Set text in a stack of fonts: each grapheme cluster in the first that has it

vega_layout takes fonts in order of preference (VegaFonts). A grapheme
cluster goes to the first font that has all its characters (default
ignorables aside: shaping hides them); a cluster of Common and Inherited
characters stays in the font before it when that one has it, so the spaces
between Arabic words stay in the Arabic font; failing that, the first font
with its first character, else the first font. Runs split where the font
changes too. Positions are in the first font's units, a run's pen scaled
as a whole so rounding does not add up. Callers can narrow what a font
has (a symbol file holds only the glyphs its codes reach).

vega_default_ignorable is shape.c's HarfBuzz 10.2 set, now public.

1 files changed, 2 insertions, 2 deletions

diff --git a/text/shape.c b/text/shape.c
index c9b8c0c..0ea2968 100644
--- a/text/shape.c
+++ b/text/shape.c
@@ -584,7 +584,7 @@ static bool cased_or_other_letter_or_space(unsigned c) {
 
 /* HarfBuzz's Default_Ignorable: Unicode's, less the Hangul fillers and a
  * few others that fonts draw. */
-static bool default_ignorable(uint32_t ch) {
+bool vega_default_ignorable(uint32_t ch) {
     uint32_t plane = ch >> 16;
     if (!plane) {
         switch (ch >> 8) {
@@ -651,7 +651,7 @@ static void init_unicode_props(Info *info, uint32_t *scratch) {
     unsigned gen = vega_category(u), props = gen;
     if (u >= 0x80) {
         *scratch |= HAS_NON_ASCII;
-        if (default_ignorable(u)) {
+        if (vega_default_ignorable(u)) {
             *scratch |= HAS_DEFAULT_IGNORABLES;
             props |= UPROPS_IGNORABLE;
             if (u == 0x200C) props |= UPROPS_ZWNJ;