How to Annotate PDFs using Foxit PDF SDK (C++)

General

An annotation associates an object such as note, line, and highlight with a location on a page of a PDF document. It provides a way to interact with users by means of the mouse and keyboard. PDF includes a wide variety of standard annotation types as listed in Table 3-1. Among these annotation types, many of them are defined as markup annotations for they are used primarily to mark up PDF documents. These annotations have text that appears as part of the annotation and may be displayed in other ways by a conforming reader, such as in a Comments pane. The ‘Markup’ column in Table 3-1 shows whether an annotation is a markup annotation.

Foxit PDF SDK supports most annotation types defined in PDF reference. PDF SDK provides APIs of annotation creation, properties access and modification, appearance setting and drawing.

Table 3-1

Annotation type	Description	Markup	Supported by SDK
Text(Note)	Text annotation	Yes	Yes
Link	Link Annotations	No	Yes
FreeText (TypeWriter/TextBox/Callout)	Free text annotation	Yes	Yes
Line	Line annotation	Yes	Yes
Square	Square annotation	Yes	Yes
Circle	Circle annotation	Yes	Yes
Polygon	Polygon annotation	Yes	Yes
PolyLine	PolyLine annotation	Yes	Yes
Highlight	Highlight annotation	Yes	Yes
Underline	Underline annotation	Yes	Yes
Squiggly	Squiggly annotation	Yes	Yes
StrikeOut	StrikeOut annotation	Yes	Yes
Stamp	Stamp annotation	Yes	Yes
Caret	Caret annotation	Yes	Yes
Ink(pencil)	Ink annotation	Yes	Yes
Popup	Popup annotation	No	Yes
File Attachment	FileAttachment annotation	Yes	Yes
Sound	Sound annotation	Yes	No
Movie	Movie annotation	No	No
Widget*	Widget annotation	No	Yes
Screen	Screen annotation	No	Yes
PrinterMark	PrinterMark annotation	No	No
TrapNet	Trap network annotation	No	No
Watermark*	Watermark annotation	No	Yes
3D	3D annotation	No	No
Redact	Redact annotation	Yes	Yes

Note:

1. The annotation widget and watermark are special. They aren’t supported in the module of ‘Annotation’. This type of widget is only used in the module as a ‘form filler’ and the watermark in the module of ‘watermark’.
2. Foxit SDK supports a customized annotation type called PSI (pressure sensitive ink) annotation. Usually, PSI is for handwriting features and Foxit SDK treats it as a PSI annotation so that it can be handled by other PDF products.

Example:

How to add a link annotation to another page in the same PDF

#include "include/common/fs_common.h"
#include "include/pdf/actions/fs_action.h"
#include "include/pdf/annots/fs_annot.h"
#include "include/pdf/fs_pdfdoc.h"
#include "include/pdf/objects/fs_pdfobject.h"
#include "include/pdf/fs_pdfpage.h"

using namespace foxit;
using namespace foxit::common;
using namespace pdf;
using namespace annots;

// Assuming PDFPage page has been loaded and parsed.
// Assuming the annnots in the page have been loaded.

// Add link annotation.
annots::Link link(page.AddAnnot( Annot::e_Link, RectF(350,350,380,400)));
link.SetHighlightingMode(Annot::e_HighlightingToggle);
...

How to add a highlight annotation to a page and set the related annotation properties

#include "include/common/fs_common.h"
#include "include/pdf/actions/fs_action.h"
#include "include/pdf/annots/fs_annot.h"
#include "include/pdf/fs_pdfdoc.h"
#include "include/pdf/objects/fs_pdfobject.h"
#include "include/pdf/fs_pdfpage.h"

using namespace foxit;
using namespace foxit::common;
using namespace pdf;
using namespace annots;

// Assuming PDFPage page has been loaded and parsed.
// Assuming the annnots in the page have been loaded.

// Add highlight annotation.
annots::Highlight highlight(page.AddAnnot(Annot::e_Highlight,RectF(10,450,100,550)));
highlight.SetContent(L"Highlight");
annots::QuadPoints quad_points;
quad_points.first = PointF(10, 500);
quad_points.second = PointF(90, 500);
quad_points.third = PointF(10, 480);
quad_points.fourth = PointF(90, 480);
annots::QuadPointsArray quad_points_array;
quad_points_array.Add(quad_points);
highlight.SetQuadPoints(quad_points_array);
highlight.SetSubject(L"Highlight");
highlight.SetTitle(L"Foxit SDK");
highlight.SetCreationDateTime(GetLocalDateTime());
highlight.SetModifiedDateTime(GetLocalDateTime());
highlight.SetUniqueID(WString::FromLocal(RandomUID()));

// Appearance should be reset.
highlight.ResetAppearanceStream();
...

How to set the popup information when creating markup annotations

#include "include/common/fs_common.h"
#include "include/pdf/actions/fs_action.h"
#include "include/pdf/annots/fs_annot.h"
#include "include/pdf/fs_pdfdoc.h"
#include "include/pdf/objects/fs_pdfobject.h"
#include "include/pdf/fs_pdfpage.h"

using namespace foxit;
using namespace foxit::common;
using namespace pdf;
using namespace annots;

// Assuming PDFPage page has been loaded and parsed.
// Assuming the annnots in the page have been loaded.

// Create a new note annot and set the properties for it.
annots::Note note(page.AddAnnot(Annot::e_Note, RectF(10,350,50,400)));
note.SetIconName("Comment");
note.SetSubject(L"Note");
note.SetTitle(L"Foxit SDK");
note.SetContent(L"Note annotation.");
note.SetCreationDateTime(GetLocalDateTime());
note.SetModifiedDateTime(GetLocalDateTime());
note.SetUniqueID(WString::FromLocal(RandomUID()));

// Create a new popup annot and set it to the new note annot.
Popup popup(page.AddAnnot(Annot::e_Popup, RectF(300,450,500,550)));
popup.SetBorderColor(0x00FF00);
popup.SetOpenStatus(false);
popup.SetModifiedDateTime(GetLocalDateTime());
note.SetPopup(popup);
...

How to get a specific annotation in a PDF using device coordinates

#include "include/common/fs_common.h"
#include "include/pdf/actions/fs_action.h"
#include "include/pdf/annots/fs_annot.h"
#include "include/pdf/fs_pdfdoc.h"
#include "include/pdf/objects/fs_pdfobject.h"
#include "include/pdf/fs_pdfpage.h"

using namespace foxit;
using namespace foxit::common;
using namespace pdf;
using namespace annots;

// Assuming PDFDoc doc has been loaded.
// Assuming PDFPage page has been loaded and parsed.
...

int width = static_cast(page.GetWidth());
int height = static_cast(page.GetHeight());

// Get page transformation matrix.
Matrix displayMatrix= page.GetDisplayMatrix(0, 0, width, height, page.GetRotation());
int iAnnotCount = page.GetAnnotCount();

for(int i=0; i

Import annotations from or export annotations to a FDF file

With Foxit PDF SDK, annotations can be created with data not only from applications but also from FDF files. At the same time, PDF SDK supports annotation exporting to FDF files.

Example:

How to load annotations from a FDF file and add them into the first page of a given PDF

#include "include/common/fs_common.h"
#include "include/pdf/actions/fs_action.h"
#include "include/pdf/annots/fs_annot.h"
#include "include/pdf/fs_pdfdoc.h"
#include "include/pdf/objects/fs_pdfobject.h"
#include "include/pdf/fs_pdfpage.h"

using namespace std;
using namespace foxit;
using namespace foxit::common;
using foxit::common::Library;
using namespace pdf;
using namespace annots;

// Assuming PDFDoc doc has been loaded.
...

FILE* file = NULL;
#if defined(_WIN32) || defined(_WIN64)
 fopen_s(&file, (const char*)(const char*)String::FromUnicode(fdf_file), "rb+");
#else
 file = fopen((const char*)(const char*)String::FromUnicode(fdf_file), "rb+");
#endif
fseek(file, 0, SEEK_END);
size_t file_size = (size_t)ftell(file);
char* buffer = (char*)malloc(file_size * sizeof(char));
memset(buffer, 0 , file_size);

fseek(file, 0, SEEK_SET);
fread(buffer, sizeof(char), file_size, file);
fclose(file);

fdf::FDFDoc fdf_doc(buffer, file_size);
pdf_doc.ImportFromFDF(fdf_doc, PDFDoc::e_Annots);