Apply ligatures patch

[st.git] / hb.c

diff --git a/hb.c b/hb.c
new file mode 100644 (file)
index 0000000..7df2828
--- /dev/null
+++ b/hb.c
@@ -0,0 +1,136 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <math.h>
+#include <X11/Xft/Xft.h>
+#include <hb.h>
+#include <hb-ft.h>
+
+#include "st.h"
+
+void hbtransformsegment(XftFont *xfont, const Glyph *string, hb_codepoint_t *codepoints, int start, int length);
+hb_font_t *hbfindfont(XftFont *match);
+
+typedef struct {
+       XftFont *match;
+       hb_font_t *font;
+} HbFontMatch;
+
+static int hbfontslen = 0;
+static HbFontMatch *hbfontcache = NULL;
+
+void
+hbunloadfonts()
+{
+       for (int i = 0; i < hbfontslen; i++) {
+               hb_font_destroy(hbfontcache[i].font);
+               XftUnlockFace(hbfontcache[i].match);
+       }
+
+       if (hbfontcache != NULL) {
+               free(hbfontcache);
+               hbfontcache = NULL;
+       }
+       hbfontslen = 0;
+}
+
+hb_font_t *
+hbfindfont(XftFont *match)
+{
+       for (int i = 0; i < hbfontslen; i++) {
+               if (hbfontcache[i].match == match)
+                       return hbfontcache[i].font;
+       }
+
+       /* Font not found in cache, caching it now. */
+       hbfontcache = realloc(hbfontcache, sizeof(HbFontMatch) * (hbfontslen + 1));
+       FT_Face face = XftLockFace(match);
+       hb_font_t *font = hb_ft_font_create(face, NULL);
+       if (font == NULL)
+               die("Failed to load Harfbuzz font.");
+
+       hbfontcache[hbfontslen].match = match;
+       hbfontcache[hbfontslen].font = font;
+       hbfontslen += 1;
+
+       return font;
+}
+
+void
+hbtransform(XftGlyphFontSpec *specs, const Glyph *glyphs, size_t len, int x, int y)
+{
+       int start = 0, length = 1, gstart = 0;
+       hb_codepoint_t *codepoints = calloc(len, sizeof(hb_codepoint_t));
+
+       for (int idx = 1, specidx = 1; idx < len; idx++) {
+               if (glyphs[idx].mode & ATTR_WDUMMY) {
+                       length += 1;
+                       continue;
+               }
+
+               if (specs[specidx].font != specs[start].font || ATTRCMP(glyphs[gstart], glyphs[idx]) || selected(x + idx, y) != selected(x + gstart, y)) {
+                       hbtransformsegment(specs[start].font, glyphs, codepoints, gstart, length);
+
+                       /* Reset the sequence. */
+                       length = 1;
+                       start = specidx;
+                       gstart = idx;
+               } else {
+                       length += 1;
+               }
+
+               specidx++;
+       }
+
+       /* EOL. */
+       hbtransformsegment(specs[start].font, glyphs, codepoints, gstart, length);
+
+       /* Apply the transformation to glyph specs. */
+       for (int i = 0, specidx = 0; i < len; i++) {
+               if (glyphs[i].mode & ATTR_WDUMMY)
+                       continue;
+
+               if (codepoints[i] != specs[specidx].glyph)
+                       ((Glyph *)glyphs)[i].mode |= ATTR_LIGA;
+
+               specs[specidx++].glyph = codepoints[i];
+       }
+
+       free(codepoints);
+}
+
+void
+hbtransformsegment(XftFont *xfont, const Glyph *string, hb_codepoint_t *codepoints, int start, int length)
+{
+       hb_font_t *font = hbfindfont(xfont);
+       if (font == NULL)
+               return;
+
+       Rune rune;
+       ushort mode = USHRT_MAX;
+       hb_buffer_t *buffer = hb_buffer_create();
+       hb_buffer_set_direction(buffer, HB_DIRECTION_LTR);
+
+       /* Fill buffer with codepoints. */
+       for (int i = start; i < (start+length); i++) {
+               rune = string[i].u;
+               mode = string[i].mode;
+               if (mode & ATTR_WDUMMY)
+                       rune = 0x0020;
+               hb_buffer_add_codepoints(buffer, &rune, 1, 0, 1);
+       }
+
+       /* Shape the segment. */
+       hb_shape(font, buffer, NULL, 0);
+
+       /* Get new glyph info. */
+       hb_glyph_info_t *info = hb_buffer_get_glyph_infos(buffer, NULL);
+
+       /* Write new codepoints. */
+       for (int i = 0; i < length; i++) {
+               hb_codepoint_t gid = info[i].codepoint;
+               codepoints[start+i] = gid;
+       }
+
+       /* Cleanup. */
+       hb_buffer_destroy(buffer);
+}