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colort.c
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colort.c
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
long hexToDec(char*,int);
void decToHex(long,char*);
int makeValid(long*,int);
void usage();
/* usage */
void usage()
{
printf("%s", "usage: colort [-s <index>] ([-l] <value> <color> | -i <color>)\n");
exit(1);
}
/* convert hexidecimal to character, eg ff -> 255. */
long hexToDec(char *input, int index)
{
char hex[2] = {input[index], input[index+1]};
return strtol(hex, NULL, 16);
}
/* convert deximal to hex char. */
void decToHex(long value, char *destination)
{
/* sprintf appends terminator by default, so we'll replace with what was prev there. */
char original = destination[2];
sprintf(destination, "%02lX", value);
destination[2] = original;
}
/* make a color valid post tinting, limit if enabled. */
/* return 1 if limit enabled and limited. */
int makeValid(long *input, int limit)
{
if (limit) {
if (*input > 255) {
*input = 255;
return 1;
} else if (*input < 0) {
*input = 0;
return 1;
}
return 0;
} else {
while(*input < 0)
*input += 256;
*input = *input % 256;
return 0;
}
}
int main(int argc, char *argv[])
{
int i, selectIndex, tintValue, optionSwitch, negativeIndex,
yiq, terse, enableRed, enableBlue, enableGreen, ret, exitStatus;
i = yiq = terse = tintValue = optionSwitch = negativeIndex =
enableRed = enableBlue = enableGreen = ret = exitStatus = 0;
selectIndex = -1;
long red, blue, green;
red = blue = green = 0;
char *colorString, *inputString;
char negativeTintInput[10] = "";
/* -l (limit), -i (invert), -s (select) */
while ((i = getopt (argc, argv, ":rghbtlis:c")) != -1)
switch(i) {
case 'l': optionSwitch = 1; break;
case 'i': optionSwitch = -1; break;
case 'c': optionSwitch = 2; break;
case 'r': enableRed = 1; break;
case 'g': enableGreen = 1; break;
case 'b': enableBlue = 1; break;
case 's': selectIndex = atoi(optarg); break;
case 'h': usage();
case 't': terse = 1; break;
case '?':
/* here we hand number arguments to a string to parse */
/* because we want to do negative args without escaping (--) */
switch(optopt) {
case '1': case '2': case '3': case '4': case '5':
case '6': case '7': case '8': case '9': case '0':
negativeTintInput[negativeIndex++] = optopt;
break;
default: usage();
}
}
/* always gonna need an input string. */
if (argv[optind] == NULL)
usage();
/* if not inverting, need tint value. */
if (optionSwitch != -1 && optionSwitch != 2 && !negativeIndex)
if (argv[optind] == NULL)
usage();
/* default to all colors. */
if (!enableRed && !enableGreen && !enableBlue)
enableRed = enableGreen = enableBlue = 1;
/* set input and color strings, default to last 6 characters. */
inputString = argv[argc - 1];
selectIndex = selectIndex == -1 ? strlen(inputString) - 6 : selectIndex;
colorString = &inputString[selectIndex];
/* set color handles. */
red = hexToDec(colorString, 0);
green = hexToDec(colorString, 2);
blue = hexToDec(colorString, 4);
/* set and apply the tint value if we're using it */
if (optionSwitch != -1 && optionSwitch != 2) {
tintValue = 0;
if (negativeIndex) {
tintValue = -1 * atoi(negativeTintInput);
}
else if ((argc - optind) > 1) {
tintValue = atoi(argv[optind]);
}
red += tintValue;
green += tintValue;
blue += tintValue;
}
/* do the thing */
switch(optionSwitch) {
case -1: /* invert */
red = 255 - red;
green = 255 - green;
blue = 255 - blue;
break;
case 0: /* normal */
case 1: /* limit */
ret = makeValid(&red, optionSwitch);
ret += makeValid(&green, optionSwitch);
ret += makeValid(&blue, optionSwitch);
exitStatus = ret >=2 ? 1 : 0;
break;
case 2: /* contrast - ref: https://24ways.org/2010/calculating-color-contrast/ */
yiq = ((red * 299) + (green * 587) + (blue * 114)) / 1000;
exit(yiq >= 128 ? 1 : 0);
}
/* insert result if enabled */
if (enableRed)
decToHex(red, &colorString[0]);
if (enableGreen)
decToHex(green, &colorString[2]);
if (enableBlue)
decToHex(blue, &colorString[4]);
/* print color only */
if (terse) {
colorString[6] = '\0';
inputString = colorString;
}
printf("%s", inputString);
exit(exitStatus);
}