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[scaled-font] Avoid repeated lookup of the same unicode during text->glyphs

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Performing the unicode to index is quite expensive, the
FcFreeTypeCharIndex() taking over 12% in the cairo-perf text benchmarks.
By adding a simple cache of translated unicode indices, we save around 25%
of the lookups during benchmarks, with a relative reduction in runtime.
This commit is contained in:
Chris Wilson 2009-01-09 14:22:36 +00:00
parent 49eca78a42
commit afce1cfe98
1 changed files with 41 additions and 22 deletions
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63
src/cairo-scaled-font.c
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@ -1534,6 +1534,12 @@ cairo_scaled_font_text_to_glyphs (cairo_scaled_font_t *scaled_font,
cairo_status_t status;
cairo_glyph_t *orig_glyphs;
cairo_text_cluster_t *orig_clusters;
struct glyph_lut_elt {
uint32_t unicode;
unsigned long index;
double x_advance;
double y_advance;
} glyph_lut[256];
status = scaled_font->status;
if (unlikely (status))
@ -1608,17 +1614,13 @@ cairo_scaled_font_text_to_glyphs (cairo_scaled_font_t *scaled_font,
orig_clusters = clusters ? *clusters : NULL;
if (scaled_font->backend->text_to_glyphs) {
status = scaled_font->backend->text_to_glyphs (scaled_font, x, y,
utf8, utf8_len,
glyphs, num_glyphs,
clusters, num_clusters,
cluster_flags);
if (status != CAIRO_INT_STATUS_UNSUPPORTED) {
if (status == CAIRO_STATUS_SUCCESS) {
/* The checks here are crude; we only should do them in
* user-font backend, but they don't hurt here. This stuff
* can be hard to get right. */
@ -1633,7 +1635,6 @@ cairo_scaled_font_text_to_glyphs (cairo_scaled_font_t *scaled_font,
}
if (clusters) {
if (*num_clusters < 0) {
status = _cairo_error (CAIRO_STATUS_NEGATIVE_COUNT);
goto DONE;
@ -1643,11 +1644,12 @@ cairo_scaled_font_text_to_glyphs (cairo_scaled_font_t *scaled_font,
goto DONE;
}
/* Dont trust the backend, validate clusters! */
status = _cairo_validate_text_clusters (utf8, utf8_len,
*glyphs, *num_glyphs,
*clusters, *num_clusters,
*cluster_flags);
/* Don't trust the backend, validate clusters! */
status =
_cairo_validate_text_clusters (utf8, utf8_len,
*glyphs, *num_glyphs,
*clusters, *num_clusters,
*cluster_flags);
}
}
@ -1675,34 +1677,51 @@ cairo_scaled_font_text_to_glyphs (cairo_scaled_font_t *scaled_font,
*num_clusters = num_chars;
}
for (i = 0; i < ARRAY_LENGTH (glyph_lut); i++)
glyph_lut[i].unicode = ~0U;
p = utf8;
for (i = 0; i < num_chars; i++) {
int num_bytes;
uint32_t unicode;
cairo_scaled_glyph_t *scaled_glyph;
struct glyph_lut_elt *glyph_slot;
num_bytes = _cairo_utf8_get_char_validated (p, &unicode);
p += num_bytes;
(*glyphs)[i].index = (*scaled_font->backend->ucs4_to_index) (scaled_font, unicode);
(*glyphs)[i].x = x;
(*glyphs)[i].y = y;
glyph_slot = &glyph_lut[unicode % ARRAY_LENGTH (glyph_lut)];
if (glyph_slot->unicode == unicode) {
(*glyphs)[i].index = glyph_slot->index;
x += glyph_slot->x_advance;
y += glyph_slot->y_advance;
} else {
(*glyphs)[i].index =
(*scaled_font->backend->ucs4_to_index) (scaled_font, unicode);
status = _cairo_scaled_glyph_lookup (scaled_font,
(*glyphs)[i].index,
CAIRO_SCALED_GLYPH_INFO_METRICS,
&scaled_glyph);
if (unlikely (status))
goto DONE;
x += scaled_glyph->metrics.x_advance;
y += scaled_glyph->metrics.y_advance;
glyph_slot->unicode = unicode;
glyph_slot->index = (*glyphs)[i].index;
glyph_slot->x_advance = scaled_glyph->metrics.x_advance;
glyph_slot->y_advance = scaled_glyph->metrics.y_advance;
}
if (clusters) {
(*clusters)[i].num_bytes = num_bytes;
(*clusters)[i].num_glyphs = 1;
}
status = _cairo_scaled_glyph_lookup (scaled_font,
(*glyphs)[i].index,
CAIRO_SCALED_GLYPH_INFO_METRICS,
&scaled_glyph);
if (unlikely (status)) {
goto DONE;
}
x += scaled_glyph->metrics.x_advance;
y += scaled_glyph->metrics.y_advance;
}
DONE: /* error that should be logged on scaled_font happened */