ODF::lpOD::Style(3)

NAME
ODF::lpOD::Style - Styles management

DESCRIPTION
This manual page describes the "odf_style" class and its specialized derivatives.

"odf_style" is an alias for "ODF::lpOD::Style".

A style object controls the formatting and/or layout properties of a family of content objects. It's identified by its own name and its family.

The lpOD API to update the properties of existing styles, and to replicate the features of existing styles. It allows the user to build new styles from scratch as well.

The full styling of a graphically sophisticated document could require a lot of complex code, because a lot of layout graphical rendering options are available. As a consequence, it's recommended to reuse and customize existing styles each time it's possible, instead of hardcoding fully new styles, in order to maintain a reasonable ratio between the style related and the content related coding efforts.

Common style features
Any style is created through a common odf_create_style() function with the family as its mandatory first argument. A name, that is the identifier of the style in the given family, is generally required. So, a typical style creation instruction looks like:

    $s = odf_create_style('text', name => 'MyTextStyleName');

The create() constructor of the "odf_style" class may be used instead of the odf_create_style() functional constructor, so the instruction below produces the same effects as the previous one:

   $s = odf_style->create('text', name => 'MyTextStyleName');

This example creates a named text style without any property. The properties are optionally passed as named parameters.

Note that in order to be really available in a document, a style, once created, must be registered in this document using insert_style() or "register_style", that is a "odf_document" method, introduced below.

Additional named parameters may be required according to the family. An optional "parent" argument, whose value is the name of another common style of the same family (existing or to be created), can be provided to "odf_create_style", knowing that a style inherits (but can override) all the properties of its parent. A "display name" additional parameter may be provided; if set, this parameter designates a visible name that may differ from the internal name. It's possible to copy (instead of inherit) all the properties of an existing style of the same family, through a "clone" option, knowing that "clone" and "parent" are mutually exclusive options. The code example below produces two text styles whose properties are the same as "MyTextStyleName", but the first one will be affected by later changes of the base style while the second one is independent:

   odf_create_style('text', name => 'NewStyle1', parent => 'MyTextStyleName');
   $proto = doc->get_style('text', 'MyTextStyleName');
   odf_create_style('text', name => 'NewStyle2', clone => $proto);

An effective style name, unique for the family, is required as soon as the style is attached to a document, unless it's inserted as a default style. This name may be set or changed with set_name() after the style creation. When a style is used as a default style, its name and display name are meaningless and ignored. The family and the name constitute the absolute identifier of a style in a document.

The parent of an existing style may be read or changed using the style-based get_parent_style() or set_parent_style() method. Beware that get_parent_style() is not the same as get_parent(); the last one is a generic, low level utility method (see ODF::lpOD::Element).

get_parent_style() returns the name of the parent style, if any. This name may be used to retrieve the parent style object with the document-based get_style() method. Symmetrically, the argument of set_parent_style() should be a style name (if this argument is a valid style object, lpOD tries to replace it by its name).

Note that an automatic style can't be used as the parent of another (common or automatic) style; a style can inherit from a common style only. However, lpOD will not warn if you specify the name of an automatic style (or the name of a not yet registered style) as a parent, knowing that you are allowed to create, change or move the parent style later.

Some styles may have a class property, that is an informative attribute, and that should not be confused with the family. A family is an application- defined property, used in order to identify a set of styles belonging to various families, for retrieval needs.

When attached to a document, a style provides a get_parent_styles() method that returns the full set of inherited styles, if any. Knowing that this method works in the context of a document where the parent styles are supposed to be registered and available, the returned list is made of style objects, not style names. The main purpose of this method is to allow the applications to check and, if needed, to extract all the dependencies of a given style in order to replicate it in another document.

The register a new style in a document, the generic insert_element() and append_element() method are not appropriate. The document-based insert_style() method, that partly hides the complex ODF style storage logic, must be used instead:

   $doc->insert_style($s);

insert_style() requires a style object as its only one mandatory argument. It's return value is the style itself.

Remember that register_style() is an alias of insert_style().

Alternatively, it's possible to register a style using the register() method of the "odf_style" class. So, the two following instructions, assuming that $doc is a "odf_document" and $s is a "odf_style", are equivalent:

   $doc->register_style($s);
   $s->register($doc);

Note that the register() method of "odf_style" allows the same optional parameters as the insert_style() or register_style() document-based method, provided that these parameters come after the mandatory argument that specifies the target document.

A style should not be registered in a document when it's already registered in another document. If you need to replicate a style in multiple documents, you should make copies:

   $style->clone->register($_) for @many_documents;

A style may be created "in place" by insert_style() if the first argument is an array ref instead of an existing style element. The array ref must contain the arguments of odf_create_style() in the same order. So the two instructions below (that create and register a text style whose font weight is bold) are equivalent:

   $doc->insert_style(
        odf_create_style('text', name => "MyText", weight => 'bold')
        );
   $doc->insert_style(['text', name => "MyText", weight => 'bold']);

An optional boolean parameter whose name is "default" is allowed with insert_style(); if provided and set to "TRUE", this parameter means that the style is registered as a default style. A default style is a style that automatically applies to elements whose style is not explicitly specified. A document can contain at most one default style for a style family, so any registration of a default style replaces any existing default style of the same family. So the following example sets a default paragraph style whose alignment rule is 'justify':

   $ps = odf_create_style('paragraph', align => 'justify');
   $doc->insert_style($ps, default => TRUE);

Note that the instruction below is equivalent:

   $ps = odf_create_style('paragraph', align => 'justify')
            ->register($doc, default => TRUE);

Such a default style definition means that, in the document, every paragraph without specified style will be justified.

All styles can't be used as default styles. Default styles are allowed for the following families: "paragraph", "text", "section", "table", "table column", "table row", "table cell", "table page", "chart", "drawing page", "graphic", "presentation", "control" and "ruby".

An existing style may be retrieved in a document using the get_style() document-based method. This method requires a family as its first argument and allows a style name as a second, optional argument. If the name is missing, this method tries to retrieve the default style for the given family, if any.

The following example extracts a paragraph style, so-called "MyParagraph", from a document and attaches a clone of this style as a default style of another document; the old default paragraph style of the target document (if any) is automatically replaced:

   $ps = $doc1->get_style('paragraph', 'MyParagraphStyle')->clone;
   $doc2->insert_style($ps, default => TRUE);

These two instructions may be replaced by the following:

   $doc1->get_style('paragraph', 'MyParagraphStyle')
            ->clone
            ->register($doc2, default => TRUE);

Knowing that a style may be "automatic" or not, and that it may be stored in the "CONTENT" or "STYLE" part of a document, insert_style() silently selects the options that work in most typical situations according to the style family. However, it's sometimes useful or necessary to store a style in a specific, non default way. To do so, insert_style() (and its derivatives) allows the following additional options:

•   "automatic": boolean; if "TRUE", the style is stored as automatic, if "FALSE", it's stored as common, and if "undef", it's stored according to the lpOD's choice (that depends on the style family);

•   "part": may be "CONTENT" or "STYLE" (note that as soon as the storage part is "CONTENT", the style will be automatic, whatever the value of the "automatic" parameter, if any).

These two last options are ignored if "default" is "TRUE".

Now, back to the style customization.

While a style is identified by name and family, it owns one or more sets of properties. A style property is a particular layout or formatting behavior. The API provides a generic set_properties() method which allows the user to set these properties, while get_properties() returns the existing properties as an associative array.

However, some styles have more than one property set.

As an example, a paragraph style owns so-called "paragraph properties" and/or "text properties" (see below). In such a situation, an additional "area" parameter, whose value identifies the particular property set, with set_properties(). Of course, the same "area" parameter applies to get_properties().

Some styles allow the applications to specify a background. Such a background is sometimes characterized by the RGB, 3-bytes hexadecimal code of an arbitrary color, with a leading "#". However some styles allow the use of background image instead of or in combination with a color. In order to deal with these possibilities, a set_background() is provided; this method (which works with some style objects only) is used with a "color" and/or a "url" named parameters. The "color" value range is #000000-#ffffff, while "url" should be set to the URL of the graphic resource. If "url" is set, some additional optional parameters may be provided, in order to control the way the image is displayed in the background, namely:

•   "position": a string that specifies the horizontal and vertical positions of the image, through one or two comma-separated words (in any order) among "center", "left", "right", "top", "bottom" (default: "center");

•   "repeat": specifies whether a background image is repeated or stretched, whose possible values are ``no-repeat`` meaning that the image should be displayed once, ``repeat`` to repeat the image in order to fill the whole background, and ``stretch`` to extend the image in order to fill the whole background;

•   "opacity": the percentage of opacity;

•   "filter": an application-specific filter to that is used to load and process the graphic file, according to the image format.

To remove the background color or image (i.e. to set the background to the default, that is transparent), the user just have to call set_background() with "color" and "url" set to "undef".

A style that apply in some way to a rectangular area (ex: shape, frame, paragraph) other than a page may have visible borders and a shadow. Borders are specified using "border xxx" attributes where "xxx" is either "left", "right", "top" or "bottom"; if all the borders are the same, a single "border" property is convenient. The value of a border property is a 3-part string that describes the thickness, the line style and the line color (according to the XSL/FO grammar), like "0.1cm solid #000000" for a one millimeter solid black line. The shadow is specified through a "shadow" property whose value is a 3-part string describing the color and the size, like "#808080 0.18cm 0.18cm".

A style can be inserted as either common (or named and visible for the user of a typical office application) or automatic, according to a boolean "automatic" option, whose default value is "FALSE". A common style may have a secondary unique name which is its "display name", which can be set through an additional option. With the exception of this optional property, and a few other ones, there is no difference between automatic and common style definitions. However, they are two major semantic differences. First, an automatic style can't be inherited. Second, the automatic styles are not displayed as available and reusable styles in the graphical user interface of a typical interactive office software.

Defaults styles and common styles are automatically inserted in the "STYLES" document part. But automatic styles may be inserted, at the user's choice, in "CONTENT" or "STYLES". The default is "CONTENT" but "STYLES" may be specified through a "part" optional parameter of insert_style(). The user must check that any automatic style is inserted in the same document part as the element that uses it (so, an automatic style must be inserted in "STYLES" if it's used by another style defined in this part).

Of course, a style is really in use when one or more content objects explicitly reference it through its style property.

The API allows the user to retrieve and select an existing style by name and family. The display name, if set, may be used as a replacement of the name for retrieval.

Once selected, a style could be removed from the document through a standard level 0 element deletion method.

Note: For some style properties that specify a color (such as a background color, a font color, and so on), the color value may be provided as a symbolic name, such as "yellow", "navy blue" or "dark slate grey" instead of a numeric code. The allowed color names are those defined in standard Xorg RGB files. However, the user can add custom color names, thanks to a load_color_map() utility, introduced in ODF::lpOD::Common.

Text styles
A text style can be defined either to control the layout of a text container, i.e. a paragraph, or to control a text range inside a paragraph. So the API allows the user to handle two families of text styles, so called text and paragraph. For any style in the text or paragraph families, the text class is recommended.

  Text family
A text style (i.e. a style whose family is "text", whatever its optional class) is a style which directly applies to characters (whatever the layout of the containing paragraph). So, it can bear any property directly related to the font and its representation. The most used properties are the font name, the font size, the font style (ex: normal, oblique, etc), the text color, the text background color (which may differ from the common background color of the paragraph).

A text style may apply to any text span in any text paragraph. However some ODF editing or viewing applications don't fully support them in some situations. For example, OpenOffice.org doesn't currently allow the use of common text styles with spreadsheets, while it allows common and automatic text styles in text documents.

A text style can apply to one or more text spans; see the "Text spans" section. It can be used as the default text style of a document. In addition, an existing text style may be reused to set the text properties of a paragraph style (see below).

The example hereafter creates a text style, so called "My Colored Text", using Times New Roman, 14-sized navy blue bold italic characters with a yellow background:

   $s = odf_create_style('text',
                        name            => 'MyColoredText',
                        'display name'  => 'My Colored Text',
                        font            => 'Times New Roman',
                        size            => '14pt',
                        weight          => 'bold',
                        style           => 'italic',
                        color           => '#000080'
                        );
   $s->set_background(color => '#ffff00');

This new style could be inserted using insert_style() then retrieved and changed later using get_style() then the set_properties() method of the style object. For example, the following code modifies an existing text style definition so the font size is increased to 16pt and the color turns green:

   $s = $document->get_style('text', 'MyColoredText');
   $s->set_properties(size => '16pt', color => '#00ff00');

The set_properties() method may be used in order to delete a property, without replacement; to do so, the target property must be set to "undef".

Note that set_properties() can't change any identifying attribute such as name, family or display name.

The lpOD level 1 API allows the applications to set any property without ODF compliance checking. The compliant property set for text styles is described in the section §15.4 of the OASIS ODF specification. Beware, some of them are not supported by any ODF text processor or viewer.

The API allows the user to set any attribute using its official name according to the ODF specification (§15.4). For example, the properties which control the character name and size are respectively "fo:font-name" and "fo:font-size". However, the API allows the use of mnemonic shortcuts for a few, frequently required properties, namely:

•   "font": font name;

•   "size": font size (absolute with unit or percentage with '%');

•   "weight": font weight, which may be "normal", "bold", or one of the official nine numeric values from 100 to 900 (§15.4.32);

•   "style": to specify whether to use normal or italic font face; the legal values are "normal", "italic" and "oblique";

•   "variant": may be set to 'small-caps' in order to display the text a small capitalized letters;

•   "color": the color of the characters (i.e. foreground color), provided as a RGB, 6-digit hexadecimal string with a leading '#';

•   "underline style": to specify if and how text is underlined; possible values are "solid" (for a continuous line), "dotted", "dash", "long dash", "dot dash", "dot dot dash", "wave", and "none";

•   "underline": same as "underline style";

•   "underline width": the width of the underline; possible values are "auto", "normal", "bold", "thin", "dash", "medium", "thick";

•   "underline color": the color that is used to underline text (as a color code or symbolic color name); if the value is 'font-color', the current text color is used for underlining;

•   "underline mode": specifies whether underlining is applied to words only or continuously; if the value is 'words' or 'skip-white-space', the spaces are not underlined, even if they are included in the underlined text span, while the whole text span is underlined if the value is 'continuous' (that is usually the default if this property is not set);

•   "display": to specify if the text should by displayed or hidden; possible values are "true" (meaning visible) "none" (meaning hidden) or "condition" (meaning that the text is to be visible or hidden according to a condition defined elsewhere).

•   "language": to specify a language code (ex: 'de' for German, 'fr' for French);

•   "country": to specify a country code (ex: 'DE' for Germany, 'FR' for France).

A text style may have a background color, but not a background image.

  Paragraph family
A paragraph style apply to paragraphs at large, i.e. to ODF paragraphs and headings, which are the common text containers. It controls the layout of both the text content and the container, so its definition is made of two distinct parts, the text part and the paragraph part.

The text part of a paragraph style definition may have exactly the same properties as a regular text style. The rules are defined by the §15.4 of the OASIS 1.1 ODF specification, and the API provides the same property shortcuts as for a text style creation. Practically, this text part defines the default text style that apply to the text content of the paragraph; any property in this part may be overridden as soon as one or more text spans with explicit styles are defined inside the paragraphs.

The creation of a full-featured paragraph style takes two steps. The first one is a regular odf_create_style() instruction, with "paragraph" as the value of the family mandatory argument, a name parameter (unless the user just wants to create a default style) and any number of named paragraph properties. The second (optional) step consists of appending a text part to the new paragraph style; it can be accomplished, at the user's choice, either by specifying a previously defined text style element, or by explicitly defining new text properties, through the set_properties() method with the "area" option set to "text". In the second case, the prototype text style is provided through the "clone" parameter.

Assuming that a "MyColoredText" text style has been defined according to the text style creation example above, the following sequence creates a new paragraph style whose text part is a clone of "MyColoredText", and whose paragraph part features are the text justification, a first line 5mm indent, a black, continuous, half-millimiter border line with a bottom-right, one millimeter grey shadow, with other possible properties inherited from a "Standard" style:

   $ps = odf_create_style(
                        'paragraph',
                        name            => 'BorderedShadowed',
                        'display name'  => 'Strange Boxed Paragraph',
                        parent          => 'Standard',
                        align           => 'justify',
                        indent          => '5mm',
                        border          => '0.5mm solid #000000',
                        shadow          => '#808080 1mm 1mm'
                        );
   $ts = $document->get_style('text', 'MyColoredText');
   $ps->set_properties(area => 'text', clone => $ts);

Note that "MyColoredText" is reused by copy, not by reference; so the new paragraph style will not be affected if "MyColoredText" is changed or deleted later.

The value of the "clone" parameter, if any, may be a paragraph style element instead of a text style element, provided that the given paragraph style contains a text part; so the text part of the given paragraph style (and this part only) is used as the prototype.

Among the creation option for a paragraph style, a "master page" parameter may be set in order to specify the style of the page where the paragraphs using the style will appear. A paragraph whose style has a "master page" option is the first of a new page (in other words, a paragraph whose style owns a "master page" property is automatically preceded by a page break unless it's the first paragraph of the document content). This option may be checked and changed in existing paragraph styles using the get_master_page() and set_master_page() accessors.

The API allows the user to set any attribute using its official name according to the ODF specification related to the paragraph formatting properties (§15.5). However, the API allows the use of mnemonic shortcuts for a few, frequently required properties, namely:

•   "align": text alignment, whose legal values are "start", "end", "left", "right", "center", or "justify";

•   "align-last": to specify how to align the last line of a justified paragraph, legal values are "start", "end", "center";

•   "indent": to specify the size of the first line indent, if any;

•   "widows": to specify the minimum number of lines allowed at the top of a page to avoid paragraph widows;

•   "orphans": to specify the minimum number of lines required at the bottom of a page to avoid paragraph orphans;

•   "together": to control whether the lines of a paragraph should be kept together on the same page or column, possible values being "always" or "auto";

•   "margin": to control all the margins of the paragraph;

•   "margin xxx" (where "xxx" is "left", "right", "top" or "bottom"): to control the margins of the paragraph separately;

•   "border": a 3-part string to specify the thickness, the line style and the line color (according to the XSL/FO grammar);

•   "border xxx" (where "xxx" is "left", "right", "top" or "bottom"): the same as "border" but to specify a particular border for one side;

•   "shadow": a 3-part string to specify the color and the size of the shadow;

•   "padding": the space around the paragraph;

•   "padding xxx" (where "xxx" is "left", "right", "top" or "bottom"): to specify the space around the paragraph side by side;

•   "keep with next": to specify whether or not to keep the paragraph and the next paragraph together on a page or in a column, possible values are "always" or "auto";

•   "break xxx" (where "xxx" is "before" or "after"): to specify if a page or column break must be inserted before or after any paragraph using the style, legal values are "page", "column", "auto".

A paragraph style may have a background color or image.

Font declarations
Every font name that is used in a text style (or in a paragraph text property) must be declared in the document, either in the "CONTENT" part or in the "STYLES" part. The basic rule is that a font declaration must appear in the part where the corresponding font name appears in a style definition.

So, both the "STYLES" and "CONTENT" ODF XML part objects provide methods for dealing with font declarations.

set_font_declaration() allows the user to put a font declaration in the calling "odf_xmlpart" object. This method requires a font name (unique for the part) as its first argument. Some additional named parameters may be provided:

•   "family": the font family, whose default is the font name itself;

•   "family generic": the generic font family name (ex: "roman");

•   "pitch": specifies whether a font has a fixed or variable width;

•   "adornments": adornments, like "bold" or "italic" that can be used to locate a font in addition to the family name;

•   "charset": the character set of the font.

For details about these options, see ODF 1.1 §14.6 and §15.4, knowing that each option corresponds to a "style:font-xxx" ODF attribute where "xxx" is the option name.

set_font_declaration() deletes and replaces any previously existing font corresponding to the given name. It returns the font declaration object, that is a "odf_element".

set_font_declaration() may be used as a odf_document() method; in this context, it inserts the same font declaration in "CONTENT" and "STYLES".

get_font_declaration() is a "odf_xmlpart" method allowing to select an existing font declaration by name (if any). The returned object may be deleted or cloned as any other "odf_element".

List family
A list style is a set of styles that control the formatting properties of the list items at every hierarchical level. As a consequence, a list style is a named container including a particular style definition for each level; in other words a list style is a set of list level styles.

The API allows the user to create a list style (if not previously existing in the document), and to create, retrieve and update it for any level.

A new list style, available for later insertion in a document, is created through the odf_create_style() function. The only mandatory argument is the style family, which is "list". However, a name is generally required as the second argument, knowing that a style list can't presently be used as a default style; an error is raised at any attempt to attach a nameless list style using insert_style() or register_style(). An optional display name argument is allowed (if the style list is about to be used as a common style); if provided, the display name should be unique as well.

An existing list style object provides a set_level_style() method, allowing the applications to set or change the list style properties for a given level. This method requires the level number as its first argument, then a "type" named parameter may be provided. The level is a positive (non zero) integer value that identifies the hierarchical position. The type specifies what kind of item mark is should be selected for the level; the possible types are "number", "bullet" or "image". The default is "number".

If the "bullet" type is selected, the affected items will be displayed after a special character (the "bullet"), which must be provided as a "character" named argument, whose value is an UTF-8 character.

If the "image" type is selected, the image resource must be linked through a "url" parameter; the affected items will be displayed after a graphical mark whose content is the corresponding image file.

A "number" list level type means that any affected list item will be marked with a leading computed number such as "1", "i", "(a)", or any auto- incremented value, whose formatting will be controlled according to other list level style properties (or to the default behavior of the viewer for ordered lists). With the "number" type, its possible to provide "prefix" and/or "suffix" options, which provide strings to be displayed before and after the number. Other optional parameters are:

•   "style": the text style to use to format the number;

•   "display levels": the number of levels whose numbers are displayed at the current level (ex: if display-levels is 3, so the displayed number could be something like "1.1.1");

•   "format": the number format (typically "1" for a simple number display), knowing that if this parameter is null the number is not visible;

•   "start value": the first number of a list item of the current level.

The following example shows the way to create a new list style then to set some properties for levels 1 to 3, each one with a different type:

   $ls = odf_create_style('list', name => 'ListStyle1');
   $ls->set_level_style(
        1, type => 'number', format => "1", prefix => ' ', suffix => '. '
        );
   $ls->set_level_style(
        2, type => 'bullet', character => '-'
        );
   $ls->set_level_style(
        3, type => 'image', url => 'bullet.jpg'
        );

The set_level_style() method returns an ODF element, representing the list level style definition, and which could be processed later through any element- or style-oriented function.

A list level style definition may be extended using its own set_properties() method, allowing the user to set properties that can't be covered by the set_level_style() parameters. These properties are:

•   "space before": the indent level, i.e. the space before the number for all paragraphs at this level;

•   "min label width": the minimum width of the item labels at this level;

•   "min label distance": the minimum distance between the number and the text of the item;

•   "align": the alignment of the item label relatively to the width as set through "min label width"; may be 'center', 'start', 'end';

•   "font": the name of a font that is used to display a bullet character (for bullet list level styles);

•   "width" and "height": the width and height of the image (for image list level styles); note that there is no default size, so these parameters must be set in order to make the image visible.

•   "size": a syntactic shortcut that replaces "width" and "height"; if provided, this option may be either a comma-separated string containing the width then the height, or an array ref of two strings in the same order.

The next example shows the way to set a level 1 number list level style with a 1cm indent and a 5mm minimal space between the label and the item text:

        $ls->set_level_style(1, type => 'number', format => '1')
                ->set_properties(
                        'space before'          => '1cm',
                        'min label distance'    => '5mm'
                        );

The following example sets a level 2 image list level style using a previously loaded image file, with a 2x2mm image size and a 3mm minimal space between the image and the item text:

        $img = $doc->add_image_file('/home/pictures/bullet.png');
        $ls->set_level_style(2, type => 'image', url => $img)
                ->set_properties(
                        size                    => '2mm, 2mm',
                        'min label distance'    => '3mm'
                );

See ODF::lpOD::Document for details about the add_image_file() method used in this example.

It's possible to avoid an explicit call to set_properties() in order to set the display attributes of a list level style; set_level_style() allows the user to specify these attributes as a hash ref through a "properties" optional parameter. It's just syntactic sugar: if this option is set, set_level_style() automatically calls set_properties() with the given content. So the last instruction of the previous example could be replaced by the following one:

        $ls->set_level_style(
                2, type => 'image', url => $img,
                properties => {
                        size                    => '2mm, 2mm',
                        'min label distance'    => '3mm'
                        }
                );

An individual list level style may be reloaded through get_level_style(), with the level number as its only one argument; it returns a regular ODF element (or "undef" if the given level is not defined for the calling list style).

It's possible to reuse an existing list level style definition at another level in the same list style, or at any level in another list style, or in another document. To do so, the existing level style (previously extracted by any mean, including the get_level_style() method) must be provided as a special "clone" parameter to set_level_style(). The following example reuses the level 3 style of "ListStyle1" to define or change the level 5 style of "ListStyle2":

   $ls1 = $document->get_style('list', 'ListStyle1');
   $source = $ls1->get_level_style(3);
   $ls2 = $document->get_style('list', 'ListStyle2');
   $ls2->set_level_style(5, clone => $source);

The object returned by set_level_style() or get_level_style() is similar to an ODF style object, without the name and the family. So the generic set_properties() method may be used later in order to set any particular property for any list level style. Possible properties are described in section §14.10 of the ODF specification.

Every list level style definition in a list style is optional; so it's not necessary to define styles for levels that will not be used in the target document. The set_level_style() method may be used with an already defined level; in such a situation, the old level style is replaced by the new one. So it's easy to clone an existing list style then modify it for one or more levels.

Outline style
According to the ODF specification, "the outline style is a list style that is applied to all headings within a text document where the heading's paragraph style does not define a list style to use itself".

Practically, the outline style is a particular list style which controls the layout of a particular hierarchical list. In other words, it's a list of default styles for headings according to their respective hierarchical levels.

The outline style, like any list style, should define a style for each level in use in the document.

The API allows the user to initialize the outline style (if not previously existing in the document), and to create, retrieve and update it for any level.

The get_style() method allows the user to get access to the outline style structure; to do so, "outline" must be provided in place of the family argument. The returned object is a nameless list style; it may be cloned in order to be reused as the outline style for another document, or as an ordinary list style (provided that it's later named). If the outline style is not initialized yet, get_style() returns a null value for the "outline" family.

If needed, the outline style can be created through odf_create_style() with "outline" as the style family and without name, then attached using insert_style(). The style for each individual level may be set, retrieved and changed at any time using the object-based set_level_style() and get_level_style() methods.

Unlike with regular list styles, the "type" option of set_level_style() is ignored with the outline style; the type is automatically "number" (i.e. the outline style is always a numbered list style).

The API allows the user to set style attributes for any level, knowing that a level is identified by a positive integer starting from 1. With the current version of the lpOD level 1 API, a few outline level style attributes are supported, namely:

•   "prefix": a string that should be displayed before the heading number;

•   "suffix": a string that should be displayed before the heading number;

•   "format": the number display format (ex: 1, "A");

•   "display levels": the number of levels whose numbers are displayed at the current level;

•   "start value": the first number of a heading at this level;

•   "style": the name of the style to use to format the number (that is a regular text style).

As an example, the following code retrieves the default style for the level 4 headings:

   $os = $document->get_style('outline');
   $head4 = $os->get_level_style(4);

The next example sets some properties for any level 1 heading, namely a numbering starting from 5 and the use of capital letters between parentheses as numbers:

   $os = $document->get_style('outline');
   $os->set_level_style(
        1,
        start_value => 5, prefix => '(', suffix => ')', format => 'A'
        ):

According to the example above, the default numbering scheme for level 1 headings will be "(E)", "(F)", "(G)", and so on.

Attributes and properties which are not explicitly supported through predefined parameter names in the present version of the API could always be set through the element-oriented methods of the level 0 API, knowing that get_level_style() returns a regular element.

Table-related styles
The API supports 4 kinds of styles that control various table formatting properties. While a table style specifies the global formatting properties of a table, row, column and cell styles allow a specific layout control for each table component.

  Table styles
A table style specifies the external size, borders and background of a table. It may be created through odf_create_style() with "table" as style family, the usual "name" parameter, and the following parameters:

•   "width": the table width (in length, not in columns), provided either in absolute values or as a percentage of the page width; both absolute and relative values may be provided as a string, separated by a comma, if needed;

•   "margin": to control all the margins of the table;

•   "margin xxx" (where "xxx" is "left", "right", "top" or "bottom"): to control the margins of the table separately;

•   "align": to specify the table alignment scheme, with "left", "right", "center", "margins" as possible values;

•   "together": to control whether the rows of the table should be kept together on the same page or column, possible values being ``always`` or ``auto``;

•   "keep with next": to specify whether or not to keep the paragraph and the next paragraph together on a page or in a column, possible values are "always" or "auto"; default is "auto";

•   "break xxx" (where "xxx" is "before" or "after"): to specify if a page or column break must be inserted before or after any paragraph using the style, legal values are "page", "column", "auto"; default is "auto";

•   "display": boolean property that specifies if a table is visible or not; default is "true".

The table styles support the set_background() method and may have a "shadow" property. However, while a table covers a rectangular area, the "border xxx" properties are not defined at the table style level; the borders are cell properties.

A set_shadow() method is available; its options are the same as the set_shadow() method for graphic styles.

  Cell styles
A cell style is created using odf_create_style() with "table cell" as the family. A "data style" may be provided as an optional parameter, which is recommended as soon as the style is about to be used for numeric cells. The value of this parameter is the identifier or a number style.

Once created, a cell style may be customized using set_properties(). See §15.11 in the ODF specification for the full list of possible properties. However, set_properties(), when used from a cell style object, allows the following shortcuts for the most used attributes:

•   "border", "border top", "border left", "border right", "border bottom", in the same way as other rectangular area styles;

•   "shadow": idem.

The set_background() method is allowed with "color" or "url" (while "url" may be replaced by "image"). Note that for this kind of style the "url" or "image" is not a standard link but a symbolic resource name depending on the viewer. More generally, set_background() works with cell styles in the same way as with graphic styles.

Caution: The most used ODF presentation software tools don't handle tables and table-related styles in the same way as ODF text or spreadsheet processors. If set_background() is executed when the cell style object is not registered in a document, lpOD doesn't know the type of the target document, so it selects a default behavior that is appropriate for text and spreadsheet documents. If the target document type is a presentation, the user should ensure that the style is registered before calling set_background(). Alternatively, it's possible to use the fill() method, that works for presentation table cells.

  Column styles
A column style is created using odf_create_style() with "table column" as the family. It may be customized using set_properties().

The most necessary property is "width", which may be an absolute width (i.e. a string containing the number and the length unit), a relative length (i.e. a string containing a number followed by a star), or both (comma-separated). See §15.9.1 in the ODF specification for details about the relative widths.

Optionally, a "optimal width" boolean property may be provided, to specify that the column width should be recalculated automatically if some content in the column changes.

The "break xxx" parameters (where "xxx" is "before" or "after"), are allowed to specify if a page or column break must be inserted before or after any column using the style, legal values are "page", "column", "auto"; default is "auto".

  Row styles
A row style is created using odf_create_style() with "table row" as the family. It may be customized using set_properties().

The most necessary property is "height", knowing that, according to the standard, the default height is the height of the tallest item in the row. The content of this property must be an absolute height, provided as a string containing the number and the length unit. If the length unit is omitted, it's automatically set to "cm" by the lpOD API.

The "break xxx" parameters (where "xxx" is "before" or "after"), are allowed to specify if a page or column break must be inserted before or after any row using the style, legal values are "page", "column", "auto"; default is "auto".

The row style supports the common set_background() method.

Graphic styles
A graphic style apply to frames, i.e. to image or text box containers.

It controls the way the content is displayed. Knowing that a frame may include text and/or graphics, a graphic style may own graphic, paragraph and/or text properties, so its full definition may require three distinct areas.

A graphic style may be created through the generic odf_create_style() constructor, with "graphic" as family and the common optional parameters ("name", "display name", "parent"). Other parameters, if any, are regarded as properties for the graphic area.

The user can get or set any property in an existing graphic style through get_properties() or set_properties() with the appropriate "area" option, whose possible values are "graphic", "text", and "paragraph". The default area is "graphic".

The text and paragraph properties are the same as those of a paragraph style (see above).

The graphic properties must be provided according to the ODF specification.

Some frequently used properties may be set through the following optional parameters:

•   "border": a 3-part string to specify the thickness, the line style and the line color (according to the XSL/FO grammar); for example '1mm solid #000080' means defines a one-millimeter thick continuous, navy blue border;

•   "shadow": a 3-part string to specify the color, the vertical shift and the horizontal shift of the shadow (for example '#808080 1mm 1mm' defines a grey shadow whose horizontal and vertical thickness is 1 millimeter);

•   'margin xxx' where 'xxx' may be "left", "right", "top", or "bottom", specifies the external margins, i.e. the reserved space between the frame and the surrounding text (number and length unit, like '1cm');

•   'red', 'green', and/or 'blue' specify a color correction parameter, provided as a positive or negative percentage (a trailing percent sign should appear in the given value);

•   "padding": the space between the border and the content (number and length unit, like '1cm');

A lot of other parameters are allowed; to get a full list, the user shoud have a look at the Graphic styles chapter in the public ODF specification. Note that many ot them are "draw" options, i.e. their names begin with the "draw" prefix; so if an option is set without prefix, lpOD generally regard it as a "draw" option. Among the exceptions, the "wrap" and "run through" options correspond to ODF attributes whose prefix is "style", while "clip" stands for "fo:clip"; lpOD can handle these exceptions, so the prefix is not required with these options, too.

The set_background() method may be used in the same way as with other style families. Example:

      my $fs = odf_style->create(
         'graphic',
         name     => "MyFrameStyle",
         border   => "1.5mm wave #00aa00"
      );
      $fs->set_background(color => 'yellow');

A graphic style supports optional shadow parameters. Thanks to the set_shadow() method, the most used ones may be easily handled. This method may be used with the following options:

•   "color" specifies the color of the shadow; the default is black;

•   "offset" controls the horizontal and vertical offset of the shadow; these two values may be provided either as a comma-separated string or as a string list reference; each one may be positive ot negative and should include a trailing length unit string; the default is "['3mm', '3mm']", giving a bottom-right 3mm shadow. Starting from the previous example, the following instruction adds a light green shadow whose origin point is located 4mm west and 2mm south from the origin point of the related object.

            $sc->set_shadow(color => 'light green', offset => '-4mm, 2mm');

The following example creates a graphic style with 50% transparency, 10% green color adjustment and 5% luminance adjustment, for frames that will appear in the background:

        $gs = odf_create_style(
                'graphic',
                name            => 'MyFilter',
                'image opacity' => '50%',
                green           => '10%',
                luminance       => '5%',
                wrap            => 'run-through',
                'run through'   => 'background'
                );

A graphic style may be filled with a gradient; to do so, a "fill" option whose value is 'gradient' must be provided, and a 'fill gradient name' parameter must specify the unique name of a gradient.

Gradient styles
A gradient is built using odf_create_style() with 'gradient' as family. It requires a "name" (unique) parameter as other styles. Its possible options are described by the ODF specification in §14.14.1. However, these options may be used without the "draw:" prefix. Example:

        $gradient = odf_create_style(
                'gradient',
                name            => "GR1",
                style           => 'axial',
                angle           => 450,
                start_color     => '#ffffcc',
                end_color       => '#ffcc99',
                start_intensity => '100%',
                end_intensity   => '95%'
                );

Page styles
A page style definition, so-called master page, is a template for pages in a document. It directly defines the static content that is displayed on all pages that use it (such as headers and footers). In addition, a master page is associated to a page layout, defined as a separate object that describes the physical properties or geometry of a page, for example, page size, margins, header height, and footer height. The same page layout may be used through several master pages.

In text documents, the pages are not statically defined; they are dynamically generated by the viewing/printing applications according to their content (which changes each time a piece of content is inserted, deleted or moved. As a consequence, a master page is not used in the same way as, say, a paragraph style or a list style, because there is no persistent text page object which could directly contain a reference to a page style. A master page is essentially referred to through page breaks. For example, each time a forced page break is inserted, it's possible to specify the master page of the following page. In addition, any master page may own a property that tells what should be the master page to use after the current page (for example, a "Right page" style may be defined in order to ensure that any page using it will be followed by a page that will use a "Left page" style and vice-versa). However, beyond the end user's point of view, a page break is not an ODF object; it's implemented through the "master page" optional property of a paragraph style.

Master page objects (and the corresponding page layouts) apply to presentation and drawing documents, too. However, the page style model is very different (and much more complicated) for these documents than for text documents. This model uses master pages, page layouts, and two additional style-related objects, namely *presentation page layouts* and *presentation page styles*.

Drawing and presentation documents use statically defined draw pages. As a consequence, the link between every draw page and its master page and other style-related objects is static and specified through explicit properties of the draw page.

  Master pages
A master page is created and retrieved the same way as other styles.

To create a master page through the generic odf_create_style() function, the family argument is "master page" and it's followed by an arbitrary optional "name" parameter, that may be provided later, but that is mandatory when the style is attached to a document using the "odf_document" based insert_style() method.

A master page may, like other styles, have a display name distinct from its name. In addition, a full master page definition allows the following named parameters:

•   "layout": the unique name of a *page layout*, existing or to be defined in the same document (see later the lpOD specifications about the page layout objects);

•   "next": the master page to apply to the following page, as soon as the current page is entirely filled, knowing that the current master page is used for the next page by default.

As any other ODF element, a master page object inherits the generic insert_element() and append_element() methods that allow the user to attach any other ODF element to it. Beware that such attachments are unchecked, and that the user should not integrate any kind of element in a master page.

A unique name is required at insert time; insert_style() raises an error at any attempt to attach a nameless master page to a document. On the other hand, insert_style() can attach a master page without layout name, but the visible result is not predictable and depends on the default page layout of the printing application.

The "parent" parameter is not allowed in master page creation, as long as there is no explicit inheritance mechanism in the ODF specification for this kind of styles. However an existing master page definition is always reusable using the "clone" option.

  Page headers and footers
Page headers and footers are optional components of master pages; they are just containers for almost any kind of document content elements (such as regular paragraphs, tables, images and so on). They are created "in place" using special master page methods, namely set_header() and set_footer(). Each of these methods returns an ODF element that can be used later as a context to append content elements. The following example creates a page style with a header and a footer, each one containing a single paragraph:

        $mp = odf_create_style('master page', name => 'MyNewPageStyle');
        $h = $mp->set_header;
        $h->append_element(
                odf_create_paragraph(
                        text    => 'Header text',
                        style   => 'Standard'
                        )
                );
        $f = $mp->set_footer;
        $f->append_element(
                odf_create_paragraph(
                        text    => 'Footer text',
                        style   => 'Standard'
                        )
                );

It's possible to call set_header() and set_footer() with one or more existing ODF elements as arguments, so the given elements are directly put in the header or footer.

Every set_header() or set_footer() removes and replaces any previously existing header/footer. It's always possible to retrieve the header or the footer using get_header() or get_footer(), and to remove them using delete_header() and delete_footer().

Note that the header and footer extensions of a master page don't include any layout information; the style of the header and footer of a master page is specified through the header and footer extensions of the corresponding page layout.

  Background objects
A page master doesn't include any direct page background specification, knowing that the background color and/or the background image are defined by the page layout that is used by the page master (see below).

However, it's possible to attach frames to a master page (through insert_element() and append_element()). Frames are containers for various kinds of content elements, including graphical ones, so they provide a practical way to compose backgrounds. However, the user should check the compatibility with the target displaying/printing applications according to the document type. Simply put, frames attached to master pages are common in presentation documents, not in text document.

  Page layouts
Page layouts are generally invisible for the end users, knowing that a typical ODF-compliant text processor regards them as extensions of the main page styles, namely master pages. However, a page layout is defined through the lpOD API using the same logic as other style objects. It may be created using odf_create_style() with "page layout" as the family argument and a unique name parameter (mandatory when the object is attached to a document). The "display name" optional parameter is ignored for this kind of style. On the other hand, a specific "page usage" parameter, whose legal values are "all", "left", "right", "mirrored" (default: "all") allows the user to specify the type of pages that the page layout should generate.

The list of other possible properties that may be set with page layouts through odf_create_style() is described in section §15.2 of the ODF specification; some of these properties may be set using the following lpOD mnemonics:

•   "height" and "width": the page size values, in regular ODF-compliant notation (ex: '21cm');

•   "size": the page size, as two comma-separated values in a single string, the width coming first; this option is a shortcut that may replace "width" and "height" (ex: '21cm, 29.7cm');

•   "number format", "number prefix", and "number suffix": the format, prefix and suffix which define the default number representation for page styles, which is used to display page numbers within headers and footers;

•   "paper tray": to specify the paper tray to use when printing the document; it's a proprietary information knowing that the paper tray names depend on the printer model; however, this property, if defined, may be safely set to "default", so the default tray specified in the printer configuration settings will be used;

•   "orientation": specifies the orientation of the printed page, may be "portrait" or "landscape" (default: "portrait");

•   "margin xxx" (where "xxx" is "left", "right", "top" or "bottom"): to control the margins of the page;

•   "margin", to specify the same width for all the margins;

•   "border xxx" (where "xxx" is "left", "right", "top", or "bottom"): a 3-part string to specify the thickness, the line style and the line color (according to the XSL/FO grammar);

•   "border": a 3-part string to specify the thickness, the line style and the line color (according to the XSL/FO grammar), for all the four borders;

•   "footnote height": defines the maximum amount of space on the page that a footnote can occupy.

Page layout objects support the set_background() method, allowing to set a background color or a background image.

A page layout object may have a header and/or a footer extension, respectively set using set_header() and/or set_footer(). These methods, when used with a page layout object, allow the applications to extend the page layout in order to specify layout information that control the header and the footer of the master page(s) that use the page layout. Of course, the layout properties are not the same as the content properties. Knowing that headers and footers may have different margins and borders than the page body, set_header() and set_footer() accept the same margin- and border-related named parameters as odf_create_style() when used to create a page layout. On the other hand, set_header() and set_footer() return ODF elements that support the generic set_background() method; so it's possible to use this method separately from the page layout main object and from both its header and footer extensions, allowing the user to set specific backgrounds in the 3 parts of the affected page.

A page layout style may specify a columned page. A set_columns() method, called from a page layout object, does the job with the number of columns as a first argument and a "gap" optional name parameter that specifies the gap between columns. By default, all columns have the same width. If the first argument is missing or less than 2, then the page layout is no longer columned. It's possible to set extra properties in order to specify each column individually and to define a separator line between columns, through the low-level (lpOD 1) API.

Presentation page layouts
A presentation page layout (whose use is optional with a draw page) is not really a style. However, it's described and designed as a style in the ODF specification, so it's processed as a style through the lpOD API. Practically, a presentation page layout typically comes from a template presentation document and consists of a set of placeholders, each one specifying the class and the coordinates of a shape (see §14.15 then §9.6 in the ODF specification for details), knowing that a placeholder indicates a location in a page where the user must fill in some information.

Like other styles, a presentation page layout is identified by a "name" and owns an optional "display name". It's created by the odf_create_style() generic style constructor, with "presentation page layout" as family name. Remember that this family is not related by any mean to the "page layout" family.

Once created, a presentation page layout is populated using its element-specific set_placeholder() method. This method can either append a previously created (and free) placeholder object, or create and append a new placeholder.

When used for creation, set_placeholder() must be called with the presentation object class (specified as a string) as its first argument. The possible values are those of the §9.6.1 in the ODF specification, namely "title", "outline", "subtitle", "text", "graphic", "object", "chart", "table", "orgchart", "page", "notes", "handout".

In addition, the following properties must be provided with set_placeholder():

•   "position", the coordinates of the placeholder, as a list of 2 strings containing the X and Y positions (each string specifies the number and the unit, ex. "1cm", "2pt");

•   "size", the absolute size of the placeholder, provided in the same format as the position, in length or percentage.

The object class argument may be replaced by a valid placeholder element (previously cloned from an existing placeholder or by any other mean). If so, this element is used as is, and the position/size parameters are ignored.

The get_placeholders() method allows the user to get all the placeholder elements belonging to the calling presentation page layout object as a list. Each one may me individually deleted, cloned, or updated. From a given placeholder element, set_position(), get_position(), set_size(), and get_size() allow the user to set or get the coordinates and/or the size.

The set_placeholder() method always returns the inserted placeholder element.

Data styles
The display format of some typed data containers, such as table cells, may be specified through appropriate data styles. A data style may be registered in a document using insert_style() or register_style() as usual.

There is no specific data style constructor. The developers should preferentially use data styles previously defined in template documents. However, it's possible to import a data style from an XML string (provided by the application or previously exported from another document/location through the generic element-based serialize() method). Remember that a typical "blind" style import from an XML source (whatever the style family) may look like:

        $doc->insert_style(odf_element->create($xml));

In order to specify a currency display format whose name is "N110", with a leading dollar sign, followed by a space, then by one or more integer digits and two decimal digits, the content of the $xml string above should be:

        <number:currency-style style:name="N110">
          <number:currency-symbol>$</number:currency-symbol>
          <number:text> </number:text>
          <number:number number:decimal-places="2"
                         number:min-integer-digits="1"
                         number:grouping="true"/>
        </number:currency-style>

A data style may be retrieved using the document-based get_style() method, with 3 arguments (instead of 2). The first argument must be 'data', the second one is the data style type, and the last one is the individual style name. The allowed data types are 'number', 'percentage', 'currency', 'date', 'time', 'boolean', and 'text'. As an example, the instructions below try to select a currency data style and a boolean one, whose respective names are "MyMoney" and "YesNo":

        my $cs = $doc->get_style('data', 'currency', 'MyMoney');
        my $bs = $doc->get_style('data', 'boolean', 'YesNo');

Inter-document style replication
A special, document-based substitute_styles(), allows the user to remove any existing style registered in the current document and to replace them by copies of the styles registered in another document. This method requires either the path/name of the ODF source file, or an already created odf_document instance. The most simple (and drastic) use looks like in the following instruction:

        $doc->substitute_styles("pretty_styled_file.odt");

This method allows the applications to use and reuse ODF files as style databases. Be careful: in order to avoid name collisions and/or unresolved dependencies, this method deletes every previously defined style in the calling document before importing the styles of the source document, so it must be used before any style creation or customization.

The effects of substitute_styles() may be restricted to a particular area through options. For example, if you want do keep your local automatic styles, you can exclude them from the substitution as shown below:

        $doc->substitute_styles(
                "pretty_styled_file.odt"
                automatic       => FALSE
                );

The substitute_styles() options are "automatic", "common" (for the common styles), "master" (for the master pages and similar styles), and "fonts" (for the font declarations). All these options are set to "TRUE" by default. Switching an option to "FALSE" may be risky unless you really know that you want, because complex dependencies may exist between styles registered in different areas.

Alternatively, you can use substitute_styles() as a part-based method, so the substitution works only with this part. As an example, the following sequence substitutes only the font declarations registered in the "CONTENT" parts of the document:

        $doc->get_part(CONTENT)->substitute_styles(
                "pretty_styled_file.odt",
                automatic       => FALSE,
                fonts           => TRUE
                );

Knowing that the "CONTENT" part (according to the ODF rules) can't contain common or master styles, the "common" and "master" options are automatically set to "FALSE" when substitute_styles() is used from this part.

Of course, the bulk style substitution in not the only way to import styles registered elsewhere. Thanks to get_style() and get_styles(), styles may be picked individually or by family, cloned and registered locally by insert_style() or register_style().

AUTHOR/COPYRIGHT
Developer/Maintainer: Jean-Marie Gouarne <http://jean.marie.gouarne.online.fr> Contact: jmgdoc@cpan.org

Copyright (c) 2010 Ars Aperta, Itaapy, Pierlis, Talend. Copyright (c) 2011 Jean-Marie Gouarne.

This work was sponsored by the Agence Nationale de la Recherche (<http://www.agence-nationale-recherche.fr>).

License: GPL v3, Apache v2.0 (see LICENSE).

POD ERRORS
Hey! The above document had some coding errors, which are explained below:

Around line 377:
    Non-ASCII character seen before =encoding in '§15.4'. Assuming UTF-8