Add a dim= style attribute to dim the colours (as best as tmux is able

to). GitHub issue 4842.

colour.c

@@ -120,6 +120,28 @@ colour_force_rgb(int c)
 	return (-1);
 }
 
+/* Dim colour by a percentage. */
+int
+colour_dim(int c, u_int dim)
+{
+	u_char	r, g, b;
+
+	if (dim == 0 || COLOUR_DEFAULT(c))
+		return (c);
+	if (dim >= 100)
+		return (colour_join_rgb(0, 0, 0));
+
+	c = colour_force_rgb(c);
+	if (c == -1)
+		return (-1);
+	colour_split_rgb(c, &r, &g, &b);
+
+	r = (r * (100 - dim)) / 100;
+	g = (g * (100 - dim)) / 100;
+	b = (b * (100 - dim)) / 100;
+	return (colour_join_rgb(r, g, b));
+}
+
 /* Convert colour to a string. */
 const char *
 colour_tostring(int c)

format.c

@@ -1006,7 +1006,7 @@ format_cb_pane_fg(struct format_tree *ft)
 	if (wp == NULL)
 		return (NULL);
 
-	tty_default_colours(&gc, wp);
+	tty_default_colours(&gc, wp, NULL);
 	return (xstrdup(colour_tostring(gc.fg)));
 }
 
@@ -1043,7 +1043,7 @@ format_cb_pane_bg(struct format_tree *ft)
 	if (wp == NULL)
 		return (NULL);
 
-	tty_default_colours(&gc, wp);
+	tty_default_colours(&gc, wp, NULL);
 	return (xstrdup(colour_tostring(gc.bg)));
 }
 

input.c

@@ -3018,7 +3018,7 @@ input_osc_10(struct input_ctx *ictx, const char *p)
 			return;
 		c = window_pane_get_fg_control_client(wp);
 		if (c == -1) {
-			tty_default_colours(&defaults, wp);
+			tty_default_colours(&defaults, wp, NULL);
 			if (COLOUR_DEFAULT(defaults.fg))
 				c = window_pane_get_fg(wp);
 			else

popup.c

@@ -328,6 +328,7 @@ popup_draw_cb(struct client *c, void *data, struct screen_redraw_ctx *rctx)
 		defaults.bg = pd->palette.bg;
 	style_ctx.defaults = &defaults;
 	style_ctx.palette = &pd->palette;
+	style_ctx.dim = 0;
 	style_ctx.hyperlinks = s.hyperlinks;
 
 	if (pd->md != NULL) {

screen-redraw.c

@@ -1212,7 +1212,7 @@ screen_redraw_draw_pane(struct screen_redraw_ctx *ctx, struct window_pane *wp)
 		}
 
 		/* Set up the default style. */
-		tty_default_colours(&defaults, wp);
+		tty_default_colours(&defaults, wp, &style_ctx.dim);
 		style_ctx.defaults = &defaults;
 		style_ctx.palette = palette;
 		style_ctx.hyperlinks = s->hyperlinks;

screen-write.c

@@ -252,7 +252,8 @@ screen_write_initctx(struct screen_write_ctx *ctx, struct tty_ctx *ttyctx,
 	} else {
 		ttyctx->redraw_cb = screen_write_redraw_cb;
 		if (ctx->wp != NULL) {
-			tty_default_colours(&ttyctx->defaults, ctx->wp);
+			tty_default_colours(&ttyctx->defaults, ctx->wp,
+			    &ttyctx->style_ctx.dim);
 			ttyctx->style_ctx.palette = &ctx->wp->palette;
 			ttyctx->set_client_cb = screen_write_set_client_cb;
 			ttyctx->arg = ctx->wp;

style.c

@@ -32,6 +32,7 @@
 static struct style style_default = {
 	{ { { ' ' }, 0, 1, 1 }, 0, 0, 8, 8, 0, 0 },
 	0,
+	0,
 
 	8,
 	STYLE_ALIGN_DEFAULT,
@@ -201,6 +202,13 @@ style_parse(struct style *sy, const struct grid_cell *base, const char *in)
 			if ((value = colour_fromstring(tmp + 5)) == -1)
 				goto error;
 			sy->fill = value;
+		} else if (end > 4 && strncasecmp(tmp, "dim=", 4) == 0) {
+			if (tmp[end - 1] == '%')
+				tmp[end - 1] = '\0';
+			n = strtonum(tmp + 4, 0, 100, &errstr);
+			if (errstr != NULL)
+				goto error;
+			sy->dim = n;
 		} else if (end > 3 && strncasecmp(tmp + 1, "g=", 2) == 0) {
 			if ((value = colour_fromstring(tmp + 3)) == -1)
 				goto error;
@@ -346,6 +354,11 @@ style_tostring(struct style *sy)
 		    colour_tostring(sy->fill));
 		comma = ",";
 	}
+	if (sy->dim != 0) {
+		off += xsnprintf(s + off, sizeof s - off, "%sdim=%d%%", comma,
+		    sy->dim);
+		comma = ",";
+	}
 	if (gc->fg != 8) {
 		off += xsnprintf(s + off, sizeof s - off, "%sfg=%s", comma,
 		    colour_tostring(gc->fg));
@@ -386,7 +399,7 @@ style_tostring(struct style *sy)
 }
 
 /* Apply a style on top of the given style. */
-void
+struct style *
 style_add(struct grid_cell *gc, struct options *oo, const char *name,
     struct format_tree *ft)
 {
@@ -409,6 +422,7 @@ style_add(struct grid_cell *gc, struct options *oo, const char *name,
 
 	if (ft0 != NULL)
 		format_free(ft0);
+	return (sy);
 }
 
 /* Apply a style on top of the default style. */

tmux.1

@@ -7011,6 +7011,9 @@ is the terminal alternate character set.
 Align text to the left, centre or right of the available space if appropriate.
 .It Ic fill=colour
 Fill the available space with a background colour if appropriate.
+.It Ic dim=percentage
+Dim foreground and background colours by
+.Ar percentage .
 .It Ic width=N
 Set the width of the styled area.
 .Ar N

tmux.h

@@ -946,6 +946,7 @@ enum style_default_type {
 struct style {
 	struct grid_cell	gc;
 	int			ignore;
+	int			dim;
 
 	int			fill;
 	enum style_align	align;
@@ -1289,6 +1290,8 @@ struct window_pane {
 
 	struct grid_cell cached_gc;
 	struct grid_cell cached_active_gc;
+	u_int		 cached_dim;
+	u_int		 cached_active_dim;
 	struct colour_palette palette;
 	enum client_theme last_theme;
 	struct style_line_entry border_status_line;
@@ -1629,6 +1632,7 @@ LIST_HEAD(tty_terms, tty_term);
 struct tty_style_ctx {
 	const struct grid_cell	*defaults;
 	struct colour_palette	*palette;
+	u_int			 dim;
 	struct hyperlinks	*hyperlinks;
 };
 
@@ -2720,7 +2724,7 @@ void	tty_cmd_reverseindex(struct tty *, const struct tty_ctx *);
 void	tty_cmd_setselection(struct tty *, const struct tty_ctx *);
 void	tty_cmd_rawstring(struct tty *, const struct tty_ctx *);
 void	tty_cmd_syncstart(struct tty *, const struct tty_ctx *);
-void	tty_default_colours(struct grid_cell *, struct window_pane *);
+void	tty_default_colours(struct grid_cell *, struct window_pane *, u_int *);
 
 /* tty-term.c */
 extern struct tty_terms tty_terms;
@@ -3157,6 +3161,7 @@ int	 colour_find_rgb(u_char, u_char, u_char);
 int	 colour_join_rgb(u_char, u_char, u_char);
 void	 colour_split_rgb(int, u_char *, u_char *, u_char *);
 int	 colour_force_rgb(int);
+int	 colour_dim(int, u_int);
 const char *colour_tostring(int);
 enum client_theme colour_totheme(int);
 int	 colour_fromstring(const char *);
@@ -3806,7 +3811,7 @@ int		 popup_modify(struct client *, const char *, const char *,
 int		 style_parse(struct style *,const struct grid_cell *,
 		     const char *);
 const char	*style_tostring(struct style *);
-void		 style_add(struct grid_cell *, struct options *,
+struct style	*style_add(struct grid_cell *, struct options *,
 		     const char *, struct format_tree *);
 void		 style_apply(struct grid_cell *, struct options *,
 		     const char *, struct format_tree *);

tty.c

@@ -80,7 +80,7 @@ static int	tty_check_overlay(struct tty *, u_int, u_int);
 #define TTY_REQUEST_LIMIT 30
 
 static struct tty_style_ctx tty_default_style_ctx = {
-	&grid_default_cell, NULL, NULL
+	&grid_default_cell, NULL, 0, NULL
 };
 
 void
@@ -2467,16 +2467,39 @@ tty_hyperlink(struct tty *tty, const struct grid_cell *gc,
 		tty_putcode_ss(tty, TTYC_HLS, id, uri);
 }
 
+static int
+tty_dim_default_colour(struct tty *tty, int c, int foreground)
+{
+	enum client_theme	 theme;
+
+	if (!COLOUR_DEFAULT(c))
+		return (c);
+
+	if (foreground && tty->fg != -1)
+		return (tty->fg);
+	if (!foreground && tty->bg != -1)
+		return (tty->bg);
+
+	theme = tty->client->theme;
+	if (theme == THEME_DARK)
+		return (foreground ? 7 : 0);
+	if (theme == THEME_LIGHT)
+		return (foreground ? 0 : 7);
+	return (c);
+}
+
 void
 tty_attributes(struct tty *tty, const struct grid_cell *gc,
     const struct tty_style_ctx *style_ctx)
 {
 	struct grid_cell	*tc = &tty->cell, gc2;
+	struct colour_palette	*palette;
 	int			 changed;
 
 	/* Use default style if not given. */
 	if (style_ctx == NULL)
 		style_ctx = &tty_default_style_ctx;
+	palette = style_ctx->palette;
 
 	/* Copy cell and update default colours. */
 	memcpy(&gc2, gc, sizeof gc2);
@@ -2485,6 +2508,24 @@ tty_attributes(struct tty *tty, const struct grid_cell *gc,
 			gc2.fg = style_ctx->defaults->fg;
 		if (gc2.bg == 8)
 			gc2.bg = style_ctx->defaults->bg;
+		if (palette != NULL) {
+			changed = colour_palette_get(palette, gc2.fg);
+			if (changed != -1)
+				gc2.fg = changed;
+			changed = colour_palette_get(palette, gc2.bg);
+			if (changed != -1)
+				gc2.bg = changed;
+		}
+	}
+	if (style_ctx->dim != 0) {
+		gc2.fg = tty_dim_default_colour(tty, gc2.fg, 1);
+		gc2.bg = tty_dim_default_colour(tty, gc2.bg, 0);
+		changed = colour_dim(gc2.fg, style_ctx->dim);
+		if (changed != -1)
+			gc2.fg = changed;
+		changed = colour_dim(gc2.bg, style_ctx->dim);
+		if (changed != -1)
+			gc2.bg = changed;
 	}
 
 	/* Ignore cell if it is the same as the last one. */
@@ -2511,9 +2552,9 @@ tty_attributes(struct tty *tty, const struct grid_cell *gc,
 	}
 
 	/* Fix up the colours if necessary. */
-	tty_check_fg(tty, style_ctx->palette, &gc2);
-	tty_check_bg(tty, style_ctx->palette, &gc2);
-	tty_check_us(tty, style_ctx->palette, &gc2);
+	tty_check_fg(tty, palette, &gc2);
+	tty_check_bg(tty, palette, &gc2);
+	tty_check_us(tty, palette, &gc2);
 
 	/*
 	 * If any bits are being cleared or the underline colour is now default,
@@ -2925,6 +2966,7 @@ tty_style_changed(struct window_pane *wp)
 {
 	struct options		*oo = wp->options;
 	struct format_tree	*ft;
+	struct style		*sy;
 
 	log_debug("%%%u: style changed", wp->id);
 	wp->flags &= ~PANE_STYLECHANGED;
@@ -2933,16 +2975,18 @@ tty_style_changed(struct window_pane *wp)
 	format_defaults(ft, NULL, NULL, NULL, wp);
 
 	tty_window_default_style(&wp->cached_active_gc, wp);
-	style_add(&wp->cached_active_gc, oo, "window-active-style", ft);
+	sy = style_add(&wp->cached_active_gc, oo, "window-active-style", ft);
+	wp->cached_active_dim = sy->dim;
 
 	tty_window_default_style(&wp->cached_gc, wp);
-	style_add(&wp->cached_gc, oo, "window-style", ft);
+	sy = style_add(&wp->cached_gc, oo, "window-style", ft);
+	wp->cached_dim = sy->dim;
 
 	format_free(ft);
 }
 
 void
-tty_default_colours(struct grid_cell *gc, struct window_pane *wp)
+tty_default_colours(struct grid_cell *gc, struct window_pane *wp, u_int *dim)
 {
 	if (wp->flags & PANE_STYLECHANGED)
 		tty_style_changed (wp);
@@ -2956,6 +3000,13 @@ tty_default_colours(struct grid_cell *gc, struct window_pane *wp)
 		gc->bg = wp->cached_active_gc.bg;
 	else
 		gc->bg = wp->cached_gc.bg;
+
+	if (dim != NULL) {
+		if (wp == wp->window->active)
+			*dim = wp->cached_active_dim;
+		else
+			*dim = wp->cached_dim;
+	}
 }
 
 void

window.c

@@ -592,6 +592,8 @@ window_redraw_active_switch(struct window *w, struct window_pane *wp)
 		gc2 = &wp->cached_active_gc;
 		if (!grid_cells_look_equal(gc1, gc2))
 			wp->flags |= PANE_REDRAW;
+		else if (wp->cached_dim != wp->cached_active_dim)
+			wp->flags |= PANE_REDRAW;
 		else {
 			c1 = window_pane_get_palette(wp, gc1->fg);
 			c2 = window_pane_get_palette(wp, gc2->fg);
@@ -1963,7 +1965,7 @@ window_pane_get_bg(struct window_pane *wp)
 
 	c = window_pane_get_bg_control_client(wp);
 	if (c == -1) {
-		tty_default_colours(&defaults, wp);
+		tty_default_colours(&defaults, wp, NULL);
 		if (COLOUR_DEFAULT(defaults.bg))
 			c = window_get_bg_client(wp);
 		else