utils.c

#include <math.h>
#include <stdbool.h>
#include <string.h>
#include "utils.h"

float clamp(float value, float minimum, float maximum)
{
   return fmin(fmax(value, minimum), maximum);
}

float map(float value, float minin, float maxin, float minout, float maxout)
{
   return minout + (value - minin) / (maxin - minin) * (maxout - minout);
}

bool ends_with(const char* str, const char* substr)
{
   int lenOfStr = strlen(str);
   int lenOfSubstr = strlen(substr);

   if (lenOfSubstr > lenOfStr)
   {
      return false;
   }

   for (int i = 0; i < lenOfSubstr; i++)
   {
      if (str[i + lenOfStr - lenOfSubstr] != substr[i])
      {
         return false;
      }
   }

   return true;
}

static int hex_to_decimal(char n1, char n2)
{
   int d1 = n1 >= '0' && n1 <= '9' ?
           n1 - '0' :
           (
            n1 >= 'A' && n1 <= 'F' ? n1 - 'A' + 10 : 0
           );
   int d2 = n2 >= '0' && n2 <= '9' ?
           n2 - '0' :
           (
            n2 >= 'A' && n2 <= 'F' ? n2 - 'A' + 10 : 0
           );
   return d2 + d1 * 16;
}

bool parse_hex_color(const char* hex, int* r, int* g, int* b)
{
   *r = 128;
   *g = 0;
   *b = 128;
   if (strlen(hex) != 6)
   {
      return false;
   }

   *r = hex_to_decimal(hex[0], hex[1]);
   *g = hex_to_decimal(hex[2], hex[3]);
   *b = hex_to_decimal(hex[4], hex[5]);

   return true;
}

unsigned long rgb_to_color(int r, int g, int b)
{
   return (0xFF << 24) | (r << 16) | (g << 8) | b;
}

void hsv_to_rgb(float H, float S, float V, int* red, int* green, int* blue)
{
   if (H > 360 || H < 0 || S > 100 || S < 0 || V > 100 || V < 0)
   {
      return;
   }

   float s = S / 100;
   float v = V / 100;
   float C = s * v;
   float X = C * (1 - fabs(fmod(H / 60.0, 2) - 1));
   float m = v - C;
   float r, g, b;
   if (H >= 0 && H < 60)
   {
      r = C, g = X, b = 0;
   }
   else if (H >= 60 && H < 120)
   {
      r = X, g = C, b = 0;
   }
   else if (H >= 120 && H < 180)
   {
      r = 0, g = C, b = X;
   }
   else if (H >= 180 && H < 240) 
   {
      r = 0, g = X, b = C;
   }
   else if (H >= 240 && H < 300)
   {
      r = X, g = 0, b = C;
   }
   else
   {
      r = C, g = 0, b = X;
   }

   *red = (r + m) * 255;
   *green = (g + m) * 255;
   *blue = (b + m) * 255;
}