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| author | Eli Zaretskii <eliz@gnu.org> | 2021-06-02 17:50:57 +0300 |
|---|---|---|
| committer | Eli Zaretskii <eliz@gnu.org> | 2021-06-02 17:50:57 +0300 |
| commit | f7d4bbceee8c3c29e2ef0bfacf9ff24fb020d3ee (patch) | |
| tree | affbac1d8f4e6152a36ff24bc63f23ae1a749d4d /src/composite.h | |
| parent | bef00aa1372dbd8a72ac84be0ee397cca46a1250 (diff) | |
| download | emacs-f7d4bbceee8c3c29e2ef0bfacf9ff24fb020d3ee.tar.gz | |
; * src/composite.h: Improve comments for LGSTRING and LGLYPH.
Diffstat (limited to 'src/composite.h')
| -rw-r--r-- | src/composite.h | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/src/composite.h b/src/composite.h index 1b346b4cdfe..ebbb55f49c0 100644 --- a/src/composite.h +++ b/src/composite.h @@ -243,6 +243,11 @@ composition_valid_p (ptrdiff_t start, ptrdiff_t end, Lisp_Object prop) /* Macros for lispy glyph-string. This is completely different from struct glyph_string. */ +/* LGSTRING is a string of font glyphs, LGLYPHs. It is represented as + a Lisp vector, with components shown below. Once LGSTRING was + processed by a shaping engine, it holds font glyphs for one or more + grapheme clusters. */ + #define LGSTRING_HEADER(lgs) AREF (lgs, 0) #define LGSTRING_SET_HEADER(lgs, header) ASET (lgs, 0, header) @@ -256,6 +261,10 @@ composition_valid_p (ptrdiff_t start, ptrdiff_t end, Lisp_Object prop) #define LGSTRING_ID(lgs) AREF (lgs, 1) #define LGSTRING_SET_ID(lgs, id) ASET (lgs, 1, id) +/* LGSTRING_GLYPH_LEN is the maximum number of LGLYPHs that the + LGSTRING can hold. This is NOT the actual number of valid LGLYPHs; + to find the latter, walk the glyphs returned by LGSTRING_GLYPH + until the first one that is nil. */ #define LGSTRING_GLYPH_LEN(lgs) (ASIZE ((lgs)) - 2) #define LGSTRING_GLYPH(lgs, idx) AREF ((lgs), (idx) + 2) #define LGSTRING_SET_GLYPH(lgs, idx, val) ASET ((lgs), (idx) + 2, (val)) @@ -275,6 +284,14 @@ enum lglyph_indices LGLYPH_SIZE }; +/* Each LGLYPH is a single font glyph, whose font code is in + LGLYPH_CODE. + LGLYPH_FROM and LGLYPH_TO are indices into LGSTRING; all the + LGLYPHs that share the same values of LGLYPH_FROM and LGLYPH_TO + belong to the same grapheme cluster. + LGLYPH_CHAR is one of the characters, usually the first one, that + contributed to the glyph (since there isn't a 1:1 correspondence + between composed characters and the font glyphs). */ #define LGLYPH_NEW() make_nil_vector (LGLYPH_SIZE) #define LGLYPH_FROM(g) XFIXNUM (AREF ((g), LGLYPH_IX_FROM)) #define LGLYPH_TO(g) XFIXNUM (AREF ((g), LGLYPH_IX_TO)) |