Percentage to Hexcolor in PHP

Question

I\'d like to make a percentage into a hexidecimal color. Kind of how HSV color degrees work...
I am using PHP.

IE: 
  0% : RED       (#FF0000)
  8% : ORANGE          


        

Answer 1

This is not my code and I don't remember where I found it. I've been using it for a couple of years and it works perfectly for me. It could be what your looking for (or part of it may be).

web = array(
        'black'   => '#000000',
        'green'   => '#008000',
          'silver'  => '#C0C0C0',
        'lime'    => '#00FF00',
        'gray'    => '#808080',
        'olive'   => '#808000',
        'white'   => '#FFFFFF',
        'yellow'  => '#FFFF00',
        'maroon'  => '#800000',
        'navy'    => '#000080',
        'red'     => '#FF0000',
        'blue'    => '#0000FF',
        'purple'  => '#800080',
        'teal'    => '#008080',
        'fuchsia' => '#FF00FF' 
    );
    //accept either R,G,B or hex colour
    //If hex, convert to RGB
    //RGB?
    if($r && $g && $b){
      //yes then save
      $this->R = $r;
      $this->G = $g;
      $this->B = $b;
    } elseif(isset($this->web[strtolower($r)])){
      //named colour?
      $this->hex = $this->web[strtolower($r)];
      $this->convertToRGB($this->hex);
    } else {
      //no - so convert
      if($r[0] != '#') $r = '#' . $r;
      $this->hex = $r;
      $this->convertToRGB($r);
    }
    $this->rgbTohsl();
    //$this->complement = $this->getComplement();
  }

  public function getLighter($factor)
  {
    //return colour lightened by %$factor in hex
    //$factor can be negative to give a darker colour
    if($factor > 1 || $factor < -1) $factor = $factor/100;
    $r = (string)round($this->R+((255 - $this->R) * $factor));
    $g = (string)round($this->G+((255 - $this->G) * $factor));
    $b = (string)round($this->B+((255 - $this->B) * $factor));

    if($r > 255)$r = 255;
    if($r < 0)$r = 0;
    if($g > 255)$g = 255;
    if($g < 0)$g = 0;
    if($b > 255)$b = 255;
    if($b < 0)$b = 0;
    var_dump($r, $g, $b);
    return $this->convertToHex($r, $g, $b);
  }

  public function opposite()
  {
    $r = $this->R;
    $g = $this->G;
    $b = $this->B;

    $r = 255 - $r;
    $g = 255 - $g;
    $b = 255 - $b;

    return $this->convertToHex($r, $g, $b); 

  }

  public function getRGB()
  {
    //returns an array (r, g, b)

    $rgb = array( 'r' => $this->R,
                  'g' => $this->G,
                  'b' => $this->B);
    return $rgb;
  }

  public function getHex()
  {
    if($this->hex) return $this->hex;
    $hex = '#' . dechex($this->R) . dechex($this->G) . dechex($this->B);
    return $hex; 
  }

  public static function namedToHex($name)
  {
    //return hex value of named colour
    $web = array(
        'black'   => '#000000',
        'green'   => '#008000',
          'silver'  => '#C0C0C0',
        'lime'    => '#00FF00',
        'gray'    => '#808080',
        'olive'   => '#808000',
        'white'   => '#FFFFFF',
        'yellow'  => '#FFFF00',
        'maroon'  => '#800000',
        'navy'    => '#000080',
        'red'     => '#FF0000',
        'blue'    => '#0000FF',
        'purple'  => '#800080',
        'teal'    => '#008080',
        'fuchsia' => '#FF00FF' 
    );
    if(isset($web[strtolower($name)])){
      return $web[strtolower($name)];
    }
    return false;
  }

  public static function contrast(colour $fg, colour $bg){
    //calculate and return contrast between $fg and $bg
    $cont = 1;
    $fglum = $fg->luminance();
    $bglum = $bg->luminance();

    if($fglum > $bglum) $cont = ($fglum + 0.05) / ($bglum + 0.05);
    if($bglum > $fglum) $cont = ($bglum + 0.05) / ($fglum + 0.05);

    return $cont;

  }

  public static function colourDiff(colour $colour1, colour $colour2)
  {
    //returns the colour difference between two colours
    $rgb1 = $colour1->getRGB();
    $rgb2 = $colour2->getRGB();

    $r1 = $rgb1['r'];
    $r2 = $rgb2['r'];

    $g1 = $rgb1['g'];
    $g2 = $rgb2['g'];

    $b1 = $rgb1['b'];
    $b2 = $rgb2['b'];

    $diff = max($r1, $r2) - min($r1, $r2);
    $diff += max($g1, $g2) - min($g1, $g2);
    $diff += max($b1, $b2) - min($b1, $b2);

    return $diff;
  }

  public function brightness()
  {
    return (($this->R * 299) + ($this->G * 587) + ($this->B * 114))/1000;
  }

  public function luminance()
  {
    //returns luminence of coulour
    $r = $this->lumCheck($this->R/255);
    $g = $this->lumCheck($this->G/255);
    $b = $this->lumCheck($this->B/255);

    $lum = (0.2126 * $r) + (0.7152 * $g) + (0.0722 * $b);
    return $lum; 
  }

  protected function lumCheck($col)
  {
    if($col <= 0.03298){
      return $col/12.92;
    } else {
      return pow((($col + 0.055)/1.055), 2.4);
    }
  }

  protected function convertToRGB($color)
  {
    $color = (string)$color;
    if($color[0] == '#'){
        $color = substr($color, 1);
    }
    if(strlen($color) == 6){
        list($r, $g, $b) = array($color[0].$color[1],
                                 $color[2].$color[3],
                                 $color[4].$color[5]);
    }
    elseif(strlen($color) == 3){
        list($r, $g, $b) = array($color[0].$color[0], $color[1].$color[1], $color[2].$color[2]);
    }
    else{
        return false;
    }

    $r = hexdec($r); $g = hexdec($g); $b = hexdec($b);

    $this->R = (int)$r;
    $this->G = (int)$g;
    $this->B = (int)$b;
  }

  protected function convertToHex($r, $g, $b)
  {
    $r = dechex($r);
    if(strlen($r) == 1)$r = '0' . $r;

    $g = dechex($g);
    if(strlen($g) == 1)$g = '0' . $g;

    $b = dechex($b);
    if(strlen($b) == 1)$b = '0' . $b;

    $hex = '#' . $r . $g . $b;
    return $hex;
  }

  protected function rgbTohsl()
  {
    $r = ( $this->R / 255 );                     //RGB from 0 to 255
    $g = ( $this->G / 255 );
    $b = ( $this->B / 255 );

    $var_Min = min( $r, $g, $b );    //Min. value of RGB
    $var_Max = max( $r, $g, $b );    //Max. value of RGB
    $del_Max = $var_Max - $var_Min;  //Delta RGB value

    $l = ( $var_Max + $var_Min ) / 2;
    $this->L = $l;

    if ( $del_Max == 0 ){           //This is a gray, no chroma...
      $this->H = 0;                                //HSL results from 0 to 1
      $this->S = 0;
    } else {                                   //Chromatic data...
      if ( $l < 0.5 ) {
        $this->S = $del_Max / ( $var_Max + $var_Min );
      } else {
        $this->S = $del_Max / ( 2 - $var_Max - $var_Min );

        $del_R = ( ( ( $var_Max - $r ) / 6 ) + ( $del_Max / 2 ) ) / $del_Max;
        $del_G = ( ( ( $var_Max - $g ) / 6 ) + ( $del_Max / 2 ) ) / $del_Max;
        $del_B = ( ( ( $var_Max - $b ) / 6 ) + ( $del_Max / 2 ) ) / $del_Max;

        if( $r == $var_Max ){
          $h = $del_B - $del_G;
        } elseif( $g == $var_Max ){
          $h = ( 1 / 3 ) + $del_R - $del_B;
        } elseif( $b == $var_Max ) {
          $h = ( 2 / 3 ) + $del_G - $del_R;
        }

        if ( $h < 0 ) $h += 1;
        if ( $h > 1 ) $h -= 1;
        $this->H = $h;
      }
    }
  }

  protected function hslTorgb($h, $s, $l)
  {
    if ( $s == 0 ){                       //HSL from 0 to 1
      $r = $l * 255;                      //RGB results from 0 to 255
      $g = $l * 255;
      $b = $l * 255;
    } else {
      if ( $l < 0.5 ) {
        $var_2 = $l * ( 1 + $s );
      } else {
        $var_2 = ( $l + $s ) - ( $s * $l );
      }

      $var_1 = 2 * $l - $var_2;
      $r = 255 * $this->hueToRGB( $var_1, $var_2, $h + ( 1 / 3 ) );
      $g = 255 * $this->hueToRGB( $var_1, $var_2, $h );
      $b = 255 * $this->hueToRGB( $var_1, $var_2, $h - ( 1 / 3 ) );
    }
    return array('r'=>$r,'g'=>$g,'b'=>$b);
  }

  protected function hueToRGB($v1, $v2, $vH)
  {

    if($vH < 0)$vH += 1;
    if($vH > 1)$vH -= 1;
    if ( ( 6 * $vH ) < 1 ) return ( $v1 + ( $v2 - $v1 ) * 6 * $vH );
    if ( ( 2 * $vH ) < 1 ) return ( $v2 );
    if ( ( 3 * $vH ) < 2 ) return ( $v1 + ( $v2 - $v1 ) * ( ( 2 / 3 ) - $vH ) * 6 );
    return ( $v1 );
  }

  public function getComplement()
  {
    $h = $this->H + 180;
    if($h > 360)$h -= 360;
    $rgb = $this->hslTorgb($h, $this->S, $this->L);
    return $this->convertToHex($rgb['r'], $rgb['g'], $rgb['b']);
  }
}