rgbcolor.cpp

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/*
_   ._       Copyright (c) 1996-2021 Freeciv21 and Freeciv contributors.
 \  |    This file is part of Freeciv21. Freeciv21 is free software: you
  \_|        can redistribute it and/or modify it under the terms of the
 .' '.              GNU General Public License  as published by the Free
 :O O:             Software Foundation, either version 3 of the License,
 '/ \'           or (at your option) any later version. You should have
  :X:      received a copy of the GNU General Public License along with
  :X:              Freeciv21. If not, see https://www.gnu.org/licenses/.
 */
 
#include <cstdarg>
 
// utility
#include "log.h"
#include "registry.h"
#include "registry_ini.h"
 
// common
#include "rgbcolor.h"
 
struct rgbcolor *rgbcolor_new(int r, int g, int b)
{
  struct rgbcolor *prgbcolor;
 
  prgbcolor = new rgbcolor;
  prgbcolor->r = r;
  prgbcolor->g = g;
  prgbcolor->b = b;
 
  return prgbcolor;
}
 
struct rgbcolor *rgbcolor_copy(const struct rgbcolor *prgbcolor)
{
  fc_assert_ret_val(prgbcolor != nullptr, nullptr);
 
  return rgbcolor_new(prgbcolor->r, prgbcolor->g, prgbcolor->b);
}
 
bool rgbcolors_are_equal(const struct rgbcolor *c1,
                         const struct rgbcolor *c2)
{
  fc_assert_ret_val(c1 != nullptr && c2 != nullptr, false);
 
  /* No check of cached 'color' member -- if values are equal, it should be
   * equivalent */
  return (c1->r == c2->r && c1->g == c2->g && c1->b == c2->b);
}
 
void rgbcolor_destroy(struct rgbcolor *prgbcolor)
{
  if (!prgbcolor) {
    return;
  }
 
  delete prgbcolor;
}
 
bool rgbcolor_load(struct section_file *file, struct rgbcolor **prgbcolor,
                   const char *path, ...)
{
  int r, g, b;
  char colorpath[256];
  va_list args;
 
  fc_assert_ret_val(file != nullptr, false);
  fc_assert_ret_val(*prgbcolor == nullptr, false);
 
  va_start(args, path);
  fc_vsnprintf(colorpath, sizeof(colorpath), path, args);
  va_end(args);
 
  if (!secfile_lookup_int(file, &r, "%s.r", colorpath)
      || !secfile_lookup_int(file, &g, "%s.g", colorpath)
      || !secfile_lookup_int(file, &b, "%s.b", colorpath)) {
    // One color value (red, green or blue) is missing.
    return false;
  }
 
  rgbcolor_check(colorpath, r, g, b);
  *prgbcolor = rgbcolor_new(r, g, b);
 
  return true;
}
 
void rgbcolor_save(struct section_file *file,
                   const struct rgbcolor *prgbcolor, const char *path, ...)
{
  char colorpath[256];
  va_list args;
 
  fc_assert_ret(file != nullptr);
  fc_assert_ret(prgbcolor != nullptr);
 
  va_start(args, path);
  fc_vsnprintf(colorpath, sizeof(colorpath), path, args);
  va_end(args);
 
  secfile_insert_int(file, prgbcolor->r, "%s.r", colorpath);
  secfile_insert_int(file, prgbcolor->g, "%s.g", colorpath);
  secfile_insert_int(file, prgbcolor->b, "%s.b", colorpath);
}
 
bool rgbcolor_to_hex(const struct rgbcolor *prgbcolor, char *hex,
                     size_t hex_len)
{
  fc_assert_ret_val(prgbcolor != nullptr, false);
  // Needs a length greater than 7 ('#' + 6 hex digites and '/* Needs a
  // length greater than 7 ('#' + 6 hex digites and '\0'). */').
  fc_assert_ret_val(hex_len > 7, false);
 
  fc_assert_ret_val(0 <= prgbcolor->r && prgbcolor->r <= 255, false);
  fc_assert_ret_val(0 <= prgbcolor->g && prgbcolor->g <= 255, false);
  fc_assert_ret_val(0 <= prgbcolor->b && prgbcolor->b <= 255, false);
 
  fc_snprintf(hex, hex_len, "#%06x",
              (prgbcolor->r * 256 + prgbcolor->g) * 256 + prgbcolor->b);
 
  return true;
}
 
bool rgbcolor_from_hex(struct rgbcolor **prgbcolor, const char *hex)
{
  int rgb, r, g, b;
  char hex2[16];
 
  fc_assert_ret_val(*prgbcolor == nullptr, false);
  fc_assert_ret_val(hex != nullptr, false);
 
  if (hex[0] == '#') {
    hex++;
  }
 
  if (strlen(hex) != 6) {
    return false;
  }
 
  fc_snprintf(hex2, sizeof(hex2), "0x%s", hex);
  if (!sscanf(hex2, "%x", &rgb)) {
    return false;
  }
 
  r = rgb / 256 / 256;
  g = (rgb - r * 256 * 256) / 256;
  b = rgb % 256;
 
  *prgbcolor = rgbcolor_new(r, g, b);
 
  return true;
}
 
int rgbcolor_brightness_score(struct rgbcolor *prgbcolor)
{
  /* This simple scoring system taken from W3C "Techniques For Accessibility
   * Evaluation And Repair Tools", http://www.w3.org/TR/AERT#color-contrast
   *
   * "Color brightness is determined by the following formula:
   * ((Red value X 299) + (Green value X 587) + (Blue value X 114)) / 1000
   * Note: This algorithm is taken from a formula for converting RGB values
   * to YIQ [NTSC] values [specifically the Y component]. This brightness
   * value gives a perceived brightness for a color." */
  return (prgbcolor->r * 299 + prgbcolor->g * 587 + prgbcolor->b * 114)
         / 1000;
}