[HarfBuzz] Arabic decoder

[Nicolas Lacombe]

problem solved:

in my loop:


  for (unsigned int j = 0; j < shaper_item.item.length; j++)

I was taking into account the number of item, not the number of glyph.

with

for (unsigned int j = 0; j < shaper_item.num_glyphs; j++)

it looks better.

I'm still having problem rendering complexe sentances, but it looks like
working fine on small letter... I'm wondering if I have to take into account
the advances given by the shaper... for now I'm just letting freetype taking
care of it for me... need some test.

Are you aware of any problem in the arabic/syriac translation module, or is
it suppose to work fine?


Behdad answear to this question with:

"Supposed to work fine.  Though you need a bidi engine also.  Try setting
bidi level to 1 instead of 0..."


Wich does not appear to change a lot of things. However I resolved my
problem by changing font... they are very important, and I'm having trouble
to find good Persian and Syriac font.



2009/12/2 Nicolas Lacombe <n.lacombe at gmail.com>

> Hi,
>
> I'm using HarfBuzz with freetype to render arabic text. I must say that
> this library was exactly what I was looking for, great job!
>
> Anyway I spotted something strange, I don't know if it's a bug or if it's
> me that didn't understand correctly the spirit behind Harfbuzz.
>
> When rendering arabic letter equivalent of la , it should give me only one
> glyph (لا).
>
> However, Harfbuzz render me correctly the glyph, but do not get rid of the
> a. See screenshot here:
>
> http://img522.yfrog.com/i/21856341.png/
>
>
> Here's my (simplified) render loop:
>
> HB_ShaperItem shaper_item;
>
>     shaper_item.string = (HB_UChar16 *) g_utf8_to_utf16((gchar*)txt, -1,
> NULL, &numberOfWords, NULL);
>
>    shaper_item.kerning_applied = 0;
>     shaper_item.stringLength = 0;
>     shaper_item.shaperFlags = 0;
>     shaper_item.font = &hbFont;
>     shaper_item.face = hbFace;
>     shaper_item.glyphIndicesPresent = 0;
>     shaper_item.initialGlyphCount = 0;
>
>     shaper_item.item.bidiLevel = 0;
>
>     out_glyphs = (HB_Glyph*)malloc(numberOfWords * sizeof(HB_Glyph));
>     memset(out_glyphs, 0, numberOfWords * sizeof(HB_Glyph));
>     out_attrs = (HB_GlyphAttributes*)malloc(numberOfWords *
> sizeof(HB_GlyphAttributes));
>     memset(out_attrs, 0, numberOfWords * sizeof(HB_GlyphAttributes));
>     out_advs = (HB_Fixed*)malloc(numberOfWords * sizeof(HB_Fixed));
>     memset(out_advs, 0, numberOfWords * sizeof(HB_Fixed));
>     out_offsets = (HB_FixedPoint*)malloc(numberOfWords *
> sizeof(HB_FixedPoint));
>     memset(out_offsets, 0, numberOfWords * sizeof(HB_FixedPoint));
>     out_logClusters = (unsigned short*)malloc(numberOfWords *
> sizeof(unsigned short));
>     memset(out_logClusters, 0, numberOfWords * sizeof(unsigned short));
>
>     shaper_item.glyphs = out_glyphs;
>     shaper_item.attributes = out_attrs;
>     shaper_item.advances = out_advs;
>     shaper_item.offsets = out_offsets;
>     shaper_item.log_clusters = out_logClusters;
>     shaper_item.num_glyphs = numberOfWords;
>     shaper_item.stringLength = numberOfWords;
>
>     int l = 0;
>     while(1){
>
>         shaper_item.num_glyphs = numberOfWords;
>         if (!hb_utf16_script_run_next(NULL, &shaper_item.item,
> shaper_item.string, numberOfWords , &iterator))
>             break;
>
>         memset(out_glyphs, 0, numberOfWords * sizeof(HB_Glyph));
>         HB_ShapeItem(&shaper_item);
>         for (unsigned int j = 0; j < shaper_item.item.length; j++)
>         {
>             ind[l++] = out_glyphs[j];
>         }
>     }
>
> so at the end, ind contains all the index of the glyph I need to draw.
>
> Is there a way harfbuzz can tell me to get rid of a glyph?
>
> Thanks, Nico.
>
>
>
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