patch 9.1.0030: Cannot use terminal alternate fontv9.1.0030

Problem:  Cannot use terminal alternate fonts (PMunch)
Solution: Support terminal alternate fonts using
          CSI SGR 10-20 and t_CF code (PMunch)

Add support for alternate font highlighting

This adds support for alternate font highlighting using CSI SGR 10-20.
Few terminals currently support this, but with added tool support this
should improve over time. The change here is more or less taken from how
colors are configured and applied, but there might be some parts I
missed while implementing it. Changing fonts is done through the new
`:hi ctermfont` attribute which takes a number, 0 is the normal font, and
the numbers 1-9 select an "alternative" font. Which fonts are in use is
up to the terminal.

fixes: #13513
closes: #13537

Signed-off-by: PMunch <peterme@peterme.net>
Signed-off-by: Christian Brabandt <cb@256bit.org>

1 files changed, 71 insertions, 3 deletions

diff --git a/src/highlight.c b/src/highlight.c
index 318564c74b..3381208fd1 100644
--- a/src/highlight.c
+++ b/src/highlight.c
@@ -59,6 +59,7 @@ typedef struct
     int		sg_cterm_bg;	// terminal bg color number + 1
     int		sg_cterm_ul;	// terminal ul color number + 1
     int		sg_cterm_attr;	// Screen attr for color term mode
+    int		sg_cterm_font;	// terminal alternative font (0 for normal)
 // for when using the GUI
 #if defined(FEAT_GUI) || defined(FEAT_TERMGUICOLORS)
     guicolor_T	sg_gui_fg;	// GUI foreground color handle
@@ -1035,6 +1036,39 @@ highlight_set_ctermul(int idx, int color, int is_normal_group)
 }
 
 /*
+ * Set the cterm font for the highlight group at 'idx'.
+ * 'arg' is the color name or the numeric value as a string.
+ * 'init' is set to TRUE when initializing highlighting.
+ * Called for the ":highlight" command and the "hlset()" function.
+ *
+ * Returns TRUE if the font is set.
+ */
+    static int
+highlight_set_cterm_font(
+	int	idx,
+	char_u	*arg,
+	int	init)
+{
+    int		font;
+
+    if (init && (HL_TABLE()[idx].sg_set & SG_CTERM))
+	return FALSE;
+
+    if (!init)
+	HL_TABLE()[idx].sg_set |= SG_CTERM;
+
+    if (VIM_ISDIGIT(*arg))
+	font = atoi((char *)arg);
+    else if (STRICMP(arg, "NONE") == 0)
+	font = -1;
+    else
+	return FALSE;
+
+    HL_TABLE()[idx].sg_cterm_font = font + 1;
+    return TRUE;
+}
+
+/*
  * Set the cterm fg/bg/ul color for the highlight group at 'idx'.
  * 'key' is one of 'CTERMFG' or 'CTERMBG' or 'CTERMUL'.
  * 'keystart' is the color name/value.
@@ -1679,6 +1713,14 @@ do_highlight(
 		    break;
 		}
 	    }
+	    else if (STRCMP(key, "CTERMFONT") == 0)
+	    {
+		if (!highlight_set_cterm_font(idx, arg, init))
+		{
+		    error = TRUE;
+		    break;
+		}
+	    }
 	    else if (STRCMP(key, "GUIFG") == 0)
 	    {
 #if defined(FEAT_GUI) || defined(FEAT_EVAL)
@@ -1865,6 +1907,7 @@ hl_has_settings(int idx, int check_link)
 	    || HL_TABLE()[idx].sg_cterm_attr != 0
 	    || HL_TABLE()[idx].sg_cterm_fg != 0
 	    || HL_TABLE()[idx].sg_cterm_bg != 0
+	    || HL_TABLE()[idx].sg_cterm_font != 0
 #ifdef FEAT_GUI
 	    || HL_TABLE()[idx].sg_gui_attr != 0
 	    || HL_TABLE()[idx].sg_gui_fg_name != NULL
@@ -1892,6 +1935,7 @@ highlight_clear(int idx)
     HL_TABLE()[idx].sg_cterm_fg = 0;
     HL_TABLE()[idx].sg_cterm_bg = 0;
     HL_TABLE()[idx].sg_cterm_attr = 0;
+    HL_TABLE()[idx].sg_cterm_font = 0;
 #if defined(FEAT_GUI) || defined(FEAT_EVAL)
     HL_TABLE()[idx].sg_gui = 0;
     VIM_CLEAR(HL_TABLE()[idx].sg_gui_fg_name);
@@ -2539,6 +2583,8 @@ get_attr_entry(garray_T *table, attrentry_T *aep)
 						  == taep->ae_u.cterm.bg_color
 			    && aep->ae_u.cterm.ul_color
 						  == taep->ae_u.cterm.ul_color
+			    && aep->ae_u.cterm.font
+						  == taep->ae_u.cterm.font
 #ifdef FEAT_TERMGUICOLORS
 			    && aep->ae_u.cterm.fg_rgb
 						    == taep->ae_u.cterm.fg_rgb
@@ -2609,6 +2655,7 @@ get_attr_entry(garray_T *table, attrentry_T *aep)
 	taep->ae_u.cterm.fg_color = aep->ae_u.cterm.fg_color;
 	taep->ae_u.cterm.bg_color = aep->ae_u.cterm.bg_color;
 	taep->ae_u.cterm.ul_color = aep->ae_u.cterm.ul_color;
+	taep->ae_u.cterm.font = aep->ae_u.cterm.font;
 #ifdef FEAT_TERMGUICOLORS
 	taep->ae_u.cterm.fg_rgb = aep->ae_u.cterm.fg_rgb;
 	taep->ae_u.cterm.bg_rgb = aep->ae_u.cterm.bg_rgb;
@@ -2639,6 +2686,7 @@ get_cterm_attr_idx(int attr, int fg, int bg)
     at_en.ae_u.cterm.fg_color = fg;
     at_en.ae_u.cterm.bg_color = bg;
     at_en.ae_u.cterm.ul_color = 0;
+    at_en.ae_u.cterm.font = 0;
     return get_attr_entry(&cterm_attr_table, &at_en);
 }
 #endif
@@ -2809,6 +2857,8 @@ hl_combine_attr(int char_attr, int prim_attr)
 		    new_en.ae_u.cterm.bg_color = prim_aep->ae_u.cterm.bg_color;
 		if (prim_aep->ae_u.cterm.ul_color > 0)
 		    new_en.ae_u.cterm.ul_color = prim_aep->ae_u.cterm.ul_color;
+		if (prim_aep->ae_u.cterm.font > 0)
+		    new_en.ae_u.cterm.font = prim_aep->ae_u.cterm.font;
 #ifdef FEAT_TERMGUICOLORS
 		// If both fg and bg are not set fall back to cterm colors.
 		// Helps for SpellBad which uses undercurl in the GUI.
@@ -2948,6 +2998,8 @@ highlight_list_one(int id)
 				    sgp->sg_cterm_bg, NULL, "ctermbg");
     didh = highlight_list_arg(id, didh, LIST_INT,
 				    sgp->sg_cterm_ul, NULL, "ctermul");
+    didh = highlight_list_arg(id, didh, LIST_INT,
+				    sgp->sg_cterm_font, NULL, "ctermfont");
 
 #if defined(FEAT_GUI) || defined(FEAT_EVAL)
     didh = highlight_list_arg(id, didh, LIST_ATTR,
@@ -3138,7 +3190,7 @@ highlight_color(
 	    return (HL_TABLE()[id - 1].sg_gui_sp_name);
 	return (HL_TABLE()[id - 1].sg_gui_bg_name);
     }
-    if (font || sp)
+    if (sp)
 	return NULL;
     if (modec == 'c')
     {
@@ -3146,6 +3198,8 @@ highlight_color(
 	    n = HL_TABLE()[id - 1].sg_cterm_fg - 1;
 	else if (ul)
 	    n = HL_TABLE()[id - 1].sg_cterm_ul - 1;
+	else if (font)
+	    n = HL_TABLE()[id - 1].sg_cterm_font - 1;
 	else
 	    n = HL_TABLE()[id - 1].sg_cterm_bg - 1;
 	if (n < 0)
@@ -3296,7 +3350,8 @@ set_hl_attr(
 
     // For the color term mode: If there are other than "normal"
     // highlighting attributes, need to allocate an attr number.
-    if (sgp->sg_cterm_fg == 0 && sgp->sg_cterm_bg == 0 && sgp->sg_cterm_ul == 0
+    if (sgp->sg_cterm_fg == 0 && sgp->sg_cterm_bg == 0 &&
+	sgp->sg_cterm_ul == 0 && sgp->sg_cterm_font == 0
 # ifdef FEAT_TERMGUICOLORS
 	    && sgp->sg_gui_fg == INVALCOLOR
 	    && sgp->sg_gui_bg == INVALCOLOR
@@ -3310,6 +3365,7 @@ set_hl_attr(
 	at_en.ae_u.cterm.fg_color = sgp->sg_cterm_fg;
 	at_en.ae_u.cterm.bg_color = sgp->sg_cterm_bg;
 	at_en.ae_u.cterm.ul_color = sgp->sg_cterm_ul;
+	at_en.ae_u.cterm.font = sgp->sg_cterm_font;
 # ifdef FEAT_TERMGUICOLORS
 	at_en.ae_u.cterm.fg_rgb = GUI_MCH_GET_RGB2(sgp->sg_gui_fg);
 	at_en.ae_u.cterm.bg_rgb = GUI_MCH_GET_RGB2(sgp->sg_gui_bg);
@@ -3717,6 +3773,8 @@ combine_stl_hlt(
 	hlt[hlcnt + i].sg_cterm_fg = hlt[id - 1].sg_cterm_fg;
     if (hlt[id - 1].sg_cterm_bg != hlt[id_S - 1].sg_cterm_bg)
 	hlt[hlcnt + i].sg_cterm_bg = hlt[id - 1].sg_cterm_bg;
+    if (hlt[id - 1].sg_cterm_font != hlt[id_S - 1].sg_cterm_font)
+	hlt[hlcnt + i].sg_cterm_font = hlt[id - 1].sg_cterm_font;
 #  if defined(FEAT_GUI) || defined(FEAT_EVAL)
     hlt[hlcnt + i].sg_gui ^=
 	hlt[id - 1].sg_gui ^ hlt[id_S - 1].sg_gui;
@@ -4180,6 +4238,10 @@ highlight_get_info(int hl_idx, int resolve_link)
 	if (dict_add_string(dict, "ctermul",
 			highlight_color(hlgid, (char_u *)"ul", 'c')) == FAIL)
 	    goto error;
+    if (sgp->sg_cterm_font != 0)
+	if (dict_add_string(dict, "ctermfont",
+			highlight_color(hlgid, (char_u *)"font", 'c')) == FAIL)
+	    goto error;
     if (sgp->sg_gui != 0)
     {
 	attr_dict = highlight_get_attr_dict(sgp->sg_gui);
@@ -4408,6 +4470,7 @@ hlg_add_or_update(dict_T *dict)
     char_u	*ctermfg;
     char_u	*ctermbg;
     char_u	*ctermul;
+    char_u	*ctermfont;
     char_u	*guifg;
     char_u	*guibg;
     char_u	*guisp;
@@ -4492,6 +4555,10 @@ hlg_add_or_update(dict_T *dict)
     if (error)
 	return FALSE;
 
+    ctermfont = hldict_get_string(dict, (char_u *)"ctermfont", &error);
+    if (error)
+	return FALSE;
+
     if (!hldict_attr_to_str(dict, (char_u *)"gui", gui_attr, sizeof(gui_attr)))
 	return FALSE;
 
@@ -4516,7 +4583,7 @@ hlg_add_or_update(dict_T *dict)
     // If none of the attributes are specified, then do nothing.
     if (term_attr[0] == NUL && start == NULL && stop == NULL
 	    && cterm_attr[0] == NUL && ctermfg == NULL && ctermbg == NULL
-	    && ctermul == NULL && gui_attr[0] == NUL
+	    && ctermul == NULL && ctermfont == NULL && gui_attr[0] == NUL
 # ifdef FEAT_GUI
 	    && font == NULL
 # endif
@@ -4536,6 +4603,7 @@ hlg_add_or_update(dict_T *dict)
     p = add_attr_and_value(p, (char_u *)" ctermfg=", 9, ctermfg);
     p = add_attr_and_value(p, (char_u *)" ctermbg=", 9, ctermbg);
     p = add_attr_and_value(p, (char_u *)" ctermul=", 9, ctermul);
+    p = add_attr_and_value(p, (char_u *)" ctermfont=", 9, ctermfont);
     p = add_attr_and_value(p, (char_u *)" gui=", 5, gui_attr);
 # ifdef FEAT_GUI
     p = add_attr_and_value(p, (char_u *)" font=", 6, font);