PDFsharp Sample: Watermark

Modified on 2018/07/11 11:27 by Thomas Hövel Categorized as PDFsharp Samples, Samples
{s:navigationPrevUpNext|UnprotectDocument-sample|PDFsharpSamples|WorkOnPdfObjects-sample}
This sample shows three variations how to add a watermark to an existing PDF file.

{s:note}Technically the watermarks in this sample are simple graphical output. They have nothing to do with the Watermark Annotations introduced in PDF 1.6.

==PDF Output File==

See the PDF file created by this sample:  {s:PdfLink|Watermark-sample%2fWatermark-GDI.pdf|Watermark.pdf} (112 kB){br}
This sample requires Acrobat Reader 5.0 or higher because it uses / demonstrates transparency.

==Screen Shots==
Here are screen shots for the three variations of watermarks implemented in this sample (click image to enlarge):

{s:ImageThumbLink|Draw watermark as text string|Watermark-sample%2fwatermark1th.png|Watermark-sample%2fwatermark1.png}
{s:ImageThumbLink|Draw watermark as outlined graphical path|Watermark-sample%2fwatermark2th.png|Watermark-sample%2fwatermark2.png}
{s:ImageThumbLink|Draw watermark as transparent graphical path above text|Watermark-sample%2fwatermark3th.png|Watermark-sample%2fwatermark3.png}{br}
Click on the images to enlarge.

==Source Code==

Here's the code that creates the first kind of watermarks:
{s:beginCsharp}
// Variation 1: Draw a watermark as a text string.
&nbsp;
// Get an XGraphics object for drawing beneath the existing content.
var gfx = XGraphics.FromPdfPage(page, XGraphicsPdfPageOptions.Prepend);
&nbsp;
// Get the size (in points) of the text.
var size = gfx.MeasureString(watermark, font);
&nbsp;
// Define a rotation transformation at the center of the page.
gfx.TranslateTransform(page.Width / 2, page.Height / 2);
gfx.RotateTransform(-Math.Atan(page.Height / page.Width) * 180 / Math.PI);
gfx.TranslateTransform(-page.Width / 2, -page.Height / 2);
&nbsp;
// Create a string format.
var format = new XStringFormat();
format.Alignment = XStringAlignment.Near;
format.LineAlignment = XLineAlignment.Near;
&nbsp;
// Create a dimmed red brush.
XBrush brush = new XSolidBrush(XColor.FromArgb(128, 255, 0, 0));
&nbsp;
// Draw the string.
gfx.DrawString(watermark, font, brush,
    new XPoint((page.Width - size.Width) / 2, (page.Height - size.Height) / 2),
    format);
{s:endCsharp}
Here's the code that creates the second kind of watermarks:
{s:beginCsharp}
// Variation 2: Draw a watermark as an outlined graphical path.
// NYI: Does not work in Core build.
&nbsp;
// Get an XGraphics object for drawing beneath the existing content.
var gfx = XGraphics.FromPdfPage(page, XGraphicsPdfPageOptions.Prepend);
&nbsp;
// Get the size (in points) of the text.
var size = gfx.MeasureString(watermark, font);
&nbsp;
// Define a rotation transformation at the center of the page.
gfx.TranslateTransform(page.Width / 2, page.Height / 2);
gfx.RotateTransform(-Math.Atan(page.Height / page.Width) * 180 / Math.PI);
gfx.TranslateTransform(-page.Width / 2, -page.Height / 2);
&nbsp;
// Create a graphical path.
var path = new XGraphicsPath();
&nbsp;
// Create a string format.
var format = new XStringFormat();
format.Alignment = XStringAlignment.Near;
format.LineAlignment = XLineAlignment.Near;
&nbsp;
// Add the text to the path.
// AddString is not implemented in PDFsharp Core.
path.AddString(watermark, font.FontFamily, XFontStyle.BoldItalic, 150,
new XPoint((page.Width - size.Width) / 2, (page.Height - size.Height) / 2),
    format);
&nbsp;
// Create a dimmed red pen.
var pen = new XPen(XColor.FromArgb(128, 255, 0, 0), 2);
&nbsp;
// Stroke the outline of the path.
gfx.DrawPath(pen, path);
{s:endCsharp}
Here's the code that creates the third kind of watermarks:
{s:beginCsharp}
// Variation 3: Draw a watermark as a transparent graphical path above text.
// NYI: Does not work in Core build.
&nbsp;
// Get an XGraphics object for drawing above the existing content.
var gfx = XGraphics.FromPdfPage(page, XGraphicsPdfPageOptions.Append);
&nbsp;
// Get the size (in points) of the text.
var size = gfx.MeasureString(watermark, font);
&nbsp;
// Define a rotation transformation at the center of the page.
gfx.TranslateTransform(page.Width / 2, page.Height / 2);
gfx.RotateTransform(-Math.Atan(page.Height / page.Width) * 180 / Math.PI);
gfx.TranslateTransform(-page.Width / 2, -page.Height / 2);
&nbsp;
// Create a graphical path.
var path = new XGraphicsPath();
&nbsp;
// Create a string format.
var format = new XStringFormat();
format.Alignment = XStringAlignment.Near;
format.LineAlignment = XLineAlignment.Near;
&nbsp;
// Add the text to the path.
// AddString is not implemented in PDFsharp Core.
path.AddString(watermark, font.FontFamily, XFontStyle.BoldItalic, 150,
    new XPoint((page.Width - size.Width) / 2, (page.Height - size.Height) / 2),
    format);
&nbsp;
// Create a dimmed red pen and brush.
var pen = new XPen(XColor.FromArgb(50, 75, 0, 130), 3);
XBrush brush = new XSolidBrush(XColor.FromArgb(50, 106, 90, 205));
&nbsp;
// Stroke the outline of the path.
gfx.DrawPath(pen, brush, path);
{s:endCsharp}

{s:sampleSourceCode}
Meta Keywords:
Meta Description:
Change Comment:
Miscellaneous
Home
PDFsharp
FAQ
Samples
Articles
MigraDoc
FAQ
Samples
Articles
PDFsharp and MigraDoc Wiki

Navigation¶

PDFsharp Sample: Watermark
