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[ft] Cache advances 

I decided to always use the cache, instead of my previous sketch direction
that was to only allocate and use cache if fast advances are not available.
The cache is a mere 1kb, so just use it...

TODO: Invalidate cache on font size change.

Fixes https://github.com/harfbuzz/harfbuzz/issues/651
Fixes https://github.com/harfbuzz/harfbuzz/pull/1082
This commit is contained in:
Behdad Esfahbod 2018-09-11 14:35:26 +02:00
parent f90bab8560
commit 54998befc4
2 changed files with 18 additions and 21 deletions
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2
src/hb-cache.hh
View File

@ -36,7 +36,7 @@ template <unsigned int key_bits, unsigned int value_bits, unsigned int cache_bit
struct hb_cache_t
{
static_assert ((key_bits >= cache_bits), "");
static_assert ((key_bits + value_bits - cache_bits < 8 * sizeof (unsigned int)), "");
static_assert ((key_bits + value_bits - cache_bits <= 8 * sizeof (unsigned int)), "");
inline void init (void) { clear (); }
inline void fini (void) {}

37
src/hb-ft.cc
View File

@ -69,6 +69,7 @@ struct hb_ft_font_t
int load_flags;
bool symbol; /* Whether selected cmap is symbol cmap. */
bool unref; /* Whether to destroy ft_face when done. */
mutable hb_advance_cache_t advance_cache;
};
static hb_ft_font_t *
@ -85,6 +86,8 @@ _hb_ft_font_create (FT_Face ft_face, bool symbol, bool unref)
ft_font->load_flags = FT_LOAD_DEFAULT | FT_LOAD_NO_HINTING;
ft_font->advance_cache.init ();
return ft_font;
}
@ -99,6 +102,8 @@ _hb_ft_font_destroy (void *data)
{
hb_ft_font_t *ft_font = (hb_ft_font_t *) data;
ft_font->advance_cache.fini ();
if (ft_font->unref)
_hb_ft_face_destroy (ft_font->ft_face);
@ -239,31 +244,23 @@ hb_ft_get_glyph_h_advances (hb_font_t* font, void* font_data,
{
const hb_ft_font_t *ft_font = (const hb_ft_font_t *) font_data;
FT_Face ft_face = ft_font->ft_face;
int load_flags;
int load_flags = ft_font->load_flags;
int mult = font->x_scale < 0 ? -1 : +1;
unsigned int i = 0;
load_flags = ft_font->load_flags | FT_ADVANCE_FLAG_FAST_ONLY;
for (; i < count; i++)
for (unsigned int i = 0; i < count; i++)
{
FT_Fixed v = 0;
if (unlikely (FT_Get_Advance (ft_face, *first_glyph, load_flags, &v)))
goto slow;
*first_advance = (v * mult + (1<<9)) >> 10;
first_glyph = &StructAtOffset<hb_codepoint_t> (first_glyph, glyph_stride);
first_advance = &StructAtOffset<hb_position_t> (first_advance, advance_stride);
}
return;
hb_codepoint_t glyph = *first_glyph;
unsigned int cv;
if (ft_font->advance_cache.get (glyph, &cv))
v = cv;
else
{
FT_Get_Advance (ft_face, glyph, load_flags, &v);
ft_font->advance_cache.set (glyph, v);
}
slow:
/* TODO Prepare and use cache. */
load_flags = ft_font->load_flags;// & ~FT_ADVANCE_FLAG_FAST_ONLY;
for (; i < count; i++)
{
FT_Fixed v = 0;
FT_Get_Advance (ft_face, *first_glyph, load_flags, &v);
*first_advance = (v * mult + (1<<9)) >> 10;
first_glyph = &StructAtOffset<hb_codepoint_t> (first_glyph, glyph_stride);
first_advance = &StructAtOffset<hb_position_t> (first_advance, advance_stride);