shithub: neatroff

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font: track kerning with .tkf request

Suggested and tested by Dirk-Wilhelm Peters <peters@schwertfisch.de>.

--- a/font.c

+++ b/font.c

@@ -30,6 +30,7 @@

 	int spacewid;

 	int special;

 	int cs, cs_ps, bd, zoom;	/* for .cs, .bd, .fzoom requests */

+	int s1, n1, s2, n2;		/* for .tkf request */

 	struct glyph *gl;		/* glyphs present in the font */

 	int gl_n, gl_sz;		/* number of glyphs in the font */

 	struct dict *gl_dict;		/* mapping from gl[i].id to i */

@@ -604,19 +605,34 @@

 	return w >= 0 ? DEVWID(sz, w) : -DEVWID(sz, -w);

 }

+/* return track kerning width for the given size */

+static int font_twid(struct font *fn, int sz)

+{

+	if (fn->s1 >= 0 && sz <= fn->s1)

+		return fn->n1 * SC_PT;

+	if (fn->s2 >= 0 && sz >= fn->s2)

+		return fn->n2 * SC_PT;

+	if (sz > fn->s1 && sz < fn->s2)

+		return ((sz - fn->s1) * fn->n1 + (fn->s2 - sz) * fn->n2) *

+				(long) SC_PT / (fn->s2 - fn->s1);

+	return 0;

+}

+

 /* glyph width, where cfn is the current font and fn is glyph's font */

 int font_gwid(struct font *fn, struct font *cfn, int sz, int w)

 {

-	if (cfn->cs)

-		return cfn->cs * (font_zoom(fn, cfn->cs_ps ? cfn->cs_ps : sz)

+	struct font *xfn = cfn ? cfn : fn;

+	if (xfn->cs)

+		return xfn->cs * (font_zoom(fn, xfn->cs_ps ? xfn->cs_ps : sz)

 					* SC_IN / 72) / 36;

-	return font_wid(fn, sz, w) + (font_getbd(cfn) ? font_getbd(cfn) - 1 : 0);

+	return font_wid(fn, sz, w) + (cfn ? font_twid(fn, sz) : 0) +

+		(font_getbd(xfn) ? font_getbd(xfn) - 1 : 0);

 }

 /* space width for the give word space or sentence space */

 int font_swid(struct font *fn, int sz, int ss)

 {

-	return font_gwid(fn, fn, sz, (fn->spacewid * ss + 6) / 12);

+	return font_gwid(fn, NULL, sz, (fn->spacewid * ss + 6) / 12);

 }

 int font_getcs(struct font *fn)

@@ -638,6 +654,14 @@

 void font_setbd(struct font *fn, int bd)

 {

 	fn->bd = bd;

+}

+

+void font_track(struct font *fn, int s1, int n1, int s2, int n2)

+{

+	fn->s1 = s1;

+	fn->n1 = n1;

+	fn->s2 = s2;

+	fn->n2 = n2;

 }

 int font_zoom(struct font *fn, int sz)

--- a/roff.h

+++ b/roff.h

@@ -168,6 +168,7 @@

 int font_getcs(struct font *fn);

 void font_setbd(struct font *fn, int bd);

 int font_getbd(struct font *fn);

+void font_track(struct font *fn, int s1, int n1, int s2, int n2);

 void font_setzoom(struct font *fn, int zoom);

 int font_zoom(struct font *fn, int sz);

 int font_feat(struct font *fn, char *name, int val);

--- a/tr.c

+++ b/tr.c

@@ -595,6 +595,14 @@

 		font_setzoom(fn, args[2] ? eval(args[2], 0) : 0);

 }

+static void tr_tkf(char **args)

+{

+	struct font *fn = args[1] ? dev_font(dev_pos(args[1])) : NULL;

+	if (fn && args[5])

+		font_track(fn, eval(args[2], 0), eval(args[3], 0),

+				eval(args[4], 0), eval(args[5], 0));

+}

+

 static void tr_ff(char **args)

 {

 	struct font *fn = args[1] ? dev_font(dev_pos(args[1])) : NULL;

@@ -1087,6 +1095,7 @@

 	{"ta", tr_ta},

 	{"tc", tr_tc},

 	{"ti", tr_ti},

+	{"tkf", tr_tkf},

 	{"tl", tr_tl, mkargs_null},

 	{"tm", tr_tm, mkargs_eol},

 	{"tr", tr_tr, mkargs_eol},