hexdec

add a note User Contributed Notes

repley at freemail dot it
29-May-2006 09:55


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.

greatwhitepine at NOSPAM dot yahoo dot ca
31-Mar-2006 04:46


Hex to binary conversion that works for large and small hex numbers.



<?php



function hexbin($str_hex) {

  $str_bin = FALSE;

  for ($i=0; $i < strlen($str_hex); $i++) {

    $str_bin .= sprintf("%04s", decbin(hexdec($str_hex[$i])));

  }

  return $str_bin;

}



$str_hex = "effffff20df";



print "\n           HEX VALUE: $str_hex\n";

printf("   REAL BINARY VALUE: %50s\n", hexbin($str_hex));

printf("CHOPPED BINARY VALUE: %50s\n\n", decbin(hexdec($str_hex)));



?>

ayadav at infoprocorp dot com
28-Dec-2005 04:03


From Amit Yadav



Hex to binary conversion



$num = hexdec("20DF");

echo binfromdec($num);



function binfromdec($num) 

{

    if ($num > 32766)    return ("Too Large!");

    if ($num & 16384)    $bit15 = 1;

    if ($num & 8192)    $bit14 = 1;

    if ($num & 4096)    $bit13 = 1;

    if ($num & 2048)    $bit12 = 1;

    if ($num & 1024)    $bit11 = 1;

    if ($num & 512)        $bit10 = 1;

    if ($num & 256)        $bit9 = 1;

    if ($num & 128)        $bit8 = 1;

    if ($num & 64)        $bit7 = 1;

    if ($num & 32)        $bit6 = 1;

    if ($num & 16)        $bit5 = 1;

    if ($num & 8)        $bit4 = 1;

    if ($num & 4)        $bit3 = 1;

    if ($num & 2)        $bit2 = 1;

    if ($num & 1)        $bit1 = 1;



    return ("" . $bit15 . $bit14 . $bit13 . $bit12 . $bit11 . $bit10 . $bit9 . $bit8 . $bit7 . $bit6 . $bit5 . $bit4 . $bit3 . $bit2 . $bit1);



}

cory at lavacube dot com
29-Oct-2005 04:59


A handy little function to convert HEX colour codes to "web safe" colours...



<?php



function color_mkwebsafe ( $in )

{

   // put values into an easy-to-use array

   $vals['r'] = hexdec( substr($in, 0, 2) );

   $vals['g'] = hexdec( substr($in, 2, 2) );

   $vals['b'] = hexdec( substr($in, 4, 2) );



   // loop through

   foreach( $vals as $val )

   {

       // convert value

       $val = ( round($val/51) * 51 );

       // convert to HEX

       $out .= str_pad(dechex($val), 2, '0', STR_PAD_LEFT);

   }



   return $out;

}



?>



Example: color_mkwebsafe('0e5c94');

Produces: 006699



Hope this helps someone out... Happy coding. :-)

hajamie@home
24-Oct-2005 10:38


This function will take a hex $color, e.g. fa34bc and make it the shade you want, e.g. anywhere between 0 and 255. The smaller the number, the darker the output color.  It keeps the color the same, only changing the shade.   



function correctshade($color, $shade)

{

$r = hexdec(substr($color,0,2));

$g = hexdec(substr($color,2,2));

$b = hexdec(substr($color,4,2));

$sum = ($r + $g + $b);

$x = (($shade * 3) - $sum) / $sum;

if ($x >= 0) {

$x = $x + 1;

} else {

$x = 1 + $x;

}

$r = intval($x * $r);

$g = intval($x * $g);

$b = intval($x * $b);

$r = dechex($r);

$g = dechex($g);

$b = dechex($b);

return $r.$g.$b;

}

09-Oct-2005 01:53


I needed to get the opposite colors so my website would be soft on the eyes.



<?php

function OppositeHex($color)

{

$r = dechex(255 - hexdec(substr($color,0,2)));

$r = (strlen($r) > 1) ? $r : '0'.$r;

$g = dechex(255 - hexdec(substr($color,2,2)));

$g = (strlen($g) > 1) ? $g : '0'.$g;

$b = dechex(255 - hexdec(substr($color,4,2)));

$b = (strlen($b) > 1) ? $b : '0'.$b;

return $r.$g.$b;

}



//Example

$color = '000000';

echo 'The opposite of #'.$color.' is #'.OppositeHex($color).';

?>

detrate at hotmail dot com
30-Sep-2005 09:38


I made this for a little phpbb mod.  It was used to take the hex value from the database and make a color 20 (in decimal) less, resulting a darker color.



EXAMPLE: #336699 to #1f5285



<?php



$row1 = "336699"; // color

$c = 20;          // difference value



$rgb = array(substr($row1,0,2), substr($row1,2,2), substr($row1,4,2));



for($i=0; $i < 3; $i++)

{

  if((hexdec($rgb[$i])-$c) >= 0)

  {

   $rgb[$i] = hexdec($rgb[$i])-$c;



   $rgb[$i] = dechex($rgb[$i]);

    if(hexdec($rgb[0]) <= 9)

     $rgb[$i] = "0".$rgb[$i];

  } else {

    $rgb[$i] = "00";

  }

}



$row2 = $rgb[0].$rgb[1].$rgb[2];



?>

Gabriel Reguly
17-Aug-2005 02:24


After esnhexdec from "rledger at gmail dot com",  the esndechex:



<?php

    function esndechex($dec){

         $a = strtoupper(dechex(substr($dec, 1,  2)));

         $b = strtoupper(dechex(substr($dec, 3, 10)));

         return $a . $b;

    }

?>

djneoform at gmail dot com
21-Jun-2005 12:51


since i couldn't find one, here's an HEX to ASCII converter..



(takes HEX strings (in ASCII) and converts each two digit HEX code into it's ASCII equivalent)



function hex2ascii($str)

{

    $p = '';

    for ($i=0; $i < strlen($str); $i=$i+2)

    {

        $p .= chr(hexdec(substr($str, $i, 2)));

    }

    return $p;

}

bishop
05-Jun-2005 10:51


Bullet-proof hex-to-rgb colour converter like brian at sagesport dot com wanted, just far fewer code lines. As a bonus, gives you the ability to return as string or array:



<?php

    function &hex2rgb($hex, $asString = true) 

    {

        // strip off any leading #

        if (0 === strpos($hex, '#')) { 

            $hex = substr($hex, 1);

        } else if (0 === strpos($hex, '&H')) {

            $hex = substr($hex, 2);

        }       



        // break into hex 3-tuple

        $cutpoint = ceil(strlen($hex) / 2)-1; 

        $rgb = explode(':', wordwrap($hex, $cutpoint, ':', $cutpoint), 3);



        // convert each tuple to decimal

        $rgb[0] = (isset($rgb[0]) ? hexdec($rgb[0]) : 0);

        $rgb[1] = (isset($rgb[1]) ? hexdec($rgb[1]) : 0);

        $rgb[2] = (isset($rgb[2]) ? hexdec($rgb[2]) : 0);



        return ($asString ? "{$rgb[0]} {$rgb[1]} {$rgb[2]}" : $rgb);

    }

?>



Handles 2, 3, and 6 character colour codes with leading # or &H.

Joey Morwick
03-May-2005 04:07


I found it helpful to have the inverse / reverse of this function laying around, since I wanted to insert some binary data into an xmlrpc call (it currently craps out when you do that), and I couldn't find one laying around, so here's a simple little function to do that:



function hex2bin($str) {

    $build = '';

    while(strlen($str) > 1) {

        $build .= chr(hexdec(substr($str, 0, 2)));

        $str = substr($str, 2, strlen($str)-2);

    }

    return $build;

}

rledger at gmail dot com
29-Mar-2005 03:59


To convert a cellular ESN from hexadecimal to decimal, use the following code. The base conversion is different due to the fact that the first two characters of a hexadecimal value must be converted seperately from the remaining six characters.

<?

function esnhexdec($hex){

   $a = sprintf("%03d", hexdec(substr($hex, 0, 2)));

   $b = sprintf("%08d", hexdec(substr($hex, 2, 6)));

   return $a . $b;

}

?>

zubfatal, root at it dot dk
25-Mar-2005 06:36


This replaces my previous class.

I've added a few more input checks in the rgb2hex function.

Also it returned incorrect hex values for 1-digit values.



color::rgb2hex(array(0,0,0)) would output 000 not 00000.



<?php 



/** 

* Convert colors 

* 

* Usage: 

*  color::hex2rgb("FFFFFF") 

*  color::rgb2hex(array(171,37,37)) 

* 

* @author      Tim Johannessen <root@it.dk> 

* @version     1.0.1 

*/ 



class color { 



    /** 

     * Convert HEX colorcode to an array of colors. 

     * @return      array        Returns the array of colors as array(red,green,blue) 

     */ 

     

    function hex2rgb($hexVal = "") { 

        $hexVal = eregi_replace("[^a-fA-F0-9]", "", $hexVal); 

        if (strlen($hexVal) != 6) { return "ERR: Incorrect colorcode, expecting 6 chars (a-f, 0-9)"; } 

        $arrTmp = explode(" ", chunk_split($hexVal, 2, " ")); 

        $arrTmp = array_map("hexdec", $arrTmp); 

        return array("red" => $arrTmp[0], "green" => $arrTmp[1], "blue" => $arrTmp[2]); 

    } 

     

    /** 

     * Convert RGB colors to HEX colorcode 

     * @return      string        Returns the converted colors as a 6 digit colorcode 

     */ 

    function rgb2hex($arrColors = null) { 

        if (!is_array($arrColors)) { return "ERR: Invalid input, expecting an array of colors"; } 

        if (count($arrColors) < 3) { return "ERR: Invalid input, array too small (3)"; } 

         

        array_splice($arrColors, 3); 

         

        for ($x = 0; $x < count($arrColors); $x++) { 

            if (strlen($arrColors[$x]) < 1) { 

                return "ERR: One or more empty values found, expecting array with 3 values"; 

            } 

             

            elseif (eregi("[^0-9]", $arrColors[$x])) { 

                return "ERR: One or more non-numeric values found."; 

            } 

             

            else { 

                if ((intval($arrColors[$x]) < 0) || (intval($arrColors[$x]) > 255)) { 

                    return "ERR: Range mismatch in one or more values (0-255)"; 

                } 

                 

                else { 

                    $arrColors[$x] = strtoupper(str_pad(dechex($arrColors[$x]), 2, 0, STR_PAD_LEFT)); 

                } 

            } 

        } 

         

        return implode("", $arrColors); 

    } 



} 



?>

brian at sagesport dot com
23-Mar-2005 01:08


The issue I've seen with the existing hex to dec conversion routines is the lack of error-trapping.  I stick to the theory that one should try to cover ALL the bases when writing a generalized routine such as this one.  I have a varied background that covers a wide variety of design/development languages, on the web as well as desktop apps.  As such I've seen multiple formats for writing hex colors.



For example, the color red COULD be written as follows:

#ff0000

&Hff0000

#ff

&Hff



Therefore I have written a function that is case-insensitive and takes into account the chance that different developers have a tendency to format hex colors in different ways.



<?php

  function convert_color($hex){

    $len = strlen($hex);

    $chars = array("#","&","H","h");

    $hex = strip_chars($hex, $chars);

    preg_match("/([0-9]|[A-F]|[a-f]){".$len."}/i",$hex,$arr);

    $hex = $arr[0];

    if ($hex) {

      switch($len) {

        case 2:

          $red = hexdec($hex);

          $green = 0;

          $blue = 0;

          break;

        case 4:

          $red = hexdec(substr($hex,0,2));

          $green=hexdec(substr($hex,2,2));

          $blue = 0;

          break;

        case 6:

          $red = hexdec(substr($hex,0,2));

          $green=hexdec(substr($hex,2,2));

          $blue = hexdec(substr($hex,4,2));

          break;       

      };

      $color[success] = true;

      $color[r] = $red;

      $color[g] = $green;

      $color[b] = $blue;

      return $color;

    } else {

      $color[success] = false;

      $color[error] = "unable to convert hex to dec";

    };

  }



  function strip_chars($string, $char){

    $len = strlen($string);

    $count = count($char);

    if ($count >= 2) {

      for ($i=0;$i<=$count;$i++) {

        if ($char[$i]) {

          $found = stristr($string,$char[$i]);

          if ($found) {

            $val = substr($string,$found+1,$len-1);

            $string = $val;

          };

        };

      };

    } else {

      $found = stristr($string,$char);

      if ($found) {

        $val = substr($string,$found+1,$len-1);

      };

    };

    echo $val;

    return $val;

  }



  /* 

    To use simply use the following function call:

      $color = convert_color("#FF");

      this will return the following assoc array if successful:

      *[success] = true

      *[r] = 255

      *[g] = 0

      *[b] = 0



      or copy and paste the following code:

      

      $hex = "FFFFFF"; // Color White

      $color = convert_color($hex);

      var_dump($color);

 */ 

?>



As you can see, the function "convert_color" accepts a hex # in most acceptable formats and returns an associative array.  [success] is set to TRUE if the function succeeds and FALSE if not.  The array members [r], [g] and [b] hold the red,green and blue values respectively.  If it fails, [error] holds a custom error message.



"strip_chars" is a support function written to remove the unwanted characters from the hex string, and sends the concatenated string back to the calling function.  It will accept either a single value or an array of values for the characters to remove.

groobo
11-Feb-2005 03:46


It's just a revision to marfastic's ligten_up script, it simply adds/subtracts mod_color to orig_color.

I use it often to adjust tonals rather than brightness only



<?

function mod_color($orig_color, $mod, $mod_color){

    /*

        $orig_color - original html color, hex

        $mod_color - modifying color, hex

        $mod - modifier '+' or '-'

        usage: mod_color('CCCCCC', '+', '000033')

    */

    // does quick validation

    preg_match("/([0-9]|[A-F]){6}/i",$orig_color,$orig_arr);

    preg_match("/([0-9]|[A-F]){6}/i",$mod_color,$mod_arr);

    if ($orig_arr[0] && $mod_arr[0]) {

        for ($i=0; $i<6; $i=$i+2) {

            $orig_x = substr($orig_arr[0],$i,2);

            $mod_x = substr($mod_arr[0],$i,2);

            if ($mod == '+') { $new_x = hexdec($orig_x) + hexdec($mod_x); }

            else { $new_x = hexdec($orig_x) - hexdec($mod_x); }

            if ($new_x < 0) { $new_x = 0; }

            else if ($new_x > 255) { $new_x = 255; };

            $new_x = dechex($new_x);

            $ret .= $new_x;

        }

        return $ret;

    } else { return false; }

}

?>

20-Jan-2005 01:33


I wondered long time what is the best way to generate RGB-color from HEX-color, and just now i found the simpliest way!



<?php

$hex = "FF00FF";

$rgb = hexdec($hex); // 16711935

?>



I hope this will save your time! :)

marfastic
10-Dec-2004 11:14


Here is a function to brighten up any color:



function lighten_up($orig_color, $fraction_denom){

            // return the color between the color and white 

            // based on the fraction denom that is passed

            

            if(!isset($fraction_denom))

                $fraction_denom = 2;

            $highest_val = hexdec("FF");

            $r = hexdec(substr($orig_color,0,2));

            $r = ($highest_val-$r)/$fraction_denom + $r;

            $g = hexdec(substr($orig_color,2,2));

            $g = ($highest_val-$g)/$fraction_denom + $g;

            $b = hexdec(substr($orig_color,4,2));

            $b = ($highest_val-$b)/$fraction_denom + $b;

            return dechex($r) . dechex($g) . dechex($b);

        }

_meto ALT+q web.de
09-May-2004 12:00


Damn, this took me some real long time! Maybe it's helpfull for those who even have no idea of color-Schemes like me ;)



If u want to generate PDF's for Print Offices u need to set all the colors in CMYK.



Here is a Function that will convert RGB to CMYK



<?

function hex2rgb($hex) {

  $color = str_replace('#','',$hex);

  $rgb = array('r' => hexdec(substr($color,0,2)),

               'g' => hexdec(substr($color,2,2)),

               'b' => hexdec(substr($color,4,2)));

  return $rgb;

}



function rgb2cmyk($var1,$g=0,$b=0) {

   if(is_array($var1)) {

      $r = $var1['r'];

      $g = $var1['g'];

      $b = $var1['b'];

   }

   else $r=$var1;

   $cyan    = 255 - $r;

   $magenta = 255 - $g;

   $yellow  = 255 - $b;

   $black   = min($cyan, $magenta, $yellow);

   $cyan    = @(($cyan    - $black) / (255 - $black)) * 255;

   $magenta = @(($magenta - $black) / (255 - $black)) * 255;

   $yellow  = @(($yellow  - $black) / (255 - $black)) * 255;

   return array('c' => $cyan / 255,

                'm' => $magenta / 255,

                'y' => $yellow / 255,

                'k' => $black / 255);

}



$color=rgb2cmyk(hex2rgb('#FF0000')); 

pdf_setcolor($pdf, "both", "cmyk", $color['c'], $color['m'], $color['y'], $color['k']);

?>



U can call it with parameters (r,g,b) or just with an array(r,g,b) that contains these values.



Hope it works correct. All testing was fine.

gelado at ip3 dot com
29-Aug-2003 07:30


Another hex to decimal converter, up to the precision of PHP floats.



function longhex($hex)

{

    $dec = 0;

    $bitval = 1;

    for($pos = 1; $pos <= strlen($hex); $pos++) {

        $dec += hexdec(substr($hex, -$pos, 1)) * $bitval;

        $bitval *= 16;

    }

    return($dec);

}

henrique at recidive dot com
28-May-2003 06:43


Function to convert a string with hexadecimal colors to an associative array with RGB values:



<?

function hex2dec($hex) {

  $color = str_replace('#', '', $hex);

  $ret = array(

    'r' => hexdec(substr($color, 0, 2)),

    'g' => hexdec(substr($color, 2, 2)),

    'b' => hexdec(substr($color, 4, 2))

  );

  return $ret;

}



/*** Example:

print_r(hex2dec('3D58BE'));



or



print_r(hex2dec('#3D58BE'));



will return



Array

(

  [r] => 61

  [g] => 88

  [b] => 190

)

***/

?>



Thanks !



Henrique Recidive

andreas.schmeiler
05-Feb-2003 09:59


Here's another hex2bin variant, works pretty well to me.



function hex2bin($hexdata) {

   

   for ($i=0;$i<strlen($hexdata);$i+=2) {

      $bindata.=chr(hexdec(substr($hexdata,$i,2)));

   }

   

   return $bindata;

}

chrism at four dot net
16-Dec-2001 02:02


hexdec from 4.1.0 onwards does not show


the same size limitation and therefore


works differently with large numbers than previous php versions.





To obtain the same results, use:





(int) hexdec (...)

andychase at yahoo dot com
18-Jan-2001 10:32


For hex numbers larger than 7FFFFFFF (E.G. PalmOS dates in seconds elapsed since 01/01/1904), I came up with this:





function bighexdec($hexnumber){ 





    $numlength = strlen($hexnumber);





    $decnumber = 0;





    for($x = 1; $x <= $numlength; $x++){





        $place = $numlength - $x;


        


        $operand = hexdec(substr($hexnumber,$place,1));


            


        $exponent = pow(16,$x-1);





        $decValue = $operand * $exponent;


    


        $decnumber += $decValue;





    }





    return $decnumber;


    


}

joe at aigraphics dot com
21-Oct-2000 06:32


Here is a fast block of code to convert HTML Style HEX colors to RGB:


--------------------


$r = hexdec(substr($color, 0, 2));


$g = hexdec(substr($color, 2, 2));


$b = hexdec(substr($color, 4, 2));


--------------------


hope it helps you, enjoy.

add a note

hexdec

说明