How to Annotate PDFs using Foxit PDF SDK (Objective-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 Annotation	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

import com.foxit.sdk.pdf.PDFPage;
import com.foxit.sdk.pdf.annots.Link;
...
// Assuming PDFPage page has been loaded and parsed.
// Add link annotation
Link link = new Link(page.addAnnot(Annot.e_Link, new RectF(350, 350, 380, 400)));
link.setHighlightingMode(Annot.e_HighlightingToggle);
// Appearance should be reset.
link.resetAppearanceStream();
...

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

import com.foxit.sdk.pdf.PDFPage;
import com.foxit.sdk.pdf.annots.Highlight;
import com.foxit.sdk.common.fxcrt.PointF;
import com.foxit.sdk.common.fxcrt.PointFArray;
import com.foxit.sdk.common.fxcrt.RectF;
import com.foxit.sdk.pdf.annots.QuadPoints;
import com.foxit.sdk.pdf.annots.QuadPointsArray;
...
// Assuming PDFPage page has been loaded and parsed.
// Add highlight annotation
Highlight highlight = new Highlight(page.addAnnot(Annot.e_Highlight, new RectF(10, 450, 100, 550)));
highlight.setContent("Highlight");
QuadPoints quad_points = new QuadPoints();
quad_points.setFirst(new PointF(10, 500));
quad_points.setSecond(new PointF(90, 500));
quad_points.setThird(new PointF(10, 480));
quad_points.setFourth(new PointF(90, 480));
QuadPointsArray quad_points_array = new QuadPointsArray();
quad_points_array.add(quad_points);
highlight.setQuadPoints(quad_points_array);
highlight.setSubject("Highlight");
highlight.setTitle("Foxit SDK");
highlight.setCreationDateTime(GetLocalDateTime());
highlight.setModifiedDateTime(GetLocalDateTime());
highlight.setUniqueID(RandomUID());
// Appearance should be reset.
highlight.resetAppearanceStream();
...

How to set the popup information when creating markup annotations

import com.foxit.sdk.pdf.PDFPage;
import com.foxit.sdk.pdf.annots.Note;
import com.foxit.sdk.pdf.annots.Popup;
import com.foxit.sdk.common.fxcrt.RectF;
...
// Assuming PDFPage page has been loaded and parsed.
// Add note annotation
Note note = new Note(page.addAnnot(Annot.e_Note, new RectF(10, 350, 50, 400)));
note.setIconName("Comment");
note.setSubject("Note");
note.setTitle("Foxit SDK");
note.setContent("Note annotation.");
note.setCreationDateTime(GetLocalDateTime());
note.setModifiedDateTime(GetLocalDateTime());
note.setUniqueID(RandomUID());
// Add popup to note annotation
Popup popup = new Popup(page.addAnnot(Annot.e_Popup, new RectF(300, 450, 500, 550)));
popup.setBorderColor(0x00FF00);
popup.setOpenStatus(false);
popup.setModifiedDateTime(GetLocalDateTime());
note.setPopup(popup);
// Appearance should be reset.
note.resetAppearanceStream();
...

How to get page transformation matrix between PDF page coordinates and rendering device coordinates

import com.foxit.sdk.pdf.PDFPage;
import com.foxit.sdk.common.fxcrt.RectF;
import com.foxit.sdk.common.fxcrt.Matrix2D;
// Assuming PDFDoc doc has been loaded.
// Assuming PDFPage page has been loaded and parsed.
...
Matrix2D mtx = page.getDisplayMatrix(0, 0, width, height, page.getRotation());
RectF srcRc = new RectF(100, 200, 200, 100);
RectF pageRc = new RectF(100, 200, 200, 100);
mtx.transformRect(pageRc);
RectF devRc = new RectF(pageRc.getLeft(), pageRc.getBottom(), pageRc.getRight(), pageRc.getTop());
Matrix2D reverse_mtx = new Matrix2D();
reverse_mtx.setReverse(mtx);
reverse_mtx.transformRect(devRc);
...

Import annotations from or export annotations to an 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

import com.foxit.sdk.common.Range;
import com.foxit.sdk.fdf.FDFDoc;
import com.foxit.sdk.pdf.PDFDoc;
import static com.foxit.sdk.pdf.PDFDoc.e_Annots;
// Assuming PDFDoc doc has been loaded.
...
Range empty_range = new Range();
{
String input_file = input_path + "AboutFoxit.pdf";
String fdf_file = input_path + "AnnotationData.fdf";
PDFDoc pdf_doc = new PDFDoc(input_file);
error_code = pdf_doc.load(null);
if (error_code != e_ErrSuccess) {
System.out.println("The Doc " + input_file + " Error: " + error_code);
return;
}
FDFDoc fdf_doc = new FDFDoc(fdf_file);
pdf_doc.importFromFDF(fdf_doc, e_Annots, empty_range);
}
...

Image Conversion

Foxit PDF SDK provides APIs for conversion between PDF files and images. Applications could easily fulfill functionalities like image creation and image conversion which supports the following image formats: BMP, TIFF, PNG, JPX, JPEG, and GIF. Foxit PDF SDK can make the conversion between PDF files and the supported image formats except for GIF. It only supports converting GIF images to PDF files.

Example:

How to convert PDF pages to bitmap files.

import com.foxit.sdk.common.Bitmap;
import com.foxit.sdk.common.Image;
import com.foxit.sdk.common.Renderer;
import com.foxit.sdk.common.fxcrt.Matrix2D;
import com.foxit.sdk.pdf.PDFDoc;
import com.foxit.sdk.pdf.PDFPage;
import static com.foxit.sdk.common.Bitmap.e_DIBArgb;
import static com.foxit.sdk.pdf.PDFPage.e_ParsePageNormal;
// Assuming PDFDoc doc has been loaded.
...
Image image = new Image();
// Get page count
int nPageCount = doc.getPageCount();
for (int i = 0; i < nPageCount; i++) {
PDFPage page = doc.getPage(i);
// Parse page.
page.startParse(e_ParsePageNormal, null, false);
int width = (int) page.getWidth();
int height = (int) page.getHeight();
Matrix2D matrix = page.getDisplayMatrix(0, 0, width, height, page.getRotation());
// Prepare a bitmap for rendering.
Bitmap bitmap = new Bitmap(width, height, e_DIBArgb, null, 0);
bitmap.fillRect(0xFFFFFFFF, null);
// Render page.
Renderer render = new Renderer(bitmap, false);
render.startRender(page, matrix, null);
image.addFrame(bitmap);
}
...

How to convert a image file to PDF file

import com.foxit.sdk.common.Image;
import com.foxit.sdk.common.fxcrt.PointF;
import com.foxit.sdk.pdf.PDFDoc;
import com.foxit.sdk.pdf.PDFPage;
import static com.foxit.sdk.pdf.PDFPage.e_ParsePageNormal;
import static com.foxit.sdk.pdf.PDFPage.e_SaveFlagNoOriginal;
Image image = new Image(input_file);
int count = image.getFrameCount();
PDFDoc doc = new PDFDoc();
for (int i = 0; i < count; i++) {
PDFPage page = doc.insertPage(i, PDFPage.e_SizeLetter);
page.startParse(e_ParsePageNormal, null, false);
// Add image to page.
page.addImage(image, i, new PointF(0, 0), page.getWidth(), page.getHeight(), true);
}
doc.saveAs("convertedPDF.pdf", e_SaveFlagNoOriginal);
...