glyph_info[0].codepoint gives the unicode codepoint at the begining. then it gives glyph index after hb_shape.
isn't it supposed to give Unicode codepoint after I set the buffer content type to HB_BUFFER_CONTENT_TYPE_UNICODE? but I still get glyph index!
this is my code:
#include <iostream>
#include <harfbuzz/hb.h>
int main()
{
hb_buffer_t *buf;
buf = hb_buffer_create();
hb_buffer_add_utf8(buf, "A", -1, 0, -1);
hb_buffer_set_direction(buf, HB_DIRECTION_LTR);
hb_buffer_set_script(buf, HB_SCRIPT_LATIN);
hb_buffer_set_language(buf, hb_language_from_string("en", -1));
hb_blob_t *blob = hb_blob_create_from_file("ARIALUNI.TTF");
hb_face_t *face = hb_face_create(blob, 0);
hb_font_t *font = hb_font_create(face);
hb_buffer_content_type_t t1 = hb_buffer_get_content_type(buf);
unsigned int glyph_count;
hb_glyph_info_t *glyph_info = hb_buffer_get_glyph_infos(buf, &glyph_count);
hb_glyph_position_t *glyph_pos = hb_buffer_get_glyph_positions(buf, &glyph_count);
printf("Codepoint befor Shaping: %d\n", t1);
printf("%x\n", glyph_info[0].codepoint);
hb_shape(font, buf, NULL, 0);
hb_buffer_content_type_t t2 = hb_buffer_get_content_type(buf);
glyph_info = hb_buffer_get_glyph_infos(buf, &glyph_count);
glyph_pos = hb_buffer_get_glyph_positions(buf, &glyph_count);
printf("Codepoint after Shaping: %d\n", t2);
printf("%x\n", glyph_info[0].codepoint);
hb_buffer_set_content_type(buf, HB_BUFFER_CONTENT_TYPE_UNICODE);
hb_buffer_content_type_t t3 = hb_buffer_get_content_type(buf);
glyph_info = hb_buffer_get_glyph_infos(buf, &glyph_count);
glyph_pos = hb_buffer_get_glyph_positions(buf, &glyph_count);
printf("Codepoint after setting content type: %d\n", t3);
printf("%x\n", glyph_info[0].codepoint);
hb_buffer_destroy(buf);
hb_font_destroy(font);
hb_face_destroy(face);
hb_blob_destroy(blob);
}
but this is my out put:
Codepoint befor Shaping: 1
41
Codepoint after Shaping: 2
24
Codepoint after setting content type: 1
24
why the last code point is still glyph index and not Unicode codepoint?
I expected unicode codepoint but i get glyph index
You can use clusters to map shaped glyphs to its source codepoint. What you can do is keep track of codepoints/clusters being passed to HarfBuzz, then compare glyph_info list against that list to see which codepoint(s) each glyph was shaped from
unsigned int glyph_count_before;
hb_glyph_info_t* glyph_infos_before = hb_buffer_get_glyph_infos(buf, &glyph_count_before);
hb_shape(font, buf, NULL, 0);
unsigned int glyph_count_after;
hb_glyph_info_t* glyph_infos_after = hb_buffer_get_glyph_infos(buf, &glyph_count_after);
int source_idx = 0;
for (int i = 0; i < glyph_count_after; ++i)
{
hb_glyph_info_t& glyph_info_after = glyph_infos_after[i];
printf("Codepoints for glyph %d\n", i);
// find the next grapheme cluster index
int next_grapheme_cluster_idx = 0;
for (next_grapheme_cluster_idx = i; next_grapheme_cluster_idx < glyph_count_after; ++next_grapheme_cluster_idx)
{
if (glyph_infos_after[next_grapheme_cluster_idx].cluster != glyph_info_after.cluster)
{
break;
}
}
for (; source_idx < glyph_count_before; ++source_idx)
{
hb_glyph_info_t& glyph_info_before = glyph_infos_before[source_idx];
if (next_grapheme_cluster_idx < glyph_count_after && glyph_info_before.cluster > glyph_infos_after[next_grapheme_cluster_idx].cluster)
{
// source_idx is now on the codepoint for the next glyph
break;
}
printf(" %d\n", glyph_info_before.codepoint);
}
}
Looking at the comment on clusters from hb_glyph_info_t
/**
* hb_glyph_info_t:
* @codepoint: either a Unicode code point (before shaping) or a glyph index
* (after shaping).
* @mask:
* @cluster: the index of the character in the original text that corresponds
* to this #hb_glyph_info_t, or whatever the client passes to
* hb_buffer_add(). More than one #hb_glyph_info_t can have the same
* @cluster value, if they resulted from the same character (e.g. one
* to many glyph substitution), and when more than one character gets
* merged in the same glyph (e.g. many to one glyph substitution) the
* #hb_glyph_info_t will have the smallest cluster value of them.
* By default some characters are merged into the same cluster
* (e.g. combining marks have the same cluster as their bases)
* even if they are separate glyphs, hb_buffer_set_cluster_level()
* allow selecting more fine-grained cluster handling.
Also worth noting that there's various ways to setup clusters for better mapping choices (the default is level 0): HarfBuzz clusters