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Evas font: fix width query for OT 

Fixes T4068.
Simply querying the last glyph to determine the width of the glyph sequence
won't always work, as OT can have negative offsets (adjusts the placement of a
specific glyph better).

The solution is to calculate the "max width" of some sequence that will
guarantee us proper width results. The worst solution would be to iterate on all
the glyphs and sum up the max width. This is a bit impractical. Instead, we will
inspect just the "cluster" of the last glyph, if one exists.

This should have no performance impact on trivial cases, and very little impact
on the others.

@fix
This commit is contained in:
Daniel Hirt 2016-07-13 11:40:36 +00:00
parent e8c396a6e2
commit ef817f15f0
1 changed files with 76 additions and 17 deletions
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93
src/lib/evas/common/evas_font_query.c
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@ -314,6 +314,81 @@ evas_common_font_ascent_descent_get(RGBA_Font *fn, const Evas_Text_Props *text_p
if (descent) *descent = (desc < max_desc) ? desc : max_desc;
}
#ifdef OT_SUPPORT
static inline Evas_Coord
_evas_common_font_query_width_ot(const Evas_Text_Props *text_props)
{
Evas_Coord ret_w = 0;
if (text_props->len > 0)
{
size_t off = text_props->start + text_props->len - 1;
const Evas_Font_Glyph_Info *glyph = text_props->info->glyph + off;
Evas_Font_OT_Info *ot = text_props->info->ot + off;
size_t cluster = ot->source_cluster;
do
{
Evas_Coord pen_x = (off > 0) ? glyph[-1].pen_after : 0;
Evas_Coord w = pen_x + glyph->x_bear + glyph->width +
EVAS_FONT_ROUND_26_6_TO_INT(EVAS_FONT_OT_X_OFF_GET(*ot));
if (w > ret_w)
{
ret_w = w;
}
glyph--;
ot--;
} while((off-- > text_props->start) && (ot->source_cluster == cluster));
if (text_props->start > 0)
{
ret_w -= text_props->info->glyph[text_props->start - 1].pen_after;
}
}
return ret_w;
}
#else
static inline Evas_Coord
_evas_common_font_query_width_regular(const Evas_Text_Props *text_props)
{
Evas_Coord ret_w = 0;
if (text_props->len > 0)
{
const Evas_Font_Glyph_Info *last_glyph = text_props->info->glyph +
text_props->start + text_props->len - 1;
if (text_props->len > 1)
{
const Evas_Font_Glyph_Info *glyph = text_props->info->glyph +
text_props->start;
ret_w = last_glyph[-1].pen_after;
if (text_props->start > 0)
ret_w -= glyph[-1].pen_after;
}
ret_w += last_glyph->width + last_glyph->x_bear;
}
return ret_w;
}
#endif
static inline Evas_Coord
_evas_common_font_query_width(const Evas_Text_Props *text_props)
{
Evas_Coord ret_w;
#ifdef OT_SUPPORT
ret_w = _evas_common_font_query_width_ot(text_props);
#else
ret_w = _evas_common_font_query_width_regular(text_props);
#endif
return ret_w;
}
/**
* @internal
* Calculate the size of the string (width and height).
@ -333,24 +408,8 @@ evas_common_font_query_size(RGBA_Font *fn, const Evas_Text_Props *text_props, in
if (text_props->len > 0)
{
const Evas_Font_Glyph_Info *glyph = text_props->info->glyph +
text_props->start;
const Evas_Font_Glyph_Info *last_glyph = glyph;
if (text_props->len > 1)
{
last_glyph += text_props->len - 1;
ret_w = last_glyph[-1].pen_after;
if (text_props->start > 0)
ret_w -= glyph[-1].pen_after;
}
#ifdef OT_SUPPORT
ret_w += EVAS_FONT_ROUND_26_6_TO_INT(EVAS_FONT_OT_X_OFF_GET(
text_props->info->ot[text_props->start + text_props->len - 1]));
#endif
ret_w += last_glyph->width + last_glyph->x_bear;
ret_w = _evas_common_font_query_width(text_props);
}
if (w) *w = ret_w;
if (h) *h = evas_common_font_max_ascent_get(fn) + evas_common_font_max_descent_get(fn);
}