Example #1 hexdec() example

<?php
var_dump(hexdec("ee")); // prints "int(238)"
var_dump(hexdec("a0")); // prints "int(160)"
?>

Example #2 hexdec() with Invalid Characters

<?php
var_dump(hexdec("See"));  // print "int(238)"
var_dump(hexdec("that")); // print "int(10)"
?>

31

Use this function to convert a hexa decimal color code to its RGB equivalent. Unlike many other functions provided here, it will work correctly with hex color short hand notation.
Also, if a proper hexa decimal color value is given (6 digits), it uses bit wise operations for faster results.
For eg: #FFF and #FFFFFF will produce the same result
<?php
/**
 * Convert a hexa decimal color code to its RGB equivalent
 *
 * @param string $hexStr (hexadecimal color value)
 * @param boolean $returnAsString (if set true, returns the value separated by the separator character. Otherwise returns associative array)
 * @param string $seperator (to separate RGB values. Applicable only if second parameter is true.)
 * @return array or string (depending on second parameter. Returns False if invalid hex color value)
 */
function hex2RGB($hexStr, $returnAsString = false, $seperator = ',') {
    $hexStr = preg_replace("/[^0-9A-Fa-f]/", '', $hexStr); // Gets a proper hex string
    $rgbArray = array();
    if (strlen($hexStr) == 6) { //If a proper hex code, convert using bitwise operation. No overhead... faster
        $colorVal = hexdec($hexStr);
        $rgbArray['red'] = 0xFF & ($colorVal >> 0x10);
        $rgbArray['green'] = 0xFF & ($colorVal >> 0x8);
        $rgbArray['blue'] = 0xFF & $colorVal;
    } elseif (strlen($hexStr) == 3) { //if shorthand notation, need some string manipulations
        $rgbArray['red'] = hexdec(str_repeat(substr($hexStr, 0, 1), 2));
        $rgbArray['green'] = hexdec(str_repeat(substr($hexStr, 1, 1), 2));
        $rgbArray['blue'] = hexdec(str_repeat(substr($hexStr, 2, 1), 2));
    } else {
        return false; //Invalid hex color code
    }
    return $returnAsString ? implode($seperator, $rgbArray) : $rgbArray; // returns the rgb string or the associative array
} ?>

OUTPUT:
hex2RGB("#FF0") -> array( red =>255, green => 255, blue => 0)
hex2RGB("#FFFF00) -> Same as above
hex2RGB("#FF0", true) -> 255,255,0
hex2RGB("#FF0", true, ":") -> 255:255:0

1

From color to color to ...... to color with fade effect. Good for dynamic bar chart.
<?php
//MultiColorFade(array hex-colors, int steps)
function MultiColorFade($hex_array, $steps) {
$tot = count($hex_array);
$gradient = array();
$fixend = 2;
$passages = $tot-1;
$stepsforpassage = floor($steps/$passages);
$stepsremain = $steps - ($stepsforpassage*$passages);
   for($pointer = 0; $pointer < $tot-1 ; $pointer++) {
       $hexstart = $hex_array[$pointer];
       $hexend = $hex_array[$pointer + 1];
       if($stepsremain > 0){
           if($stepsremain--){
               $stepsforthis = $stepsforpassage + 1;
           }
       }else{
           $stepsforthis = $stepsforpassage;
       }
       if($pointer > 0){
           $fixend = 1;
       }
       $start['r'] = hexdec(substr($hexstart, 0, 2));
       $start['g'] = hexdec(substr($hexstart, 2, 2));
       $start['b'] = hexdec(substr($hexstart, 4, 2));
       $end['r'] = hexdec(substr($hexend, 0, 2));
       $end['g'] = hexdec(substr($hexend, 2, 2));
       $end['b'] = hexdec(substr($hexend, 4, 2));
       $step['r'] = ($start['r'] - $end['r']) / ($stepsforthis);
       $step['g'] = ($start['g'] - $end['g']) / ($stepsforthis);
       $step['b'] = ($start['b'] - $end['b']) / ($stepsforthis);
       for($i = 0; $i <= $stepsforthis-$fixend; $i++) {
           $rgb['r'] = floor($start['r'] - ($step['r'] * $i));
           $rgb['g'] = floor($start['g'] - ($step['g'] * $i));
           $rgb['b'] = floor($start['b'] - ($step['b'] * $i));
           $hex['r'] = sprintf('%02x', ($rgb['r']));
           $hex['g'] = sprintf('%02x', ($rgb['g']));
           $hex['b'] = sprintf('%02x', ($rgb['b']));
           $gradient[] = strtoupper(implode(NULL, $hex));
       }
   }
   $gradient[] = $hex_array[$tot-1];
return $gradient;
}
//end MultiColorFade()
//start test
$multi_hex_array = array();
$multi_hex_array[] = array('FF0000','FFFF00');
$multi_hex_array[] = array('FF0000','FFFF00','00FF00');
$multi_hex_array[] = array('FF0000','FFFF00','00FF00','00FFFF');
$multi_hex_array[] = array('FF0000','FFFF00','00FF00','00FFFF','0000FF');
$multi_hex_array[] = array('FF0000','FFFF00','00FF00','00FFFF','0000FF','000000');
$multi_hex_array[] = array('FF0000','FFFF00','00FF00','00FFFF','0000FF','000000','FFFFFF');
foreach($multi_hex_array as $hex_array){
   $totcolors = count($hex_array);
   $steps = 44;
   $a = MultiColorFade($hex_array, $steps);
   $tot = count($a);
   $table = '<table border=1 width="300">' . "\n";
   for ($i = 0; $i < $tot; $i++){
       $table .= ' <tr><td bgcolor="' . $a[$i] . '">' . ($i+1) .'</td><td><pre>' . $a[$i] . '</pre></td></tr>' . "\n";
   }
   $table .= '</table><br /><br />';
   echo '<br />Demanded steps = ' . $steps . '<br />';
   echo 'Returned steps = ' . $tot;
   if($steps == $tot){
       echo '<br />OK.' . $steps . ' = ' . $tot . '<br />';
   }else{
       echo '<br /><span style="color:#FF0000">FAILED! Demanded steps and returned steps are NOT equal!: ' . $steps . ' != ' . $tot . '</span><br />';
   }
   echo $table;
}
//end test
?>

Repley.