[Freetype] Confusion about bidirectional line breaks...

[Paul Pedriana]

The Unicode bidi algorithm
(www.unicode.org/reports/tr9/) states:

   The process of breaking a paragraph into one 
   or more lines that fit within particular bounds 
   is outside the scope of the bidirectional 
   algorithm. Where character shaping is involved, 
   it can be somewhat more complicated. Logically
   there are the following steps:

   1 The levels of the text are determined according 
     to the bidirectional algorithm.
   2 The characters are shaped into glyphs according 
     to their context (taking embedding levels into
     account for mirroring!).
   3 The accumulated widths of those glyphs (in 
     logical order) are used to determine line breaks.
   4 For each line, rules L1-L4 are used to reorder 
     the characters on that line.
   5 The glyphs corresponding to the characters on 
     the line are displayed in that order.

So as I'm reading this, glyphs are shaped (#2) before
line breaks happen (#3) which is before reordering
occurs (#4). I must be missing something, because I
don't see how you can do line breaks properly before
you have done reordering. Won't the order of the words
on the line possibly be very different, thus changing
how the line is properly broken?

Example, from the doc:
   Logical: DID YOU SAY ‘he said "car MEANS CAR"’?
   Display: ?‘he said "RAC SNAEM car"’ YAS UOY DID


 


                
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