proposal for 15.5.36 style:writing-mode, add 'auto'

[Thomas Zander <zander@kde.org>]

In 15.5.36 Writing Mode this is written;
The style:writing mode attribute specifies the writing mode of a 
paragraph. The attribute is similar to the writing-mode attribute 
specified in §7.27.7 of [XSL], 

Writing modes basically are things like left-to-right or right-to-left 
etc.

This writing mode is referenced from paragraph-styles, from 
section-formatting properties, table properties, Frame formatting 
properties and Page formatting properties.

The fact that this is referenced from paragraph-styles indicates that we 
store a text direction in the style.  Doing this means that when we apply 
a style to a certain text we specify if its RTL or LTR text.  And this is 
a behavior I find wrong.
The actual text in the paragraph can be used, in combination with unicode 
tables, to determine the text layout direction but that is no longer 
possible due to the style always overriding this value.

Imagine the following use case;
A user types some text in Hebrew. The word processor detects it is RTL 
text and thus sets the paragraphs text-layout to be rl-tb.
The user then applies a paragraph style 'Header1' to the paragraph. But 
this paragraph style has the layout-direction set to 'left-to-right' and 
thus my Hebrew text is now left-aligned. Which is wrong.
You could argue that the paragraph style should then be altered to be 
right-to-left, but that means I can't use it anymore with BIDI or 
left-to-right paragraphs anymore.

I would like to suggest we add an 'auto' value to the above list of 
options which would take the value from the text instead of specifying 
this.
I would strongly suggest making this the default value in 1.2 for when no 
direction is specified in the xml. The reason is simple; in normal (i.e. 
not automatic) styles specifying a layout direction is something that is 
hardly ever useful as the user doesn't want to specify the direction 
before starting to type the text.

Backwards compatibility:
Looking at the biggest 2 implementors of ODF I see that both of them 
currently ignore the writing mode for text alignment completely; see
http://testsuite.opendocumentfellowship.org/testcases/TextContents/textFormatting/alignment/TestCase.html
So, as both of them are not really implementing this part of the spec 
anyway, I don't see any problems with backwards compatibility when 
changing this.

-- 
Thomas Zander

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