Added ligature-boxdraw v0.9 patch

Makefile

@@ -4,7 +4,7 @@
 
 include config.mk
 
-SRC = st.c x.c
+SRC = st.c x.c boxdraw.c hb.c
 OBJ = $(SRC:.c=.o)
 
 all: options st
@@ -22,7 +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
 

boxdraw.c

@@ -0,0 +1,194 @@
+/*
+ * Copyright 2018 Avi Halachmi (:avih) avihpit@yahoo.com https://github.com/avih
+ * MIT/X Consortium License
+ */
+
+#include <X11/Xft/Xft.h>
+#include "st.h"
+#include "boxdraw_data.h"
+
+/* Rounded non-negative integers division of n / d  */
+#define DIV(n, d) (((n) + (d) / 2) / (d))
+
+static Display *xdpy;
+static Colormap xcmap;
+static XftDraw *xd;
+static Visual *xvis;
+
+static void drawbox(int, int, int, int, XftColor *, XftColor *, ushort);
+static void drawboxlines(int, int, int, int, XftColor *, ushort);
+
+/* public API */
+
+void
+boxdraw_xinit(Display *dpy, Colormap cmap, XftDraw *draw, Visual *vis)
+{
+	xdpy = dpy; xcmap = cmap; xd = draw, xvis = vis;
+}
+
+int
+isboxdraw(Rune u)
+{
+	Rune block = u & ~0xff;
+	return (boxdraw && block == 0x2500 && boxdata[(uint8_t)u]) ||
+	       (boxdraw_braille && block == 0x2800);
+}
+
+/* the "index" is actually the entire shape data encoded as ushort */
+ushort
+boxdrawindex(const Glyph *g)
+{
+	if (boxdraw_braille && (g->u & ~0xff) == 0x2800)
+		return BRL | (uint8_t)g->u;
+	if (boxdraw_bold && (g->mode & ATTR_BOLD))
+		return BDB | boxdata[(uint8_t)g->u];
+	return boxdata[(uint8_t)g->u];
+}
+
+void
+drawboxes(int x, int y, int cw, int ch, XftColor *fg, XftColor *bg,
+          const XftGlyphFontSpec *specs, int len)
+{
+	for ( ; len-- > 0; x += cw, specs++)
+		drawbox(x, y, cw, ch, fg, bg, (ushort)specs->glyph);
+}
+
+/* implementation */
+
+void
+drawbox(int x, int y, int w, int h, XftColor *fg, XftColor *bg, ushort bd)
+{
+	ushort cat = bd & ~(BDB | 0xff);  /* mask out bold and data */
+	if (bd & (BDL | BDA)) {
+		/* lines (light/double/heavy/arcs) */
+		drawboxlines(x, y, w, h, fg, bd);
+
+	} else if (cat == BBD) {
+		/* lower (8-X)/8 block */
+		int d = DIV((uint8_t)bd * h, 8);
+		XftDrawRect(xd, fg, x, y + d, w, h - d);
+
+	} else if (cat == BBU) {
+		/* upper X/8 block */
+		XftDrawRect(xd, fg, x, y, w, DIV((uint8_t)bd * h, 8));
+
+	} else if (cat == BBL) {
+		/* left X/8 block */
+		XftDrawRect(xd, fg, x, y, DIV((uint8_t)bd * w, 8), h);
+
+	} else if (cat == BBR) {
+		/* right (8-X)/8 block */
+		int d = DIV((uint8_t)bd * w, 8);
+		XftDrawRect(xd, fg, x + d, y, w - d, h);
+
+	} else if (cat == BBQ) {
+		/* Quadrants */
+		int w2 = DIV(w, 2), h2 = DIV(h, 2);
+		if (bd & TL)
+			XftDrawRect(xd, fg, x, y, w2, h2);
+		if (bd & TR)
+			XftDrawRect(xd, fg, x + w2, y, w - w2, h2);
+		if (bd & BL)
+			XftDrawRect(xd, fg, x, y + h2, w2, h - h2);
+		if (bd & BR)
+			XftDrawRect(xd, fg, x + w2, y + h2, w - w2, h - h2);
+
+	} else if (bd & BBS) {
+		/* Shades - data is 1/2/3 for 25%/50%/75% alpha, respectively */
+		int d = (uint8_t)bd;
+		XftColor xfc;
+		XRenderColor xrc = { .alpha = 0xffff };
+
+		xrc.red = DIV(fg->color.red * d + bg->color.red * (4 - d), 4);
+		xrc.green = DIV(fg->color.green * d + bg->color.green * (4 - d), 4);
+		xrc.blue = DIV(fg->color.blue * d + bg->color.blue * (4 - d), 4);
+
+		XftColorAllocValue(xdpy, xvis, xcmap, &xrc, &xfc);
+		XftDrawRect(xd, &xfc, x, y, w, h);
+		XftColorFree(xdpy, xvis, xcmap, &xfc);
+
+	} else if (cat == BRL) {
+		/* braille, each data bit corresponds to one dot at 2x4 grid */
+		int w1 = DIV(w, 2);
+		int h1 = DIV(h, 4), h2 = DIV(h, 2), h3 = DIV(3 * h, 4);
+
+		if (bd & 1)   XftDrawRect(xd, fg, x, y, w1, h1);
+		if (bd & 2)   XftDrawRect(xd, fg, x, y + h1, w1, h2 - h1);
+		if (bd & 4)   XftDrawRect(xd, fg, x, y + h2, w1, h3 - h2);
+		if (bd & 8)   XftDrawRect(xd, fg, x + w1, y, w - w1, h1);
+		if (bd & 16)  XftDrawRect(xd, fg, x + w1, y + h1, w - w1, h2 - h1);
+		if (bd & 32)  XftDrawRect(xd, fg, x + w1, y + h2, w - w1, h3 - h2);
+		if (bd & 64)  XftDrawRect(xd, fg, x, y + h3, w1, h - h3);
+		if (bd & 128) XftDrawRect(xd, fg, x + w1, y + h3, w - w1, h - h3);
+
+	}
+}
+
+void
+drawboxlines(int x, int y, int w, int h, XftColor *fg, ushort bd)
+{
+	/* s: stem thickness. width/8 roughly matches underscore thickness. */
+	/* We draw bold as 1.5 * normal-stem and at least 1px thicker.      */
+	/* doubles draw at least 3px, even when w or h < 3. bold needs 6px. */
+	int mwh = MIN(w, h);
+	int base_s = MAX(1, DIV(mwh, 8));
+	int bold = (bd & BDB) && mwh >= 6;  /* possibly ignore boldness */
+	int s = bold ? MAX(base_s + 1, DIV(3 * base_s, 2)) : base_s;
+	int w2 = DIV(w - s, 2), h2 = DIV(h - s, 2);
+	/* the s-by-s square (x + w2, y + h2, s, s) is the center texel.    */
+	/* The base length (per direction till edge) includes this square.  */
+
+	int light = bd & (LL | LU | LR | LD);
+	int double_ = bd & (DL | DU | DR | DD);
+
+	if (light) {
+		/* d: additional (negative) length to not-draw the center   */
+		/* texel - at arcs and avoid drawing inside (some) doubles  */
+		int arc = bd & BDA;
+		int multi_light = light & (light - 1);
+		int multi_double = double_ & (double_ - 1);
+		/* light crosses double only at DH+LV, DV+LH (ref. shapes)  */
+		int d = arc || (multi_double && !multi_light) ? -s : 0;
+
+		if (bd & LL)
+			XftDrawRect(xd, fg, x, y + h2, w2 + s + d, s);
+		if (bd & LU)
+			XftDrawRect(xd, fg, x + w2, y, s, h2 + s + d);
+		if (bd & LR)
+			XftDrawRect(xd, fg, x + w2 - d, y + h2, w - w2 + d, s);
+		if (bd & LD)
+			XftDrawRect(xd, fg, x + w2, y + h2 - d, s, h - h2 + d);
+	}
+
+	/* double lines - also align with light to form heavy when combined */
+	if (double_) {
+		/*
+		* going clockwise, for each double-ray: p is additional length
+		* to the single-ray nearer to the previous direction, and n to
+		* the next. p and n adjust from the base length to lengths
+		* which consider other doubles - shorter to avoid intersections
+		* (p, n), or longer to draw the far-corner texel (n).
+		*/
+		int dl = bd & DL, du = bd & DU, dr = bd & DR, dd = bd & DD;
+		if (dl) {
+			int p = dd ? -s : 0, n = du ? -s : dd ? s : 0;
+			XftDrawRect(xd, fg, x, y + h2 + s, w2 + s + p, s);
+			XftDrawRect(xd, fg, x, y + h2 - s, w2 + s + n, s);
+		}
+		if (du) {
+			int p = dl ? -s : 0, n = dr ? -s : dl ? s : 0;
+			XftDrawRect(xd, fg, x + w2 - s, y, s, h2 + s + p);
+			XftDrawRect(xd, fg, x + w2 + s, y, s, h2 + s + n);
+		}
+		if (dr) {
+			int p = du ? -s : 0, n = dd ? -s : du ? s : 0;
+			XftDrawRect(xd, fg, x + w2 - p, y + h2 - s, w - w2 + p, s);
+			XftDrawRect(xd, fg, x + w2 - n, y + h2 + s, w - w2 + n, s);
+		}
+		if (dd) {
+			int p = dr ? -s : 0, n = dl ? -s : dr ? s : 0;
+			XftDrawRect(xd, fg, x + w2 + s, y + h2 - p, s, h - h2 + p);
+			XftDrawRect(xd, fg, x + w2 - s, y + h2 - n, s, h - h2 + n);
+		}
+	}
+}

boxdraw_data.h

@@ -0,0 +1,214 @@
+/*
+ * Copyright 2018 Avi Halachmi (:avih) avihpit@yahoo.com https://github.com/avih
+ * MIT/X Consortium License
+ */
+
+/*
+ * U+25XX codepoints data
+ *
+ * References:
+ *   http://www.unicode.org/charts/PDF/U2500.pdf
+ *   http://www.unicode.org/charts/PDF/U2580.pdf
+ *
+ * Test page:
+ *   https://github.com/GNOME/vte/blob/master/doc/boxes.txt
+ */
+
+/* Each shape is encoded as 16-bits. Higher bits are category, lower are data */
+/* Categories (mutually exclusive except BDB): */
+/* For convenience, BDL/BDA/BBS/BDB are 1 bit each, the rest are enums */
+#define BDL (1<<8)   /* Box Draw Lines (light/double/heavy) */
+#define BDA (1<<9)   /* Box Draw Arc (light) */
+
+#define BBD (1<<10)  /* Box Block Down (lower) X/8 */
+#define BBL (2<<10)  /* Box Block Left X/8 */
+#define BBU (3<<10)  /* Box Block Upper X/8 */
+#define BBR (4<<10)  /* Box Block Right X/8 */
+#define BBQ (5<<10)  /* Box Block Quadrants */
+#define BRL (6<<10)  /* Box Braille (data is lower byte of U28XX) */
+
+#define BBS (1<<14)  /* Box Block Shades */
+#define BDB (1<<15)  /* Box Draw is Bold */
+
+/* (BDL/BDA) Light/Double/Heavy x Left/Up/Right/Down/Horizontal/Vertical      */
+/* Heavy is light+double (literally drawing light+double align to form heavy) */
+#define LL (1<<0)
+#define LU (1<<1)
+#define LR (1<<2)
+#define LD (1<<3)
+#define LH (LL+LR)
+#define LV (LU+LD)
+
+#define DL (1<<4)
+#define DU (1<<5)
+#define DR (1<<6)
+#define DD (1<<7)
+#define DH (DL+DR)
+#define DV (DU+DD)
+
+#define HL (LL+DL)
+#define HU (LU+DU)
+#define HR (LR+DR)
+#define HD (LD+DD)
+#define HH (HL+HR)
+#define HV (HU+HD)
+
+/* (BBQ) Quadrants Top/Bottom x Left/Right */
+#define TL (1<<0)
+#define TR (1<<1)
+#define BL (1<<2)
+#define BR (1<<3)
+
+/* Data for U+2500 - U+259F except dashes/diagonals */
+static const unsigned short boxdata[256] = {
+	/* light lines */
+	[0x00] = BDL + LH,       /* light horizontal */
+	[0x02] = BDL + LV,       /* light vertical */
+	[0x0c] = BDL + LD + LR,  /* light down and right */
+	[0x10] = BDL + LD + LL,  /* light down and left */
+	[0x14] = BDL + LU + LR,  /* light up and right */
+	[0x18] = BDL + LU + LL,  /* light up and left */
+	[0x1c] = BDL + LV + LR,  /* light vertical and right */
+	[0x24] = BDL + LV + LL,  /* light vertical and left */
+	[0x2c] = BDL + LH + LD,  /* light horizontal and down */
+	[0x34] = BDL + LH + LU,  /* light horizontal and up */
+	[0x3c] = BDL + LV + LH,  /* light vertical and horizontal */
+	[0x74] = BDL + LL,       /* light left */
+	[0x75] = BDL + LU,       /* light up */
+	[0x76] = BDL + LR,       /* light right */
+	[0x77] = BDL + LD,       /* light down */
+
+	/* heavy [+light] lines */
+	[0x01] = BDL + HH,
+	[0x03] = BDL + HV,
+	[0x0d] = BDL + HR + LD,
+	[0x0e] = BDL + HD + LR,
+	[0x0f] = BDL + HD + HR,
+	[0x11] = BDL + HL + LD,
+	[0x12] = BDL + HD + LL,
+	[0x13] = BDL + HD + HL,
+	[0x15] = BDL + HR + LU,
+	[0x16] = BDL + HU + LR,
+	[0x17] = BDL + HU + HR,
+	[0x19] = BDL + HL + LU,
+	[0x1a] = BDL + HU + LL,
+	[0x1b] = BDL + HU + HL,
+	[0x1d] = BDL + HR + LV,
+	[0x1e] = BDL + HU + LD + LR,
+	[0x1f] = BDL + HD + LR + LU,
+	[0x20] = BDL + HV + LR,
+	[0x21] = BDL + HU + HR + LD,
+	[0x22] = BDL + HD + HR + LU,
+	[0x23] = BDL + HV + HR,
+	[0x25] = BDL + HL + LV,
+	[0x26] = BDL + HU + LD + LL,
+	[0x27] = BDL + HD + LU + LL,
+	[0x28] = BDL + HV + LL,
+	[0x29] = BDL + HU + HL + LD,
+	[0x2a] = BDL + HD + HL + LU,
+	[0x2b] = BDL + HV + HL,
+	[0x2d] = BDL + HL + LD + LR,
+	[0x2e] = BDL + HR + LL + LD,
+	[0x2f] = BDL + HH + LD,
+	[0x30] = BDL + HD + LH,
+	[0x31] = BDL + HD + HL + LR,
+	[0x32] = BDL + HR + HD + LL,
+	[0x33] = BDL + HH + HD,
+	[0x35] = BDL + HL + LU + LR,
+	[0x36] = BDL + HR + LU + LL,
+	[0x37] = BDL + HH + LU,
+	[0x38] = BDL + HU + LH,
+	[0x39] = BDL + HU + HL + LR,
+	[0x3a] = BDL + HU + HR + LL,
+	[0x3b] = BDL + HH + HU,
+	[0x3d] = BDL + HL + LV + LR,
+	[0x3e] = BDL + HR + LV + LL,
+	[0x3f] = BDL + HH + LV,
+	[0x40] = BDL + HU + LH + LD,
+	[0x41] = BDL + HD + LH + LU,
+	[0x42] = BDL + HV + LH,
+	[0x43] = BDL + HU + HL + LD + LR,
+	[0x44] = BDL + HU + HR + LD + LL,
+	[0x45] = BDL + HD + HL + LU + LR,
+	[0x46] = BDL + HD + HR + LU + LL,
+	[0x47] = BDL + HH + HU + LD,
+	[0x48] = BDL + HH + HD + LU,
+	[0x49] = BDL + HV + HL + LR,
+	[0x4a] = BDL + HV + HR + LL,
+	[0x4b] = BDL + HV + HH,
+	[0x78] = BDL + HL,
+	[0x79] = BDL + HU,
+	[0x7a] = BDL + HR,
+	[0x7b] = BDL + HD,
+	[0x7c] = BDL + HR + LL,
+	[0x7d] = BDL + HD + LU,
+	[0x7e] = BDL + HL + LR,
+	[0x7f] = BDL + HU + LD,
+
+	/* double [+light] lines */
+	[0x50] = BDL + DH,
+	[0x51] = BDL + DV,
+	[0x52] = BDL + DR + LD,
+	[0x53] = BDL + DD + LR,
+	[0x54] = BDL + DR + DD,
+	[0x55] = BDL + DL + LD,
+	[0x56] = BDL + DD + LL,
+	[0x57] = BDL + DL + DD,
+	[0x58] = BDL + DR + LU,
+	[0x59] = BDL + DU + LR,
+	[0x5a] = BDL + DU + DR,
+	[0x5b] = BDL + DL + LU,
+	[0x5c] = BDL + DU + LL,
+	[0x5d] = BDL + DL + DU,
+	[0x5e] = BDL + DR + LV,
+	[0x5f] = BDL + DV + LR,
+	[0x60] = BDL + DV + DR,
+	[0x61] = BDL + DL + LV,
+	[0x62] = BDL + DV + LL,
+	[0x63] = BDL + DV + DL,
+	[0x64] = BDL + DH + LD,
+	[0x65] = BDL + DD + LH,
+	[0x66] = BDL + DD + DH,
+	[0x67] = BDL + DH + LU,
+	[0x68] = BDL + DU + LH,
+	[0x69] = BDL + DH + DU,
+	[0x6a] = BDL + DH + LV,
+	[0x6b] = BDL + DV + LH,
+	[0x6c] = BDL + DH + DV,
+
+	/* (light) arcs */
+	[0x6d] = BDA + LD + LR,
+	[0x6e] = BDA + LD + LL,
+	[0x6f] = BDA + LU + LL,
+	[0x70] = BDA + LU + LR,
+
+	/* Lower (Down) X/8 block (data is 8 - X) */
+	[0x81] = BBD + 7, [0x82] = BBD + 6, [0x83] = BBD + 5, [0x84] = BBD + 4,
+	[0x85] = BBD + 3, [0x86] = BBD + 2, [0x87] = BBD + 1, [0x88] = BBD + 0,
+
+	/* Left X/8 block (data is X) */
+	[0x89] = BBL + 7, [0x8a] = BBL + 6, [0x8b] = BBL + 5, [0x8c] = BBL + 4,
+	[0x8d] = BBL + 3, [0x8e] = BBL + 2, [0x8f] = BBL + 1,
+
+	/* upper 1/2 (4/8), 1/8 block (X), right 1/2, 1/8 block (8-X) */
+	[0x80] = BBU + 4, [0x94] = BBU + 1,
+	[0x90] = BBR + 4, [0x95] = BBR + 7,
+
+	/* Quadrants */
+	[0x96] = BBQ + BL,
+	[0x97] = BBQ + BR,
+	[0x98] = BBQ + TL,
+	[0x99] = BBQ + TL + BL + BR,
+	[0x9a] = BBQ + TL + BR,
+	[0x9b] = BBQ + TL + TR + BL,
+	[0x9c] = BBQ + TL + TR + BR,
+	[0x9d] = BBQ + TR,
+	[0x9e] = BBQ + BL + TR,
+	[0x9f] = BBQ + BL + TR + BR,
+
+	/* Shades, data is an alpha value in 25% units (1/4, 1/2, 3/4) */
+	[0x91] = BBS + 1, [0x92] = BBS + 2, [0x93] = BBS + 3,
+
+	/* U+2504 - U+250B, U+254C - U+254F: unsupported (dashes) */
+	/* U+2571 - U+2573: unsupported (diagonals) */
+};

config.def.h

@@ -67,6 +67,18 @@ static unsigned int blinktimeout = 800;
  */
 static unsigned int cursorthickness = 2;
 
+/*
+ * 1: render most of the lines/blocks characters without using the font for
+ *    perfect alignment between cells (U2500 - U259F except dashes/diagonals).
+ *    Bold affects lines thickness if boxdraw_bold is not 0. Italic is ignored.
+ * 0: disable (render all U25XX glyphs normally from the font).
+ */
+const int boxdraw = 0;
+const int boxdraw_bold = 0;
+
+/* braille (U28XX):  1: render as adjacent "pixels",  0: use font */
+const int boxdraw_braille = 0;
+
 /*
  * bell volume. It must be a value between -100 and 100. Use 0 for disabling
  * it

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

hb.c

@@ -0,0 +1,124 @@
+#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 }
+#define BUFFER_STEP 256
+
+hb_font_t *hbfindfont(XftFont *match);
+
+typedef struct {
+	XftFont *match;
+	hb_font_t *font;
+} HbFontMatch;
+
+typedef struct {
+	size_t capacity;
+	HbFontMatch *fonts;
+} HbFontCache;
+
+static HbFontCache hbfontcache = { 0, NULL };
+
+typedef struct {
+	size_t capacity;
+	Rune *runes;
+} RuneBuffer;
+
+static RuneBuffer hbrunebuffer = { 0, 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 < hbfontcache.capacity; i++) {
+		hb_font_destroy(hbfontcache.fonts[i].font);
+		XftUnlockFace(hbfontcache.fonts[i].match);
+	}
+
+	if (hbfontcache.fonts != NULL) {
+		free(hbfontcache.fonts);
+		hbfontcache.fonts = NULL;
+	}
+	hbfontcache.capacity = 0;
+}
+
+hb_font_t *
+hbfindfont(XftFont *match)
+{
+	for (int i = 0; i < hbfontcache.capacity; i++) {
+		if (hbfontcache.fonts[i].match == match)
+			return hbfontcache.fonts[i].font;
+	}
+
+	/* Font not found in cache, caching it now. */
+	hbfontcache.fonts = realloc(hbfontcache.fonts, sizeof(HbFontMatch) * (hbfontcache.capacity + 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.fonts[hbfontcache.capacity].match = match;
+	hbfontcache.fonts[hbfontcache.capacity].font = font;
+	hbfontcache.capacity += 1;
+
+	return font;
+}
+
+void hbtransform(HbTransformData *data, XftFont *xfont, const Glyph *glyphs, int start, int length) {
+	ushort mode = USHRT_MAX;
+	unsigned int glyph_count;
+	int rune_idx, glyph_idx, 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);
+
+	/* Resize the buffer if required length is larger. */
+	if (hbrunebuffer.capacity < length) {
+		hbrunebuffer.capacity = (length / BUFFER_STEP + 1) * BUFFER_STEP;
+		hbrunebuffer.runes = realloc(hbrunebuffer.runes, hbrunebuffer.capacity * sizeof(Rune));
+	}
+
+	/* Fill buffer with codepoints. */
+	for (rune_idx = 0, glyph_idx = start; glyph_idx < end; glyph_idx++, rune_idx++) {
+		hbrunebuffer.runes[rune_idx] = glyphs[glyph_idx].u;
+		mode = glyphs[glyph_idx].mode;
+		if (mode & ATTR_WDUMMY)
+			hbrunebuffer.runes[rune_idx] = 0x0020;
+	}
+	hb_buffer_add_codepoints(buffer, hbrunebuffer.runes, length, 0, length);
+
+	/* 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));
+}

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 *);

st.c

@@ -1215,6 +1215,9 @@ tsetchar(Rune u, const Glyph *attr, int x, int y)
 	term.dirty[y] = 1;
 	term.line[y][x] = *attr;
 	term.line[y][x].u = u;
+
+	if (isboxdraw(u))
+		term.line[y][x].mode |= ATTR_BOXDRAW;
 }
 
 void
@@ -2652,7 +2655,8 @@ 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();

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)
@@ -33,9 +34,16 @@ enum glyph_attribute {
 	ATTR_WRAP       = 1 << 8,
 	ATTR_WIDE       = 1 << 9,
 	ATTR_WDUMMY     = 1 << 10,
+	ATTR_BOXDRAW    = 1 << 11,
 	ATTR_BOLD_FAINT = ATTR_BOLD | ATTR_FAINT,
 };
 
+enum drawing_mode {
+    DRAW_NONE = 0,
+    DRAW_BG = 1 << 0,
+    DRAW_FG = 1 << 1,
+};
+
 enum selection_mode {
 	SEL_IDLE = 0,
 	SEL_EMPTY = 1,
@@ -111,6 +119,14 @@ void *xmalloc(size_t);
 void *xrealloc(void *, size_t);
 char *xstrdup(const char *);
 
+int isboxdraw(Rune);
+ushort boxdrawindex(const Glyph *);
+#ifdef XFT_VERSION
+/* only exposed to x.c, otherwise we'll need Xft.h for the types */
+void boxdraw_xinit(Display *, Colormap, XftDraw *, Visual *);
+void drawboxes(int, int, int, int, XftColor *, XftColor *, const XftGlyphFontSpec *, int);
+#endif
+
 /* config.h globals */
 extern char *utmp;
 extern char *scroll;
@@ -124,3 +140,4 @@ extern unsigned int tabspaces;
 extern unsigned int defaultfg;
 extern unsigned int defaultbg;
 extern unsigned int defaultcs;
+extern const int boxdraw, boxdraw_bold, boxdraw_braille;

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);

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 {
@@ -141,8 +142,9 @@ 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 xdrawglyphfontspecs(const XftGlyphFontSpec *, Glyph, int, int, int, int);
 static void xdrawglyph(Glyph, int, int);
 static void xclear(int, int, int, int);
 static int xgeommasktogravity(int);
@@ -757,7 +759,7 @@ xresize(int col, int row)
 	xclear(0, 0, win.w, win.h);
 
 	/* resize to new width */
-	xw.specbuf = xrealloc(xw.specbuf, col * sizeof(GlyphFontSpec));
+	xw.specbuf = xrealloc(xw.specbuf, col * sizeof(GlyphFontSpec) * 4);
 }
 
 ushort
@@ -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);
@@ -1185,7 +1190,7 @@ xinit(int cols, int rows)
 	XFillRectangle(xw.dpy, xw.buf, dc.gc, 0, 0, win.w, win.h);
 
 	/* font spec buffer */
-	xw.specbuf = xmalloc(cols * sizeof(GlyphFontSpec));
+	xw.specbuf = xmalloc(cols * sizeof(GlyphFontSpec) * 4);
 
 	/* Xft rendering context */
 	xw.draw = XftDrawCreate(xw.dpy, xw.buf, xw.vis, xw.cmap);
@@ -1237,6 +1242,24 @@ xinit(int cols, int rows)
 	xsel.xtarget = XInternAtom(xw.dpy, "UTF8_STRING", 0);
 	if (xsel.xtarget == None)
 		xsel.xtarget = XA_STRING;
+
+	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
@@ -1253,49 +1276,72 @@ 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;
+	float cluster_xp = xp, cluster_yp = yp;
+	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 && i < (len - 1))
 			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;
-			}
-			yp = winy + font->ascent;
+		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);
 			}
 
-		/* 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;
+			/* Shape the segment. */
+			hbtransform(&shaped, font->match, glyphs, start, length);
+			runewidth = win.cw * ((glyphs[start].mode & ATTR_WIDE) ? 2.0f : 1.0f);
+			cluster_xp = xp; cluster_yp = yp;
+			for (int code_idx = 0; code_idx < shaped.count; code_idx++) {
+				int idx = shaped.glyphs[code_idx].cluster;
+
+				if (glyphs[start + idx].mode & ATTR_WDUMMY)
+					continue;
+
+				/* Advance the drawing cursor if we've moved to a new cluster */
+				if (code_idx > 0 && idx != shaped.glyphs[code_idx - 1].cluster) {
 					xp += runewidth;
-			numspecs++;
-			continue;
+					cluster_xp = xp;
+					cluster_yp = yp;
+					runewidth = win.cw * ((glyphs[start + idx].mode & ATTR_WIDE) ? 2.0f : 1.0f);
 				}
 
-		/* Fallback on font cache, search the font cache for match. */
+				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;
+					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 = cluster_xp + (short)(shaped.positions[code_idx].x_offset / 64.);
+					specs[numspecs].y = cluster_yp - (short)(shaped.positions[code_idx].y_offset / 64.);
+					cluster_xp += shaped.positions[code_idx].x_advance / 64.;
+					cluster_yp += shaped.positions[code_idx].y_advance / 64.;
+					numspecs++;
+				} else {
+					/* If it's not found, try to fetch it through the font cache. */
+					rune = glyphs[start + idx].u;
 					for (f = 0; f < frclen; f++) {
 						glyphidx = XftCharIndex(xw.dpy, frc[f].font, rune);
 						/* Everything correct. */
@@ -1364,15 +1410,29 @@ xmakeglyphfontspecs(XftGlyphFontSpec *specs, const Glyph *glyphs, int len, int x
 					specs[numspecs].glyph = glyphidx;
 					specs[numspecs].x = (short)xp;
 					specs[numspecs].y = (short)yp;
-		xp += runewidth;
 					numspecs++;
 				}
+			}
 
+			/* Cleanup and get ready for next segment. */
+			hbcleanup(&shaped);
+			start = i;
+
+			/* Determine font for glyph if different from previous glyph. */
+			if (prevmode != mode) {
+				prevmode = mode;
+				xresetfontsettings(mode, &font, &frcflags);
+				yp = winy + font->ascent;
+			}
+		}
+	}
+
+	hbcleanup(&shaped);
 	return numspecs;
 }
 
 void
-xdrawglyphfontspecs(const XftGlyphFontSpec *specs, Glyph base, int len, int x, int y)
+xdrawglyphfontspecs(const XftGlyphFontSpec *specs, Glyph base, int len, int x, int y, int dmode)
 {
 	int charlen = len * ((base.mode & ATTR_WIDE) ? 2 : 1);
 	int winx = borderpx + x * win.cw, winy = borderpx + y * win.ch,
@@ -1463,6 +1523,7 @@ xdrawglyphfontspecs(const XftGlyphFontSpec *specs, Glyph base, int len, int x, i
 	if (base.mode & ATTR_INVISIBLE)
 		fg = bg;
 
+    if (dmode & DRAW_BG) {
         /* Intelligent cleaning up of the borders. */
         if (x == 0) {
             xclear(0, (y == 0)? 0 : winy, borderpx,
@@ -1477,33 +1538,30 @@ xdrawglyphfontspecs(const XftGlyphFontSpec *specs, Glyph base, int len, int x, i
             xclear(winx, 0, winx + width, borderpx);
         if (winy + win.ch >= borderpx + win.th)
             xclear(winx, winy + win.ch, winx + width, win.h);
-
-	/* Clean up the region we want to draw to. */
+        /* Fill the background */
         XftDrawRect(xw.draw, bg, winx, winy, width, win.ch);
+    }
 
-	/* Set the clip region because Xft is sometimes dirty. */
-	r.x = 0;
-	r.y = 0;
-	r.height = win.ch;
-	r.width = width;
-	XftDrawSetClipRectangles(xw.draw, winx, winy, &r, 1);
 
+    if (dmode & DRAW_FG) {
+		if (base.mode & ATTR_BOXDRAW) {
+			drawboxes(winx, winy, width / len, win.ch, fg, bg, specs, len);
+		} else {
 			/* Render the glyphs. */
 			XftDrawGlyphFontSpec(xw.draw, fg, specs, len);
+		}
 
         /* Render underline and strikethrough. */
         if (base.mode & ATTR_UNDERLINE) {
-		XftDrawRect(xw.draw, fg, winx, winy + dc.font.ascent * chscale + 1,
+            XftDrawRect(xw.draw, fg, winx, winy + dc.font.ascent + 1,
                         width, 1);
         }
 
         if (base.mode & ATTR_STRUCK) {
-		XftDrawRect(xw.draw, fg, winx, winy + 2 * dc.font.ascent * chscale / 3,
+            XftDrawRect(xw.draw, fg, winx, winy + 2 * dc.font.ascent / 3,
                         width, 1);
         }
-
-	/* Reset clip to none. */
-	XftDrawSetClip(xw.draw, 0);
+    }
 }
 
 void
@@ -1513,18 +1571,21 @@ xdrawglyph(Glyph g, int x, int y)
 	XftGlyphFontSpec spec;
 
 	numspecs = xmakeglyphfontspecs(&spec, &g, 1, x, y);
-	xdrawglyphfontspecs(&spec, g, numspecs, x, y);
+	xdrawglyphfontspecs(&spec, g, numspecs, x, y, DRAW_BG | DRAW_FG);
 }
 
 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;
@@ -1532,7 +1593,7 @@ xdrawcursor(int cx, int cy, Glyph g, int ox, int oy, Glyph og)
 	/*
 	 * Select the right color for the right mode.
 	 */
-	g.mode &= ATTR_BOLD|ATTR_ITALIC|ATTR_UNDERLINE|ATTR_STRUCK|ATTR_WIDE;
+	g.mode &= ATTR_BOLD|ATTR_ITALIC|ATTR_UNDERLINE|ATTR_STRUCK|ATTR_WIDE|ATTR_BOXDRAW;
 
 	if (IS_SET(MODE_REVERSE)) {
 		g.mode |= ATTR_REVERSE;
@@ -1648,22 +1709,26 @@ xstartdraw(void)
 void
 xdrawline(Line line, int x1, int y1, int x2)
 {
-	int i, x, ox, numspecs;
+	int i, x, ox, numspecs, numspecs_cached;
 	Glyph base, new;
-	XftGlyphFontSpec *specs = xw.specbuf;
+	XftGlyphFontSpec *specs;
 
-	numspecs = xmakeglyphfontspecs(specs, &line[x1], x2 - x1, x1, y1);
+	numspecs_cached = xmakeglyphfontspecs(xw.specbuf, &line[x1], x2 - x1, x1, y1);
+
+	/* Draw line in 2 passes: background and foreground. This way wide glyphs
+       won't get truncated (#223) */
+	for (int dmode = DRAW_BG; dmode <= DRAW_FG; dmode <<= 1) {
+		specs = xw.specbuf;
 		i = ox = 0;
-	for (x = x1; x < x2 && i < numspecs; x++) {
+		for (x = x1; x < x2; x++) {
 			new = line[x];
 			if (new.mode == ATTR_WDUMMY)
 				continue;
 			if (selected(x, y1))
 				new.mode ^= ATTR_REVERSE;
-		if (i > 0 && ATTRCMP(base, new)) {
-			xdrawglyphfontspecs(specs, base, i, ox, y1);
-			specs += i;
-			numspecs -= i;
+			if ((i > 0) && ATTRCMP(base, new)) {
+                        	numspecs = xmakeglyphfontspecs(specs, &line[ox], x - ox, ox, y1);
+                		xdrawglyphfontspecs(specs, base, numspecs, ox, y1);
 				i = 0;
 			}
 			if (i == 0) {
@@ -1672,8 +1737,11 @@ xdrawline(Line line, int x1, int y1, int x2)
 			}
 			i++;
 		}
-	if (i > 0)
-		xdrawglyphfontspecs(specs, base, i, ox, y1);
+		 if (i > 0) {
+                 	numspecs = xmakeglyphfontspecs(specs, &line[ox], x2 - ox, ox, y1);
+                	xdrawglyphfontspecs(specs, base, numspecs, ox, y1);
+        	}
+	}
 }
 
 void