NAME¶
OpenOffice::OODoc::Intro - Introduction to the Open OpenDocument Connector
DESCRIPTION¶
This introductory notice is intended to allow the user to understand the general
principles and to learn some basic features of the OODoc module without
browsing the whole reference manual.
The reference manual is a set of OpenOffice::OODoc::xxx separate documents,
where xxx is the codename of a particular functional area. The present
introduction, as well as the OpenOffice::OODoc main chapter, should be read in
order to get the big picture before any attempt to dig in the detailed
documentation.
Just before reading this intro, it's a good idea to have a look at the short
(and commented) examples provided in the distribution.
Another general introduction to this Perl OpenDocument Connector has been
published in The Perl Review (issue #3.1, dec. 2006)
<
http://www.theperlreview.com>
There is an alternative intro for french-reading users. It's available in ODT
(<
http://jean.marie.gouarne.online.fr/doc/oodoc_guide.odt>) or PDF
(<
http://jean.marie.gouarne.online.fr/doc/oodoc_guide.pdf>). In
addition, a general presentation in French can be downloaded at
<
http://jean.marie.gouarne.online.fr/doc/perl_odf_connector.pdf>
Overview¶
The main goal of the Open OpenDocument Connector (OODoc) is to allow quick
application development in 2 areas:
- replacement of old-style, proprietary, client-based macros for intensive and
non-interactive document processing;
- direct read/write operations by enterprise software on office documents,
and/or document-driven applications.
OODoc provides an abstraction of the document objects and isolates the
programmer from low level XML navigation, UTF8 encoding and file compression
details. For example:
use OpenOffice::OODoc;
my $document = odfDocument(file => 'filename.odt');
$document->appendParagraph
(
text => 'Some new text',
style => 'Text body'
);
$document->appendTable("My Table", 6, 4);
$document->cellValue("My Table", 2, 1, "New value");
$document->save;
The script above appends a new paragraph, with given text and style, and a table
with 6 lines and 4 columns, to an existing document, then inserts a value at a
given position in the table. It takes much less time than the opening of the
document with your favourite text processor, and can be executed without any
desktop software connection. A program using this library can run without any
OpenOffice.org installation (and, practically, OODoc has been tested on
platforms where OpenOffice.org is not available yet).
More generally, OpenOffice::OODoc provides a lot of methods (probably most of
them are not useful for you) allowing create/search/update/delete operations
with document elements such as:
- ordinary text containers (paragraphs, headings, item lists); - tables and
cells; - user fields; - sections; - images; - styles; - bookmarks; -
bibliography entries; - page layout; - metadata (i.e. title, subject, and
other general properties).
Every document processing begins by the initialization of an object abstraction
of the document. The most usual constructor for this object is the
odfDocument() function. When an object is initialized using this
function, it brings a lot of methods allowing allowing the application to
retrieve, read, update, delete or create almost every content and style
element. Another constructor,
odfMeta() is available in order to allow
metadata processing (see below). These
odfXxx() methods (and others)
are shortcuts for
OpenOffice::OODoc::Xxx->new(options)
where "Xxx" is generally "Document", for full access to the
content, but may be another specialized object such as "Manifest" or
"Meta". The long "OpenOffice::OODoc::...->
new()" syntax can (and should) be avoided, and replaced by the
odfDocument(),
odfMeta() or
odfManitest() functions.
A document object initialization requires one or more options. The most usual
option is the file name, as in the first example. By default, this parameter
is regarded as a previously existing file. It's possible to instantiate a
document object with a new, empty document, with an additional
"create" option giving the content class of the document to be
generated. So, in our first example, the constructor could be:
my $document = odfDocument
(
file => 'filename.odt',
create => 'text'
);
This instruction creates a new file containing a text (i.e. an OpenDocument
Text) document (and replaces any previously existing file with the same name).
However, the new file will be actually created by the $document->save
instruction, not by the object initialization. If "create" is set,
the documents are generated according to ODF templates. By default, OODoc uses
a set of templates which are included in the CPAN package, but it's possible
to use custom templates instead.
When the 'create' option is in use, the newly created document may be formatted
either in the OASIS OpenDocument format (ODF) or in the primary OpenOffice.org
1.0 format. If an additional 'opendocument' is provided and set to 'true',
then the new document will be ODF-compliant. If the same option is present and
set to 'false', the old OOo 1.0 format will be selected instead. Without the
'opendocument' option, the format will depend on the installation default (in
the CPAN distribution, the default is set to OpenDocument but it can be
changed by the user at the install time). In the other hand, the provided
filename is not used by OODoc in order to select the file format, so you are
free to create an ODF file with an OOo-like ".sxw" extension, and so
on. The only one filename suffix that is meaningful for OODoc is
".xml" (by default, a file whose name is like "*.xml" is
processed as flat XML and not as a regular, compressed ODF file).
For existing files, the format (ODF or OOo) is automatically detected according
to the real content of the file (whatever the filename).
The present version of OpenOffice::OODoc is based on the OpenDocument
specification, which has been published (May 2005) as an OASIS standard under
the following title:
"Open Document Format for Office Applications (OpenDocument) v1.0"
It works with ODF 1.1 and 1.2 documents as well, knowing that these newer
versions use the same basic data structure as 1.0, and (hopefully) this
library doesn't depend on any particular feature which could be removed from
the specification.
Architecture¶
The OODoc toolbox is organized in 3 logical layers. It's not necessary for you
to remember the (annoying) details given in the next few paragraphs, but these
details are described only to explain the general organisation of the modules.
If you have only a few dozens of seconds for reading this document, please
jump directly at the part III (practical examples) and come back later if you
want to know more.
OpenDocument packaging¶
The first layer consists of the OpenOffice::OODoc::File class (defined in the
File.pm module). This class is responsible of read/write operations with the
ODF physical files. It does every I/O and compression/uncompression
processing. It's mainly an easy-to-use, OpenDocument-oriented wrapper for the
standard Archive::Zip Perl module (but it could be extended to encapsulate any
other physical storage method for the ODF documents).
Every physical access to a document through the OpenOffice::OODoc API requires
the use of one or more "connectors", each one being associated to an
ODF "container". The appropriate constructor is the
odfContainer() function, which requires a file name/path as its first
(and mandatory) argument:
my $resource = odfContainer("myfile.odt");
The instruction above creates an instance of ODF container, associated to a
given filename. The returned object (assuming the specified file exists and is
readable) is an OpenOffice::OODoc::File instance, i.e. an abstraction of the
ODF physical file. However, it's possible to associate a container with an ODF
that doesn't exist yet, provided that an additional 'create' named parameter,
whose value is the class of the new document, is set. The following example
creates an instance of spreadsheet ODF package:
my $container = odfContainer("accounts.ods", create => 'spreadsheet');
Note that no persistent resource is created at this time. Without the 'create'
option, the
odfContainer() function attempts to load the structure of
the specified ODF file (and fails if something is wrong). With the 'create'
option, the structure is loaded in memory according to defaut ODF templates
that belong to the OpenOffice::OODoc installation. But any persistent change
(including the creation of the new ODF file, if any) requires the
save() method. As an example, the following code really created a new
ODF presentation file (without content):
my $container = odfContainer("show.odp", create => 'presentation');
$container->save;
Or, more concisely:
odfContainer("show.odp", create => 'presentation')->save;
So, the most minimalistic OpenOffice::OODoc application is a one-liner that
creates an empty document.
For an existing resource, an open IO::File is allowed instead of a file name.
Once initialized, such a container is typically used as a basis to instantiate
one or more document-oriented connectors using
odfDocument(),
introduced later. However, for the users who know exactly what they do, an ODF
container brings some low-level methods, such as physical export and/or import
of document parts. The next example exports all the named persistent styles of
"doc1.odt" then imports them in "doc2.odt":
my $p1 = odfContainer("doc1.odt");
my $p2 = odfContainer("doc2.odt");
$p1->raw_export("styles.xml");
$p2->raw_import("styles.xml");
$p2->save;
Caution: there is no consistency check with
raw_import(), so the
application may ensure that the imported part makes sense according to the
remainder of the target container (so, in this example, it may ensure that all
the styles needed in the document content are conveniently defined in the
imported part). Note that the
raw_import() method doesn't produce any
persistent effect before the
save() method is issued from the importing
container. All the changes are lost if the program ends or the objects goes
out of scope before
save().
XML access¶
An OpenOffice::OODoc::File object which has been instantiated using
odfContainer(), it becomes available for processing through
document-oriented, XML-based connectors. A typical OpenOffice::OODoc user
doesn't need to be really "XML-aware", and most applications will
probably use the high-level, XML-free methods provided by the Document and
Meta objects, introduced later. However, the present section could prove
useful for the general knowledge of the API.
The second layer is made of the OpenOffice::OODoc::XPath class (XPath.pm), which
is an ODF/XML-aware class. This class is generally not directly used by the
applications; it's mainly a common ancestor for more specialised (and more
user-friendly) other classes. OpenOffice::OODoc::XPath is an object-oriented
representation of an XML part of an OpenDocument file (ex: content.xml,
meta.xml, styles.xml, etc.), using the XML::Twig Perl API to access individual
XML elements. It provides an XPath-based syntax for advanced users who want to
directly get or set any element or attribute in any part of a document. If you
want to deal in the same time with several XML components of the same
document, you can/must create several OpenOffice::OODoc::XPath against the
document (ex: one OpenOffice::OODoc::XPath will be associated with 'meta.xml'
to represent the metadata, another one will be associated with 'content.xml'
to give access to the content. OpenOffice::OODoc::XPath accepts and provides
only XML strings from/to the application; but it's able to connect with an
OpenOffice::OODoc::File object for file I/O operation, so you can use it
without explicit file management coding.
For an example, if you want to get access to the content of any ODF file (say
'foo.odt'), you have to write something like:
use OpenOffice::OODoc;
my $container = odfContainer("foo.odt");
my $doc = odfDocument
(
container => $container,
part => 'content'
);
then $doc becomes an abstraction of the 'content' part of the document
(corresponding to the document body and some automatic styles). This new
object brings a lot of methods allowing the applications to retrieve, read,
modify, delete and creates elements in the documents.
An element is a consistent piece of content or style definition. Any element may
contain a text and/or one or more attributes. As an example, the following
example selects a paragraph, then gets its text content and the name of its
style:
my $element = $doc->getElement('//text:p', 2);
my $text = $doc->getText($element);
my $style = $doc->getAttribute($element, 'style name');
Note that the
getElement() method works with XPath expressions. According
to the ODF specification, "text:p" specifies a paragraph. The double
slash ("//") means "everything from the root of the
document". The second argument of
getElement() is the position of
the needed element in the list (knowing that "//text:p" designates
all the paragraphs); this position is zero-based, so in this example the third
paragraph is selected. The search space of
getElement() is the whole
document by default, but it's possible to restrict it to a given context,
specified through a additional argument. A context is a particular element,
previously selected. As an example, the following code selects the 3rd
paragraph in the 4th section (if any):
my $section = $doc->getElement('//text:section', 3);
my $paragraph = $doc->getElement('//text:p', 2, $section);
(Of course, there is a
getSection() method that allows you to forget the
XPath expression and to retrieve a section by name instead of number.)
In a real application, the user doesn't need to known such an XPath expression,
because there is a more convenient
getParagraph() method that just
requires the paragraph number. However, the generic, XPath-based
getElement() method remains available in order to retrieve any element
that is not covered by a specialized accessor.
The
getText() method is self-documented in the example. The
getAttribute() method requires, after the element itself, the name of
the attribute whose value is needed. The real ODF name of the style attribute
of a paragraph is "text:style-name"; however, the application may
use the "style name" simplified form knowing that
getAttribute() is able to translate the attribute names according to a
simple logic: every space in the given name is replaced by a "-"
and, if no prefix is specified, the prefix of the element itself is used, so
"style name" is automatically interpreted as
"text:style-name" in this particular context.
You don't need to remember the path of such usual objects as paragraphs,
headings, lists, images, ..., and other well known document components,
because the 3rd layer (see below) provides easy-to-use, predefined accessors
for these objects.
The text content and the attributes of a selected element may be changed. The
following sequence puts a new text content and affects a new style to our
previously selected paragraph:
$doc->setText($element, "A new text content");
$doc->setAttribute($element, 'style name' => "Text Body Style");
The same layer of the API allows one to append of insert new elements. The next
example demonstrates the use of
appendElement(); it creates a new
paragraph with given text and style and appends it to the existing content:
$doc->appendElement(
'text:p',
text => "Hello world",
attributes => {
'style name' => "Text Body Style"
}
);
For those who hate complex instructions, the 3 lines below do the same job as
the example above:
my $new_element = $doc->appendElement('text:p');
$doc->setText($new_element, "Hello world");
$doc->setAttribute($new_element, 'style name' => "Text Body Style");
Remember that the changes above are done in the volatile content of document
object; up to now; nothing is changed in the corresponding file. In order to
commit the changes and make them persistent, we need to call the
save()
method of the container that has been used to instantiate the document.
The API allows the user, in simple situations, to "forget" the ODF
container behind the document. The following "hello world" example,
that creates and saves a new document, works without explicit use of the
odfContainer() constructor:
my $doc = odfDocument(
file => "foo.odt",
create => 'text',
part => 'content'
);
$doc->appendElement(
'text:p',
text => "Hello World !",
attributes => {
'style name' => "Text Body Style"
}
);
$doc->save;
Note that
odfDocument() is used here with a 'file' parameter, whose value
is a file name, instead of a 'container'. At the end,
save() is called
from the document instance itself instead of a container. However, a container
is always instantiated, but it's just hidden; and
save() is only a stub
method, the real job being done by the
save() method of the container.
Such a shortcut is useful in this example because the program processes one
part only, i.e. the content; for applications that uses more than one part
(content, styles, meta- data), two or more document connectors must be
instantiated in association with the same container connector, and, as a
consequence, the explicit use of
odfContainer() is recommended.
OpenOffice::OODoc::XPath allows some quick element manipulation and exchange,
and can operate on several documents in the same session. For example:
my $doc1 = odfDocument(file => 'file1.odt', part => 'content');
my $doc2 = odfDocument(file => 'file2.odt', part => 'content');
my $paragraph = $doc1->getElement('//text:p', 15);
$doc2->insertElement
('//text:h', 0, $paragraph, position => 'after');
This sequence takes an arbitrary paragraph (the 16th one) of a document and
inserts it immediately after an arbitrary heading (the first one) in another
document. Here, we used an
insertElement() method to directly transfer
an existing text element, but the same method (with different arguments) can
create a new element according to application data, or from a well- formed XML
string describing any document element in regular Open Document syntax.
Example:
# a program
my $doc = odfDocument(file => 'file1.odt', part => 'content');
open MYFILE, "> transfer.xml";
print MYFILE $doc1->exportXMLElement('//text:p', 15);
close MYFILE;
# another program
my $doc2 = odfDocument(file => 'file2.odt', part => 'content');
open MYFILE, "< transfer.xml";
$doc2->insertElement
('//text:h', 0, <MYFILE>, position => 'after');
close MYFILE;
These last two short programs produce the same effect as the preceding one, but
the target file can be processed later than the source one and in a different
location, because there is no direct link in the two documents. The first
program exports an XML description of the selected element, then the second
program uses this description to create and insert a new element that is an
exact replicate of the exported one. In the meantime, the XML intermediate
file can be checked, processed and transmitted with any language and protocol.
The OpenOffice::OODoc::XPath manual page describes a lot more common features
that may be used through the document-oriented API introduced below.
But it's just a beginning, because, in the real world, you have to do much more
sophisticated processing, and you have not a lot of time to learn the XML path
of any kind of document element (paragraph, heading, item list, table, draw
frame, style, ...).
Document-oriented API¶
So there is a third, more user-friendly layer, that should be the only one
visible for most of the applications.
The third layer is designed as a set of application-oriented classes, inherited
from OpenOffice::OODoc::XPath. In this layer, the basic principle is
"allow the user to forget XML". Each document element is considered
from the user's point of view, and the XML path to get it is hidden. This
approach works only if a specialized OpenOffice::OODoc::XPath class is defined
for each kind of content. So, we ultimately need the following classes:
OpenOffice::OODoc::Text for the textual content of any document;
OpenOffice::OODoc::Image to deal with the graphic objects;
OpenOffice::OODoc::Styles for page/style definitions;
OpenOffice::OODoc::Meta for the metadata (meta.xml);
Fortunately, the 3 first ones should not be expressly used in real applications,
knowing that the toolbox provides a compound OpenOffice::OODoc::Document class
which inherits all their features. As a consequence, ordinary users have just
to deal with OpenOffice::OODoc::Document to process any content (graphic or
textual) or layout. An OpenOffice::OODoc::Document object is instantiated
through the
odfDocument() function, that is a shortcut for
OpenOffice::OODoc::Document->
new(). For other parts, such as the
metadata or the file manifest, other constructors are available.
Simply put, a typical application will need OpenOffice::OODoc::Document in order
to process the content and the layout, and OpenOffice::OODoc::Meta for a
read/write access to the global properties.
However, the reference manual in organized according to the kind of features, in
order to avoid a huge manual page for the Document class. As a consequence,
the documentation of this compound class includes 4 chapters (::Text,
::Styles, ::Image and ::Document, the last one describing a few transverse
methods. In addition, the user should remember that all the low-level
attributes and methods described in the ::Xpath manual chapter are inherited
by both ::Document and ::Meta.
The OpenOffice::OODoc::Text class brings some table processing methods (table
creation, direct access to individual cells). These methods, (under some
conditions) can be used with spreadsheets (ODF spreadsheet documents) as well
as with tables included in text documents.
To illustrate the differences between the layers, the two following instructions
are equivalent:
print $doc->getText('//text:p', 2);
print $doc->getParagraphText(2);
provided that $doc has been previously created through an
odfDocument()
call.
The difference looks tiny, but in fact OODoc::Text contains much more
sophisticated text-aware methods that avoid a lot of coding and probably a lot
of errors. For example, the following code puts the content of an ordinary
perl list (@mydata) in an ODF document as an regular item list:
my $list = $doc->appendItemList();
$doc->setText($list, @mydata);
The first instruction creates an empty list at the end of the document body. The
second one populates the new list with the content of an application- provided
table. The
setText() method automatically modify its behaviour
according to the functional type of its first argument (with is not the same
for a paragraph as for an itemlist or a table cell).
The same layer provides some global processing methods such as:
my $result = $doc->selectTextContent($filter, \&myFunction);
that produces a double effect:
1) it scans the whole document body and extracts the content of every text
element matching a given filter expression (that is an exact string or a
conventional Perl regular expression);
2) it triggers automatically an application-provided function each time a
matching content is found; the called function can execute any on-the-fly
search/replace/delete operation on the current content and get data from any
external database or communication channel; the return value of the function
automatically replaces the matching string.
So such a method can be used in sophisticated conditional fusion- transformation
scripts.
But you can use the same method to get a flat ASCII export of the whole
document, without other processing, if you provide neither filter nor action:
print $doc->getTextContent;
Of course, OODoc can process presentation and not only content. Example:
$filter = 'Dear valued customer';
foreach $element ($doc->selectElementsByContent($filter))
{
$doc->setStyle($element, 'Welcome')
if $element->isParagraph;
}
After this last code sequence, every paragraph containing the string 'Dear
valued customer' has the 'Welcome' style (assuming 'Welcome' is a paragraph
style, already defined or to be defined in the document).
A style (like any other document element) can be completely created by program,
or imported (directly or through an XML string) from another document. The
second way is generally the better because you need a lot of parameters to
build a completely new style by program, but the creation of a simple style is
not a headache with the OODoc::Styles module, provided that you have an ODF
attributes glossary at hand. The following example show the way to build the
"Welcome" style. This piece of code declares "Welcome" as
a paragraph style, whith "Standard" as parent style, and with some
private properties (Times 16 bold font and navy blue foreground).
$doc->createStyle
(
"Welcome",
family => 'paragraph',
parent => 'Standard',
properties =>
{
'area' => 'text',
'style:font-name' => 'Times',
'fo:font-size' => '16pt',
'fo:font-weight' => 'bold',
'fo:color' => '#000080'
}
);
The color attributes are encoded in RGB hexadecimal format. It's possible to use
more mnemonic values or symbols, through conversion functions provided by the
Styles module, and optional user-provided colour maps. For example,
"#000080" could be replaced by odfColor('navy blue'), provided that
an appropriate color table is available at the run time; see
odfLoadColorMap() in the OpenOffice::OODoc::Styles manual chapter.
According to the application logic, each newly created style can be registered
either as a "named" style (i.e. visible and reusable through a
typical office software suite) or as an "automatic" style.
For an ordinary application that needs the best processing facility for any kind
of content and presentation element, the OODoc::Document module is the best
choice. This module defines a special class that inherits from Text, Image and
Styles classes. It allows the programmer, for example, to simply insert a new
paragraph, create an image object, anchor the image to the paragraph, then
create the styles needed to control the presentation of both the paragraph and
the image, all that in the same sequence and in any order.
Caution: In order to get a convenient translation between the user's local
character set and the common ODF encoding (utf8), the application must
indicate the appropriate encoding. The default one is iso-8859-1 in the CPAN
distribution; it can be set using the
odfLocalEncoding() function.
Example:
use OpenOffice::OODoc;
odfLocalEncoding 'iso-8859-15';
The default encoding can be selected by the user during the installation, and
changed later by editing a configuration file. In addition, a program working
with several documents in the same time can select a distinct character set
for each one.
Some practical uses¶
To begin playing with the modules, you should before all see the self-documented
sample scripts provided in the package. These scripts do nothing really
useful, but they show the way to use the modules.
You should directly load the full library with the single "use
OpenOffice::OODoc" in the beginning of your scripts. Then you should only
use (in the beginning) the Document and/or Meta classes only. We encourage
you, in the first time, to avoid any explicit OODoc::XPath basic method
invocation, and to deal only with available "intelligent" modules
(Text, Image, Styles, via Document, and Meta), in order to get immediate
results with a minimal effort. And, if you use this stuff for evangelization
purpose, you can show the code to prove that the OpenDocument format allows a
lot of things with a few lines.
You can avoid the heavy object oriented notation such as:
my $meta = OpenOffice::OODoc::Meta->new(file => "xxx.ods");
and use the shortcuts like:
my $meta = odfMeta(file => "xxx.ods");
The first thing you have to do with a document is to create an object focused on
the member you want to work with, and "feed" it with regular ODF
XML. The most straightforward way to do that is to create the object in
association with an ODF file.
We need metadata access, so we use OODoc::Meta
use OpenOffice::OODoc;
my $doc = odfMeta(file => 'myfile.odt');
my $title = $doc->title;
if ($title) { print "The title is $title"; }
else { print "There is no title"; }
Here, because the constructor of OODoc::Meta is called with a 'file' parameter,
OODoc::Meta knows it needs a file access and it dynamically requires the
OODoc::File module, instantiates a corresponding object using the file name,
connects to it, and asks it for the 'meta.xml' member of the file. All that
annoying processing is hidden for the programmer. We have just to query for
the useful object, the title.
In the same way, we could get (or even change) the document creation or last
modification date registered by the editing software:
my $d1 = $doc->creation_date;
my $d2 = $doc->date;
The dates, in the ODF documents properties, are stored in ISO-8601 format
(yyyy-mm-ddThh:mm:ss); this format is readable but not necessarily convenient
for any application. But the API provides easy to use tools allowing
conversion to or from the regular numeric
time() format of the system,
allowing any kind of formatting or calculation.
We could get more complex metadata structures, such as the user defined fields:
my %ud = $doc->user_defined;
foreach my $name (keys %ud)
{ print $name . '->' . $ud{$name} . "\n"; }
This code captures the user defined fields (names and values) in a hash table,
which then is displayed in a "name->value" form. You could see
the way to update the user defined fields in the 'set_fields' script, provided
with the distribution. The most usual metadata accessors have a symmetrical
behaviour. To update the title, for example, you have to call the 'title'
method with a string argument:
$doc->title("New title");
You can proceed in the same way with subject, description, keywords.
The 'keywords' is an example of polymorphic behaviour (which is quite common for
many OODoc methods):
my $keywords = $doc->keywords;
my @keywords = $doc->keywords;
In the first form, the keywords are returned concatenated and comma- separated
in a single editable text line. In the second one, we get the keywords as a
list. But if 'keywords' is called to add new keywords, these ones must be
provided as a list:
$doc->keywords("kw1", "kw2", "kw3");
$doc->keywords(@my_keywords);
The program is automatically prevented from introducing redundancy in the
keyword list (the 'keywords' method deletes duplicates). While 'keywords' can
only add new keywords, you have to call removeKeyword to delete an existing
keyword. If you want to destroy the entire list of keywords in a single call,
you have just to write:
$doc->removeKeywords;
Well, we have done some updates in the metadata, but these updates apply only in
memory. To make it persistent in the file, we have just to issue a:
$doc->save;
I said OODoc::Meta (which is an OODoc::XPath) did not know anything about the
OpenDocument compressed files. But in my example,the object has been created
with a 'file' argument and associated with an implicit OODoc::File object. So,
the 'save' method of OODoc::XPath is only a stub method which sends a 'save'
command to the connected OODoc::File object. With an object created with an
'xml' parameter (providing the metadata through an XML string, without
reference to a file), a 'save' call generates a 'No archive object' error.
However, if the object had been created from an XML flat file (instead of a
regular ODF compressed file), the output would be a flat XML file as well.
Note: A document is always saved in the same file format as it's source. The
save() can't act as a format converter. So, you can't save an OOo 1.0
file in OASIS OpenDocument format and vice versa, and you can't directly
(without intermediate processing) save in ODF compressed format a document
loaded from XML data. However, thanks to the
getXMLContent() method,
you can write the flat XML to the standard output or a given file handle.
If you prefer to keep the original file unchanged, you can issue a
$doc->save('my_other_file.odt');
that produces the same thing as 'File/SaveAs' in your favorite office software:
if called with an argument, 'save' creates a new file containing all the
changed and unchanged members of the original one.
Of course, whatever the way you will use (or not use) the
save() method,
you will never process valuable documents without a backup copy...
Example 2 - Manipulating text¶
Here we must read and update some text content elements. By "text
content", we mean not only "flat text". While the most
interesting module is named OpenOffice::OODoc::Text, it's not fully dedicated
to text documents. It can deal with the text content of presentations, as well
as the sheets and cells of a spreadsheet.
Our program begins with something like that:
use OpenOffice::OODoc;
my $doc = odfDocument(file => 'myfile.odt');
The second line produces an OpenOffice::OODoc::Document object, which inherits
from O::O::Text, O::O::Image and O::O::Styles. However, in the present
example, we'll use its O::O::Text features only.
To give a very high level abstract, we can say that OODoc::Text provides 2 kinds
of read access methods: - the 'get' methods that return data referred by
unconditional addressing, like
getParagraph(4); - the 'select' methods
that return data selected against a given filter, related to a text content or
an attribute value, like selectParagraphsByStyle('Text body').
Some 'get' or 'select' methods return lists while other return individual
elements or values.
Returned data may be elements or texts. Text data can be exported or displayed,
but the application needs elements to do any read/write operation on the
content. For example:
my $text = $doc->getTextContent;
extracts the whole content of the document as a flat, editable text in the local
character set, for immediate use (or display on a dumb terminal). Of course,
there are more the one way to do the same thing, so you can get the same
result with a 'select' method as with a 'get' one if you use a
"non-filtering filter". So:
my $text = $doc->selectTextContent('.*');
will also return the whole text content. But this last method, with some
additional arguments and an appropriate filter, is much more powerful, because
it can do 'on-the-fly' processing in each text element matching the filter
(for example, insert values extracted from an enterprise database or resulting
from complex calculations). The output of getTextContent can be tagged
according to the type of each text element, so the application can easily use
this method to export the text in an alternative (simple) markup language.
To do some intelligent processing in the text, we need to deal with individual
text objects such as paragraphs, headings, list items or table cells. For
example, to export the content of the 5th paragraph (paragraph numbering
beginning with 0), we could directly get the text with:
my $text = $doc->getParagraphText(4);
But in order to update the same paragraph, or change its style, I need the
paragraph element, not only its text content:
my $para = $doc->getParagraph(4);
# text processing takes place here
$doc->setText($para, $other_text);
$doc->setStyle($para, $my_style);
Some methods can dynamically adapt to the text element type they have to
process. For example, the getText method (exporting the text content of a
given text element), can return the content of many kinds of element
(paragraphs, headings, table cells, item lists or individuals list items). In
addition, any text content extracted with an high-level OODoc method is
transcoded in the local character set (UTF-8 issues are (we hope) hidden for
the application). Optionally, the text output can be instrumented with begin
and end application-provided tags according to the element type (so it's
possible to export the text in an alternative, simple XML dialect, or in
LaTeX, or in an application-specific markup language).
In order to facilitate some kinds of massive document processing operations,
OODoc::Text provides a few high level methods that do iterative processing
upon whole sets of text elements. One example is selectElementsByContent: this
method looks for any text container matching a given pattern (string or
regular expression) and, each time an element is selected, it executes an
application-provided callback function. An example of use is provided in the
'search' demo script, which selects any text element in a document matching a
given expression, and appends the selected content as a sequence of paragraphs
in another document.
The more usual methods have explicit names, and can be used without their
exhaustive documentation, provided that the programmer has a good
understanding of the general philosophy. Heading and paragraph manipulations
are quite simple. The situation is more complex with other text content such
as item lists, tables and graphics.
To get an individual list item, you must point to it from a previously obtained
list element:
my $item_list = $doc->getList(2);
my $item = $doc->getListItem($item_list, 4);
Here, $item contains the 5th item of the 3rd list of the document. The content
of the item could then be exported by a generic method such as
getText(), or processed using another method. Note that, if the
application doesn't need the $item_list object for any other use, it can
directly get the list item with the same method with a list number (instead of
s list object) as its first argument:
my $item = $doc->getListItem(2, 4);
Playing with tables and spreadsheets¶
Because the need of data capture within table structures is more evident, there
is a direct accessor to get any individual table cell:
my $value = $doc->getCellValue($table, $line, $col);
For example:
my $value = $doc->getCellValue(0, 12, 0);
This code example returns the value of the 1st cell of the 13th row of the 1st
table in the document. Note the 'cell value' is simply the text content if the
cell type is string; but if the cell type is any numeric type,
getCellValuereturns the content of the value attribute and ignores the text.
The first argument (the table) can be either the table number (zero-based,
according to its sequential position in the document) or the logical table
name (as it's get or set by the end-user with OOo Writer or Calc).
A cell can be selected in a table using either it's numeric (row, column)
coordinates or a "spreadsheet-like" alphanumeric notation. So, the
example above could be written as
my $value = $doc->getCellValue(0, "A11");
Caution, in the classical spreadsheet notation, the column comes first while it
comes last in the numeric coordinates. In addition, knowing that the numeric
coordinates are zero-based, "A1" corresponds to (0,0). Finally,
remember that the alphanumeric coordinates must be provided in a single string
while numeric coordinates require two arguments.
This alphanumeric notation is probably more user-friendly for OOo Calc
documents, but it's allowed by OODoc whatever the document class: you can use
it with tables in text documents as well.
Caution: The direct cell addressing works only when the table XML storage is
"normalized", i.e. when every table object (row, column or cell) is
mapped to an exclusive XML element. The application program can easily ensure
this "normalization" thanks to the
normalizeSheet() method,
described in the OpenOffice::OODoc::Text manual page. However, up to now, the
tables included in text document through OpenOffice.org Writer are normalized,
so they are immediately available for direct addressing. In the other hand,
with OpenOffice.org Calc spreadsheets, several contiguous objects are mapped
to a single XML element as long as they have the same content, the same type
and the same presentation. It's not an issue; it's a feature allowed by the
OpenDocument specification in order to save storage space, knowing that
typical large spreadsheets contain a lot of empty, or repetitive, cells. As a
consequence, several cells may be located at the same coordinates. The
normalizeSheet() method allows the application to define a safe area,
sized according to its needs, where the direct object addressing works
whatever the XML storage method in use.
The table-related methods can be used with spreadsheets (i.e. OOo Calc
documents) as well as with tables included in text documents. However, before
addressing cells in a spreadsheet document, a program must "declare"
the size of the used area in each target sheet (this requirement is due to
performance considerations, for Calc documents only).
You can also change the content of a cell:
$doc->updateCell($table, $line, $col, $value);
$doc->updateCell($table, $line, $col, $value, $string);
$doc->updateCell($cell, $value);
$doc->updateCell($cell, $value, $string);
The first form puts the $value in the target cell, assuming it's a string cell
or, if it's a numeric one, your choice is to put the same content as the value
and the displayable string. The second form (assuming the target cell is
numeric) provides independent content for value and string (the programmer
must know what (s)he does, for example in case of currency or date cell). The
3rd and 4th forms do respectively the same things, but use a previously
obtained cell element in place of 3D coordinates (in order to avoid
unnecessary low-level XPath recalculation).
For a flat text (non-numeric) cell whose the reference is already available,
setText() produces the same result as
updateCell():
my $cell = $doc->getCell($table, $row, $col);
$doc->setText($cell, "The text in the cell");
Both
getCellValue() and
updateCell() can be replaced by the
cellValue() shortcut, that is a read/write accessor to indivudual
cells. So:
my $value = $doc->cellValue("Sheet4", "B12");
$doc->cellValue("Sheet1", "P5", $value);
copies a value from one cell to another one in another table.
In this intro, the cells are assumed to be text-only. Of course, the code is
more complex with numeric cells, because the program have to get or set some
additional information, according to its data type.
OODoc::Text allows the program to create a new table, using the appendTable or
insertTable method. The following example appends a new table with 8 lines and
5 columns to the document.
my $table = $doc->appendTable("MyTable", 8, 5);
But this new table is (by default) a pure text table. It's possible to build
very sophisticated table structures, with an appropriate data type and a
special presentation for each cell. But, to complete this task, the
application must provide a lot of parameters. So, it's recommended to avoid
purely programmatic table construction, and to reuse existing table structures
and styles in template documents previously created with an ODF compatible
software.
Sections, subdocuments and hyperlinks¶
For sophisticated document structures, paragraphs and other text containers may
be included in sections. The API allows the applications to easily create or
retrieve sections, whith the
getSection(),
appendSection(), and
insertSection() methods. A given section may be either populated with a
local content or provided with an external link (file path or URL) in order to
include a subdocument. In addition, using
lockSection() and
unlockSection(), the programs can control the end-user write protection
of any section.
The following example (working with OOo 2.0) appends to a master document a new,
write-protected section including a new document which can be reached through
an internet link:
my $url = "http://jean.marie.gouarne.online.fr/doc/oodoc_guide.odt";
$doc->appendSection
(
"Getting Started",
link => $url,
protected => "true"
);
And, if an unfortunate end-user is barred from updating a section by a lost
password, the programmer can help with a single line such as:
$doc->unlockSection($section_name);
Of course, a section can host any local content instead of an external link.
my $section = $doc->appendSection("Section 1");
$doc->appendParagraph
(
attachment => $section,
text => "The first paragraph in the section",
style => "Standard"
);
Here, a section is created and receives a paragraph as its first content.
An existing set of content elements could migrate under a section. The next
example, more sophisticated, selects the list of all the elements that
hierarchically depend on the first level 1 title of the document and moves
these elements to a given section:
my @content = $doc->getChapterContent(0, level => 1);
$doc->moveElementsToSection("Section 1");
The sections are not the only places for using hyperlinks. The applications can
associate hyperlinks to any portion of text. The following example puts a
remote (http) link on every "OpenDocument" character string in a
given paragraph:
$doc->setHyperlink
($para, "OpenDocument", "http://www.oasis-open.org");
The target of an hyperlink may be a bookmark or a heading in the current
document or in another ODF document. For example, if the target is a bookmark
included in the same document, the link is the name of the bookmark with a
leading "#":
$doc->setHyperlink($para, "a string", "#MyMark");
When the target is a heading (i.e. a hierarchical title), the link is made of
the text of the heading, prefixed with "#" and suffixed by
"|outline".
If an hyperlink is aimed at any target belonging to another document (in the
local filesystem or elsewhere), you have just to concatenate the file path and
the internal path. The example below puts an hyperlink to a particular heading
located in a remote document:
$doc->setHyperlink
(
$para, "read the conclusion",
"http://somewhere.com/somewhat.odt#Conclusion|outline"
);
Manipulating variables, bibliographic entries, bookmarks¶
The OODoc toolbox provides easy read/write accessors to some useful objects that
can be included in OOo text documents.
If a text document contains a user-defined field, the corresponding value can be
read and updated. For example, if the user needs to increase a numeric by a
given value, the corresponding code could be:
$old_value = $doc->userFieldValue("FieldName");
$doc->userFieldValue("FieldName", $old_value + $added_value);
In addition, the OODoc API allows the user to "declare" new
user-defined fields if needed (see
setUserFieldDeclaration() in
OpenOffice::OODoc::XPath).
Any OpenDocument-compliant variable text field may be inserted in a document
through the
textField() method. The next example appends a paragraph
whose text content is "This document contains <page-count>
pages", knowing that the real page count will be dynamically displayed by
the office software:
my $p = $doc->appendParagraph
(text => "This document contains ");
$doc->appendElement($p, $doc->textField('page-count'));
$doc->extendText($p, " pages");
While the sequence above appends a text field at the end of a paragraph, the
setTextField() method may insert a text field anywhere within an
existing paragraph according to various positioning parameters. The example
hereafter creates a date field immediately after the last occurrence of the
substring "the current date is "; the 'after' option provides the
search string while the 'way' option specifies that it must be searched
backward:
$doc->setTextField(
$paragraph, 'date',
after => "the current date is ",
way => 'backward'
);
It's possible to get or set any property of a bibliography entry. An entry can
be selected by its identifier (as it appears for the end-user). The first
example below prints the title and the author of the first found occurrence of
a "[GEN99]" entry, while the second one creates (or updates) its
"ISBN" and "pages" properties:
# 1
my %properties = $doc->bibliographyEntryContent("GEN99");
print "Title = $properties{'title'}\n";
print "Author = $properties{'author'}\n";
# 2
$doc->bibliographyEntryContent
(
"GEN99",
isbn => 'xxxxyyyyzzzz',
pages => 254
);
In addition, a
getBibliographyEntries() method allows the user to
retrieve the full list of the entries included in a document.
An additional bibliography entry may be inserted within a paragraph using
setBibliographyMark(). As an example, the following instruction inserts
a new bibliography mark as a replacement of the first substring
"reference needed" that may occur after the 20th character in a
given paragraph:
$doc->setBibliographyMark (
$paragraph,
offset => 20,
replace => "reference needed",
attributes => {
identifier => "JDE",
title => "OASIS OpenDocument Essentials",
author => "J. David Eisenberg",
year => 2005,
isbn => "1-4116-6832-4"
}
);
We can put a bookmark in a paragraph containing a given string. Example:
my $paragraph = $doc->selectElementByContent("my search string");
$doc->setBookmark($paragraph, "MyMark");
The instruction above puts the mark at the beginning of the paragraph; however,
setBookmark() could put the mark at any position within the text,
according to optional parameters. To illustrate the positioning logic, the
following instruction puts the bookmark immediately after the first occurrence
of "xyz" that appear after the first 20 characters:
$doc->setBookmark(
$paragraph, "MyMark",
offset => 20,
after => "xyz"
);
Note that there are many possible positioning parameter combinations for
bookmarks and any other markup elements intended to be inserted within text
containers; the various possibilities are inherited from the
setChildElement() method, that is described in the
OpenOffice::OODoc::XPath manual page.
A bookmark (created either through OpenOffice::OODoc or through this Perl API)
can be used to retrieve a text element:
my $paragraph = $doc->selectElementByBookmark("MyMark");
Note that the insert position of text fields, bibliography marks, bookmarks, and
other markup elements may be specified using the same set of position
parameters and according to the same logic, that are inherited from the common
setChildElement() method, described in OpenOffice::OODoc::XPath.
Dealing with text AND metadata¶
Sometimes we must access both the text content and the metadata. So, we need two
OODoc::XPath objects : one OODoc::Document and one OODoc::Meta. And to avoid
collisions and inefficient I/O operations, we need to connect the 2 objects
with the same OODoc::File "server".
use OpenOffice::OODoc;
my $archive = odfContainer('myfile.odt');
my $content = odfDocument(container => $archive);
my $meta = odfMeta(container => $archive);
# process content and metadata
$archive->save;
In this case, the $content and $meta are explicitly linked to a common
container. As a consequence, when the
save() method of this container
is triggered, all the changes through them are made persistent.
There is an example of simultaneous access to content and metadata in the script
'set_title' (where some text content is used to generate a piece of metadata).
Manipulating graphics¶
The module OODoc::Image brings some functionalities that can be used against any
OO document. The following code (combining the capabilities of OODoc::Text and
OODoc::Image) selects the first paragraph containing the string
"OpenOffice" and attach an imported image to it.
my $p = $doc->selectElementByContent("OpenOffice");
die "Paragraph not found" unless $p;
$doc->createImageElement
(
"Paris landscape",
description => "Montmartre in winter",
attachment => $p,
import => "C:\MyDocuments\montmartre.jpg",
size => "5cm, 3.5cm",
style => "graphics2"
);
In a spreadsheet document, the same image could be attached to a cell instead of
a paragraph; to do so, the "attachment" option should be set to a
cell element, previously obtained using
getCell(). With the same
syntax, in a presentation document, the "attachment" should be a
draw page, previously selected using
getDrawPage(). A "page"
option allows the user to anchor an image to a page, instead of attaching it
to a text container.
In this example, the image is physically imported. But I could replace the
"import" parameter by a "link" one, in order to use the
image as an external link (cf. the "link" option when you insert an
image in OpenOffice.org). This link could use a local filesystem path as well
as a remote access path such as "
http://...".
My new image needs a style (called "graphics2" in my example) to be
presented. This style could be an existing one, but my program could create it
if needed, using an OODoc::Styles method (see below).
Any characteristic of an existing image can be read or updated using simple
methods. For example, it's easy to change the size and the position of my
image:
$doc->imageSize("Paris landscape", "10cm, 7cm");
$doc->imagePosition("Paris landscape", "3cm, 0cm");
The size and position strings indicate the used length unit. OODoc doesn't the
provided unit, so the application should ensure that only ODF-compliant units
are used. Possible units are, for example, "cm" (centimeter),
"mm" (meter), "in" (inch), "pt" (point).
The logical name of the image (here "Paris landscape") is the best way
to retrieve an image object, so it's a mandatory argument with the
createImageElement method. With OpenOffice.org Writer, each image is created
with an unique name (that is "Image1", "Image2", etc. if
the user doesn't provide a more significant one). But with OpenOffice.org
Impress, the images are unnamed by default. We recommend you to give a
significant name to each object that you want to process later by program,
knowing that if an object can be easily caught by program, it's potentially
reusable.
An image can be selected by his description (i.e. the text the end-user can edit
in the image properties dialog in OpenOffice.org). So, the following sequence
provides the list of images whose the description contains the string
"Montmartre":
my @images = $doc->selectImageElementsByDescription("Montmartre");
If you have to store and process a graphical content out of the end user's
editing software, you can export it as an ordinary file:
$doc->exportImage("Paris landscape", "/home/pictures/montmartre.jpg");
And you can use a symmetric importImage method to change the content of an image
element.
Managing styles¶
The OODoc::Styles allows the programmer to get any style definition, to change
it and, if really needed, to create new styles. In the first part of this
document, you can see an example of paragraph style creation. Unfortunately,
createStyle could drive you to heavy coding efforts, because a very
sophisticated style definition needs a lot of parameters and requires the
knowledge of a lot of ODF attribute names. So we recommend you to
systematically reuse existing styles (stored in ODF template documents used as
"style repositories" or in XML databases). The createStyle method
supports a "prototype" parameter that allows you to clone an
existing style, contained in the same document or in another one.
The next code sequence selects the "Text body" style of a document,
and uses it as a template to create a "My Text body" style in
another document, changing the font size only:
my $template = $doc1->getStyleElement("Text body");
$doc2->createStyle
(
"My Text Body",
family => "paragraph",
prototype => $template,
properties =>
{
"area" => "text",
"fo:font-size" => "12pt",
"fo:color" => odfColor("dark blue")
}
);
Here a "dark blue" color has been given to the text; but "dark
blue" is an arbitrary string, that must be present in a user-provided,
previously loaded color map; without this color map, the users must, at their
choice, either directly provide an hexadecimal, six-digit color code, with a
leading "#" (such as "#00008b", that is the translation of
"dark blue" in my installation), or get it through the
odfColor() function with 3 decimal RGB values as arguments.
Because a style is required for each image in a document, the OODoc::Document
brings a more user-friendly createImageStyle method. This method allows you to
create an image style without any mandatory parameter (excepted the name). So,
the "graphics2" style I invoked in a previous createImage example
could be simply created by:
$doc->createImageStyle("graphics2");
Without other indication, the module automatically creates a style with
"reasonable" values, so the image is really visible in the document.
Of course, the application could provide explicit values for some parameters
if needed. The following call, for example, provides specific values for
contrast, luminance and gamma correction:
$doc->createImageStyle
(
"graphics2",
properties =>
{
'draw:contrast' => '2%',
'draw:luminance' => '-3%',
'draw:gamma' => '1.1'
}
);
Styles are not made only to control the presentation of individual elements.
There are special styles for page layout. While these styles are described
with very specific data structures, the OODoc::Styles module contains some
methods dedicated to page styling.
Dealing with styles AND content¶
While the OpenOffice::OODoc::Document methods can process both the content
(text, complex structures and graphics) and the styles, it's not always
possible any style and any content through the same object in the same
session.
Each individual instance of ::Document wraps an indivudual part of an ODF
package. The default part is "content.xml", but all the named style
definitions are stored in the "styles.xml" part (in a few words, a
named style is a style which was designed in order to be used by more than one
content element; for example, any style which could be selected through the
style dialog box of a typical user-oriented office software is a
"named" style).
In order to avoid a lot of useless XML parsing, only one part at a time is
loaded. As a consequence, if the application needs to process content and
named styles during the same session, it must create 2 instances of ::Document
objects, associated with the same ODF container. Each instance must be
associated with the appropriate target. For example:
use OpenOffice::OODoc;
my $archive = odfContainer('myfile.odt');
my $content = odfDocument
(
container => $archive,
part => 'content'
);
my $styles = odfDocument
(
container => $archive,
part => 'styles'
);
After this sequence, the $styles object gives access to any named style while
all the document body can be processed through the $content object. Note that
in this last example, we could avoid the "part" option for the
"content" member of the package (because "content" is the
default).
Knowing that its always possible to process content, named styles and metadata
in the same session, we could instantiate a ::Meta object through
odfMeta() as well. So up to 3 connecting objects can be used as
interfaces for the same ODF file.
Of course, a single $archive->
save() can make persistent all the
changes made through all the connected objects.
Comments, questions and answers are welcome through the CPAN forum
http://www.cpanforum.com/dist/OpenOffice-OODoc
<
http://www.cpanforum.com/dist/OpenOffice-OODoc>
Bug reports should be sent using
http://rt.cpan.org/NoAuth/Bugs.html?Dist=OpenOffice-OODoc
<
http://rt.cpan.org/NoAuth/Bugs.html?Dist=OpenOffice-OODoc>
AUTHOR/COPYRIGHT¶
Developer/Maintainer: Jean-Marie Gouarne
<
http://jean.marie.gouarne.online.fr>
Contact: jmgdoc@cpan.org
Copyright 2004-2010 by Genicorp, S.A. <
http://www.genicorp.com>
Initial English version of the reference manual by Graeme A. Hunter
(graeme.hunter@zen.co.uk).
License: GNU Lesser General Public License v2.1