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WYSIWIG (What You See Is What You Get). This is the basic principle in PDF format, because
from the very beginning PDF has been created as the format for storing of electronic documents
which shouldn’t be greatly edited. PDF document has been always presented as one or more
fixed size pages. As part of its layout, PDF document maintains the precise positional placement
of page content elements independently of the display or print device in use. A page’s
appearance is described by a sequence of graphics elements (any combination of text, graphics,
and images) to be painted on the page. This appearance is fully specified; all layout and
formatting decisions have already been made by the application generating the page
appearance.
If the documents of other fixed layout formats (e.g. XPS) will be converted to PDF, Perfect PDF
transforms the original objects to PDF format straight forward. To convert the Flow Layout
Documents (plain or RTF text, HTML, etc.) the original content should be divided in the certain
size pages. The content of each page gets a fixed layout which cannot be changed later on.
Perfect PDF offers wide functionality for page content editing
: add, remove and modify pages,
text and text properties, images, graphical elements (see “Page Editor” for more information).
However it doesn’t allow automatic relayout of page content as for example in Microsoft Word,
which documents don’t have fixed layout. That’s why it’s not possible to convert PDF document
to Word document, if you want to preserve original PDF layout and don’t restrict the usual Word
editing possibilities at the same time.
Document Outline (Bookmarks)
A PDF document may optionally contain a document outline (in PDF community traditionally
called “bookmarks”), allowing the user to navigate interactively from one part of the document
to another. The outline consists of a tree-structured hierarchy of outline, which serve as a visual
table of contents to display the document’s structure to the user.
Use “Bookmarks” panel in Perfect PDF
to display, use and edit bookmarks in your PDF
document.
Page Annotations
Due to basic principle of PDF - the format for the documents which shouldn’t be edited a lot;
there are many possibilities to annotate the PDF content. The annotation types include sticky
notes, text markup, stamps, watermarks, text boxes, shapes and pen drawings, audio, video and
3D-illustrations.
Each annotation is an object being associated with one or more document pages. Usually it has
an icon or graphic appearance to be displayed on that page(s) which it has been associated with,
and occupies a rectangular area on the page. Page content (graphic objects sequence) and page
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annotations collection are two independent structures. Their elements have a different nature
and cannot be mixed together. By displaying on a screen or printing the page content will be
drawn before the annotations. Usually every PDF software allows displaying / printing the
annotations optionally, depending on their type.
Almost all annotation types are interactive: user can manipulate the annotation object in order
to get detailed comfortable annotation presentation. These handlings don’t change the PDF
document itself, but only change the displaying of the given annotation in the PDF program
window. For example you can open the comment to sticky note as a pop-up appearance or play
video annotation.
All annotations for a document page you can see in Perfect PDF
in the panel “Review and
form”. The tools for processing annotations you can find in the toolbar of this panel or in the
ribbon tab “Review and form”.
Hyperlinks and Named Destinations
PDF as any modern format for electronic documents has a hyperlinks mechanism to connect
documents and the part of an individual document. Technically the links are a special kind of
annotations. As opposed to another annotation types the hyperlinks don’t have any own
graphical reflection. The link annotation area is a hotspot (region of the page) over content
element (for example, blue underlined text or image). The hyperlink reference (target) can be a
page or a part of page in the same document, another PDF file, web or e-mail address.
If there are many links to the same page or page region from different places in the same
document, it is possible in PDF format to create so called “named destination objects” (almost
the same as the bookmarks in Word). Such a target object has unique name within the whole
document and has been associated with a rectangular region on a PDF page, e.g. on a formula
in text. All hyperlinks in PDF document which reference to this object can have as a target the
name of this named destination. These links are more convenient and clear then the links used
page numbers.
Links and named destinations associated with a certain page can be seen in the program
Perfect PDF
can be seen in the panel “Review and form”. The tools for adding and processing
hyperlinks and named destinations you can find in the toolbar of this panel or in the ribbon tab
“Document/Navigation”.
Form, Fields and Controls (Widgets)
PDF document may have a set of interactive form fields of different type such as: text fields,
checkboxes and radio buttons, push buttons, combo boxes and list boxes, barcodes and
signature fields. Form field is an object that stores a field data and has a set of own properties
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according to its type. Every field has a name, unique within a whole document. The name can
be hierarchical, i.e. consists of several names divided with the point “.”. It helps to group the
names in the structure, e.g. three fields with the names “Address.City”, “Address.PostalCode”
and “Address.Street” belong to the group “Address”.
Every field object usually has been associated with a special annotation object - control (usually
called “widget” in PDF community). Control objects as also other annotations which have been
placed on the pages, reflect values or states of the fields connected with them. The controls let a
user to change field values and to fill out the electronic form in PDF document.
Appearance and interactive logic of a control object has been defined by the type of a field
object, e.g. the control associated with a text field gives a possibility to edit string value, and the
control associated with a list box field reflects a list of possible values and gives a possibility to
select one of them.
PDF format allows a field object without any control. These fields are hidden from the end user
and can be used only programmatically. PDF allows also associating several controls with one
field object; these controls show the same value. If you change the value in one of the controls,
it will be changed also in the associated field object.
The field list you can see in the panel “Form fields” in Perfect PDF
, the controls as also other
annotations – in the panel “Review and form”. The tools for processing form fields and controls
you can find in the toolbar of this panel or in the ribbon tab “Review and form”.
Layers (Optional Content Groups)
Optional content is a block of graphics elements in a page content that can be selectively viewed
or hidden by document authors or users. This capability is useful in items such as CAD drawings,
layered artwork, maps, and multi-language documents.
A layer (in PDF format called “optional content group”) is an named object representing a
collection of optional content blocks that can be made visible or invisible dynamically by users of
PDF Reader. The graphics belonging to such a group can reside on several pages anywhere in
the document.
The layers list you can see in the panel “Layers” in Perfect PDF
. The tools for processing layers
you can find in the toolbar of this panel.
Portfolio and Embedded Files
Except of PDF document PDF file may contain any number of embedded files. The data of these
files has been stored in PDF file (as for example in a ZIP file). Usually these files are PDF files also,
e.g. if a documentation consists of several chapters (PDF documents) being stored as embedded
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files in one PDF file. As well as PDF files can be embedded images, files of any special format,
etc.
The embedded files list you can see in the panel “Files” in Perfect PDF
. The tools for
embedding, deleting or export of embedded files you can find in the toolbar of this panel and in
ribbon “Document/Files”.
From the version 1.7 PDF format allows to create PDF Portfolio. It is PDF file consisting of other
files and doesn’t have a main PDF document. Instead of this document a pseudo page will be
inserted for that case if this PDF file will be loaded in an old version of PDF reader which doesn’t
support PDF portfolio. Modern versions of PDF reader software ignore pseudo page in PDF
portfolio.
In Perfect PDF you can create new PDF portfolio or edit existing using the tools for processing
PDF portfolio in the ribbon “Portfolio”, it appears if you’ve loaded a portfolio file or create new
portfolio.
Fonts and Images
Any text character in computer typography (and in PDF document) is an abstract symbol and a
glyph is a specific graphical appearance of this character.
Glyphs are organized into fonts. A font file defines glyphs for a particular character set. Every
glyph represented by micro-program is written in a special-purpose language, such as the
“TrueType” or “Type 1” font format, that is understood by PDF software and used to draw text
characters.
A font is represented in PDF document as an object specifying the type of font, its PostScript
name, and information that can be used to provide a substitute font from the system fonts
when the glyph data is not embedded in the PDF. Optionally, the glyph data can be embedded
as a stream object in the PDF file (embedded font). Embedded font leads to a bigger PDF file,
but guarantees a correct appearance of the text in PDF document on any computer. If you don’t
embed the font, it is possible to get a wrong appearance for the font characters or even no
appearance at all (e.g. for Arabic or Asiatic languages with special fonts).
The list of embedded files used by PDF document, as well as the detailed information about
every font has been displayed in Perfect PDF
in the panel “Fonts”. The tools for managing
document fonts you can find in the toolbar of this panel.
PDF format allows you to use raster images (bitmaps) as graphic elements of page content or
annotation appearance, page thumbnails and other elements of PDF document.
Every bitmap object has following properties: width (number of dots (pixels) in a line), height
(number of lines in a bitmap), color depth (number of available colors per pixel - monochrome,
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palette or true color), color space (abstract mathematical model describing the digital colors,
traditionally used RGB, CMYK, Gray and other), data compression method (algorithm for
compressing bitmap data). Following compression algorithms can be used in PDF: ZIP, RLE, JPEG,
JPEG2000, CCITT, JBIG2. All mentioned properties influence the image quality and the size of
PDF file. Higher quality leads to the bigger PDF file. If you want to reduce the file size try to
change the compression method, image size or other image properties until the quality doesn’t
satisfies you. The used bitmaps should always be embedded in the PDF file.
The images list in PDF document as well as detailed information about each image you can see
in the panel “Images” in Perfect PDF. The tools for processing images you can find in the
toolbar of this panel.
Events and Actions, Using JavaScript
If user clicks on a hyperlink on a PDF page, a PDF reader usually acts in such a way, that the
other document page will be displayed in the viewer area. As a default handling for the event
“mouse up” (releasing the left mouse button) is normally the action “go to certain page” with
the page number.
PDF format declares several action types, which may be associated with particular event types.
An event is a particular change of state of PDF document objects or interactive action of end-
user. If an event happens, the actions associated with the event are automatically invoked. These
actions may be any of the following:
Go to a destination in the current document
Go to a destination in another document
Go to a destination in an embedded file
Go to a web address or create e-mail message
Launch an application, usually to open a file
Show/hide an annotation (or form field)
Send form data to a web address
Set form fields to their default values
Import form field values from a file
Set the states of optional content groups
Play a sound
Play a movie
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Controls the playing of multimedia content
Execute a JavaScript script
Execute an action predefined by the viewer application
PDF format introduces six events affecting the document as a whole:
After opening a document
Before closing a document (JavaScript action)
After saving a document (JavaScript action)
Before saving a document (JavaScript action)
After printing a document (JavaScript action)
Before printing a document (JavaScript action)
The actions for these events are reflected in the dialog “File Menu/Document Properties/Events
and Actions” in Perfect PDF
program.
Two events are defined for the document page:
After opening (displaying) a page
Before closing (hiding) a page
Actions for these events are reflected in the page objects properties in “Pages” panel.
Next events are defined for the annotation (including links and controls):
Mouse cursor enters the annotation’s area
Mouse cursor exits the annotation’s area
Mouse button is pressed inside the annotation’s area
Mouse button is released inside the annotation’s area
The annotation receives the input focus
The annotation loses the input focus
The page containing the annotation is opened
The page containing the annotation is closed
The page containing the annotation becomes visible in the PDF Reader
The page containing the annotation is no longer visible in the PDF Reader
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