256408 - Layout ignores explicit CSS direction and chooses direction based on character range

Status: VERIFIED INVALID

(Core :: Layout: Text and Fonts, defect)

Description

[Jonadab the Unsightly One (Nathan Eady)]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7) Gecko/20040615 Firefox/0.9
Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7) Gecko/20040615 Firefox/0.9

Characters from certain ranges appear to always be layed out flowing in a
certain direction, irrespective of the CSS2 direction flag.  For example,
characters in the ASCII range are always layed out left-to-right, even if
their CSS says { direction: rtl; }, and characters in the Hebrew unicode
range (0590-05FF) seem to always be layed out right-to-left, even if their
CSS says { direction: ltr; }.  These directions are excellent defaults if
the direction is not specified in CSS, but an explicit CSS direction should
be followed.

Reproducible: Always
Steps to Reproduce:
1. Load a page with CSS that directs the text flow opposite what would
   normally be expected


Actual Results:  
Text flow is determined by character range only

Expected Results:  
Text flow should follow what CSS says, if the CSS actually says, or guess
based on character range otherwise.

One reason a page author might want to direct text written in a normally-rtl
script (such as Hebrew) to run left-to-right would be pasting in legacy text
that was originally typed in using software that did not support rtl flow.
One reason a page author might want to direct text apparently written in Latin
characters to flow right-to-left would be for using a transliterative font,
such as TekniaHebrew or cetera.  These are both probably minority cases
(especially the latter, and especially on the web), but I've run into the
latter case recently and in the course of my debugging discovered the former
case also.

It may be that the severity on this should be Enhancement, though it feels
like a bug to the page author.  It may also be that it should have the CSS2
keyword.  And I'm not absolutely certain I've put it in the right component,
but I did not see a component dedicated to CSS support.

I will shortly upload a test case HTML file with embedded CSS that will
demonstrate the issue.

Comment 1

[Jonadab the Unsightly One (Nathan Eady)]

Attachment: HTML document demonstrating the issue.

Cursory information about the CSS2 direction property is here:
http://www.w3schools.com/css/css_reference.asp#text
http://www.w3schools.com/css/pr_text_direction.asp

Comment 2

[Ilya Konstantinov]

You misunderstood the standard. 
 
The CSS 'direction' property (as well as HTML 4 DIR attribute) only defines the 
base writing direction of the block. For example, for Hebrew paragraphs, 
direction:rtl is what you want to use. 
 
If you want to override the natural direction of the characters; in other 
words, if you want to say "layout as I say, not as BiDi algorithm says", then 
in addition to 'direction', you should also set 'unicode-bidi:bidi-override'. 
 
Alternatively, you can use the HTML 4 BDO element, or Unicode 
Right-to-Left-Override (RLO) control character, to achieve the same result. 

Comment 3

[Simon Montagu :smontagu]

verified INVALID.