New drawing: A6 postcard labels. Draw a sheet of postcards, ISO A6 si…

…ze, just the rear with space for message, address and stamp.

.gitignore

@@ -5,6 +5,7 @@ private
 *.nc
 *.png
 *.svg
+a6cardlabels
 allover12
 allover13
 arches

Makefile

@@ -22,7 +22,7 @@ HPGL=flake.hpgl op.hpgl dala1.hpgl hconic2.hpgl tree.hpgl dome.hpgl \
      qrplot.hpgl lotus.hpgl celticstep.hpgl op_moire.hpgl sutpent.hpgl \
      morphpoly.hpgl pin_circle.hpgl isogrid.hpgl circle_lines.hpgl \
      star_grid.hpgl ternary_arcs.hpgl hexspiral.hpgl poly_oval.hpgl \
-     libtest.hpgl linetiles.hpgl
+     libtest.hpgl linetiles.hpgl a6cardlabels.hpgl
 
 SVG=$(HPGL:.hpgl=.svg)
 
@@ -57,6 +57,15 @@ op.o: op.c
 
 # HPGL library programs
 
+a6cardlabels.hpgl: a6cardlabels Makefile
+	./a6cardlabels $(TITLE) $(BOLDPEN) -o $@
+
+a6cardlabels: a6cardlabels.o hpgllib.o
+	$(LD) -o $@ a6cardlabels.o hpgllib.o -lm
+
+a6cardlabels.o: a6cardlabels.c hpgllib.h
+	$(CC) $(CFLAGS) -o $@ a6cardlabels.c
+
 piscis.hpgl: piscis Makefile
 	./piscis $(TITLE) $(BOLDPEN) -o $@
 

a6cardlabels.c

@@ -0,0 +1,132 @@
+/* a6cardlabels --- plot labelling for A6 postcards         2020-08-23 */
+/* Copyright (c) 2020 John Honniball, Froods Software Development      */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <math.h>
+#include <unistd.h>
+#include "hpgllib.h"
+
+void postcard_port(const double x, const double y, const double wd, const double ht);
+void postcard_land(const double x, const double y, const double wd, const double ht);
+
+int main(int argc, char * const argv[])
+{
+   int opt;
+   int i, j;
+   bool portrait;
+   double x, y;
+   double dx, dy;
+   int nx, ny;
+   double maxx, maxy;
+   PlotInfo_t info;
+
+   while ((opt = getopt(argc, argv, "no:p:q:s:t:v:")) != -1) {
+      switch (opt) {
+      case 's':
+      case 'n':
+      case 'o':
+      case 'p':
+      case 'q':
+      case 'v':
+         plotopt(opt, optarg);
+         break;
+      case 't':   // Suppress title, which would spoil the lower-left postcard
+         break;
+      default: /* '?' */
+         fprintf(stderr, "Usage: %s [-p pen] [-q plotter] [-s <size>] [-t title]\n", argv[0]);
+         fprintf(stderr, "       <size> ::= A1 | A2 | A3 | A4 | A5 | A6\n");
+         exit(EXIT_FAILURE);
+      }
+   }
+
+   if (plotbegin(1) < 0) {
+      fputs("Failed to initialise HPGL library\n", stderr);
+      exit(EXIT_FAILURE);
+   }
+
+   if (getplotinfo(&info, sizeof (info)) < 0) {
+      fputs("Failed to get plot information\n", stderr);
+      exit(EXIT_FAILURE);
+   }
+
+   getplotsize(&maxx, &maxy);
+
+   switch (info.paperSize) {
+   case ISO_A3:
+      nx = 4;
+      ny = 2;
+      portrait = true;
+      break;
+   case ISO_A4:
+      nx = 2;
+      ny = 2;
+      portrait = false;
+      break;
+   case ISO_A5:
+      nx = 2;
+      ny = 1;
+      portrait = true;
+      break;
+   case ISO_A6:
+      nx = 1;
+      ny = 1;
+      portrait = false;
+      break;
+   }
+
+   dx = maxx / (double)nx;
+   dy = maxy / (double)ny;
+
+   for (i = 1; i < nx; i++) {
+      x = dx * (double)i;
+      moveto(x, 0);
+      lineto(x, maxy);
+   }
+
+   for (i = 1; i < ny; i++) {
+      y = dy * (double)i;
+      moveto(0, y);
+      lineto(maxx, y);
+   }
+
+   for (i = 0; i < nx; i++)
+      for (j = 0; j < ny; j++) {
+         x = dx * (double)i;
+         y = dy * (double)j;
+
+         if (portrait)
+            postcard_port(x, y, dx, dy);
+         else
+            postcard_land(x, y, dx, dy);
+      }
+
+   plotend();
+
+   return (0);
+}
+
+
+void postcard_port(const double x, const double y, const double wd, const double ht)
+{
+   double yc = y + (ht / 2.0);
+   double x1 = x + (wd / 16.0);
+   double x2 = x + wd - (wd / 16.0);
+   double sx2 = x + wd - (5.0 * 40.0);
+   double sy2 = y + (5.0 * 40.0);
+   double sx1 = sx2 - (22.0 * 40.0);
+   double sy1 = sy2 + (19.0 * 40.0);
+
+   moveto(x1, yc);
+   lineto(x2, yc);
+
+   rectangle(sx1, sy1, sx2, sy2);
+}
+
+
+void postcard_land(const double x, const double y, const double wd, const double ht)
+{
+}
+