The whole package of PdfSharp comes with lots of sample applications, one of them is watermark sample which shows three variations how to add a watermark to an existing PDF file.
You can see the resulting PDF as shown below.
The following is the original C# console application of Watermark sample. The C# source code was released under MIT and it was written by Thomas Hövel.
using System;
using System.Diagnostics;
using System.IO;
using PdfSharp.Drawing;
using PdfSharp.Pdf.IO;
namespace Watermark
{
/// This sample shows three variations how to add a watermark text to an existing PDF file.
class Program
{
static void Main()
{
const string watermark = "PDFsharp";
const int emSize = 150;
// Get a fresh copy of the sample PDF file.
const string filename = "Portable Document Format.pdf";
var file = Path.Combine(Directory.GetCurrentDirectory(), filename);
File.Copy(Path.Combine("../../../../assets/PDFs/", filename), file, true);
// Remove ReadOnly attribute from the copy.
File.SetAttributes(file, File.GetAttributes(file) & ~FileAttributes.ReadOnly);
// Create the font for drawing the watermark.
var font = new XFont("Times New Roman", emSize, XFontStyle.BoldItalic);
// Open an existing document for editing and loop through its pages.
var document = PdfReader.Open(filename);
// Set version to PDF 1.4 (Acrobat 5) because we use transparency.
if (document.Version < 14)
document.Version = 14;
for (var idx = 0; idx < document.Pages.Count; idx++)
{
var page = document.Pages[idx];
switch (idx % 3)
{
case 0:
{
// Variation 1: Draw a watermark as a text string.
// Get an XGraphics object for drawing beneath the existing content.
var gfx = XGraphics.FromPdfPage(page, XGraphicsPdfPageOptions.Prepend);
// Get the size (in points) of the text.
var size = gfx.MeasureString(watermark, font);
// 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);
// Create a string format.
var format = new XStringFormat();
format.Alignment = XStringAlignment.Near;
format.LineAlignment = XLineAlignment.Near;
// Create a dimmed red brush.
XBrush brush = new XSolidBrush(XColor.FromArgb(128, 255, 0, 0));
// Draw the string.
gfx.DrawString(watermark, font, brush,
new XPoint((page.Width - size.Width) / 2, (page.Height - size.Height) / 2),
format);
}
break;
case 1:
{
// Variation 2: Draw a watermark as an outlined graphical path.
// NYI: Does not work in Core build.
// Get an XGraphics object for drawing beneath the existing content.
var gfx = XGraphics.FromPdfPage(page, XGraphicsPdfPageOptions.Prepend);
// Get the size (in points) of the text.
var size = gfx.MeasureString(watermark, font);
// 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);
// Create a graphical path.
var path = new XGraphicsPath();
// Create a string format.
var format = new XStringFormat();
format.Alignment = XStringAlignment.Near;
format.LineAlignment = XLineAlignment.Near;
// 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);
// Create a dimmed red pen.
var pen = new XPen(XColor.FromArgb(128, 255, 0, 0), 2);
// Stroke the outline of the path.
gfx.DrawPath(pen, path);
}
break;
case 2:
{
// Variation 3: Draw a watermark as a transparent graphical path above text.
// NYI: Does not work in Core build.
// Get an XGraphics object for drawing above the existing content.
var gfx = XGraphics.FromPdfPage(page, XGraphicsPdfPageOptions.Append);
// Get the size (in points) of the text.
var size = gfx.MeasureString(watermark, font);
// 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);
// Create a graphical path.
var path = new XGraphicsPath();
// Create a string format.
var format = new XStringFormat();
format.Alignment = XStringAlignment.Near;
format.LineAlignment = XLineAlignment.Near;
// 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);
// 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));
// Stroke the outline of the path.
gfx.DrawPath(pen, brush, path);
}
break;
}
}
// Save the document...
document.Save(filename);
// ...and start a viewer
Process.Start(filename);
}
}
}
In the previous article, we talked about how to use xInterop C++ .NET Bridge with Native C++ to .NET Bridge to generate the native C++ bridge DLL for PDFsharp .NET library assembly. In this Watermark example, we will need to use the native C++ bridge DLL PdbSharpgidBridge.DLL.
The following is the complete source code of the example.
// ----------------------------------------------------------------------------
// <copyright file="TestApp.cpp" company="xInterop Software, LLC">
// Copyright (c) 2016 xInterop Software, LLC. All rights reserved.
// http://www.xinterop.com
// </copyright>
//
// NOTICE: All information contained herein is, and remains the property of
// xInterop Software, LLC, if any. The intellectual and technical concepts
// contained herein are proprietary to xInterop Software, LLC and may be
// covered by U.S. and Foreign Patents, patents in process, and are protected
// by trade secret or copyright law. Dissemination of this information or
// reproduction of this material is strictly forbidden unless prior written
// permission is obtained from xInterop Software, LLC.
//
// This copyright header must be kept intact without any change under any circumstances.
//
// The source code of this file can NOT be re-distributed to any third parties
// unless certain OEM license has been arranged and written permission has been
// authorized by xInterop Software, LLC.
//
// ----------------------------------------------------------------------------
#include "stdafx.h"
#include <Ole2.h>
#include "../Native/Include/PdfSharpgdiBridge.h"
#ifdef _WIN64
#pragma comment(lib, "../Native/Lib/x64/PdfSharpgdiBridge.lib")
#else
#pragma comment(lib, "../Native/Lib/win32/PdfSharpgdiBridge.lib")
#endif
using namespace::xinterop;
using namespace::System::IO;
using namespace::PdfSharp::Drawing;
using namespace::PdfSharp::Pdf;
using namespace::PdfSharp::Pdf::IO;
using namespace::System::Diagnostics;
int _tmain(int argc, _TCHAR* argv[])
{
///////////////////////////////////////////////////////////////////////////////////////////////
//
// Notes:
//
// This file was created when "Load .NET bridge assembly automatically" option was turned on.
//
// The C# bridge assembly shall be loaded and initialized automatically when any c++
// class of the C++ bridge DLL is accessed.
//
// The C# bridge assembly can also be loaded and initialized by calling xiInitializeBridgeAssembly.
//
///////////////////////////////////////////////////////////////////////////////////////////////
CoInitializeEx(0, COINIT_APARTMENTTHREADED);
///////////////////////////////////////////////////////////////////////////////////////////////
// Add your code here.
///////////////////////////////////////////////////////////////////////////////////////////////
const TCHAR* watermark = _T("xInterop");
const int emSize = 150;
// Get a fresh copy of the sample PDF file.
const TCHAR* filename = _T("Portable Document Format.pdf");
TCHAR currentDirectory[MAX_PATH];
GetCurrentDirectory(sizeof(currentDirectory), currentDirectory);
auto file = Path::Combine(currentDirectory, filename);
File::Copy(Path::Combine(_T("..//..//assets//PDFs//"), filename).c_str(), file.c_str(), true);
// Remove ReadOnly attribute from the copy.
File::SetAttributes(file.c_str(), File::GetAttributes(file.c_str()) & ~FileAttributes::ReadOnly);
// Create the font for drawing the watermark.
XFont font(_T("Times New Roman"), emSize, XFontStyle::BoldItalic);
// Open an existing document for editing and loop through its pages.
auto document = PdfReader::Open(filename);
// Set version to PDF 1.4 (Acrobat 5) because we use transparency.
if (document->Version < 14)
document->Version = 14;
auto pages = document->get_Pages();
for (int idx = 0; idx < pages->Count; idx++)
{
auto page = (*pages)[idx];
switch (idx % 3)
{
case 0:
{
// Variation 1: Draw a watermark as a text string.
// Get an XGraphics object for drawing beneath the existing content.
auto gfx = XGraphics::FromPdfPage(page.get(), XGraphicsPdfPageOptions::Prepend);
// Get the size (in points) of the text.
auto size = gfx->MeasureString(watermark, &font);
// Define a rotation transformation at the center of the page.
gfx->TranslateTransform(page->Width->Value / 2, page->Height->Value / 2);
gfx->RotateTransform(-System::Math::Atan(page->Height->Value / page->Width->Value) * 180 / System::Math::XI_PI);
gfx->TranslateTransform(-page->Width->Value / 2, -page->Height->Value / 2);
// Create a string format.
XStringFormat format;
format.set_Alignment(XStringAlignment::Near);
format.set_LineAlignment(XLineAlignment::Near);
// Create a dimmed red brush.
XSolidBrush brush(XColor::FromArgb(128, 255, 0, 0).get());
// Draw the string.
XPoint point((page->Width->Value - size->Width) / 2, (page->Height->Value - size->Height) / 2);
gfx->DrawString(watermark, &font, &brush, &point, &format);
}
break;
case 1:
{
// Variation 2: Draw a watermark as an outlined graphical path.
// NYI: Does not work in Core build.
// Get an XGraphics object for drawing beneath the existing content.
auto gfx = XGraphics::FromPdfPage(page.get(), XGraphicsPdfPageOptions::Prepend);
// Get the size (in points) of the text.
auto size = gfx->MeasureString(watermark, &font);
// Define a rotation transformation at the center of the page.
gfx->TranslateTransform(page->Width->Value / 2, page->Height->Value / 2);
gfx->RotateTransform(-System::Math::Atan(page->Height->Value / page->Width->Value) * 180 / System::Math::XI_PI);
gfx->TranslateTransform(-page->Width->Value / 2, -page->Height->Value / 2);
// Create a graphical path.
XGraphicsPath path;
// Create a string format.
XStringFormat format;
format.set_Alignment(XStringAlignment::Near);
format.set_LineAlignment(XLineAlignment::Near);
// Add the text to the path.
// AddString is not implemented in PDFsharp Core.
XPoint point((page->Width->Value - size->Width) / 2, (page->Height->Value - size->Height) / 2);
path.AddString(watermark, font.get_FontFamily().get(), XFontStyle::BoldItalic, 150, &point, &format);
// Create a dimmed red pen.
XPen pen(XColor::FromArgb(128, 255, 0, 0).get());
// Stroke the outline of the path.
gfx->DrawPath(&pen, &path);
}
break;
case 2:
{
// Variation 3: Draw a watermark as a transparent graphical path above text.
// NYI: Does not work in Core build.
// Get an XGraphics object for drawing beneath the existing content.
auto gfx = XGraphics::FromPdfPage(page.get(), XGraphicsPdfPageOptions::Prepend);
// Get the size (in points) of the text.
auto size = gfx->MeasureString(watermark, &font);
// Define a rotation transformation at the center of the page.
gfx->TranslateTransform(page->Width->Value / 2, page->Height->Value / 2);
gfx->RotateTransform(-System::Math::Atan(page->Height->Value / page->Width->Value) * 180 / System::Math::XI_PI);
gfx->TranslateTransform(-page->Width->Value / 2, -page->Height->Value / 2);
// Create a graphical path.
XGraphicsPath path;
// Create a string format.
XStringFormat format;
format.set_Alignment(XStringAlignment::Near);
format.set_LineAlignment(XLineAlignment::Near);
// Add the text to the path.
// AddString is not implemented in PDFsharp Core.
XPoint point((page->Width->Value - size->Width) / 2, (page->Height->Value - size->Height) / 2);
path.AddString(watermark, font.get_FontFamily().get(), XFontStyle::BoldItalic, 150, &point, &format);
// Create a dimmed red pen and brush.
XPen pen(XColor::FromArgb(50, 75, 0, 130).get(), 3);
XSolidBrush brush(XColor::FromArgb(50, 106, 90, 205).get());
// Stroke the outline of the path.
gfx->DrawPath(&pen, &brush, &path);
}
break;
}
}
// Save the document...
document->Save(filename);
// ...and start a viewer
Process::Start(filename);
///////////////////////////////////////////////////////////////////////////////////////////////
// End of your code.
///////////////////////////////////////////////////////////////////////////////////////////////
CoUninitialize();
exit(0);
return 0;
}
The C++ code is very similar to the C# counterpart since we can simulate the C# property in the C++ code. The native C++ application creates exactly same PDF file as the one generated by the C# console sample application. Let’s go over the important steps before we can start calling the functions.
1. Include the header file for the native C++ Bridge DLL.
2. Reference the native C++ Bridge lib files.
3. Define all the required namespace inclusion.
See the difference between .NET namespace and Native C++ namespace
There are a few things worth mentioning in the C++ code.
1. Open an existing document.
2. Using properties.
In the preceding screen-shot, Version is a property. We are using them just like using the properties in the C# code.
3. System.Diagnostics.Process class
We also created the native C++ bridge class for the .NET class of Process, the screen-shot above shows how to use them.
The post Using PdfSharp for Processing PDF from Native C++ : Watermark Sample appeared first on xInterop C++ .NET Bridge.