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(PHP 4, PHP 5)
hexdec — Hexadezimal zu Dezimal Umwandlung
Wandelt den hexadezimal kodierten Eingabestring hex_string in einen Dezimalwert um.
hexdec() ignoriert alle nicht hexadezimal kodierten Zeichen (0-9 a-f) in hex_string.
Der zu konvertierende Hexadezimalstring
Dezimaldarstellung von hex_string
| Version | Beschreibung |
|---|---|
| Seit 4.1.0 | Die Funktion kann nun auch Werte umwandeln, die zu groß für den integer Typ der jeweiligen Plattform sind, das Ergebnis wird dann als float zurückgegeben. |
Beispiel #1 hexdec() Beispiel
<?php
var_dump(hexdec("See"));
var_dump(hexdec("ee"));
// both print "int(238)"
var_dump(hexdec("that")); // print "int(10)"
var_dump(hexdec("a0")); // print "int(160)"
?>
Here's a short example to convert strings between hex and chars:
<?php
print hextostr("616E647940686176656C616E642E636F6D")."\n";
print strtohex("Knowledge is power")."\n";
function hextostr($x) {
$s='';
foreach(explode("\n",trim(chunk_split($x,2))) as $h) $s.=chr(hexdec($h));
return($s);
}
function strtohex($x) {
$s='';
foreach(str_split($x) as $c) $s.=sprintf("%02X",ord($c));
return($s);
}
?>
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) : $rgbArray; // returns the rgb string or the associative array
} ?>
OUTPUT:
hex2RGB("#FF0") -> array( red =>255, green => 255, blue => 0)
hex2RGB("#FFFF00) -> Same as above
hex2RGB("#FF0", true) -> 255,255,0
hex2RGB("#FF0", true, ":") -> 255:255:0
The correct version is:
function bchexdec($hex) {
static $hexdec = array(
"0" => 0,
"1" => 1,
"2" => 2,
"3" => 3,
"4" => 4,
"5" => 5,
"6" => 6,
"7" => 7,
"8" => 8,
"9" => 9,
"A" => 10,
"B" => 11,
"C" => 12,
"D" => 13,
"E" => 14,
"F" => 15
);
$dec = 0;
for ($i = strlen($hex) - 1, $e = 1; $i >= 0; $i--, $e = bcmul($e, 16)) {
$factor = $hexdec[$hex[$i]];
$dec = bcadd($dec, bcmul($factor, $e));
}
return $dec;
}
Here My version of converting a hex string to a signed decimal value:
<?php
function hexdecs($hex)
{
// ignore non hex characters
$hex = preg_replace('/[^0-9A-Fa-f]/', '', $hex);
// converted decimal value:
$dec = hexdec($hex);
// maximum decimal value based on length of hex + 1:
// number of bits in hex number is 8 bits for each 2 hex -> max = 2^n
// use 'pow(2,n)' since '1 << n' is only for integers and therefore limited to integer size.
$max = pow(2, 4 * (strlen($hex) + (strlen($hex) % 2)));
// complement = maximum - converted hex:
$_dec = $max - $dec;
// if dec value is larger than its complement we have a negative value (first bit is set)
return $dec > $_dec ? -$_dec : $dec;
}
?>
RGB to Hex
Hex to RGB
Function
<?PHP
function rgb2hex2rgb($c){
if(!$c) return false;
$c = trim($c);
$out = false;
if(preg_match("/^[0-9ABCDEFabcdef\#]+$/i", $c)){
$c = str_replace('#','', $c);
$l = strlen($c) == 3 ? 1 : (strlen($c) == 6 ? 2 : false);
if($l){
unset($out);
$out[0] = $out['r'] = $out['red'] = hexdec(substr($c, 0,1*$l));
$out[1] = $out['g'] = $out['green'] = hexdec(substr($c, 1*$l,1*$l));
$out[2] = $out['b'] = $out['blue'] = hexdec(substr($c, 2*$l,1*$l));
}else $out = false;
}elseif (preg_match("/^[0-9]+(,| |.)+[0-9]+(,| |.)+[0-9]+$/i", $c)){
$spr = str_replace(array(',',' ','.'), ':', $c);
$e = explode(":", $spr);
if(count($e) != 3) return false;
$out = '#';
for($i = 0; $i<3; $i++)
$e[$i] = dechex(($e[$i] <= 0)?0:(($e[$i] >= 255)?255:$e[$i]));
for($i = 0; $i<3; $i++)
$out .= ((strlen($e[$i]) < 2)?'0':'').$e[$i];
$out = strtoupper($out);
}else $out = false;
return $out;
}
?>
Output
#FFFFFF =>
Array{
red=>255,
green=>255,
blue=>255,
r=>255,
g=>255,
b=>255,
0=>255,
1=>255,
2=>255
}
#FFCCEE =>
Array{
red=>255,
green=>204,
blue=>238,
r=>255,
g=>204,
b=>238,
0=>255,
1=>204,
2=>238
}
CC22FF =>
Array{
red=>204,
green=>34,
blue=>255,
r=>204,
g=>34,
b=>255,
0=>204,
1=>34,
2=>255
}
0 65 255 => #0041FF
255.150.3 => #FF9603
100,100,250 => #6464FA
[EDIT BY danbrown AT php DOT net - Contains multiple bugfixes by (ajim1417 AT gmail DOT com) on 27-JAN-2010: Replaces typo in explode() and updates eregi() calls to preg_match().]
I made these functions to pack up to 64 ID's into a mysql unsigned bigint.
ID's cannot repeat, must be <= bit's limit and > 0.
The functions uses php 32 bit's int as unsigned because we don't actually read the number, just the bits. Then 0xFFFFFFFF display -1 but the bit's are there (tested with linux 2.6 i686 and x86_64)
---
This is an other way to make hex to bin conversions:
<?php
function hexbin($hex, $padding = false)
{
// Validation
$hex = preg_replace('/^(0x|X)?/i', '', $hex);
$hex = preg_replace('/[[:blank:]]/', '', $hex);
if(empty($hex))
{
$hex = '0';
}
if(!preg_match('/^[0-9A-F]*$/i', $hex))
{
trigger_error('Argument is not a hex', E_USER_WARNING);
return false;
}
// Conversion
$bin = '';
$hex = array_reverse(str_split($hex));
foreach($hex as $n)
{
$n = hexdec($n);
for($i = 1; $i <= 8; $i <<= 1)
{
$bin .= ($i & $n)? '1' : '0';
}
if($padding)
{
$bin .= ' ';
}
}
return ltrim(strrev($bin));
}
// Tests
echo "<b>Debug:</b> <pre>";
// Randomly choosed padded number
var_dump(hexbin('00FF FF8F 7F3F FF1F', true));
// string(79) "0000 0000 1111 1111 1111 1111 1000 1111 0111 1111 0011 1111 1111 1111 0001 1111"
// Yellow RGB
var_dump(hexbin('0xF8F800'));
// string(24) "111110001111100000000000"
// Green RGB (padded)
var_dump(hexbin('0x008800', true));
//string(29) "0000 0000 1000 1000 0000 0000"
die("\n<br>debug");
?>
Have fun ;D
hexdec doesn't accept numbers following the period.
What if you have a number like c20.db18?
<?php
function floatinghexdec($str)
{
list($intgr,$hex)=explode('.',$str,2);
$intgr=ereg_replace("[^A-Fa-f0-9]", "", $intgr);
$hex=ereg_replace("[^A-Fa-f0-9]", "", $hex);
$answer=0;
for($i=0;$i < strlen($hex); $i++)
{
$digit=hexdec(substr($hex,$i,1))/16; // .f is 15/16 because in decimal .9 is 9/10
$answer += $digit/pow(16,$i);
}
return hexdec($intgr)+$answer;
}
echo floatinghexdec("ff.ff");//255.99609375
?>
Here's my hexdec function for greater numbers using BC Math
<?php
function bchexdec($hex)
{
$len = strlen($hex);
for ($i = 1; $i <= $len; $i++)
$dec = bcadd($dec, bcmul(strval(hexdec($hex[$i - 1])), bcpow('16', strval($len - $i))));
return $dec;
}
echo bchexdec('ffffffffffffffffffffffffffffffff') . "\n" . (pow(2, 128));
?>
I tried the example by joquius at kakugo dot com, but it didn't work. i changed it to the following, which did work.
<?php
$str = preg_replace_callback ("([a-zA-Z0-9]{2})", create_function ('$matches', 'return chr (hexdec ($matches[0]));'), $str);
?>
Help a hex-stricken string get back to normal:
<?php
$str = preg_replace_callback ("/%([a-zA-Z0-9]{2})/", create_function ('$matches', 'return chr (hexdec ($matches[1]));'), $str);
?>
In reply to Amit Yadav's post (hex to binary conversion):
function binfromdec($num)
{
$primary = "bit";
for ($i=1; $i<=16; $i++)
${$primary.$i} = 0;
if ($num & 32768) $bit16 = 1;
if ($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) $bit1 = 1;
return ($bit16. $bit15. $bit14. $bit13. $bit12. $bit11. $bit10. $bit9. $bit8. $bit7. $bit6. $bit5. $bit4. $bit3. $bit2. $bit1);
}
One of my favourite, multi-purpose, bidirectional solution I wrote many years ago:
function bgr2rgb($cr) { // bidirectional
return (($cr & 0x0000FF) << 16 | ($cr & 0x00FF00) | ($cr & 0xFF0000) >> 16);
}
Which you might want to use as :
function hex2cr($hex) { // strips any leading characters, like #
return bgr2rgb(hexdec($hex));
}
function cr2hex($cr) { // the usual HTML format, #rrggbb
return '#'.str_pad(strtoupper(dechex(bgr2rgb($cr))), 6, '0', STR_PAD_LEFT);
}
And, if like me you tend to mistype function names, the synonym :
function rgb2bgr($val) { return bgr2rgb($val); }
Function that combines two rgb colors.
function combineColors($color1, $color2) {
$color1 = str_replace("#", '', $color1);
$color2 = str_replace("#", '', $color2);
$r1 = hexdec(substr($color1, 0, 2));
$g1 = hexdec(substr($color1, 2, 2));
$b1 = hexdec(substr($color1, 4, 2));
$r2 = hexdec(substr($color2, 0, 2));
$g2 = hexdec(substr($color2, 2, 2));
$b2 = hexdec(substr($color2, 4, 2));
$r3 = ceil(($r1 + $r2) / 2);
$g3 = ceil(($g1 + $g2) / 2);
$b3 = ceil(($b1 + $b2) / 2);
$color = rgbhex($r3, $g3, $b3);
return $color = str_replace("#", '', $color);
}
// Função GET Cor Hexadecima e Retorna em RGB
function hexrgb($hexstr, $rgb) {
$int = hexdec($hexstr);
switch($rgb) {
case "r":
return 0xFF & $int >> 0x10;
break;
case "g":
return 0xFF & ($int >> 0x8);
break;
case "b":
return 0xFF & $int;
break;
default:
return array(
"r" => 0xFF & $int >> 0x10,
"g" => 0xFF & ($int >> 0x8),
"b" => 0xFF & $int
);
break;
}
}// END GET Cor Hex => RGB
//Uso
echo hexrgb("1a2b3c", r); // 26
echo hexrgb("1a2b3c", g); // 43
echo hexrgb("1a2b3c", b); // 60
//ou
var_dump(hexrgb("1a2b3c", rgb)); //array(3) { ["r"]=> int(26) ["g"]=> int(43) ["b"]=> int(60) }
<?
function hexrgb($hexstr) {
$int = hexdec($hexstr);
return array("red" => 0xFF & ($int >> 0x10), "green" => 0xFF & ($int >> 0x8), "blue" => 0xFF & $int);
}
?>
Reply To Halit Yesil's script:
Great Function!! But, there's a problem with your script if the user passes something with three letters/numbers (eg/ #000). You need to use str_repeat to duplicate each character.
if($l == 3){
unset($out);
$out[0] = $out['r'] = $out['red'] = hexdec(str_repeat(substr($c, 0,1),2));
$out[1] = $out['g'] = $out['green'] = hexdec(str_repeat(substr($c, 1,1),2));
$out[2] = $out['b'] = $out['blue'] = hexdec(str_repeat(substr($c, 2,1),2));
}
This tiny function will return foreground colors (either black or white) in contrast to the color you provide:
<?php
function getContrastColor($color)
{
return (hexdec($color) > 0xffffff/2) ? '000000' : 'ffffff';
}
?>
This function will return the opposite (negative):
<?php
function negativeColor($color)
{
//get red, green and blue
$r = substr($color, 0, 2);
$g = substr($color, 2, 2);
$b = substr($color, 4, 2);
//revert them, they are decimal now
$r = 0xff-hexdec($r);
$g = 0xff-hexdec($g);
$b = 0xff-hexdec($b);
//now convert them to hex and return.
return dechex($r).dechex($g).dechex($b);
}
?>
RGB to Hex
Hex to RGB
Function
<?PHP
function rgb2hex2rgb($c){
if(!$c) return false;
$c = trim($c);
$out = false;
if(eregi("^[0-9ABCDEFabcdef\#]+$", $c)){
$c = str_replace('#','', $c);
$l = strlen($c);
if($l == 3){
unset($out);
$out[0] = $out['r'] = $out['red'] = hexdec(substr($c, 0,1));
$out[1] = $out['g'] = $out['green'] = hexdec(substr($c, 1,1));
$out[2] = $out['b'] = $out['blue'] = hexdec(substr($c, 2,1));
}elseif($l == 6){
unset($out);
$out[0] = $out['r'] = $out['red'] = hexdec(substr($c, 0,2));
$out[1] = $out['g'] = $out['green'] = hexdec(substr($c, 2,2));
$out[2] = $out['b'] = $out['blue'] = hexdec(substr($c, 4,2));
}else $out = false;
}elseif (eregi("^[0-9]+(,| |.)+[0-9]+(,| |.)+[0-9]+$", $c)){
if(eregi(",", $c))
$e = explode(",",$c);
else if(eregi(" ", $c))
$e = explode(" ",$c);
else if(eregi(".", $c))
$e = explode(".",$c);
else return false;
if(count($e) != 3) return false;
$out = '#';
for($i = 0; $i<3; $i++)
$e[$i] = dechex(($e[$i] <= 0)?0:(($e[$i] >= 255)?255:$e[$i]));
for($i = 0; $i<3; $i++)
$out .= ((strlen($e[$i]) < 2)?'0':'').$e[$i];
$out = strtoupper($out);
}else $out = false;
return $out;
}
echo '#FFFFFF => '.rgb2hex2rgb('#FFFFFF').'<br>';
echo '#FFCCEE => '.rgb2hex2rgb('#FFCCEE').'<br>';
echo 'CC22FF => '.rgb2hex2rgb('CC22FF').'<br>';
echo '0 65 255 => '.rgb2hex2rgb('0 65 255').'<br>';
echo '255.150.3 => '.rgb2hex2rgb('255.150.3').'<br>';
echo '100,100,250 => '.rgb2hex2rgb('100,100,250').'<br>';
?>
Output
#FFFFFF =>
Array{
red=>255,
green=>255,
blue=>255,
r=>255,
g=>255,
b=>255,
0=>255,
1=>255,
2=>255
}
#FFCCEE =>
Array{
red=>255,
green=>204,
blue=>238,
r=>255,
g=>204,
b=>238,
0=>255,
1=>204,
2=>238
}
CC22FF =>
Array{
red=>204,
green=>34,
blue=>255,
r=>204,
g=>34,
b=>255,
0=>204,
1=>34,
2=>255
}
0 65 255 => #0041FF
255.150.3 => #FF9603
100,100,250 => #6464FA
Here is my version of hex2rgb for web colors to 24bit colors.
<?php
function hex2rgb_webcolors($hex) {
$hex = eregi_replace("[^a-fA-F0-9]", "", $hex);
switch( strlen($hex) ) {
case 2:
$hex = substr($hex,0,2)."0000";
break;
case 3:
$hex = substr($hex,0,1).substr($hex,0,1)
.substr($hex,1,1).substr($hex,1,1)
.substr($hex,2,1).substr($hex,2,1);
break;
case 4:
$hex = substr($hex,0,4)."00";
break;
case 6:
break;
default:
$hex = 0;
break;
}
return hexdec($hex);
}
?>
Function converting HEX to signed DEC
function hex2sdec ($hex)
{
//how many bytes
$ib = strlen ($hex) - (strlen ($hex) % $hex)) / $hex;
if ((strlen ($hex) % 2) > 0)
$ib = $ib + 1;
//how many bites
$ibb = 8 * $ib;
//search for -1 value (max_uj)
$buf = '1';
for ($i = 1; $i <= $ibb - 1; $i++)
{
$buf .= '0';
}
$max_uj = bindec ($buf);
//decide a sign, and calculate a value
if (hexdec ($hex) < $max_uj)
//+
{
$sdec = hexdec ($hex);
}
else
//-
{
//search for max value + 1
//(for ex. if hex = 23ef then max_p1 = ffff + 1)
$buf = '';
for ($i = 1; $i <= $ib; $i++)
{
$buf .= 'ff';
}
$max_p1 = hexdec ($buf) + 1;
$sdec = hexdec ($hex) - $max_p1;
}
return $sdec;
}
From color to color to ...... to color with fade effect. Good for dynamic bar chart.
<?php
//MultiColorFade(array hex-colors, int steps)
function MultiColorFade($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 $table;
}
//end test
?>
Repley.
Hex to binary conversion that works for large and small hex numbers.
<?php
function hexbin($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)));
?>
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);
}
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. :-)
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.$b;
}
I needed to get the opposite colors so my website would be soft on the eyes.
<?php
function OppositeHex($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).';
?>
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].$rgb[2];
?>
After esnhexdec from "rledger at gmail dot com", the esndechex:
<?php
function esndechex($dec){
$a = strtoupper(dechex(substr($dec, 1, 2)));
$b = strtoupper(dechex(substr($dec, 3, 10)));
return $a . $b;
}
?>
since i couldn't find one, here's an HEX to ASCII converter..
(takes HEX strings (in ASCII) and converts each two digit HEX code into it's ASCII equivalent)
function hex2ascii($str)
{
$p = '';
for ($i=0; $i < strlen($str); $i=$i+2)
{
$p .= chr(hexdec(substr($str, $i, 2)));
}
return $p;
}
Bullet-proof hex-to-rgb colour converter like brian at sagesport dot com wanted, just far fewer code lines. As a bonus, gives you the ability to return as string or array:
<?php
function &hex2rgb($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]}" : $rgb);
}
?>
Handles 2, 3, and 6 character colour codes with leading # or &H.
I found it helpful to have the inverse / reverse of this function laying around, since I wanted to insert some binary data into an xmlrpc call (it currently craps out when you do that), and I couldn't find one laying around, so here's a simple little function to do that:
function hex2bin($str) {
$build = '';
while(strlen($str) > 1) {
$build .= chr(hexdec(substr($str, 0, 2)));
$str = substr($str, 2, strlen($str)-2);
}
return $build;
}
To convert a cellular ESN from hexadecimal to decimal, use the following code. The base conversion is different due to the fact that the first two characters of a hexadecimal value must be converted seperately from the remaining six characters.
<?
function esnhexdec($hex){
$a = sprintf("%03d", hexdec(substr($hex, 0, 2)));
$b = sprintf("%08d", hexdec(substr($hex, 2, 6)));
return $a . $b;
}
?>
This replaces my previous class.
I've added a few more input checks in the rgb2hex function.
Also it returned incorrect hex values for 1-digit values.
color::rgb2hex(array(0,0,0)) would output 000 not 00000.
<?php
/**
* Convert colors
*
* Usage:
* color::hex2rgb("FFFFFF")
* color::rgb2hex(array(171,37,37))
*
* @author Tim Johannessen <root@it.dk>
* @version 1.0.1
*/
class color {
/**
* Convert HEX colorcode to an array of colors.
* @return array Returns the array of colors as array(red,green,blue)
*/
function hex2rgb($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("", $arrColors);
}
}
?>
The issue I've seen with the existing hex to dec conversion routines is the lack of error-trapping. I stick to the theory that one should try to cover ALL the bases when writing a generalized routine such as this one. I have a varied background that covers a wide variety of design/development languages, on the web as well as desktop apps. As such I've seen multiple formats for writing hex colors.
For example, the color red COULD be written as follows:
#ff0000
&Hff0000
#ff
&Hff
Therefore I have written a function that is case-insensitive and takes into account the chance that different developers have a tendency to format hex colors in different ways.
<?php
function convert_color($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($color);
*/
?>
As you can see, the function "convert_color" accepts a hex # in most acceptable formats and returns an associative array. [success] is set to TRUE if the function succeeds and FALSE if not. The array members [r], [g] and [b] hold the red,green and blue values respectively. If it fails, [error] holds a custom error message.
"strip_chars" is a support function written to remove the unwanted characters from the hex string, and sends the concatenated string back to the calling function. It will accept either a single value or an array of values for the characters to remove.
It's just a revision to marfastic's ligten_up script, it simply adds/subtracts mod_color to orig_color.
I use it often to adjust tonals rather than brightness only
<?
function mod_color($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; }
}
?>
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! :)
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);
}
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'], $color['k']);
?>
U can call it with parameters (r,g,b) or just with an array(r,g,b) that contains these values.
Hope it works correct. All testing was fine.
Another hex to decimal converter, up to the precision of PHP floats.
function longhex($hex)
{
$dec = 0;
$bitval = 1;
for($pos = 1; $pos <= strlen($hex); $pos++) {
$dec += hexdec(substr($hex, -$pos, 1)) * $bitval;
$bitval *= 16;
}
return($dec);
}
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 $ret;
}
/*** Example:
print_r(hex2dec('3D58BE'));
or
print_r(hex2dec('#3D58BE'));
will return
Array
(
[r] => 61
[g] => 88
[b] => 190
)
***/
?>
Thanks !
Henrique Recidive
Here's another hex2bin variant, works pretty well to me.
function hex2bin($hexdata) {
for ($i=0;$i<strlen($hexdata);$i+=2) {
$bindata.=chr(hexdec(substr($hexdata,$i,2)));
}
return $bindata;
}
hexdec from 4.1.0 onwards does not show
the same size limitation and therefore
works differently with large numbers than previous php versions.
To obtain the same results, use:
(int) hexdec (...)
For hex numbers larger than 7FFFFFFF (E.G. PalmOS dates in seconds elapsed since 01/01/1904), I came up with this:
<?php
function bighexdec($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;
}
?>
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