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Now we have a brand new HarfBuzz buffer. Let's start filling it
with text! From HarfBuzz's perspective, a buffer is just a stream
of Unicode code points, but your input string is probably in one of
the standard Unicode character encodings (UTF-8, UTF-16, or
UTF-32). HarfBuzz provides convenience functions that accept
each of these encodings:
hb_buffer_add_utf8(),
hb_buffer_add_utf16(), and
hb_buffer_add_utf32(). Other than the
character encoding they accept, they function identically.
You can add UTF-8 text to a buffer by passing in the text array, the array's length, an offset into the array for the first character to add, and the length of the segment to add:
hb_buffer_add_utf8 (hb_buffer_t *buf,
const char *text,
int text_length,
unsigned int item_offset,
int item_length)
So, in practice, you can say:
hb_buffer_add_utf8(buf, text, strlen(text), 0, strlen(text));
This will append your new characters to
buf, not replace its existing
contents. Also, note that you can use -1 in
place of the first instance of strlen(text)
if your text array is NULL-terminated. Similarly, you can also use
-1 as the final argument want to add its full
contents.
Whatever start item_offset and
item_length you provide, HarfBuzz will also
attempt to grab the five characters before
the offset point and the five characters
after the designated end. These are the
before and after "context" segments, which are used internally
for HarfBuzz to make shaping decisions. They will not be part of