=head1	NAME

OpenOffice::OODoc::Image - Image manipulation methods

=head1	DESCRIPTION

The OpenOffice::OODoc::Image class is a derivative of
OpenOffice::OODoc::XPath designed for the manipulation of graphics
objects contained in documents. It mainly allows you to modify the
size and position of an image and exchange its content outside the
document.

This class should not be explictly used in an ordinary application, because
all its features are available in the OpenOffice::OODoc::Document class, in
combination with other features. So, each time an application needs to get
an image-focused access to a document, it should use the general odfDocument()
constructor instead of the odfImage() one.

Practically, the present manual is provided to describe the image-container
processing features of OpenOffice::OODoc::Document (knowing that these
features are technically supported by the OpenOffice::OODoc::Image
component of the API).

Knowing that an image is displayed or printed according to a style,
the OpenOffice::OODoc::Image features should be used in conjunction with
the OpenOffice::OODoc::Styles ones. The OpenOffice::OODoc::Document class
allows the user to invoke text-, style- and image-focused methods from
the same object.

All the methods described here can equally be used with images contained in
style sheets (headers, footers) as with images contained in the body of a
document. It can therefore be associated just as well with a "styles.xml"
member as with a "content.xml" member of an OpenOffice.org file.

This class works with all types of document (text, presentation,
etc.).

For all methods where the first argument is given below as "image",
it is (unless otherwise stated) either the name of an image as it
appears to the end user when editing its properties in
OpenOffice.org or StarOffice or the image's element reference
obtained previously by the program. All these methods fail and
return a null value (or in some cases produce an error message) if
the argument does not correspond to a known image contained in the
document.

Note: This module is not an image-processing tool. It can insert or
remove images, and control the way the images are displayed in the
documents. But it can't process the images themselves.

=head2	Methods

=head3	Constructor : OpenOffice::OODoc::Image->new(<parameters>) 

	Short Form: odfImage(<parameters>)

	This constructor should not be explicitly used in ordinary applications
	knowing that all the features of the returned object are inherited by
	any Document object.

        See OpenOffice::OODoc::XPath->new for commun arguments.

        The XML member loaded by default is 'content.xml', but only member
        => 'styles' is required if you want to work with page background
        images. Example:

        	my $doc = odfImage
        		(
        		file	=> 'my_presentation.odp',
        		part	=> 'styles.xml'
        		);

	Real applications should not expressly use this constructor,
	knowing that the compound OpenOffice::OODoc::Document (whose
	usual constructor is ooDocument) inherits all the features
	of OpenOffice::OODoc::Image.
			
=head3	createImageElement(name [, options])

        Creates an element which represents an image and inserts it into the
        document according to given parameters. The image element created is
        only an anchor. It then needs to have a graphical content loaded
        into it and, if needed, be given parameters using other methods.

        Example:

        	$doc->createImageElement("Logo");

        inserts a default image element called "Logo".

        Normally, the image name is unique in an OpenOffice.org document but
        no checking of its uniqueness is performed here. Things you should
        know, however, are:

            - if several images have the same name, one only of them can be
            retrieved and handled by methods which use the name to identify
            them. It is almost impossible to know which of them it will be,
            without a thorough knowledge of the OpenOffice.org format and
            the internal logic of OODoc.
            - if the document is subsequently read and saved by
            OpenOffice.org (which controls the uniqueness of image names),
            sequential numbers will be given to all but one of the repeated
            names in order to make them unique.

        Attributes can be passed in pairs [parameter => value]. Such as:

        	style		=> image style name

        It should be noted that an image should normally be associated with
        a graphic style. The presence of a style is not obligatory when
        calling createImageElement (and this is not checked), but the image
        should preferably be actually linked to an existing style before
        displaying or printing the document. See OpenOffice::OODoc::Styles
	for style creation or, better, OpenOffice::OODoc::Document for image
	styles.

        	attachment	=> anchor element

        indicates if the image is attached to a text element (for ex. a
        paragraph), and which one. This parameter must be an existing
        element reference (obtained, for example, using getElement or
        selectElementxxx). It is useless if the image is linked to a page.
	The OASIS OpenDocument specification doesn't provide the list of
	possible attachments for an image, and OpenOffice.org make some
	differences in this area between the different document classes.
	For example, OOo Writer doesn't display images which are directly
	attached to table cells, while OOo Calc does (in text documents,
	an image which appears in a table cell is attached to a paragraph,
	possibly empty, belonging to the cell; see the example below).

        	page		=> anchor page

        If this parameter is used, it indicates that the image will be
        anchored to a page, and the given value is a page number. It does
        not matter if, when createImageElement is called, this number is
        beyond the end of the document or not. If the content class of the
	document is "presentation" (Impress) or "drawing" (Draw), then the
	page option is mandatory and must be either the visible name or the
	element reference of an existing draw page. In a "text" content,
	all that matters is that the particular page exists when it is opened
	by OpenOffice.org and if this parameter is absent, the image is
	anchored to a paragraph.

        	position	=> coordinates

        This parameter indicates the x,y coordinates of the image in
        relation to its anchor point. By default and generally, if the page
        parameter is given, the origin (0,0) is the top left corner of the
        physical page. When attached to a text element, if there is no given
	position, the image is appended to the text.

	Coordinates go from left to right and top to bottom, however
	everything really depends on the image style. Coordinates should be
	given here in the form of a string "x,y", and the default unit is
	centimeters. You can choose millimeters instead by attaching the
	usual abbreviation, such as "12.5cm, 35mm" which is the same as
	"125mm, 3.5cm" or "12.5,3.5", etc. The point ("pt") unit is allowed
	as well.

        	size		=> size

        The image's size (width, height) is given here in the same syntax as
        for position. Caution: if no size is given, you must not assume that
        the image will be spontaneously displayed in the document in a
        convenient size. Remember that the "original" size of the image is
	not automatically selected by default; the application must provide
	a display size. If an image is to be displayed according to its
	original size which is not known in advance, you can get it using,
	for example, the imgsize() function of Image::Size (this function
	returns the size in points, so the "pt" unit must be expressly
	selected unless you convert the size in centimeters).

        	description	=> label

        This optional parameter gives the descriptive text (long label) for
        the image as it will appear to the end user when editing the image's
        properties.

        	link		=> link

        The link parameter contains a reference to the image's physical
        content which can be inserted into an OpenOffice.org file (internal
        link) or a reference to an external file or even the URL of an image
        accessible using a communication protocol supported by the
        OpenOffice.org suite.
	
	Remember that, with OpenOffice.org, physical images are "referenced",
	and not "loaded" into XML elements. The reverse of course would not
	only be against "good practice" but would result in outrageously
	large documents. According to the OpenDocument specification, the
	conforming applications could embed base-64-encoded graphics in the
	XML elements, but this option is not used when you insert an image
	in a document through the OOo GUI.
	
	If the target link is unavailable when the document is displayed,
	an error message is displayed in place of the image. (See imageLink
        about links.) This parameter is useless if import is given.
	
	Relative paths in the local filesystem are allowed, but should be
	used with care, due to differences between operating systems... and
	between editing applications (for example, in a Unix environment,
	OOo 2.x requires "../image.jpg" while OOo 1.x allows "image.jpg" for
	a link to an image file in the current directory).

        	import		=> image file

        The presence of this parameter indicates that the image content
        should be imported from an external file and, implicitly, that the
        image link (which it is useless to give here) points to the image
        imported into the OpenOffice.org file. The import will only be made
        when all the updates are validated by a save(). See importImage()
        about importing images. An imported image is *not* embedded in the
	XML image element; it's always referred to through a link, and stored
	in a separate, non-XML member of the ODF archive. However, with the
	"import" option, the appropriate internal link is automatically
	created and the new member, containing the image, is automatically
	built later, when the save() method is executed from the current
	document (provided that the image file is available). 

        For those who know the appropriate XML vocabulary, there are other
        parameters you can pass. Parameters other than those described above
        are written to the image's XML element as is and without any checks.

        All of these attributes, and others, can be read or modified later
        by other methods.

        We would discourage you from relying on the default choices in a
        serious application, but it is still a possibility. With no
        parameters (other than mandatory image name), the createImageElement
        method chooses its own often arbitrary course according to the
        following circumstances:

            - if the OODoc::Image object is associated with a document body
            (document-content) then a new paragraph is created at the end of
            the document and the image is inserted into this paragraph
            (appears at the end of the text). Repeated image creations
            without parameters will therefore add images one after the other
            at the end of the document.
            - if the OODoc::Image object is associated with a background
            (document-styles) then it tries to create a paragraph in the
            first available header and insert the image into it. If no page
            style contains a header, the same is attempted in the first
            available footer. If there is no footer either, the creation
            fails with the message "No valid attachment".

        This method otherwise tries to be "intelligent" whenever the set of
        parameters is incomplete. If the results are useful, then the rest
        is up to you...

        The method returns the new image element's reference (undef if it
        fails).

        The following example attaches an image to a paragraph, gives it a
        size, loads its content into it from an external file and attributes
        a style to it which has been defined elsewhere. You will note that
        this example combines an OODoc::Image method (createImageElement)
        with an OODoc::Text method (getParagraph). This means that, here,
        the $doc object is a OODoc::Document class. See also
        createImageStyle in OODoc::Document.

        	$doc->createImageElement
			(
        		"Landscape",
        		description	=> "Kilimanjaro in winter",
        		attachment	=> $doc->getParagraph(4),
        		size		=> "5cm, 3.5cm",
        		style		=> "gr1",
        		import		=> "C:\Images\Landscape.jpg"
        		);
			
	The same image element could be inserted in a table cell. To do
	so, in a spreadsheet document, the "attachment" option could be
	set with a $doc->getCell($table, $row, $column) value. But the
	present version of OpenOffice.org doesn't allow direct cell
	attachments in text documents; the image element must be attached
	to a paragraph which is in turn attached to the target cell. So
	a possible approach consists of 1) issuing a setText($cell, "") in
	order to ensure the target cell contains an empty text paragraph
	and 2) provide an "attachment" option set to
	$doc->getCellParagraph($cell) in order to anchor the image to this
	paragraph.

        Remember: creating an image element will only make that image appear
        in the document if 1) the image has a valid link which points to a
        valid image, 2) the corresponding graphics file exists (loaded
        possibly using importImage) in the archive if it is an internal
        link, and 3) the image has a style actually defined elsewhere
        (either pre-existing, created using the createStyle method of
        OODoc::Styles, copied from another document using replicateElement,
        or coming from another source).

=head3	exportImage(image [, destination])

        Exports the content of an image contained in a document if the
        OODoc::Image object was linked to a file when it was created (with
        file or archive parameters passed to the new constructor).

        The first argument is either the name of the image (as it would
        appear to the end user in the image's properties in OpenOffice.org),
        or the image element's reference if the program already has it.

        The second optional argument is the destination file. Example:

        	$doc->exportImage("Logo1", "C:\My Documents\logo.jpg");

        It is up to the application to choose an appropriate extension for
        the exported file (.jpg, .gif, .png, etc.). You can easily find out
        which extension using the imageLink accessor.

        Without the second argument, the image file is created in the
	current directory, and its name is the name of the image in the
	document, with an extension depending on the format (.jpg, .png,
	etc), according to the information stored in the document (but
	the format is not checked). Be careful, the export fails unless 
	such a construct provides a valid file name for the operating system.
	If the image is unnamed in the document, exportImage() tries to
	build a path/name which replicates the internal path/name of the
	image in the archive and to use it under the current directory
	(this path normally begins with "Pictures/").

        Caution: this method only exports what is exportable i.e. internal
        images (physically contained in the file). It has no effect if used
        with an image inserted by an external link into the document.

=head3	exportImages([options])

        Exports all or part of the images contained in a document.

        By default, and with no parameters, each internal image is exported
        to a file whose access path is the same as it would be if using
        exportImage. This behaviour can be changed by parameters passed
	in hash form (parameter => value).
	
	Possible parameters are as follows:

        	selection	=> filtering of image names (regex)
        	filter		=> filtering of image names (regex)
        	name		=> filtering of image names (regex)
        	target		=> path and/or basic filename
        	path		=> path and/or basic filename
        	suffix		=> extension to be given to filenames
        	extension	=> extension to be given to filenames
        	start_count	=> begin count indicator

        The "filter", "selection" or "name" parameters allow you to export
        only those images whose names match the given regular expression.
        Such filtering works on the name as the document "knows" it, i.e. as
        it appears to the end user in the image's properties within the
        document. It is not a technical filter and does not allow, for
        example, selection of images according to their file type.

        The "target" or "path" parameters allow you to choose the access
        path and basic filename for exported files (e.g.
        "/usr/local/images/img"). If given, a sequential number will
        automatically be added to the basic filename to identify each file.
        The "suffix" or "extension" parameters allow the application to
        force a common extension for each file instead of leaving the
        extension as it existed in the archive (which normally identifies the
	physical image type).

        By default, the sequential numbers given to filenames (between basic
        name and extension) are reset to zero each time exportImages is
        called. An application can however force the numbering to start at a
        different value using the "start_count" parameter.

        In a list context, this method returns a list of exported files
        which the application can use later. In a scalar context, it returns
        the number of exported files.

=head3	getImageElementList()

        Returns the list of all image elements in the active context. If the
        current OODoc::Image object is associated with document-content,
        this will be the images contained in the body of the document. If
        associated with document-styles, this will be the images linked to
        headers and footers.

=head3	getImageElement(image)

=head3	getImageElement(element)

        Returns the element which corresponds to the image whose name is
        given as an argument. This name is usually unique as OpenOffice.org
        does not allow the user to give two files the same name in a
        document. It is the name which appears in the "Options" tab when
        editing the object's properties in OpenOffice.org Writer, or in the
        "Name object" dialog box when you right-click an image in
        OpenOffice.org Impress. Returns undef if the image is not found.

        Can also be used as a check method by specifying an element as the
        argument instead of a name. In this case, the given element is
        simply returned without modification if it is indeed an image or
        undef if not.

        Caution: images do not always have names. OpenOffice.org Writer gives
	default names to images (e.g. Image1, Image2, ...) if the user does
	not deliberately name them. This is not the case in Impress.

=head3	getInternalImagePath(image)

        This method returns the given image's link (see definition of "link"
        in the section on imageLink), but only if it is an internal link in
        a form which is directly usable by a zip archive management tool
        (without the initial "#").

=head3	imageAttribute(image, attribute [, value])

        Accessor which allows you to check or modify (even create) an
        image's XML attributes directly. The attribute is modified or
        created if a value is given as the third argument. If not, it
        returns the current value of the attribute if found, or undef if
        not. The name and value of the attribute must be given according to
        the OpenOffice.org vocabulary.

        This generic accessor remains invisible to most applications as
        specialist accessors are available for the most useful attributes
        (e.g. imageLink, imageName, etc.).

=head3	imageDescription(image [, text])

        Returns an image's description, or if the "text" argument is given,
        replaces it. This description corresponds to the optional text which
        appears in the Options tab when editing the image's properties in
        OpenOffice.org. It is not used in Impress or Draw documents.

=head3	imageLink(image [, link])

        Reads or modifies an image's link. A link is the address of the file
        which physically contains the image.

        If working with an image loaded into the document (often but not
        always the case), the link is internal and the file is physically
        stored in the zip archive containing the document. In this case, the
        link is written as "#Pictures/xxxx". It corresponds to what the user
        would see if opening the file using a zip archive tool instead of
        opening it in OpenOffice.org.

        If working with an external image, the link is then the URL of the
        image.

        The same method allows you to read and modify the link. If a second
        argument is given, it cancels and replaces the existing link, or
        creates a link if the image was still "empty".

        Example:

        	$doc->imageLink("Logo", "http://www.mysite.com/logo.png");

        Caution: the actual physical existence of a valid image which
        corresponds to the link is not checked.

=head3	imageName(image [, name])

        Reads an image's name, or if the second argument is given, replaces
        it.

        Returns undef if the first argument (name or reference) is not an
        image.

=head3	imagePosition(image [, x, y])

        Allows you to read or modify the coordinates of an image in relation
        to its anchor point. Coordinates are returned in the form of a pair
        of values.

        Example:

        	my ($x, $y) = $doc->imagePosition("Landscape");

        If the coordinate arguments are given, they replace the image's old
        coordinates.

        Caution: coordinates are not numeric values in the classic sense of
        the word. They are character strings starting with numeric values
        and ending with units of measure (normally "cm" or "mm"). If an
        application passes only numeric arguments without giving a unit of
        measure, the default unit is assumed to be the centimetre.

        Example:

        	$doc->imagePosition("Landscape", "2.5cm", "5.125cm");

        Normally, coordinates are measured from left to right and from top
        to bottom starting from the point of reference. The point of
        reference is normally the top left corner of the page or paragraph
        to which it is anchored (depending on the type of anchorage). All
        this can depend on the page style.

=head3	imageSize(image [, height, width])

        Allows you to read or modify the display size of an image. Returns
        the height and width as a pair of values. If height and width
        arguments are provided, they replace the image's old size.

	Note that this method deals with the display size only, and ignores
	the original size of the image; in other words, it doesn't change
	anything in the graphic object itself.

	Caution: it is up to the application to maintain the aspect ratio of
	the image if needed.

	See the "size" option about the createImageElement() method.

        See imagePosition() about measure formats.

=head3	imageStyle(image [, style])

        Returns the name of the image's current style, or changes this style
        if the second argument "style" is given. In the second case, the
        presence or pertinence of the called style is not checked. This can
        otherwise be created or imported later.

=head3	importImage(image, filename)

        Loads an image's content from an external file.

        Example:

        	$doc->importImage("Image1", "C:\Images\Portrait.jpg");

        This import cancels and replaces any previous image content, if any.

        The first argument is either the image's name (as the user would see
        it) or the image's corresponding element reference. In any case, the
        image element must already exist, created if necessary using
        insertImageElement().

	The second argument is the full path of the image file to be
	imported and associated to the ODF image object. If this argument is
	omitted, importImage() assumes that the full path of the needed
	resource file is indicated by an external link already associated
	with the image object in the document (see imageLink).

	Obviously, the imported file should preferably be in a graphic format
	supported by most office software products, but this method actually
	allows you to import anything, including data which could not be
	displayed.

        Caution: this method does not carry out the import immediately and
        does not check for the presence of the file to be imported. It only
        sends the request to the associated OODoc::File object (via its
        raw_import method) which performs the operation at the next save()
        call. As a consequence, the image file is needed later, but its
	availability is not required by the importImage() method itself.

=head3	insertImageElement(name [, options])

        See createImageElement.

=head3	isImage

        Method added to OpenOffice::OODoc::Element class objects by the
        OODoc::Image package and is an element method rather than a document
        method. Allows you to "ask" an element if it is an image.

        Example:

        	print "This is an image" if $element->isImage;

=head3	removeImageDescription(image)

        Deletes an image's optional image description.

=head3	selectImageElementByDescription(expression)

        Returns the first (or only) image (if found) which has an image
        description matching the provided regular expression.

	See also selectImageElementsByDescription().

=head3	selectImageElementByLink(link)

        Allows you to select an image element by its link (as in imageLink)
        instead of by its name. The link can be an approximation and
        represented in this case by a regular expression.

        It should only be used if you are sure that the link is unique in
        the document. This is not normally the case, as many images can
        share the same content. Conversely, the returned element is the
        first image, in the physical XML order, which has the given link
        (and not necessarily in the logical order of the document).

        Returns undef if no image has the given link and therefore allows
        you to find out if a particular target (e.g. URL) is used in the
        document.

        Note: if an application needs to get a list of individual or
        multiple images which share the same target, the easiest way is to
        loop through the list returned by getImageElementList() and perform an
        imageLink() on each element.

	See also selectImageElementsByLink().

=head3	selectImageElementsByDescription(expression)

        Returns a list of images whose image descriptions match the given
        regular expression.

=head3	selectImageElementsByLink(expression)

        Returns a list of images whose internal or external links match the
        given regular expression.

        Allows you, for example, to get a list of image elements which share
        the same physical image file or even those which use a particular
        transport protocol to access these images.

        Example:

        	my @webimages = $doc->selectImageElementsByLink("^http:");

        allows you to get a list of images referred to through an HTTP URL
	(i.e. which will not be visible if the user's machine is not connected
	to the internet).

=head3	selectImageElementsByName(expression)

        Returns a list of images whose names match the given regular
        expression.

=head2	Properties

        No variable is exported.

        There is a static class variable which contains the description of a
        default image style (in hash form):

        	%OpenOffice::OODoc::Image::DEFAULT_IMAGE_STYLE

        This hash is not used directly by the module itself (which offers no
        styles functions), but it is available to any application which
        needs to create image styles using either XPath base methods or the
        Styles module. Its structure is exactly the same as the parameters
        hash expected by the createStyle method. By default, it is
        automatically used by the createImageStyle method of the Document
        module.

=head1	AUTHOR/COPYRIGHT

Developer/Maintainer: Jean-Marie Gouarne L<http://jean.marie.gouarne.online.fr>

Contact: jmgdoc@cpan.org

Copyright 2004-2009 by Genicorp, S.A. L<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

=cut
