scripts/C/xaspect.c

   1 /*
   2  * Copyright (C) 2007 Nick Bowler
   3  * Copying and distribution of this file, with or without modification,
   4  * are permitted in any medium without royalty provided the copyright
   5  * notice and this notice are preserved.  This file is offered as-is,
   6  * without any warranty.
   7  */
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11 #include <math.h>
  12 #include <inttypes.h>
  13 #include <xcb/xcb.h>
  14
  15 #define MKASPECT(w, h) { (double)w/h, #w ":" #h }
  16
  17 /* Table of common monitor aspect ratios.  Add to this as necessary. */
  18 static struct aspect {
  19         double ratio;
  20         char *name;
  21 } aspects[] = {
  22         MKASPECT(16, 10),
  23         MKASPECT(16, 9),
  24         MKASPECT(8, 3),
  25         MKASPECT(5, 4),
  26         MKASPECT(4, 3)
  27 };
  28
  29 /*
  30  * Get the xcb screen structure for the specified screen, or NULL if it doesn't
  31  * exist.
  32  */
  33 static xcb_screen_t *getscreen(xcb_connection_t *c, int screen)
  34 {
  35         xcb_screen_iterator_t iter;
  36
  37         iter = xcb_setup_roots_iterator(xcb_get_setup(c));
  38         while (iter.rem) {
  39                 if (screen == 0)
  40                         return iter.data;
  41                 screen--;
  42                 xcb_screen_next(&iter);
  43         }
  44
  45         return NULL;
  46 }
  47
  48 char *testaspect(xcb_screen_t *screen)
  49 {
  50         unsigned int w = screen->width_in_millimeters;
  51         unsigned int h = screen->height_in_millimeters;
  52
  53         double ratio = (double)w/h;
  54         double diff = 0;
  55         char *best = NULL;
  56         int i;
  57
  58         for (i = 0; i < (sizeof aspects / sizeof aspects[0]); i++) {
  59                 if (!best || fabs(aspects[i].ratio - ratio) < diff) {
  60                         best = aspects[i].name;
  61                         diff = fabs(aspects[i].ratio - ratio);
  62                 }
  63         }
  64
  65         return best;
  66 }
  67
  68 struct options {
  69         char *displayname;
  70         int showdimensions;
  71 } *parseoptions(int argc, char **argv)
  72 {
  73         static struct options opts = { 0 };
  74         int i;
  75
  76         for (i = 1; i < argc; i++) {
  77                 if (strcmp(argv[i], "-display") == 0) {
  78                         if (++i < argc) {
  79                                 opts.displayname = argv[i];
  80                                 continue;
  81                         }
  82                         fprintf(stderr, "-display requires an argument\n");
  83                 } else if (strcmp(argv[i], "-dimensions") == 0) {
  84                         opts.showdimensions = 1;
  85                 }
  86         }
  87
  88         return &opts;
  89 }
  90
  91 int main(int argc, char **argv)
  92 {
  93         xcb_connection_t *display;
  94         xcb_screen_t     *screen;
  95         int screen_num;
  96
  97         struct options *opts = parseoptions(argc, argv);
  98
  99         display = xcb_connect(opts->displayname, &screen_num);
 100         if (xcb_connection_has_error(display)) {
 101                 fprintf(stderr, "Failed to open display.\n");
 102                 xcb_disconnect(display);
 103                 return EXIT_FAILURE;
 104         }
 105
 106         screen = getscreen(display, screen_num);
 107         if (!screen) {
 108                 fprintf(stderr, "Invalid screen number.\n");
 109                 xcb_disconnect(display);
 110                 return EXIT_FAILURE;
 111         }
 112
 113         if (opts->showdimensions) {
 114                 printf("%" PRIu16 "x%" PRIu16 "-",
 115                        screen->width_in_pixels, screen->height_in_pixels);
 116         }
 117         printf("%s\n", testaspect(screen));
 118
 119         xcb_disconnect(display);
 120         return EXIT_SUCCESS;
 121 }