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Subject: Hebrew: bidirectional patch (782511)
From: Gadi Cohen (dragon_at_wastelands.net)
Date: 2003-08-04


This patch introduces a compile time option which will correctly display
hebrew text, from right-to-left, from inside of rockbox. It is
emplemented on an 'OS' level, meaning any text displayed through the
firmware will be affected (including directly display, wps and text file
viewer). [Read on for more technical info.]
 
This was mostly a quick hack, using some Hebrew code I found (and
modded) in BitchX by crisk. Using the Unicode BiDi algorythm on an
application level seemed a bit of an overkill, especially since we have
no need for logical-to-visual mapping for cut and paste, or vice versa.
Ideally we might have wanted a right-to-left interface / 'document
direction', but for me this patch is more than adequate.
 
The code affects any text with an ASCII value between 224 and 250
(according to ISO8859-8, the encoding generally used in Hebrew
filesystems) but the macros could probably be modified very easily to
include Arabic characters aswell.
 
Only major problem: on my rockbox, whenever the scrolling algorythm is
called, I get some junk appearing on the 2nd last column of all non
scrolling lines. This does not happen in the UI simulator. My main
change is a "str = hebrew_process(str)" in lcd_putsxyofs, and it seems
the problem only manifests itself when s->offset > 0. Maybe someone
familiar with the LCD code can comment. Nevertheless despite this
oddity the code _seems_ stable and I've been quite enjoying it.
 
Only other cause for attention: I wasn't sure how big to make the
buffers, so set some fairly arbitary values. This should probably be
something like sizeof(scrollinfo->line) but I thought I'd leave this to
someone who is actually sure what kind of data gets pumped into the
putsxyofs routine.
 
  _____

Gadi Cohen
Habonim Dror Southern Africa
National Youth Worker and Webmaster גדי כהן
הבונים דרור דרום אפריקה
עובד נוער ארצי ומומחה רשת
Cell: +27 84 555 4234 Israel: +927 55 204 878 email:
<mailto:gadi_at_habo.org.za> gadi_at_habo.org.za
 



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