Suckless/st/patches/st-ligatures-boxdraw-20221120-0.9.diff

diff --git a/Makefile b/Makefile
index 6dfa212..adfa07a 100644
--- a/Makefile
+++ b/Makefile
@@ -4,7 +4,7 @@
 
 include config.mk
 
-SRC = st.c x.c boxdraw.c
+SRC = st.c x.c boxdraw.c hb.c
 OBJ = $(SRC:.c=.o)
 
 all: options st
@@ -22,8 +22,9 @@ config.h:
 	$(CC) $(STCFLAGS) -c $<
 
 st.o: config.h st.h win.h
-x.o: arg.h config.h st.h win.h
+x.o: arg.h config.h st.h win.h hb.h
 boxdraw.o: config.h st.h boxdraw_data.h
+hb.o: st.h
 
 $(OBJ): config.h config.mk
 
diff --git a/config.mk b/config.mk
index 1e306f8..3e13e53 100644
--- a/config.mk
+++ b/config.mk
@@ -15,10 +15,12 @@ PKG_CONFIG = pkg-config
 # includes and libs
 INCS = -I$(X11INC) \
        `$(PKG_CONFIG) --cflags fontconfig` \
-       `$(PKG_CONFIG) --cflags freetype2`
+       `$(PKG_CONFIG) --cflags freetype2` \
+       `$(PKG_CONFIG) --cflags harfbuzz`
 LIBS = -L$(X11LIB) -lm -lrt -lX11 -lutil -lXft \
        `$(PKG_CONFIG) --libs fontconfig` \
-       `$(PKG_CONFIG) --libs freetype2`
+       `$(PKG_CONFIG) --libs freetype2` \
+       `$(PKG_CONFIG) --libs harfbuzz`
 
 # flags
 STCPPFLAGS = -DVERSION=\"$(VERSION)\" -D_XOPEN_SOURCE=600
diff --git a/hb.c b/hb.c
new file mode 100644
index 0000000..59b9200
--- /dev/null
+++ b/hb.c
@@ -0,0 +1,107 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <math.h>
+#include <X11/Xft/Xft.h>
+#include <X11/cursorfont.h>
+#include <hb.h>
+#include <hb-ft.h>
+
+#include "st.h"
+#include "hb.h"
+
+#define FEATURE(c1,c2,c3,c4) { .tag = HB_TAG(c1,c2,c3,c4), .value = 1, .start = HB_FEATURE_GLOBAL_START, .end = HB_FEATURE_GLOBAL_END }
+
+hb_font_t *hbfindfont(XftFont *match);
+
+typedef struct {
+	XftFont *match;
+	hb_font_t *font;
+} HbFontMatch;
+
+static int hbfontslen = 0;
+static HbFontMatch *hbfontcache = NULL;
+
+/*
+ * Poplulate the array with a list of font features, wrapped in FEATURE macro,
+ * e. g.
+ * FEATURE('c', 'a', 'l', 't'), FEATURE('d', 'l', 'i', 'g')
+ */
+hb_feature_t features[] = { };
+
+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(HbTransformData *data, XftFont *xfont, const Glyph *glyphs, int start, int length) {
+	Rune rune;
+	ushort mode = USHRT_MAX;
+	unsigned int glyph_count;
+	int i, end = start + length;
+
+	hb_font_t *font = hbfindfont(xfont);
+	if (font == NULL)
+		return;
+
+	hb_buffer_t *buffer = hb_buffer_create();
+	hb_buffer_set_direction(buffer, HB_DIRECTION_LTR);
+
+	/* Fill buffer with codepoints. */
+	for (i = start; i < end; i++) {
+		rune = glyphs[i].u;
+		mode = glyphs[i].mode;
+		if (mode & ATTR_WDUMMY)
+			rune = 0x0020;
+		hb_buffer_add_codepoints(buffer, &rune, 1, 0, 1);
+	}
+
+	/* Shape the segment. */
+	hb_shape(font, buffer, features, sizeof(features)/sizeof(hb_feature_t));
+
+	/* Get new glyph info. */
+	hb_glyph_info_t *info = hb_buffer_get_glyph_infos(buffer, &glyph_count);
+	hb_glyph_position_t *pos = hb_buffer_get_glyph_positions(buffer, &glyph_count);
+
+	/** Fill the output. */
+	data->buffer = buffer;
+	data->glyphs = info;
+	data->positions = pos;
+	data->count = glyph_count;
+}
+
+void hbcleanup(HbTransformData *data) {
+	hb_buffer_destroy(data->buffer);
+	memset(data, 0, sizeof(HbTransformData));
+}
diff --git a/hb.h b/hb.h
new file mode 100644
index 0000000..88de9bd
--- /dev/null
+++ b/hb.h
@@ -0,0 +1,14 @@
+#include <X11/Xft/Xft.h>
+#include <hb.h>
+#include <hb-ft.h>
+
+typedef struct {
+  hb_buffer_t *buffer;
+  hb_glyph_info_t *glyphs;
+  hb_glyph_position_t *positions;
+  unsigned int count;
+} HbTransformData;
+
+void hbunloadfonts();
+void hbtransform(HbTransformData *, XftFont *, const Glyph *, int, int);
+void hbcleanup(HbTransformData *);
diff --git a/st.c b/st.c
index 41d5ace..1c2edd6 100644
--- a/st.c
+++ b/st.c
@@ -2643,7 +2643,8 @@ draw(void)
 
 	drawregion(0, 0, term.col, term.row);
 	xdrawcursor(cx, term.c.y, term.line[term.c.y][cx],
-			term.ocx, term.ocy, term.line[term.ocy][term.ocx]);
+			term.ocx, term.ocy, term.line[term.ocy][term.ocx],
+			term.line[term.ocy], term.col);
 	term.ocx = cx;
 	term.ocy = term.c.y;
 	xfinishdraw();
diff --git a/st.h b/st.h
index 808f5f7..ae41368 100644
--- a/st.h
+++ b/st.h
@@ -11,7 +11,8 @@
 #define DIVCEIL(n, d)		(((n) + ((d) - 1)) / (d))
 #define DEFAULT(a, b)		(a) = (a) ? (a) : (b)
 #define LIMIT(x, a, b)		(x) = (x) < (a) ? (a) : (x) > (b) ? (b) : (x)
-#define ATTRCMP(a, b)		((a).mode != (b).mode || (a).fg != (b).fg || \
+#define ATTRCMP(a, b)		(((a).mode & (~ATTR_WRAP)) != ((b).mode & (~ATTR_WRAP)) || \
+				(a).fg != (b).fg || \
 				(a).bg != (b).bg)
 #define TIMEDIFF(t1, t2)	((t1.tv_sec-t2.tv_sec)*1000 + \
 				(t1.tv_nsec-t2.tv_nsec)/1E6)
diff --git a/win.h b/win.h
index 6de960d..94679e4 100644
--- a/win.h
+++ b/win.h
@@ -25,7 +25,7 @@ enum win_mode {
 
 void xbell(void);
 void xclipcopy(void);
-void xdrawcursor(int, int, Glyph, int, int, Glyph);
+void xdrawcursor(int, int, Glyph, int, int, Glyph, Line, int);
 void xdrawline(Line, int, int, int);
 void xfinishdraw(void);
 void xloadcols(void);
diff --git a/x.c b/x.c
index bf6bbf9..440bd2a 100644
--- a/x.c
+++ b/x.c
@@ -19,6 +19,7 @@ char *argv0;
 #include "arg.h"
 #include "st.h"
 #include "win.h"
+#include "hb.h"
 
 /* types used in config.h */
 typedef struct {
@@ -141,6 +142,7 @@ typedef struct {
 } DC;
 
 static inline ushort sixd_to_16bit(int);
+static void xresetfontsettings(ushort mode, Font **font, int *frcflags);
 static int xmakeglyphfontspecs(XftGlyphFontSpec *, const Glyph *, int, int, int);
 static void xdrawglyphfontspecs(const XftGlyphFontSpec *, Glyph, int, int, int);
 static void xdrawglyph(Glyph, int, int);
@@ -1062,6 +1064,9 @@ xunloadfont(Font *f)
 void
 xunloadfonts(void)
 {
+	/* Clear Harfbuzz font cache. */
+	hbunloadfonts();
+
 	/* Free the loaded fonts in the font cache.  */
 	while (frclen > 0)
 		XftFontClose(xw.dpy, frc[--frclen].font);
@@ -1241,6 +1246,22 @@ xinit(int cols, int rows)
 	boxdraw_xinit(xw.dpy, xw.cmap, xw.draw, xw.vis);
 }
 
+void
+xresetfontsettings(ushort mode, Font **font, int *frcflags)
+{
+  *font = &dc.font;
+	if ((mode & ATTR_ITALIC) && (mode & ATTR_BOLD)) {
+		*font = &dc.ibfont;
+		*frcflags = FRC_ITALICBOLD;
+	} else if (mode & ATTR_ITALIC) {
+		*font = &dc.ifont;
+		*frcflags = FRC_ITALIC;
+	} else if (mode & ATTR_BOLD) {
+		*font = &dc.bfont;
+		*frcflags = FRC_BOLD;
+	}
+}
+
 int
 xmakeglyphfontspecs(XftGlyphFontSpec *specs, const Glyph *glyphs, int len, int x, int y)
 {
@@ -1255,124 +1276,145 @@ xmakeglyphfontspecs(XftGlyphFontSpec *specs, const Glyph *glyphs, int len, int x
 	FcPattern *fcpattern, *fontpattern;
 	FcFontSet *fcsets[] = { NULL };
 	FcCharSet *fccharset;
-	int i, f, numspecs = 0;
+	int i, f, length = 0, start = 0, numspecs = 0;
+	HbTransformData shaped = { 0 };
+
+	/* Initial values. */
+	mode = prevmode = glyphs[0].mode;
+	xresetfontsettings(mode, &font, &frcflags);
 
 	for (i = 0, xp = winx, yp = winy + font->ascent; i < len; ++i) {
-		/* Fetch rune and mode for current glyph. */
-		rune = glyphs[i].u;
 		mode = glyphs[i].mode;
 
 		/* Skip dummy wide-character spacing. */
-		if (mode == ATTR_WDUMMY)
+		if (mode & ATTR_WDUMMY)
 			continue;
 
-		/* Determine font for glyph if different from previous glyph. */
-		if (prevmode != mode) {
-			prevmode = mode;
-			font = &dc.font;
-			frcflags = FRC_NORMAL;
-			runewidth = win.cw * ((mode & ATTR_WIDE) ? 2.0f : 1.0f);
-			if ((mode & ATTR_ITALIC) && (mode & ATTR_BOLD)) {
-				font = &dc.ibfont;
-				frcflags = FRC_ITALICBOLD;
-			} else if (mode & ATTR_ITALIC) {
-				font = &dc.ifont;
-				frcflags = FRC_ITALIC;
-			} else if (mode & ATTR_BOLD) {
-				font = &dc.bfont;
-				frcflags = FRC_BOLD;
+		if (
+			prevmode != mode
+			|| ATTRCMP(glyphs[start], glyphs[i])
+			|| selected(x + i, y) != selected(x + start, y)
+			|| i == (len - 1)
+		) {
+			/* Handle 1-character wide segments and end of line */
+			length = i - start;
+			if (i == start) {
+				length = 1;
+			} else if (i == (len - 1)) {
+				length = (i - start + 1);
 			}
-			yp = winy + font->ascent;
-		}
 
-		if (mode & ATTR_BOXDRAW) {
-			/* minor shoehorning: boxdraw uses only this ushort */
-			glyphidx = boxdrawindex(&glyphs[i]);
-		} else {
-			/* Lookup character index with default font. */
-			glyphidx = XftCharIndex(xw.dpy, font->match, rune);
-		}
-		if (glyphidx) {
-			specs[numspecs].font = font->match;
-			specs[numspecs].glyph = glyphidx;
-			specs[numspecs].x = (short)xp;
-			specs[numspecs].y = (short)yp;
-			xp += runewidth;
-			numspecs++;
-			continue;
-		}
-
-		/* Fallback on font cache, search the font cache for match. */
-		for (f = 0; f < frclen; f++) {
-			glyphidx = XftCharIndex(xw.dpy, frc[f].font, rune);
-			/* Everything correct. */
-			if (glyphidx && frc[f].flags == frcflags)
-				break;
-			/* We got a default font for a not found glyph. */
-			if (!glyphidx && frc[f].flags == frcflags
-					&& frc[f].unicodep == rune) {
-				break;
+			/* Shape the segment. */
+			hbtransform(&shaped, font->match, glyphs, start, length);
+			for (int code_idx = 0; code_idx < shaped.count; code_idx++) {
+				rune = glyphs[start + code_idx].u;
+				runewidth = win.cw * ((glyphs[start + code_idx].mode & ATTR_WIDE) ? 2.0f : 1.0f);
+
+				if (glyphs[start + code_idx].mode & ATTR_WDUMMY)
+					continue;
+
+				if (glyphs[start + code_idx].mode & ATTR_BOXDRAW) {
+					/* minor shoehorning: boxdraw uses only this ushort */
+					specs[numspecs].font = font->match;
+					specs[numspecs].glyph = boxdrawindex(&glyphs[start + code_idx]);
+					specs[numspecs].x = xp;
+					specs[numspecs].y = yp;
+					xp += runewidth;
+					numspecs++;
+				} else if (shaped.glyphs[code_idx].codepoint != 0) {
+					/* If symbol is found, put it into the specs. */
+					specs[numspecs].font = font->match;
+					specs[numspecs].glyph = shaped.glyphs[code_idx].codepoint;
+					specs[numspecs].x = xp + (short)shaped.positions[code_idx].x_offset;
+					specs[numspecs].y = yp + (short)shaped.positions[code_idx].y_offset;
+					xp += runewidth;
+					numspecs++;
+				} else {
+					/* If it's not found, try to fetch it through the font cache. */
+					for (f = 0; f < frclen; f++) {
+						glyphidx = XftCharIndex(xw.dpy, frc[f].font, rune);
+						/* Everything correct. */
+						if (glyphidx && frc[f].flags == frcflags)
+							break;
+						/* We got a default font for a not found glyph. */
+						if (!glyphidx && frc[f].flags == frcflags
+								&& frc[f].unicodep == rune) {
+							break;
+						}
+					}
+
+					/* Nothing was found. Use fontconfig to find matching font. */
+					if (f >= frclen) {
+						if (!font->set)
+							font->set = FcFontSort(0, font->pattern,
+																		 1, 0, &fcres);
+						fcsets[0] = font->set;
+
+						/*
+						 * Nothing was found in the cache. Now use
+						 * some dozen of Fontconfig calls to get the
+						 * font for one single character.
+						 *
+						 * Xft and fontconfig are design failures.
+						 */
+						fcpattern = FcPatternDuplicate(font->pattern);
+						fccharset = FcCharSetCreate();
+
+						FcCharSetAddChar(fccharset, rune);
+						FcPatternAddCharSet(fcpattern, FC_CHARSET,
+								fccharset);
+						FcPatternAddBool(fcpattern, FC_SCALABLE, 1);
+
+						FcConfigSubstitute(0, fcpattern,
+								FcMatchPattern);
+						FcDefaultSubstitute(fcpattern);
+
+						fontpattern = FcFontSetMatch(0, fcsets, 1,
+								fcpattern, &fcres);
+
+						/* Allocate memory for the new cache entry. */
+						if (frclen >= frccap) {
+							frccap += 16;
+							frc = xrealloc(frc, frccap * sizeof(Fontcache));
+						}
+
+						frc[frclen].font = XftFontOpenPattern(xw.dpy,
+								fontpattern);
+						if (!frc[frclen].font)
+							die("XftFontOpenPattern failed seeking fallback font: %s\n",
+								strerror(errno));
+						frc[frclen].flags = frcflags;
+						frc[frclen].unicodep = rune;
+
+						glyphidx = XftCharIndex(xw.dpy, frc[frclen].font, rune);
+
+						f = frclen;
+						frclen++;
+
+						FcPatternDestroy(fcpattern);
+						FcCharSetDestroy(fccharset);
+					}
+
+					specs[numspecs].font = frc[f].font;
+					specs[numspecs].glyph = glyphidx;
+					specs[numspecs].x = (short)xp;
+					specs[numspecs].y = (short)yp;
+					xp += runewidth;
+					numspecs++;
+				}
 			}
-		}
 
-		/* Nothing was found. Use fontconfig to find matching font. */
-		if (f >= frclen) {
-			if (!font->set)
-				font->set = FcFontSort(0, font->pattern,
-				                       1, 0, &fcres);
-			fcsets[0] = font->set;
+			/* Cleanup and get ready for next segment. */
+			hbcleanup(&shaped);
+			start = i;
 
-			/*
-			 * Nothing was found in the cache. Now use
-			 * some dozen of Fontconfig calls to get the
-			 * font for one single character.
-			 *
-			 * Xft and fontconfig are design failures.
-			 */
-			fcpattern = FcPatternDuplicate(font->pattern);
-			fccharset = FcCharSetCreate();
-
-			FcCharSetAddChar(fccharset, rune);
-			FcPatternAddCharSet(fcpattern, FC_CHARSET,
-					fccharset);
-			FcPatternAddBool(fcpattern, FC_SCALABLE, 1);
-
-			FcConfigSubstitute(0, fcpattern,
-					FcMatchPattern);
-			FcDefaultSubstitute(fcpattern);
-
-			fontpattern = FcFontSetMatch(0, fcsets, 1,
-					fcpattern, &fcres);
-
-			/* Allocate memory for the new cache entry. */
-			if (frclen >= frccap) {
-				frccap += 16;
-				frc = xrealloc(frc, frccap * sizeof(Fontcache));
+			/* Determine font for glyph if different from previous glyph. */
+			if (prevmode != mode) {
+				prevmode = mode;
+				xresetfontsettings(mode, &font, &frcflags);
+				yp = winy + font->ascent;
 			}
-
-			frc[frclen].font = XftFontOpenPattern(xw.dpy,
-					fontpattern);
-			if (!frc[frclen].font)
-				die("XftFontOpenPattern failed seeking fallback font: %s\n",
-					strerror(errno));
-			frc[frclen].flags = frcflags;
-			frc[frclen].unicodep = rune;
-
-			glyphidx = XftCharIndex(xw.dpy, frc[frclen].font, rune);
-
-			f = frclen;
-			frclen++;
-
-			FcPatternDestroy(fcpattern);
-			FcCharSetDestroy(fccharset);
 		}
-
-		specs[numspecs].font = frc[f].font;
-		specs[numspecs].glyph = glyphidx;
-		specs[numspecs].x = (short)xp;
-		specs[numspecs].y = (short)yp;
-		xp += runewidth;
-		numspecs++;
 	}
 
 	return numspecs;
@@ -1528,14 +1570,17 @@ xdrawglyph(Glyph g, int x, int y)
 }
 
 void
-xdrawcursor(int cx, int cy, Glyph g, int ox, int oy, Glyph og)
+xdrawcursor(int cx, int cy, Glyph g, int ox, int oy, Glyph og, Line line, int len)
 {
 	Color drawcol;
 
 	/* remove the old cursor */
 	if (selected(ox, oy))
 		og.mode ^= ATTR_REVERSE;
-	xdrawglyph(og, ox, oy);
+
+	/* Redraw the line where cursor was previously.
+	 * It will restore the ligatures broken by the cursor. */
+	xdrawline(line, 0, oy, len);
 
 	if (IS_SET(MODE_HIDE))
 		return;