Add option to show arrows for active pane indicator, GitHub issue 3022

from Marcel Partap.

options-table.c

@@ -64,6 +64,9 @@ static const char *options_table_cursor_style_list[] = {
 static const char *options_table_pane_status_list[] = {
 	"off", "top", "bottom", NULL
 };
+static const char *options_table_pane_border_indicators_list[] = {
+	"off", "colour", "arrows", "both", NULL
+};
 static const char *options_table_pane_border_lines_list[] = {
 	"single", "double", "heavy", "simple", "number", NULL
 };
@@ -971,6 +974,15 @@ const struct options_table_entry options_table[] = {
 	  .text = "Format of text in the pane status lines."
 	},
 
+	{ .name = "pane-border-indicators",
+	  .type = OPTIONS_TABLE_CHOICE,
+	  .scope = OPTIONS_TABLE_WINDOW,
+	  .choices = options_table_pane_border_indicators_list,
+	  .default_num = PANE_BORDER_COLOUR,
+	  .text = "Whether to indicate the active pane by colouring border or "
+		  "displaying arrow markers."
+	},
+
 	{ .name = "pane-border-lines",
 	  .type = OPTIONS_TABLE_CHOICE,
 	  .scope = OPTIONS_TABLE_WINDOW,

screen-redraw.c

@@ -34,11 +34,16 @@ static void	screen_redraw_set_context(struct client *,
 #define START_ISOLATE "\342\201\246"
 #define END_ISOLATE   "\342\201\251"
 
+/* Border in relation to a pane. */
 enum screen_redraw_border_type {
 	SCREEN_REDRAW_OUTSIDE,
 	SCREEN_REDRAW_INSIDE,
-	SCREEN_REDRAW_BORDER
+	SCREEN_REDRAW_BORDER_LEFT,
+	SCREEN_REDRAW_BORDER_RIGHT,
+	SCREEN_REDRAW_BORDER_TOP,
+	SCREEN_REDRAW_BORDER_BOTTOM
 };
+#define BORDER_MARKERS "  +,.-"
 
 /* Get cell border character. */
 static void
@@ -102,64 +107,74 @@ static enum screen_redraw_border_type
 screen_redraw_pane_border(struct window_pane *wp, u_int px, u_int py,
     int pane_status)
 {
-	u_int	ex = wp->xoff + wp->sx, ey = wp->yoff + wp->sy;
+	struct options	*oo = wp->window->options;
+	int		 split = 0;
+	u_int	 	 ex = wp->xoff + wp->sx, ey = wp->yoff + wp->sy;
 
 	/* Inside pane. */
 	if (px >= wp->xoff && px < ex && py >= wp->yoff && py < ey)
 		return (SCREEN_REDRAW_INSIDE);
 
+	/* Get pane indicator. */
+	switch (options_get_number(oo, "pane-border-indicators")) {
+	case PANE_BORDER_COLOUR:
+	case PANE_BORDER_BOTH:
+		split = 1;
+		break;
+	}
+
 	/* Left/right borders. */
 	if (pane_status == PANE_STATUS_OFF) {
-		if (screen_redraw_two_panes(wp->window, 0)) {
+		if (screen_redraw_two_panes(wp->window, 0) && split) {
 			if (wp->xoff == 0 && px == wp->sx && py <= wp->sy / 2)
-				return (SCREEN_REDRAW_BORDER);
+				return (SCREEN_REDRAW_BORDER_RIGHT);
 			if (wp->xoff != 0 &&
 			    px == wp->xoff - 1 &&
 			    py > wp->sy / 2)
-				return (SCREEN_REDRAW_BORDER);
+				return (SCREEN_REDRAW_BORDER_LEFT);
 		} else {
 			if ((wp->yoff == 0 || py >= wp->yoff - 1) && py <= ey) {
 				if (wp->xoff != 0 && px == wp->xoff - 1)
-					return (SCREEN_REDRAW_BORDER);
+					return (SCREEN_REDRAW_BORDER_LEFT);
 				if (px == ex)
-					return (SCREEN_REDRAW_BORDER);
+					return (SCREEN_REDRAW_BORDER_RIGHT);
 			}
 		}
 	} else {
 		if ((wp->yoff == 0 || py >= wp->yoff - 1) && py <= ey) {
 			if (wp->xoff != 0 && px == wp->xoff - 1)
-				return (SCREEN_REDRAW_BORDER);
+				return (SCREEN_REDRAW_BORDER_LEFT);
 			if (px == ex)
-				return (SCREEN_REDRAW_BORDER);
+				return (SCREEN_REDRAW_BORDER_RIGHT);
 		}
 	}
 
 	/* Top/bottom borders. */
 	if (pane_status == PANE_STATUS_OFF) {
-		if (screen_redraw_two_panes(wp->window, 1)) {
+		if (screen_redraw_two_panes(wp->window, 1) && split) {
 			if (wp->yoff == 0 && py == wp->sy && px <= wp->sx / 2)
-				return (SCREEN_REDRAW_BORDER);
+				return (SCREEN_REDRAW_BORDER_BOTTOM);
 			if (wp->yoff != 0 &&
 			    py == wp->yoff - 1 &&
 			    px > wp->sx / 2)
-				return (SCREEN_REDRAW_BORDER);
+				return (SCREEN_REDRAW_BORDER_TOP);
 		} else {
 			if ((wp->xoff == 0 || px >= wp->xoff - 1) && px <= ex) {
 				if (wp->yoff != 0 && py == wp->yoff - 1)
-					return (SCREEN_REDRAW_BORDER);
+					return (SCREEN_REDRAW_BORDER_TOP);
 				if (py == ey)
-					return (SCREEN_REDRAW_BORDER);
+					return (SCREEN_REDRAW_BORDER_BOTTOM);
 			}
 		}
 	} else if (pane_status == PANE_STATUS_TOP) {
 		if ((wp->xoff == 0 || px >= wp->xoff - 1) && px <= ex) {
 			if (wp->yoff != 0 && py == wp->yoff - 1)
-				return (SCREEN_REDRAW_BORDER);
+				return (SCREEN_REDRAW_BORDER_TOP);
 		}
 	} else {
 		if ((wp->xoff == 0 || px >= wp->xoff - 1) && px <= ex) {
 			if (py == ey)
-				return (SCREEN_REDRAW_BORDER);
+				return (SCREEN_REDRAW_BORDER_BOTTOM);
 		}
 	}
 
@@ -189,10 +204,10 @@ screen_redraw_cell_border(struct client *c, u_int px, u_int py, int pane_status)
 		switch (screen_redraw_pane_border(wp, px, py, pane_status)) {
 		case SCREEN_REDRAW_INSIDE:
 			return (0);
-		case SCREEN_REDRAW_BORDER:
-			return (1);
 		case SCREEN_REDRAW_OUTSIDE:
 			break;
+		default:
+			return (1);
 		}
 	}
 
@@ -346,7 +361,7 @@ screen_redraw_check_is(u_int px, u_int py, int pane_status,
 	enum screen_redraw_border_type	border;
 
 	border = screen_redraw_pane_border(wp, px, py, pane_status);
-	if (border == SCREEN_REDRAW_BORDER)
+	if (border != SCREEN_REDRAW_INSIDE && border != SCREEN_REDRAW_OUTSIDE)
 		return (1);
 	return (0);
 }
@@ -637,11 +652,12 @@ screen_redraw_draw_borders_cell(struct screen_redraw_ctx *ctx, u_int i, u_int j)
 	struct options		*oo = w->options;
 	struct tty		*tty = &c->tty;
 	struct format_tree	*ft;
-	struct window_pane	*wp;
+	struct window_pane	*wp, *active = server_client_get_pane(c);
 	struct grid_cell	 gc;
 	const struct grid_cell	*tmp;
 	struct overlay_ranges	 r;
 	u_int			 cell_type, x = ctx->ox + i, y = ctx->oy + j;
+	int			 arrows = 0, border;
 	int			 pane_status = ctx->pane_status, isolates;
 
 	if (c->overlay_check != NULL) {
@@ -689,6 +705,32 @@ screen_redraw_draw_borders_cell(struct screen_redraw_ctx *ctx, u_int i, u_int j)
 		tty_cursor(tty, i, j);
 	if (isolates)
 		tty_puts(tty, END_ISOLATE);
+
+	switch (options_get_number(oo, "pane-border-indicators")) {
+	case PANE_BORDER_ARROWS:
+	case PANE_BORDER_BOTH:
+		arrows = 1;
+		break;
+	}
+
+	if (wp != NULL && arrows) {
+		border = screen_redraw_pane_border(active, x, y, pane_status);
+		if (((i == wp->xoff + 1 &&
+		    (cell_type == CELL_LEFTRIGHT ||
+		    (cell_type == CELL_TOPJOIN &&
+		    border == SCREEN_REDRAW_BORDER_BOTTOM) ||
+		    (cell_type == CELL_BOTTOMJOIN &&
+		    border == SCREEN_REDRAW_BORDER_TOP))) ||
+		    (j == wp->yoff + 1 &&
+		    (cell_type == CELL_TOPBOTTOM ||
+		    (cell_type == CELL_LEFTJOIN &&
+		    border == SCREEN_REDRAW_BORDER_RIGHT) ||
+		    (cell_type == CELL_RIGHTJOIN &&
+		    border == SCREEN_REDRAW_BORDER_LEFT)))) &&
+		    screen_redraw_check_is(x, y, pane_status, active))
+			utf8_set(&gc.data, BORDER_MARKERS[border]);
+	}
+
 	tty_cell(tty, &gc, &grid_default_cell, NULL);
 	if (isolates)
 		tty_puts(tty, START_ISOLATE);

tmux.1

@@ -4223,6 +4223,12 @@ but set the starting index for pane numbers.
 .It Ic pane-border-format Ar format
 Set the text shown in pane border status lines.
 .Pp
+.It Xo Ic pane-border-indicators
+.Op Ic off | colour | arrows | both
+.Xc
+Indicate active pane by colouring only half of the border in windows with
+exactly two panes, by displaying arrow markers, by drawing both or neither.
+.Pp
 .It Ic pane-border-lines Ar type
 Set the type of characters used for drawing pane borders.
 .Ar type

tmux.h

@@ -842,6 +842,12 @@ enum pane_lines {
 	PANE_LINES_NUMBER
 };
 
+/* Pane border indicator option. */
+#define PANE_BORDER_OFF 0
+#define PANE_BORDER_COLOUR 1
+#define PANE_BORDER_ARROWS 2
+#define PANE_BORDER_BOTH 3
+
 /* Screen redraw context. */
 struct screen_redraw_ctx {
 	struct client	*c;