Add a "fill" style attribute to clear the entire format drawing area in

a colour, GitHub issue 1815.

format-draw.c

@@ -511,8 +511,9 @@ format_draw(struct screen_write_ctx *octx, const struct grid_cell *base,
 	u_int			 ocx = os->cx, ocy = os->cy, i, width[TOTAL];
 	u_int			 map[] = { LEFT, LEFT, CENTRE, RIGHT };
 	int			 focus_start = -1, focus_end = -1;
-	int			 list_state = -1;
+	int			 list_state = -1, fill = -1;
 	enum style_align	 list_align = STYLE_ALIGN_DEFAULT;
+	struct grid_cell	 gc;
 	struct style		 sy;
 	struct utf8_data	*ud = &sy.gc.data;
 	const char		*cp, *end;
@@ -590,6 +591,10 @@ format_draw(struct screen_write_ctx *octx, const struct grid_cell *base,
 		    style_tostring(&sy));
 		free(tmp);
 
+		/* If this style has a fill colour, store it for later. */
+		if (sy.fill != 8)
+			fill = sy.fill;
+
 		/* Check the list state. */
 		switch (sy.list) {
 		case STYLE_LIST_ON:
@@ -711,6 +716,14 @@ format_draw(struct screen_write_ctx *octx, const struct grid_cell *base,
 		    fr->argument, names[fr->index], fr->start, fr->end);
 	}
 
+	/* Clear the available area. */
+	if (fill != -1) {
+		memcpy(&gc, &grid_default_cell, sizeof gc);
+		gc.bg = fill;
+		for (i = 0; i < available; i++)
+			screen_write_putc(octx, &gc, ' ');
+	}
+
 	/*
 	 * Draw the screens. How they are arranged depends on where the list
 	 * appearsq.

style.c

@@ -32,6 +32,7 @@
 static struct style style_default = {
 	{ 0, 0, 8, 8, 0, { { ' ' }, 0, 1, 1 } },
 
+	8,
 	STYLE_ALIGN_DEFAULT,
 	STYLE_LIST_OFF,
 
@@ -127,6 +128,10 @@ style_parse(struct style *sy, const struct grid_cell *base, const char *in)
 				sy->align = STYLE_ALIGN_RIGHT;
 			else
 				goto error;
+		} else if (end > 5 && strncasecmp(tmp, "fill=", 5) == 0) {
+			if ((value = colour_fromstring(tmp + 5)) == -1)
+				goto error;
+			sy->fill = value;
 		} else if (end > 3 && strncasecmp(tmp + 1, "g=", 2) == 0) {
 			if ((value = colour_fromstring(tmp + 3)) == -1)
 				goto error;
@@ -213,6 +218,11 @@ style_tostring(struct style *sy)
 		    tmp);
 		comma = ",";
 	}
+	if (sy->fill != 8) {
+		off += xsnprintf(s + off, sizeof s - off, "%sfill=%s", comma,
+		    colour_tostring(sy->fill));
+		comma = ",";
+	}
 	if (gc->fg != 8) {
 		off += xsnprintf(s + off, sizeof s - off, "%sfg=%s", comma,
 		    colour_tostring(gc->fg));
@@ -290,6 +300,8 @@ style_equal(struct style *sy1, struct style *sy2)
 		return (0);
 	if ((gc1->attr & STYLE_ATTR_MASK) != (gc2->attr & STYLE_ATTR_MASK))
 		return (0);
+	if (sy1->fill != sy2->fill)
+		return (0);
 	if (sy1->align != sy2->align)
 		return (0);
 	return (1);

tmux.1

@@ -4337,6 +4337,9 @@ to unset.
 .Ic align=right
 .Xc
 Align text to the left, centre or right of the available space if appropriate.
+.It Xo Ic fill=colour
+.Xc
+Fill the available space with a background colour if appropriate.
 .It Xo Ic list=on ,
 .Ic list=focus ,
 .Ic list=left-marker ,

tmux.h

@@ -682,6 +682,7 @@ TAILQ_HEAD(style_ranges, style_range);
 struct style {
 	struct grid_cell	gc;
 
+	int			fill;
 	enum style_align	align;
 	enum style_list		list;