Add Watermark to PDF using PDFSHarp

2020-08-02

Question

_{Sunday, August 2, 2020 1:45 AM}

I could use some help trying to add a Watermark to PDF files.

Here is the function I converted from C#.

Sub PDFWatermark(ByRef PDFName As String, ByRef PDFProject As String, PDFQty As String)
Dim Watermark As String
Watermark = "Project: " + PDFProject + " - Project Qty: " + PDFQty
Dim emSize As Integer = 50

Dim font = New XFont("Times New Roman", emSize, XFontStyle.BoldItalic)
Dim document = PdfReader.Open(PDFName)
If document.Version < 14 Then document.Version = 14

For idx = 0 To document.Pages.Count - 1
Dim page = document.Pages(idx)

Dim gfx = XGraphics.FromPdfPage(page, XGraphicsPdfPageOptions.Prepend)
Dim size = gfx.MeasureString(Watermark, font)
gfx.TranslateTransform(1000, 1000)
gfx.RotateTransform(-Math.Atan(2000 / 2000) * 180 / Math.PI)
gfx.TranslateTransform(-2000 / 2, -2000 / 2)
Dim format = New XStringFormat()
format.Alignment = XStringAlignment.Near
format.LineAlignment = XLineAlignment.Near
Dim brush As XBrush = New XSolidBrush(XColor.FromArgb(128, 255, 0, 0))
gfx.DrawString(Watermark, font, brush, New XPoint(500, 500), format)
Next
End Sub

All replies (3)

_{Wednesday, August 5, 2020 8:46 AM ✅Answered}

Hi JRDumont,

Thank you for posting here.

Here's an example of adding Watermark to PDF using PDFSHarp.

You can refer to the following code:

        Const watermark As String = "your content"
        Const emSize As Integer = 150
        Const filename As String = "your pdf path"
        Dim font As XFont = New XFont("Times New Roman", emSize, XFontStyle.BoldItalic)
        Dim document As PdfDocument = PdfReader.Open(filename)
        If document.Version < 14 Then document.Version = 14

        For idx As Integer = 0 To document.Pages.Count - 1
            Dim page As PdfPage = document.Pages(idx)
            Dim gfx = XGraphics.FromPdfPage(page, XGraphicsPdfPageOptions.Prepend)
            Dim size = gfx.MeasureString(watermark, font)
            Dim width = Convert.ToDouble(page.Width)
            Dim height = Convert.ToDouble(page.Height)

            gfx.TranslateTransform(width / 2, height / 2)
            gfx.RotateTransform(-Math.Atan(height / width) * 180 / Math.PI)
            gfx.TranslateTransform(-width / 2, -height / 2)
            Dim format = New XStringFormat()
            format.Alignment = XStringAlignment.Near
            format.LineAlignment = XLineAlignment.Near
            Dim brush As XBrush = New XSolidBrush(XColor.FromArgb(128, 255, 0, 0))
            gfx.DrawString(watermark, font, brush, New XPoint((width - size.Width) / 2, (height - size.Height) / 2), format)
        Next

        document.Save(filename)

If you need other variations of watermarks, here's the reference you can refer to:

PDFsharp Sample: Watermark

Hope it can help you.

Best Regards,

Xingyu Zhao

MSDN Community Support
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_{Monday, August 3, 2020 2:59 AM}

What's the problem? Alternatively, you can install free spire.pdf nuget package and try the following solution:

Dim pdf As New PdfDocument()
pdf.LoadFromFile("test.pdf")

Dim page As PdfPageBase = pdf.Pages(0)
Dim brush As New PdfTilingBrush(New SizeF(page.Canvas.ClientSize.Width / 2, page.Canvas.ClientSize.Height / 3))
brush.Graphics.SetTransparency(0.3F)
brush.Graphics.Save()
brush.Graphics.TranslateTransform(brush.Size.Width / 2, brush.Size.Height / 2)
brush.Graphics.RotateTransform(-45)
Dim font As New PdfTrueTypeFont(New Font("Arial Unicode MS", 20F), True)
brush.Graphics.DrawString("Draft", font, PdfBrushes.Red, 0, 0, New PdfStringFormat(PdfTextAlignment.Center))
brush.Graphics.Restore()
brush.Graphics.SetTransparency(1)
page.Canvas.DrawRectangle(brush, New RectangleF(New PointF(0, 0), page.Canvas.ClientSize))

pdf.SaveToFile("TextWaterMark.pdf")

Hope it helps.

_{Friday, August 7, 2020 12:03 AM}

Thank you for your input.

I forgot to add the document.Save at the end of the function.

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Add Watermark to PDF using PDFSHarp

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