scripts/C/xaspect.c

   1 /*
   2  * Copyright © 2008, 2017 Nick Bowler
   3  *
   4  * License WTFPL2: Do What The Fuck You Want To Public License, version 2.
   5  * This is free software: you are free to do what the fuck you want to.
   6  * There is NO WARRANTY, to the extent permitted by law.
   7  */
   8
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include <math.h>
  13 #include <inttypes.h>
  14 #include <xcb/xcb.h>
  15
  16 /* Table of common monitor aspect ratios.  Add to this as necessary. */
  17 static const struct aspect {
  18         unsigned num, denom;
  19 } aspects[] = {
  20         { 16, 10 },
  21         { 16, 9 },
  22         { 8, 3 },
  23         { 5, 4 },
  24         { 4, 3 }
  25 };
  26
  27 /*
  28  * Get the xcb screen structure for the specified screen, or NULL if it doesn't
  29  * exist.
  30  */
  31 static xcb_screen_t *getscreen(xcb_connection_t *c, int screen)
  32 {
  33         xcb_screen_iterator_t iter;
  34
  35         iter = xcb_setup_roots_iterator(xcb_get_setup(c));
  36         while (iter.rem) {
  37                 if (screen == 0)
  38                         return iter.data;
  39                 screen--;
  40                 xcb_screen_next(&iter);
  41         }
  42
  43         return NULL;
  44 }
  45
  46 void find_nearest_aspect(xcb_screen_t *screen, struct aspect *out)
  47 {
  48         unsigned int w = screen->width_in_millimeters;
  49         unsigned int h = screen->height_in_millimeters;
  50
  51         double r = (double)w/h;
  52         double d = HUGE_VAL;
  53         int i;
  54
  55         for (i = 0; i < (sizeof aspects / sizeof aspects[0]); i++) {
  56                 double t = (double) aspects[i].num / aspects[i].denom;
  57                 double cmp;
  58
  59                 cmp = fabs(r - t);
  60                 if (cmp < d) {
  61                         *out = aspects[i];
  62                         d = cmp;
  63                 }
  64
  65                 cmp = fabs(r - 1/t);
  66                 if (cmp < d) {
  67                         out->num = aspects[i].denom;
  68                         out->denom = aspects[i].num;
  69                         d = cmp;
  70                 }
  71         }
  72 }
  73
  74 struct options {
  75         char *displayname;
  76         int showdimensions;
  77 } *parseoptions(int argc, char **argv)
  78 {
  79         static struct options opts = { 0 };
  80         int i;
  81
  82         for (i = 1; i < argc; i++) {
  83                 if (strcmp(argv[i], "-display") == 0) {
  84                         if (++i < argc) {
  85                                 opts.displayname = argv[i];
  86                                 continue;
  87                         }
  88                         fprintf(stderr, "-display requires an argument\n");
  89                 } else if (strcmp(argv[i], "-dimensions") == 0) {
  90                         opts.showdimensions = 1;
  91                 }
  92         }
  93
  94         return &opts;
  95 }
  96
  97 int main(int argc, char **argv)
  98 {
  99         struct aspect screenaspect;
 100         xcb_connection_t *display;
 101         xcb_screen_t     *screen;
 102         int screen_num;
 103
 104         struct options *opts = parseoptions(argc, argv);
 105
 106         display = xcb_connect(opts->displayname, &screen_num);
 107         if (xcb_connection_has_error(display)) {
 108                 fprintf(stderr, "Failed to open display.\n");
 109                 xcb_disconnect(display);
 110                 return EXIT_FAILURE;
 111         }
 112
 113         screen = getscreen(display, screen_num);
 114         if (!screen) {
 115                 fprintf(stderr, "Invalid screen number.\n");
 116                 xcb_disconnect(display);
 117                 return EXIT_FAILURE;
 118         }
 119
 120         if (opts->showdimensions) {
 121                 printf("%" PRIu16 "x%" PRIu16 "-",
 122                        screen->width_in_pixels, screen->height_in_pixels);
 123         }
 124
 125         find_nearest_aspect(screen, &screenaspect);
 126         printf("%u:%u\n", screenaspect.num, screenaspect.denom);
 127
 128         xcb_disconnect(display);
 129         return EXIT_SUCCESS;
 130 }