].Value = "World";
row0.Cells[4].Style.Font = new PdfTrueTypeFont(new Font("Arial", 10f, FontStyle.Bold | FontStyle.Italic), true);
row0.Cells[4].StringFormat = new PdfStringFormat(PdfTextAlignment.Center, PdfVerticalAlignment.Middle);
row0.Cells[4].Style.BackgroundBrush = PdfBrushes.LightGreen;

row1.Cells[1].Value = "Diving International Unlimited";
row1.Cells[1].StringFormat = new PdfStringFormat(PdfTextAlignment.Center, PdfVerticalAlignment.Middle);
row1.Cells[1].ColumnSpan = 4;

grid.Draw(page, new PointF(0, 0));

doc.SaveToFile("result.pdf");

Q4: How to add signature to a PDF file?

A : First, create a certificate instance using class PdfCertificate. The certificate instance will be used in creating a PdfSignature instance. Then create a signature instance using class PdfSignature. And you need to set the properties of the signature instance. Full code:

PdfDocument doc = new PdfDocument();
doc.LoadFromFile("sample.pdf");
PdfCertificate cert = new PdfCertificate("Demo.pfx", "e-iceblue");

//add signature to every page of PDF file
foreach (PdfPageBase page in doc.Pages)
{
    PdfSignature signature = new PdfSignature(page.Document, page, cert, "demo");
    signature.ContactInfo = "Harry";
    signature.Certificated = true;
    signature.DocumentPermissions = PdfCertificationFlags.AllowFormFill;
}

doc.SaveToFile("result.pdf");

Q5: How to rearrange the pages of a PDF file?

A : Please call the method ReArrange. The method takes an int array as parameter. The int array represents the new order of the pages. Full code:

PdfDocument document = new PdfDocument();

//sample.pdf has four pages
document.LoadFromFile("sample.pdf");

//rearrange the pages of the PDF file
int[] range = new int[] { 0, 2, 1, 3 };
document.Pages.ReArrange(range);
document.SaveToFile("result.pdf");

Q6: How to add image watermark?

A : Spire.PDF don't support image watermark directly. But you can set an image as BackgroundImage. If the image is big enough, the BackgroundImage will be like image watermark. Full code:

PdfDocument document = new PdfDocument();
PdfPageBase page = document.Pages.Add(PdfPageSize.A4);
page.Canvas.DrawString("This is a demo about image watermark!",
                        new PdfFont(PdfFontFamily.Helvetica, 25f),
                        new PdfSolidBrush(Color.Green),
                        10, 40);

//set image as BackgroundImage to make image watermark
Image img = Image.FromFile("scene.bmp");
page.BackgroundImage = img;
document.SaveToFile("result.pdf");

Q7: How to repeat header on all pages?

A : Things in PdfDocumentTemplate will apply to every page of the PDF file. All you have to do is to create a method that add header to PdfDocumentTemplate. Then header will be added to every page. Full code:

static void Main(string[] args)
{
    PdfDocument doc = new PdfDocument();
    PdfUnitConvertor unitCvtr = new PdfUnitConvertor();
    PdfMargins margin = new PdfMargins();
    margin.Top = unitCvtr.ConvertUnits(3.0f, PdfGraphicsUnit.Centimeter, PdfGraphicsUnit.Point);
    margin.Bottom = margin.Top;
    margin.Left = unitCvtr.ConvertUnits(3.17f, PdfGraphicsUnit.Centimeter, PdfGraphicsUnit.Point);
    margin.Right = margin.Left;

    // create three page
    PdfPageBase page = doc.Pages.Add(PdfPageSize.A4, margin);
    page = doc.Pages.Add(PdfPageSize.A4, margin);
    page = doc.Pages.Add(PdfPageSize.A4, margin);

    //apply template
    SetDocumentTemplate(doc, PdfPageSize.A4, margin);
    doc.SaveToFile("result.pdf");

}
//method to add header to every page
private static void SetDocumentTemplate(PdfDocument doc, SizeF pageSize, PdfMargins margin)
{
    PdfPageTemplateElement leftSpace
        = new PdfPageTemplateElement(margin.Left, pageSize.Height);
    doc.Template.Left = leftSpace;

    PdfPageTemplateElement topSpace
        = new PdfPageTemplateElement(pageSize.Width, margin.Top);
    topSpace.Foreground = true;
    doc.Template.Top = topSpace;

    //draw header label
    PdfTrueTypeFont font = new PdfTrueTypeFont(new Font("Arial", 9f, FontStyle.Italic));
    PdfStringFormat format = new PdfStringFormat(PdfTextAlignment.Right);
    String label = "Demo about Header Repeating";

    //set the header style
    SizeF size = font.MeasureString(label, format);
    float y = topSpace.Height - font.Height - 40;
    PdfPen pen = new PdfPen(Color.Black, 0.75f);
    topSpace.Graphics.SetTransparency(0.5f);
    topSpace.Graphics.DrawLine(pen, margin.Left - 30, y, pageSize.Width - margin.Right + 30, y);
    y = y - 1 - size.Height;
    topSpace.Graphics.DrawString(label, font, PdfBrushes.Black, pageSize.Width - margin.Right, y, format);

    PdfPageTemplateElement rightSpace
        = new PdfPageTemplateElement(margin.Right, pageSize.Height);
    doc.Template.Right = rightSpace;

    PdfPageTemplateElement bottomSpace
        = new PdfPageTemplateElement(pageSize.Width, margin.Bottom);
    bottomSpace.Foreground = true;
    doc.Template.Bottom = bottomSpace;
}