Fix option -B+n in psscale (#8737)

This addresses one of the points raised in the Forum issue
https://forum.generic-mapping-tools.org/t/colour-scheme-without-outline/5967

Now we can do `psscale -Dx6.5/1+w340p/36p+h -B+n -Ccyclic > cyclic.ps` and have no frames at all.

I would like also that `-B0` did that work (a nicer syntax, IMO) and in fact, this PR also implements it but it requires that GMT is built with `-DB0_IS_NO_FRAME`. The reason for wrapping it in a `#ifdef` is that changing `-B0` to do what it originally should have been since the beginning (that is, to DO NOT PLOT ANY FRAME, ANNOTS AT ALL) is a breaking change. I would like, however, to discuss if we should do it nevertheless.

Co-authored-by: Federico Esteban <[email protected]>

Author: joa-quim

src/gmt_init.c

@@ -4987,6 +4987,9 @@ GMT_LOCAL int gmtinit_parse5_B_option (struct GMT_CTRL *GMT, char *in) {
 			if (GMT->common.J.zactive) GMT->current.map.frame.drawz = true;	/* Also brings z-axis into contention */
 			GMT->current.setting.map_frame_type = GMT_IS_PLAIN;	/* Since checkerboard without intervals look stupid */
 			GMT->current.map.frame.set[no] = true;	/* Since we want this axis drawn */
+#ifdef B0_IS_NO_FRAME
+			GMT->current.map.frame.no_frame = true;		/* Understand format '0' to mean "NO FRAME AT ALL" */
+#endif
 			continue;
 		}
 

src/psscale.c

@@ -1388,30 +1388,34 @@ GMT_LOCAL void psscale_draw_colorbar (struct GMT_CTRL *GMT, struct PSSCALE_CTRL
 
 		PSL_setlinecap (PSL, PSL_SQUARE_CAP);	/* Square cap required for box of scale bar */
 
-		if (gap == 0.0) {
-			if ((flip & PSSCALE_FLIP_ANNOT) || !B_set) PSL_plotsegment (PSL, xleft, 0.0, xleft + length, 0.0);
-			if (!(flip & PSSCALE_FLIP_ANNOT) || !B_set) PSL_plotsegment (PSL, xleft, width, xleft + length, width);
-			PSL_plotsegment (PSL, xleft, 0.0, xleft, width);
-			PSL_plotsegment (PSL, xright, 0.0, xright, width);
+		if (gap == 0.0 && !GMT->current.map.frame.no_frame) {
+			if ((flip & PSSCALE_FLIP_ANNOT) || !B_set) PSL_plotsegment(PSL, xleft, 0.0, xleft + length, 0.0);
+			if (!(flip & PSSCALE_FLIP_ANNOT) || !B_set) PSL_plotsegment(PSL, xleft, width, xleft + length, width);
+			PSL_plotsegment(PSL, xleft, 0.0, xleft, width);
+			PSL_plotsegment(PSL, xright, 0.0, xright, width);
 		}
 
 		if (B_set) {	/* Used -B */
-			gmt_xy_axis2 (GMT, xleft, y_base, length, start_val, stop_val, A, !(flip & PSSCALE_FLIP_ANNOT), GMT->current.map.frame.side[flip & PSSCALE_FLIP_ANNOT ? N_SIDE : S_SIDE] & PSSCALE_FLIP_LABEL, GMT->current.map.frame.side[flip & PSSCALE_FLIP_ANNOT ? N_SIDE : S_SIDE]);
+			if (!GMT->current.map.frame.no_frame)
+				gmt_xy_axis2(GMT, xleft, y_base, length, start_val, stop_val, A, !(flip & PSSCALE_FLIP_ANNOT),
+				             GMT->current.map.frame.side[flip & PSSCALE_FLIP_ANNOT ? N_SIDE : S_SIDE] & PSSCALE_FLIP_LABEL,
+				             GMT->current.map.frame.side[flip & PSSCALE_FLIP_ANNOT ? N_SIDE : S_SIDE]);
+			
 			if (A->item[GMT_GRID_UPPER].active) {
-				dx = gmtlib_get_map_interval (GMT, A->type, &A->item[GMT_GRID_UPPER]);
+				dx = gmtlib_get_map_interval(GMT, A->type, &A->item[GMT_GRID_UPPER]);
 				gmt_setpen (GMT, &GMT->current.setting.map_grid_pen[GMT_PRIMARY]);
 				if (A->type == GMT_TIME)
-					gmt_plot_timex_grid (GMT, PSL, P->data[0].z_low, P->data[P->n_colors-1].z_high, 0.0, width, GMT_GRID_UPPER);
+					gmt_plot_timex_grid(GMT, PSL, P->data[0].z_low, P->data[P->n_colors-1].z_high, 0.0, width, GMT_GRID_UPPER);
 				else
-					gmt_linearx_grid (GMT, PSL, P->data[0].z_low, P->data[P->n_colors-1].z_high, 0.0, width, dx);
+					gmt_linearx_grid(GMT, PSL, P->data[0].z_low, P->data[P->n_colors-1].z_high, 0.0, width, dx);
 			}
 		}
-		else {	/* When no -B we annotate every CPT bound which may be non-equidistant, hence this code (i.e., we cannot fake a call to -B) */
+		else if (!GMT->current.map.frame.no_frame) {	/* When no -B we annotate every CPT bound which may be non-equidistant, hence this code (i.e., we cannot fake a call to -B) */
 
 			if (!skip_lines) {	/* First draw gridlines, unless skip_lines is true */
-				gmt_setpen (GMT, &GMT->current.setting.map_grid_pen[GMT_PRIMARY]);
+				gmt_setpen(GMT, &GMT->current.setting.map_grid_pen[GMT_PRIMARY]);
 				for (i = 0; i < n_xpos; i++)
-					PSL_plotsegment (PSL, xpos[i], 0.0, xpos[i], width);
+					PSL_plotsegment(PSL, xpos[i], 0.0, xpos[i], width);
 			}
 
 			/* Then draw annotation and frame tickmarks */