getrandmax
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. $bit1);
}
hexdec
(PHP 4, PHP 5)
hexdec — 16 進数を 10 進数に変換する
説明
引数 hex_string により指定された 16 進数に 等価な 10 進数を返します。hexdec() は、16 進数を 表す文字列を 10 進数に変換します。
hexdec() は、16 進数以外の文字を一切無視します。
パラメータ
- hex_string
-
変換したい 16 進文字列。
返り値
hex_string を 10 進で表した値を返します。
例
例1 hexdec() の例
<?php
var_dump(hexdec("See"));
var_dump(hexdec("ee"));
// 共に "int(238)" を出力
var_dump(hexdec("that")); // "int(10)" を出力
var_dump(hexdec("a0")); // "int(160)" を出力
?>
add a note
User Contributed Noteshexdec
this1is4me at hotmail dot com
27-May-2008 02:46
27-May-2008 02:46
Walter Wlodarski
31-Jan-2008 01:33
31-Jan-2008 01:33
One of my favourite, multi-purpose, bidirectional solution I wrote many years ago:
function bgr2rgb($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($val); }
maddddidley at yahoo dot com
27-Jan-2008 12:17
27-Jan-2008 12:17
Function that combines two rgb colors.
function combineColors($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("#", '', $color);
}
Anonymous
13-Nov-2007 08:34
13-Nov-2007 08:34
// Função GET Cor Hexadecima e Retorna em RGB
function hexrgb($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 & $int
);
break;
}
}// END GET Cor Hex => RGB
//Uso
echo hexrgb("1a2b3c", r); // 26
echo hexrgb("1a2b3c", g); // 43
echo hexrgb("1a2b3c", b); // 60
//ou
var_dump(hexrgb("1a2b3c", rgb)); //array(3) { ["r"]=> int(26) ["g"]=> int(43) ["b"]=> int(60) }
k10206 at naver dot com
27-Oct-2007 09:42
27-Oct-2007 09:42
<?
function hexrgb($hexstr) {
$int = hexdec($hexstr);
return array("red" => 0xFF & ($int >> 0x10), "green" => 0xFF & ($int >> 0x8), "blue" => 0xFF & $int);
}
?>
venk
16-Jun-2007 03:27
16-Jun-2007 03:27
Reply To Halit Yesil's script:
Great Function!! But, there's a problem with your script if the user passes something with three letters/numbers (eg/ #000). You need to use str_repeat to duplicate each character.
if($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));
}
Manithu
23-Mar-2007 05:23
23-Mar-2007 05:23
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($b);
}
?>
Halit Yesil mail at halityesil dot com
22-Mar-2007 06:46
22-Mar-2007 06:46
RGB to Hex
Hex to RGB
Function
<?PHP
function rgb2hex2rgb($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 $out;
}
echo '#FFFFFF => '.rgb2hex2rgb('#FFFFFF').'<br>';
echo '#FFCCEE => '.rgb2hex2rgb('#FFCCEE').'<br>';
echo 'CC22FF => '.rgb2hex2rgb('CC22FF').'<br>';
echo '0 65 255 => '.rgb2hex2rgb('0 65 255').'<br>';
echo '255.150.3 => '.rgb2hex2rgb('255.150.3').'<br>';
echo '100,100,250 => '.rgb2hex2rgb('100,100,250').'<br>';
?>
Output
#FFFFFF =>
Array{
red=>255,
green=>255,
blue=>255,
r=>255,
g=>255,
b=>255,
0=>255,
1=>255,
2=>255
}
#FFCCEE =>
Array{
red=>255,
green=>204,
blue=>238,
r=>255,
g=>204,
b=>238,
0=>255,
1=>204,
2=>238
}
CC22FF =>
Array{
red=>204,
green=>34,
blue=>255,
r=>204,
g=>34,
b=>255,
0=>204,
1=>34,
2=>255
}
0 65 255 => #0041FF
255.150.3 => #FF9603
100,100,250 => #6464FA
cgarvis at gmail dot com
09-Oct-2006 10:39
09-Oct-2006 10:39
Here is my version of hex2rgb for web colors to 24bit colors.
<?php
function hex2rgb_webcolors($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);
}
?>
Lukasz (Zajonc) Zajaczkowski
18-Aug-2006 01:44
18-Aug-2006 01:44
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 $sdec;
}
repley at freemail dot it
28-May-2006 06:55
28-May-2006 06:55
From color to color to ...... to color with fade effect. Good for dynamic bar chart.
<?php
//MultiColorFade(array hex-colors, int steps)
function MultiColorFade($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 $table;
}
//end test
?>
Repley.
greatwhitepine at NOSPAM dot yahoo dot ca
30-Mar-2006 12:46
30-Mar-2006 12:46
Hex to binary conversion that works for large and small hex numbers.
<?php
function hexbin($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 12:03
28-Dec-2005 12:03
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
28-Oct-2005 01:59
28-Oct-2005 01:59
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 07:38
24-Oct-2005 07:38
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.$b;
}
08-Oct-2005 10:53
I needed to get the opposite colors so my website would be soft on the eyes.
<?php
function OppositeHex($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
29-Sep-2005 06:38
29-Sep-2005 06:38
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].$rgb[2];
?>
Gabriel Reguly
16-Aug-2005 11:24
16-Aug-2005 11:24
After esnhexdec from "rledger at gmail dot com", the esndechex:
<?php
function esndechex($dec){
$a = strtoupper(dechex(substr($dec, 1, 2)));
$b = strtoupper(dechex(substr($dec, 3, 10)));
return $a . $b;
}
?>
djneoform at gmail dot com
20-Jun-2005 09:51
20-Jun-2005 09:51
since i couldn't find one, here's an HEX to ASCII converter..
(takes HEX strings (in ASCII) and converts each two digit HEX code into it's ASCII equivalent)
function hex2ascii($str)
{
$p = '';
for ($i=0; $i < strlen($str); $i=$i+2)
{
$p .= chr(hexdec(substr($str, $i, 2)));
}
return $p;
}
bishop
04-Jun-2005 07:51
04-Jun-2005 07:51
Bullet-proof hex-to-rgb colour converter like brian at sagesport dot com wanted, just far fewer code lines. As a bonus, gives you the ability to return as string or array:
<?php
function &hex2rgb($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]}" : $rgb);
}
?>
Handles 2, 3, and 6 character colour codes with leading # or &H.
Joey Morwick
02-May-2005 01:07
02-May-2005 01:07
I found it helpful to have the inverse / reverse of this function laying around, since I wanted to insert some binary data into an xmlrpc call (it currently craps out when you do that), and I couldn't find one laying around, so here's a simple little function to do that:
function hex2bin($str) {
$build = '';
while(strlen($str) > 1) {
$build .= chr(hexdec(substr($str, 0, 2)));
$str = substr($str, 2, strlen($str)-2);
}
return $build;
}
rledger at gmail dot com
28-Mar-2005 11:59
28-Mar-2005 11:59
To convert a cellular ESN from hexadecimal to decimal, use the following code. The base conversion is different due to the fact that the first two characters of a hexadecimal value must be converted seperately from the remaining six characters.
<?
function esnhexdec($hex){
$a = sprintf("%03d", hexdec(substr($hex, 0, 2)));
$b = sprintf("%08d", hexdec(substr($hex, 2, 6)));
return $a . $b;
}
?>
zubfatal, root at it dot dk
25-Mar-2005 02:36
25-Mar-2005 02:36
This replaces my previous class.
I've added a few more input checks in the rgb2hex function.
Also it returned incorrect hex values for 1-digit values.
color::rgb2hex(array(0,0,0)) would output 000 not 00000.
<?php
/**
* Convert colors
*
* Usage:
* color::hex2rgb("FFFFFF")
* color::rgb2hex(array(171,37,37))
*
* @author Tim Johannessen <root@it.dk>
* @version 1.0.1
*/
class color {
/**
* Convert HEX colorcode to an array of colors.
* @return array Returns the array of colors as array(red,green,blue)
*/
function hex2rgb($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("", $arrColors);
}
}
?>
brian at sagesport dot com
22-Mar-2005 09:08
22-Mar-2005 09:08
The issue I've seen with the existing hex to dec conversion routines is the lack of error-trapping. I stick to the theory that one should try to cover ALL the bases when writing a generalized routine such as this one. I have a varied background that covers a wide variety of design/development languages, on the web as well as desktop apps. As such I've seen multiple formats for writing hex colors.
For example, the color red COULD be written as follows:
#ff0000
&Hff0000
#ff
&Hff
Therefore I have written a function that is case-insensitive and takes into account the chance that different developers have a tendency to format hex colors in different ways.
<?php
function convert_color($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($color);
*/
?>
As you can see, the function "convert_color" accepts a hex # in most acceptable formats and returns an associative array. [success] is set to TRUE if the function succeeds and FALSE if not. The array members [r], [g] and [b] hold the red,green and blue values respectively. If it fails, [error] holds a custom error message.
"strip_chars" is a support function written to remove the unwanted characters from the hex string, and sends the concatenated string back to the calling function. It will accept either a single value or an array of values for the characters to remove.
groobo
10-Feb-2005 11:46
10-Feb-2005 11:46
It's just a revision to marfastic's ligten_up script, it simply adds/subtracts mod_color to orig_color.
I use it often to adjust tonals rather than brightness only
<?
function mod_color($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; }
}
?>
19-Jan-2005 09:33
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 07:14
10-Dec-2004 07:14
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
08-May-2004 09:00
08-May-2004 09:00
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'], $color['k']);
?>
U can call it with parameters (r,g,b) or just with an array(r,g,b) that contains these values.
Hope it works correct. All testing was fine.
gelado at ip3 dot com
29-Aug-2003 04:30
29-Aug-2003 04:30
Another hex to decimal converter, up to the precision of PHP floats.
function longhex($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
27-May-2003 03:43
27-May-2003 03:43
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 $ret;
}
/*** Example:
print_r(hex2dec('3D58BE'));
or
print_r(hex2dec('#3D58BE'));
will return
Array
(
[r] => 61
[g] => 88
[b] => 190
)
***/
?>
Thanks !
Henrique Recidive
andreas.schmeiler
05-Feb-2003 05:59
05-Feb-2003 05:59
Here's another hex2bin variant, works pretty well to me.
function hex2bin($hexdata) {
for ($i=0;$i<strlen($hexdata);$i+=2) {
$bindata.=chr(hexdec(substr($hexdata,$i,2)));
}
return $bindata;
}
chrism at four dot net
15-Dec-2001 10:02
15-Dec-2001 10:02
hexdec from 4.1.0 onwards does not show
the same size limitation and therefore
works differently with large numbers than previous php versions.
To obtain the same results, use:
(int) hexdec (...)
andychase at yahoo dot com
17-Jan-2001 06:32
17-Jan-2001 06:32
For hex numbers larger than 7FFFFFFF (E.G. PalmOS dates in seconds elapsed since 01/01/1904), I came up with this:
<?php
function bighexdec($hexnumber){
$numlength = strlen($hexnumber);
$decnumber = 0;
for($x = 1; $x <= $numlength; $x++){
$place = $numlength - $x;
$operand =