PHP rgb颜色互转

rgb颜色转换16进制
16进制转换为rgb颜色

/**
   * RGB转 十六进制
   * @param $rgb RGB颜色的字符串 如：rgb(255,255,255);
   * @return string 十六进制颜色值 如：#FFFFFF
   */
  function RGBToHex($rgb){
    $regexp = "/^rgb\(([0-9]{0,3})\,\s*([0-9]{0,3})\,\s*([0-9]{0,3})\)/";
    $re = preg_match($regexp, $rgb, $match);
    $re = array_shift($match);
    $hexColor = "#";
    $hex = array('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F');
    for ($i = 0; $i < 3; $i++) {
      $r = null;
      $c = $match[$i];
      $hexAr = array();
      while ($c > 16) {
        $r = $c % 16;
        $c = ($c / 16) >> 0;
        array_push($hexAr, $hex[$r]);
      }
      array_push($hexAr, $hex[$c]);
      $ret = array_reverse($hexAr);
      $item = implode('', $ret);
      $item = str_pad($item, 2, '0', STR_PAD_LEFT);
      $hexColor .= $item;
    }
    return $hexColor;
  }

/**
 * 十六进制 转 RGB
 */
function hex2rgb($hexColor) {
  $color = str_replace('#', '', $hexColor);
  if (strlen($color) > 3) {
    $rgb = array(
      'r' => hexdec(substr($color, 0, 2)),
      'g' => hexdec(substr($color, 2, 2)),
      'b' => hexdec(substr($color, 4, 2))
    );
  } else {
    $color = $hexColor;
    $r = substr($color, 0, 1) . substr($color, 0, 1);
    $g = substr($color, 1, 1) . substr($color, 1, 1);
    $b = substr($color, 2, 1) . substr($color, 2, 1);
    $rgb = array(
      'r' => hexdec($r),
      'g' => hexdec($g),
      'b' => hexdec($b)
    );
  }
  return $rgb;
}