diff options
Diffstat (limited to 'thirdparty/harfbuzz/src/hb-buffer.h')
| -rw-r--r-- | thirdparty/harfbuzz/src/hb-buffer.h | 92 |
1 files changed, 77 insertions, 15 deletions
diff --git a/thirdparty/harfbuzz/src/hb-buffer.h b/thirdparty/harfbuzz/src/hb-buffer.h index a183cb9d4a..9fbd7b1ec3 100644 --- a/thirdparty/harfbuzz/src/hb-buffer.h +++ b/thirdparty/harfbuzz/src/hb-buffer.h @@ -76,18 +76,68 @@ typedef struct hb_glyph_info_t { * @HB_GLYPH_FLAG_UNSAFE_TO_BREAK: Indicates that if input text is broken at the * beginning of the cluster this glyph is part of, * then both sides need to be re-shaped, as the - * result might be different. On the flip side, - * it means that when this flag is not present, - * then it's safe to break the glyph-run at the - * beginning of this cluster, and the two sides - * represent the exact same result one would get - * if breaking input text at the beginning of - * this cluster and shaping the two sides - * separately. This can be used to optimize - * paragraph layout, by avoiding re-shaping - * of each line after line-breaking, or limiting - * the reshaping to a small piece around the - * breaking point only. + * result might be different. + * On the flip side, it means that when this + * flag is not present, then it is safe to break + * the glyph-run at the beginning of this + * cluster, and the two sides will represent the + * exact same result one would get if breaking + * input text at the beginning of this cluster + * and shaping the two sides separately. + * This can be used to optimize paragraph + * layout, by avoiding re-shaping of each line + * after line-breaking. + * @HB_GLYPH_FLAG_UNSAFE_TO_CONCAT: Indicates that if input text is changed on one + * side of the beginning of the cluster this glyph + * is part of, then the shaping results for the + * other side might change. + * Note that the absence of this flag will NOT by + * itself mean that it IS safe to concat text. + * Only two pieces of text both of which clear of + * this flag can be concatenated safely. + * This can be used to optimize paragraph + * layout, by avoiding re-shaping of each line + * after line-breaking, by limiting the + * reshaping to a small piece around the + * breaking positin only, even if the breaking + * position carries the + * #HB_GLYPH_FLAG_UNSAFE_TO_BREAK or when + * hyphenation or other text transformation + * happens at line-break position, in the following + * way: + * 1. Iterate back from the line-break position + * until the first cluster start position that is + * NOT unsafe-to-concat, 2. shape the segment from + * there till the end of line, 3. check whether the + * resulting glyph-run also is clear of the + * unsafe-to-concat at its start-of-text position; + * if it is, just splice it into place and the line + * is shaped; If not, move on to a position further + * back that is clear of unsafe-to-concat and retry + * from there, and repeat. + * At the start of next line a similar algorithm can + * be implemented. That is: 1. Iterate forward from + * the line-break position untill the first cluster + * start position that is NOT unsafe-to-concat, 2. + * shape the segment from beginning of the line to + * that position, 3. check whether the resulting + * glyph-run also is clear of the unsafe-to-concat + * at its end-of-text position; if it is, just splice + * it into place and the beginning is shaped; If not, + * move on to a position further forward that is clear + * of unsafe-to-concat and retry up to there, and repeat. + * A slight complication will arise in the + * implementation of the algorithm above, + * because while our buffer API has a way to + * return flags for position corresponding to + * start-of-text, there is currently no position + * corresponding to end-of-text. This limitation + * can be alleviated by shaping more text than needed + * and looking for unsafe-to-concat flag within text + * clusters. + * The #HB_GLYPH_FLAG_UNSAFE_TO_BREAK flag will + * always imply this flag. + * Since: 3.3.0 * @HB_GLYPH_FLAG_DEFINED: All the currently defined flags. * * Flags for #hb_glyph_info_t. @@ -96,8 +146,9 @@ typedef struct hb_glyph_info_t { */ typedef enum { /*< flags >*/ HB_GLYPH_FLAG_UNSAFE_TO_BREAK = 0x00000001, + HB_GLYPH_FLAG_UNSAFE_TO_CONCAT = 0x00000002, - HB_GLYPH_FLAG_DEFINED = 0x00000001 /* OR of all defined flags */ + HB_GLYPH_FLAG_DEFINED = 0x00000003 /* OR of all defined flags */ } hb_glyph_flags_t; HB_EXTERN hb_glyph_flags_t @@ -170,6 +221,9 @@ hb_segment_properties_equal (const hb_segment_properties_t *a, HB_EXTERN unsigned int hb_segment_properties_hash (const hb_segment_properties_t *p); +HB_EXTERN void +hb_segment_properties_overlay (hb_segment_properties_t *p, + const hb_segment_properties_t *src); /** @@ -185,6 +239,13 @@ HB_EXTERN hb_buffer_t * hb_buffer_create (void); HB_EXTERN hb_buffer_t * +hb_buffer_create_similar (const hb_buffer_t *src); + +HB_EXTERN void +hb_buffer_reset (hb_buffer_t *buffer); + + +HB_EXTERN hb_buffer_t * hb_buffer_get_empty (void); HB_EXTERN hb_buffer_t * @@ -391,8 +452,9 @@ HB_EXTERN hb_codepoint_t hb_buffer_get_not_found_glyph (hb_buffer_t *buffer); -HB_EXTERN void -hb_buffer_reset (hb_buffer_t *buffer); +/* + * Content API. + */ HB_EXTERN void hb_buffer_clear_contents (hb_buffer_t *buffer); |