> On 31 May 2015, at 7:09 pm, Ian C <[email protected]> wrote:
>
> We also need to take into account the style hierarchy. I see from some of the
> CSS documentation that there are mechanisms in place to manage that but have
> not looked in detail. Any advice Peter?
First, some general comments - what I recommend is to first build up a custom
data structure representing all the styles which can later be queried when
needed, e.g. when you encounter an element in content.xml that has a particular
style associated with it.
In the Word filter, there are two classes used for this purpose: WordSheet and
WordStyle (the former being a collection of the latter). These are defined in
WordSheet.h and WordSheet.c. Early in the conversion process, the filter goes
through the XML document containing the styles and builds up this data
structure. This results in the code being able to deal with the styles at a
higher-level of abstraction than examining the DOM tree of styles.xml directly.
A while ago I made a start on the same thing for ODF - there’s ODFSheet and
ODFStyle classes defined for the same purpose. So a good next step for tackling
styles would be to traverse the DOM tree of styles.xml and populate this data
structure, creating a new ODFStyle object for each style in the document, and
adding them to the (single) ODFSheet object for the document. This data
structure could then be used to generate the CSS text, as is done in the Word
filter.
> I just generated to div tags do we want that? Mapping to h1... hn could be a
> better way but not sure how to really map the correct heading styles to the
> hn.
In the case of ODF, the information about what header to map to is (usually)
available more directly than in OOXML. Both specs refer to it as the “outline
level”. In an ODF document, heading outline levels start from 1 (just like
HTML), but you also have the distinction between <text:h> and <text:p>
elements, so you can know whether something is a heading or a regular paragraph.
When encountering a <text:h> element, you can determine the outline level from
the attribute, e.g.:
<text:h text:style-name="Heading_20_1" text:outline-level="1">Headline
One</text:h>
So here the value ‘1’ is sufficient information to indicate that you need to
create a h1 element. The style-name attribute is Heading_20_1, so the
corresponding CSS would need to be:
h1.Heading_20_1 {
}
and similarly for other levels, e.g.
h2.Heading_20_2 {
}
Note that, as with your existing code, this would be generated separately from
the content itself, solely based on the information in styles.xml, for the
non-automatic styles.
So I suggest separating buildCSS_Styles into two separate functions: One which
populates the CSSSheet object associated with the package (that is,
package->sheet, which I think is already created), and another which examines
the ODFSheet object and populates the CSSSheet object.
--
Dr. Peter M. Kelly
[email protected]
http://www.kellypmk.net/
PGP key: http://www.kellypmk.net/pgp-key <http://www.kellypmk.net/pgp-key>
(fingerprint 5435 6718 59F0 DD1F BFA0 5E46 2523 BAA1 44AE 2966)
