[HarfBuzz] bug in graphite integration

[Behdad Esfahbod]

Thanks Martin.  I pushed your patch out.  This issue was on my list to fix for
quite a while...

I don't believe it fixes this issue though:

  https://bugs.freedesktop.org/show_bug.cgi?id=77433

Can you please take a look?

Thanks,
behdad

On 14-05-30 12:11 PM, Martin Hosken wrote:
> Dear Behdad,
> 
> I came across this bug in the graphite integration code. The cluster component of the info structure needs to point back into the original string. Currently the code is returning a character offset that is zero based. The fix is to use the cluster attributes passed in. I don't think we can get away without storing the cluster again. I enclose a patch.
> 
> This fix could well clean up some of the instabilities in using graphite fonts in hbng applications I've been seeing and wondering about. I think it's a pretty key bug fix for people like Debian.
> 
> Yours,
> Martin
> 
> diff --git a/src/hb-graphite2.cc b/src/hb-graphite2.cc
> index a309ca8..709aa94 100644
> --- a/src/hb-graphite2.cc
> +++ b/src/hb-graphite2.cc
> @@ -209,6 +209,7 @@ struct hb_graphite2_cluster_t {
>    unsigned int num_chars;
>    unsigned int base_glyph;
>    unsigned int num_glyphs;
> +  unsigned int cluster;
>  };
>  
>  hb_bool_t
> @@ -299,6 +300,7 @@ _hb_graphite2_shape (hb_shape_plan_t    *shape_plan,
>    memset (clusters, 0, sizeof (clusters[0]) * buffer->len);
>  
>    hb_codepoint_t *pg = gids;
> +  clusters[0].cluster = buffer->info[0].cluster;
>    for (is = gr_seg_first_slot (seg), ic = 0; is; is = gr_slot_next_in_segment (is), ic++)
>    {
>      unsigned int before = gr_slot_before (is);
> @@ -316,6 +318,7 @@ _hb_graphite2_shape (hb_shape_plan_t    *shape_plan,
>      {
>        hb_graphite2_cluster_t *c = clusters + ci + 1;
>        c->base_char = clusters[ci].base_char + clusters[ci].num_chars;
> +      c->cluster = buffer->info[c->base_char].cluster;
>        c->num_chars = before - c->base_char;
>        c->base_glyph = ic;
>        c->num_glyphs = 0;
> @@ -335,7 +338,7 @@ _hb_graphite2_shape (hb_shape_plan_t    *shape_plan,
>      {
>        hb_glyph_info_t *info = &buffer->info[clusters[i].base_glyph + j];
>        info->codepoint = gids[clusters[i].base_glyph + j];
> -      info->cluster = gr_cinfo_base(gr_seg_cinfo(seg, clusters[i].base_char));
> +      info->cluster = clusters[i].cluster;
>      }
>    }
>    buffer->len = glyph_count;
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-- 
behdad
http://behdad.org/