imagecharup
If you even in a situation where it's not allocating the color you want it could be because of your images color allocation table. GIF and 8-bit PNG images are very susceptible to this.
If your using an GIF and PNG try dropping a color from the table, should let you allocate another.
imagecolorallocate
(PHP 4, PHP 5)
imagecolorallocate — Allocate a color for an image
Description
int imagecolorallocate
( resource
$image
, int $red
, int $green
, int $blue
)Returns a color identifier representing the color composed of the given RGB components.
imagecolorallocate() must be called
to create each color that is to be used in the image represented
by image.
Note:
The first call to imagecolorallocate() fills the background color in palette-based images - images created using imagecreate().
Parameters
-
image -
An image resource, returned by one of the image creation functions, such as imagecreatetruecolor().
-
red -
Value of red component.
-
green -
Value of green component.
-
blue -
Value of blue component.
Return Values
A color identifier or FALSE if the allocation failed.
Warning
This function may
return Boolean FALSE, but may also return a non-Boolean value which
evaluates to FALSE. Please read the section on Booleans for more
information. Use the ===
operator for testing the return value of this
function.
Changelog
| Version | Description |
|---|---|
| 5.1.3 |
Returns FALSE if the allocation failed. Previously
-1 was returned.
|
Examples
Example #1 imagecolorallocate() example
<?php
$im = imagecreate(100, 100);
// sets background to red
$background = imagecolorallocate($im, 255, 0, 0);
// sets some colors
$white = imagecolorallocate($im, 255, 255, 255);
$black = imagecolorallocate($im, 0, 0, 0);
// hexadecimal way
$white = imagecolorallocate($im, 0xFF, 0xFF, 0xFF);
$black = imagecolorallocate($im, 0x00, 0x00, 0x00);
?>
See Also
- imagecolorallocatealpha() - Allocate a color for an image
- imagecolordeallocate() - De-allocate a color for an image
add a note
User Contributed Notes
imagecolorallocate - [28 notes]
phillip dot gooch at gmail dot com ¶
2 years ago
Ludo ¶
5 years ago
When working on an existant GIF images, if the number of different colours has reached the limits of the GIF format, imagecolorallocate will not use to the colour you ask her within the parameters, she will apply black !
That's a problem when generating images "on-the-fly" with many manipulations, from a GIF image.
To go round the problem, you have to convert the GIF image into a PNG one, and then you can work on the PNG and everything will be ok.
For example :
<?php
// first, convert into a PNG image
$handle = imagecreatefromgif('my_image.gif');
imagepng($handle, 'my_image.png');
imagedestroy($handle);
// then, you can work on it
$handle = imagecreatefrompng('my_image.png');
/*
* work on the image
*/
imagegif($handle);
?>
SW ¶
7 years ago
This works! A Black-Image with vertical centered white Aliased Arial-Text and same left and right margin - used for Menu-Buttons.
<?php
function createImgText ($string="", $fontsize=0, $marginX=0, $imgH=0 , $fontfile="", $imgColorHex="", $txtColorHex=""){
if($string!=""){
Header("Content-type: image/png");
//
$spacing = 0;
$line = array("linespacing" => $spacing);
$box = @imageftbbox($fontsize,0,$fontfile,$string,$line)
or die("ERROR");
$tw=$box[4]-$box[0]; //image width
$marginY = $imgH - (($imgH - $fontsize) / 2);
$imgWidth = $tw + (2*$marginX);
$im = ImageCreate($imgWidth, $imgH);
$int = hexdec($imgColorHex);
$arr = array("red" => 0xFF & ($int >> 0x10),
"green" => 0xFF & ($int >> 0x8),
"blue" => 0xFF & $int);
$black = ImageColorAllocate($im, $arr["red"], $arr["green"], $arr["blue"]);
$int = hexdec($txtColorHex);
$arr = array("red" => 0xFF & ($int >> 0x10),
"green" => 0xFF & ($int >> 0x8),
"blue" => 0xFF & $int);
$white = ImageColorAllocate($im, $arr["red"], $arr["green"], $arr["blue"]);
ImageFtText($im, $fontsize, 0, $marginX, $marginY, $white, $fontfile, $string, array());
ImagePng($im);
ImageDestroy($im);
}else{
echo "ERROR!";
}
}
createImgText ("Hello World", 9, 10, 18, "arial.ttf", "000000", "FFFFFF");
?>
jahservant 13 at gmail dot com ¶
3 years ago
Note that you can only assign 255 colors to any image palette. If you try assigning more, imagecolorallocate() will fail.
If, for example, you are randomly allocating colors, it will be wise to check if you have used up all of the colors possible. You can use imagecolorclosest() to get the closest assigned color:
<?php
//assign random rgb values
$c1 = mt_rand(50,200); //r(ed)
$c2 = mt_rand(50,200); //g(reen)
$c3 = mt_rand(50,200); //b(lue)
//test if we have used up palette
if(imagecolorstotal($pic)>=255) {
//palette used up; pick closest assigned color
$color = imagecolorclosest($pic, $c1, $c2, $c3);
} else {
//palette NOT used up; assign new color
$color = imagecolorallocate($pic, $c1, $c2, $c3);
}
?>
Also, imagecolorallocate() will assign a new color EVERY time the function is called, even if the color already exists in the palette:
<?php
// [...]
imagecolorallocate($pic,125,125,125); //returns 5
imagecolorallocate($pic,125,125,125); //returns 6
imagecolorallocate($pic,125,125,125); //returns 7
// [...]
imagecolorallocate($pic,125,125,125); //returns 23
imagecolorallocate($pic,125,125,125); //returns 25
// [...]
// etc...
?>
So here, imagecolorexact() is useful:
<?php
//see if color already exists
$color = imagecolorexact($pic, $c1, $c2, $c3);
if($color==-1) {
//color does not exist; allocate a new one
$color = imagecolorallocate($pic, $c1, $c2, $c3);
}
?>
And, for nerdy-ness sake, we can put the two ideas together:
<?php
//assign random rgb values
$c1 = mt_rand(50,200); //r(ed)
$c2 = mt_rand(50,200); //g(reen)
$c3 = mt_rand(50,200); //b(lue)
//get color from palette
$color = imagecolorexact($pic, $c1, $c2, $c3);
if($color==-1) {
//color does not exist...
//test if we have used up palette
if(imagecolorstotal($pic)>=255) {
//palette used up; pick closest assigned color
$color = imagecolorclosest($pic, $c1, $c2, $c3);
} else {
//palette NOT used up; assign new color
$color = imagecolorallocate($pic, $c1, $c2, $c3);
}
}
?>
Or as a function:
<?php
function createcolor($pic,$c1,$c2,$c3) {
//get color from palette
$color = imagecolorexact($pic, $c1, $c2, $c3);
if($color==-1) {
//color does not exist...
//test if we have used up palette
if(imagecolorstotal($pic)>=255) {
//palette used up; pick closest assigned color
$color = imagecolorclosest($pic, $c1, $c2, $c3);
} else {
//palette NOT used up; assign new color
$color = imagecolorallocate($pic, $c1, $c2, $c3);
}
}
return $color;
}
for($i=0; $i<1000; $i++) { //1000 because it is significantly greater than 255
//assign random rgb values
$c1 = mt_rand(50,200); //r(ed)
$c2 = mt_rand(50,200); //g(reen)
$c3 = mt_rand(50,200); //b(lue)
//generate the color
$color = createcolor($pic,$c1,$c2,$c3);
//do something with color...
}
?>
William Barath ¶
5 years ago
Lots of hsv2rgb commentary but no working example, so here's mine:
<?php // hsv2rgb example translated from ImageMagick C code
function hsv2rgb($h, $s, $v)
{
$s /= 256.0;
if ($s == 0.0) return array($v,$v,$v);
$h /= (256.0 / 6.0);
$i = floor($h);
$f = $h - $i;
$p = (integer)($v * (1.0 - $s));
$q = (integer)($v * (1.0 - $s * $f));
$t = (integer)($v * (1.0 - $s * (1.0 - $f)));
switch($i) {
case 0: return array($v,$t,$p);
case 1: return array($q,$v,$p);
case 2: return array($p,$v,$t);
case 3: return array($p,$q,$v);
case 4: return array($t,$p,$v);
default: return array($v,$p,$q);
}
}
$image = ImageCreateTrueColor(256,128);
for ($y=0; $y<64; $y++) for($x=0; $x<256; $x++){
list($r,$g,$b) = hsv2rgb($x | 7,255,($y*4) |7);
$color = ($r << 16 ) | ($g << 8) | $b;
imagesetpixel($image, $x, $y-4, $color);
}
for ($y=64; $y<128; $y++) for($x=0; $x<256; $x++){
list($r,$g,$b) = hsv2rgb($x|7,((127-$y)*4)|7,255);
$color = ($r << 16) | ($g << 8) | $b;
imagesetpixel($image, $x, $y-4, $color);
}
for ($y=120; $y<128; $y++) for($x=0; $x<256; $x++){
$color = (($x |7) << 16) | (($x |7) << 8) | ($x |7);
imagesetpixel($image, $x, $y, $color);
}
header("Content-Type: image/png");
imagepng($image);
?>
picklecj at rose-hulman dot edu ¶
5 years ago
Another solution to color limitation issues when creating gradients. This file takes width (px) and left and right colors (hex) and makes a gradient while only allocating 250 colors.
<?php
$leftR = hexdec(substr($_GET["left"],0,2));
$leftG = hexdec(substr($_GET["left"],2,2));
$leftB = hexdec(substr($_GET["left"],4,2));
$rightR = hexdec(substr($_GET["right"],0,2));
$rightG = hexdec(substr($_GET["right"],2,2));
$rightB = hexdec(substr($_GET["right"],4,2));
$image=imagecreate($_GET["width"],1);
for($i=0;$i<250;$i++) {
$colorset[$i] = imagecolorallocate($image, $leftR + ($i*(($rightR-$leftR)/250)), $leftG + ($i*(($rightG-$leftG)/250)), $leftB + ($i*(($rightB-$leftB)/250)));
}
for($i=0;$i<($_GET["width"]);$i++) {
imagesetpixel ($image, $i, 0, $colorset[(int)($i/($_GET["width"]/250))] );
}
header("Content-type: image/png");
imagepng($image);
imagedestroy($image);
?>
example: gradient.php?width=640&left=000000&right=FF0000
Makes a 640px-wide image that fades from black to red.
LPEspecial at home dot nl ¶
6 years ago
This might help someone who want to use 'ImageColorAllocate ' with a hex value
<?php
function ImageColorAllocateFromHex ($img, $hexstr)
{
$int = hexdec($hexstr);
return ImageColorAllocate ($img,
0xFF & ($int >> 0x10),
0xFF & ($int >> 0x8),
0xFF & $int);
}
?>
behun at webconsult dot sk ¶
6 years ago
Also, when you need more then 256 colors, use imagecreatetruecolor function. With this function you can use unlimited number of colors.
mlse ¶
7 years ago
Another more general variation on the theme using the same naming conventions as the hexdec and dechex built-in functions ...
Prototype:
array hexrgb ( string hex_string )
Returns:
An associative array of the RGB components specified in hex_string.
hexrgb() example:
<?php
$rgb = hexrgb("0xAABBCC");
print_r($rgb);
?>
Output is:
Array
(
[red] => 170
[green] => 187
[blue] => 204
)
Implementation:
<?php
function hexrgb ($hexstr)
{
$int = hexdec($hexstr);
return array("red" => 0xFF & ($int >> 0x10),
"green" => 0xFF & ($int >> 0x8),
"blue" => 0xFF & $int);
}
?>
The output of hexdec can then be passed to imagecolorallocate and manipulated as required.
Zigbigidorlu at hotmail dot com ¶
7 years ago
Here's a very simple and very effective code to change a HEX color to RGB.
<?php
function HEX2RGB($color){
$color_array = array();
$hex_color = strtoupper($color);
for($i = 0; $i < 6; $i++){
$hex = substr($hex_color,$i,1);
switch($hex){
case "A": $num = 10; break;
case "B": $num = 11; break;
case "C": $num = 12; break;
case "D": $num = 13; break;
case "E": $num = 14; break;
case "F": $num = 15; break;
default: $num = $hex; break;
}
array_push($color_array,$num);
}
$R = (($color_array[0] * 16) + $color_array[1]);
$G = (($color_array[2] * 16) + $color_array[3]);
$B = (($color_array[4] * 16) + $color_array[5]);
return array($R,$G,$B);
unset($color_array,$hex,$R,$G,$B);
}
?>
mail at kailashnadh dot name ¶
7 years ago
This nifty function will produce the negative of a given image!
<?php
/********************************
Code by Kailash Nadh
http://kailashnadh.name
usage:
img2neg("my_pic.jpg");
*********************************/
function img2neg($pic) {
header("Content-type: image/jpeg");
$source=imagecreatefromjpeg($pic); // Source
$width=imagesx($source); $height=imagesy($source);
$im = imagecreatetruecolor($width, $height); // Our negative img in the making
for($y=0; $y < $height; $y++) {
for($x=0; $x < $width; $x++) {
$colors=imagecolorsforindex($source, imagecolorat($source, $x,$y));
// this is what makes the colors negative
$r=255-$colors['red'];
$g=255-$colors['green'];
$b=255-$colors['blue'];
$test=imagecolorallocate($im, $r,$g,$b);
imagesetpixel($im,$x, $y, $test);
}
}
imagejpeg($im);
imagedestroy($im);
}
?>
andreoli dot carlo at libero dot it ¶
7 years ago
hsl to RGB
(not yet optimized but it function)
<?php
function hslToRgb ($h, $s, $l) {
if ($h>240 || $h<0) return array(0,0,0);
if ($s>240 || $s<0) return array(0,0,0);
if ($l>240 || $l<0) return array(0,0,0);
if ($h<=40) {
$R=255;
$G=(int)($h/40*256);
$B=0;
}
elseif ($h>40 && $h<=80) {
$R=(1-($h-40)/40)*256;
$G=255;
$B=0;
}
elseif ($h>80 && $h<=120) {
$R=0;
$G=255;
$B=($h-80)/40*256;
}
elseif ($h>120 && $h<=160) {
$R=0;
$G=(1-($h-120)/40)*256;
$B=255;
}
elseif ($h>160 && $h<=200) {
$R=($h-160)/40*256;
$G=0;
$B=255;
}
elseif ($h>200) {
$R=255;
$G=0;
$B=(1-($h-200)/40)*256;
}
$R=$R+(240-$s)/240*(128-$R);
$G=$G+(240-$s)/240*(128-$G);
$B=$B+(240-$s)/240*(128-$B);
if ($l<120) {
$R=($R/120)*$l;
$G=($G/120)*$l;
$B=($B/120)*$l;
}
else {
$R=$l*((256-$R)/120)+2*$R-256;
$G=$l*((256-$G)/120)+2*$G-256;
$B=$l*((256-$B)/120)+2*$B-256;
}
if ($R<0) $R=0;
if ($R>255) $R=255;
if ($G<0) $G=0;
if ($G>255) $G=255;
if ($B<0) $B=0;
if ($B>255) $B=255;
return array((int)$R,(int)$G,(int)$B);
}
?>
mv at brazil dot com ¶
8 years ago
<?php
/**
* Create a image bar using lib GD
* Ege. <img src="color_sample.php?color=FF0000" width="10 height="30">
*/
// Split the HTML color representation
$hexcolor = str_split($_GET["color"], 2);
// Convert HEX values to DECIMAL
$bincolor[0] = hexdec("0x{$hexcolor[0]}");
$bincolor[1] = hexdec("0x{$hexcolor[1]}");
$bincolor[2] = hexdec("0x{$hexcolor[2]}");
$im = ImageCreate(100, 100);
$colorallocate = ImageColorAllocate($im, $bincolor[0], $bincolor[1], $bincolor[2]);
ImageFilledRectangle($im, 0, 0, 100, 100, $colorallocate);
header('Content-Type: image/png');
ImagePNG($im);
?>
Anonymous ¶
8 years ago
When you are using truecolor images, you can also use bitwise operations to generate the color:
<?php
$color = ($r << 16) | ($g << 8) | $b; // 2261213
?>
This is identical to the imagecolorallocate() function, in truecolor images!
aaron at parecki dot com ¶
8 years ago
This will let you tint an image to any specific color. The blacks of the source image become your specified color, and the whites remain white. Works best for colorizing greyscale images.
<?php
$r = 224;
$g = 192;
$b = 0;
$source_file = "picture.jpg";
$im_src = ImageCreateFromJpeg($source_file);
$im_tint = ImageCreate(imagesx($im_src),imagesy($im_src));
for ($c = 0; $c < 255; $c++) {
ImageColorAllocate($im_tint, max($r,$c), max($g,$c), max($b,$c));
}
ImageCopyMerge($im_tint,$im_src,0,0,0,0, imagesx($im_src), imagesy($im_src), 100);
ImageDestroy($im_src);
header("Content-type: image/jpeg");
imagejpeg($im_tint);
?>
tyberis ¶
8 years ago
2 functions to convert from HSV colorspace (hue/saturation/brightness) to RGB (red/green/blue) colorspace and back.
<?php
// $c = array($red, $green, $blue)
// $red=[0..1], $green=[0..1], $blue=[0..1];
function rgb2hsv($c) {
list($r,$g,$b)=$c;
$v=max($r,$g,$b);
$t=min($r,$g,$b);
$s=($v==0)?0:($v-$t)/$v;
if ($s==0)
$h=-1;
else {
$a=$v-$t;
$cr=($v-$r)/$a;
$cg=($v-$g)/$a;
$cb=($v-$b)/$a;
$h=($r==$v)?$cb-$cg:(($g==$v)?2+$cr-$cb:(($b==$v)?$h=4+$cg-$cr:0));
$h=60*$h;
$h=($h<0)?$h+360:$h;
}
return array($h,$s,$v);
}
// $c = array($hue, $saturation, $brightness)
// $hue=[0..360], $saturation=[0..1], $brightness=[0..1]
function hsv2rgb($c) {
list($h,$s,$v)=$c;
if ($s==0)
return array($v,$v,$v);
else {
$h=($h%=360)/60;
$i=floor($h);
$f=$h-$i;
$q[0]=$q[1]=$v*(1-$s);
$q[2]=$v*(1-$s*(1-$f));
$q[3]=$q[4]=$v;
$q[5]=$v*(1-$s*$f);
//return(array($q[($i+4)%5],$q[($i+2)%5],$q[$i%5]));
return(array($q[($i+4)%6],$q[($i+2)%6],$q[$i%6])); //[1]
}
}
?>
[1] - EDITOR NOTE: THIS IS A FIX FROM "hc at hob(removethis)soft dot net".
smoli at paranoya dot ch ¶
8 years ago
Some of you maybe want to use HSV color model for drawing color selectors and circles:
<?php
function &colormap_hsv_to_rgb($h, $s, $v)
{
$ret = new stdClass();
if($s == 0)
{
$ret->r = $v;
$ret->g = $v;
$ret->b = $v;
return $ret;
}
else
{
$h = floatval($h) / 255.0;
$s = floatval($s) / 255.0;
$v = floatval($v) / 255.0;
$hue = $h;
if($hue == 1.0)
$hue = 0.0;
$hue *= 6.0;
$i = intval($hue);
$f = $hue - floatval($i);
$w = $v * (1.0 - $s);
$q = $v * (1.0 - ($s * $f));
$t = $v * (1.0 - ($s * (1.0 - $f)));
switch($i)
{
case 0: $ret->r = $v; $ret->g = $t; $ret->b = $w; break;
case 1: $ret->r = $q; $ret->g = $v; $ret->b = $w; break;
case 2: $ret->r = $w; $ret->g = $v; $ret->b = $t; break;
case 3: $ret->r = $w; $ret->g = $q; $ret->b = $v; break;
case 4: $ret->r = $t; $ret->g = $w; $ret->b = $v; break;
case 5: $ret->r = $v; $ret->g = $w; $ret->b = $q; break;
}
}
$ret->r = intval($ret->r * 255.0);
$ret->g = intval($ret->g * 255.0);
$ret->b = intval($ret->b * 255.0);
return $ret;
}
?>
jernberg at fairytale dot se ¶
9 years ago
this might help someone, how to allocate an color from an html color-definition:
<?php
$fg = "#ff0080";
$red = 100;
$green = 100;
$blue = 100;
if( eregi( "[#]?([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})", $fg, $ret ) )
{
$red = hexdec( $ret[1] );
$green = hexdec( $ret[2] );
$blue = hexdec( $ret[3] );
}
$text_color = ImageColorAllocate( $img1, $red, $green, $blue );
?>
chris at drunkenpirates dot co dot uk ¶
9 years ago
<?php
/*
An example combining the use of ImageColorAllocate, Imagesetpixel, Imagecopyresized and some basic Trig
*/
Header("Content-type: image/png");
$height = 128;
$width = 128;
$imA = ImageCreate($width, $height);
$imB = ImageCreate($width*4, $height*4);
$bckA = ImageColorAllocate($imA, 0,0,0);
$bckB = ImageColorAllocate($imB, 0,0,0);
//GENERATE GRAY SCALE PALLETE
for($c=0;$c<256;$c++){
ImageColorAllocate($imA, $c, $c, $c);
}
//PRODUCE DATA
$m=rand(0,10);
for($c=0;$c<128;$c++){
$s= (sin( deg2rad($c*360*$m/128) )+1)*127;
$col_arr[$c]=$s;
}
for($y=0;$y<$height;$y++){
for($x=0;$x<$width;$x++){
$imgA[$x][$y]=$col_arr[$x];
}
}
for($y=0;$y<$height;$y++){
for($x=0;$x<$width;$x++){
$imgB[$x][$y]=$col_arr[$y];
}
}
//SET PIXELS
for($y=0;$y<$height;$y++){
for($x=0;$x<$width;$x++){
$imgC[$x][$y]=$imgA[$x][$y]+$imgB[$x][$y];
$s=$imgC[$x][$y]/2;
Imagesetpixel($imA,$x,$y,$s);
}
}
//RESIZE IMAGE FOR DISPLAY
Imagecopyresized ($imB, $imA, 0, 0, 0, 0, $width*4, $height*4, $width, $width);
ImagePNG($imB);
?>
leif at harmsen dot net ¶
10 years ago
I was unable to get any of the posted methods for converting colour to grayscale to work. The problem appears to be the way gd creates images from jpeg inconsistently over various versions. Eventually I wrote my own that works for me - this approach allocates the 256 color pallete first. You can also play with separate $r, $g, $b variables before using imagecolorallocate in order to tone or tint the image.
<?php
$resource = 'whatever.jpg';
$im_size = GetImageSize($resource);
$imageWidth = $im_size[0];
$imageHeight = $im_size[1];
$im = imageCreate($imageWidth,$imageHeight);
for ($c = 0; $c < 256; $c++) {
ImageColorAllocate($im, $c,$c,$c);
}
$im2 = ImageCreateFromJpeg($resource);
ImageCopyMerge($im,$im2,0,0,0,0, $imageWidth, $imageHeight, 100);
ImageDestroy($im2);
?>
go on using $im as your image, it is now grayscale ....
jasper at pointless dot net ¶
10 years ago
a patch to php 4.3.0 to add imagecolorallocatealpha is here:
http://pointless.net/~jasper/php-4.3.0-imagecolorallocatealpha.patch
cd php-4.3.0/ext/gd
patch < path/to/patch
and recompile and reinstall.
bisqwit at iki dot fi ¶
11 years ago
Actually, you can't allocate more than 256 colours for an paletted image (ImageCreate).
Use ImageCreateTrueColor instead. For it to work, you need libgd version 2 support in php though.
oni-kun[at]oni-kun[dot]com ¶
2 years ago
If you're uncomfortable with using RGB codes you can bypass this function completely by assigning the hex values directly, two example replacements are:
<?php
//Equivalents
$white = imagecolorallocate($im, 255, 255, 255);
$white = 0x00FFFFFF; //First two are alpha, then triplet
$grey = imagecolorallocate($im, 62, 62, 62);
$grey = 0x003E3E3E;
?>
This should work in all applications, as it seems that is all the function returns.
yettycz at gmail dot com ¶
3 years ago
Two useful functions for convert integer from imageCollorAllocate to RGB hex (FFFFFF eg.) and to array of integers 0..255:
<?php
/**
* Convert color from imageColorAllocate() to hex in XXXXXX (eg. FFFFFF, 000000, FF0000)
*
* name: color2rgb
* author: Yetty
* @param $color value from imageColorAllocate()
* @return string; color in style XXXXXX (eg. FFFFFF, 000000, FF0000)
*/
function color2rgb($color) {
return str_pad(base_convert($color, 10, 16), 6, 0, STR_PAD_LEFT);
}
/**
* Convert color from hex in XXXXXX (eg. FFFFFF, 000000, FF0000) to array(R, G, B)
* of integers (0-255).
*
* name: rgb2array
* author: Yetty
* @param $color hex in XXXXXX (eg. FFFFFF, 000000, FF0000)
* @return string; array(R, G, B) of integers (0-255)
*/
function rgb2array($rgb) {
return array(
base_convert(substr($rgb, 0, 2), 16, 10),
base_convert(substr($rgb, 2, 2), 16, 10),
base_convert(substr($rgb, 4, 2), 16, 10),
);
}
?>
shinesoldier at gmail dot com ¶
3 years ago
Here's a very simple function that basically does the same as imagecolorallocate(), only without needing an image resource to work.
<?php
function createcolor($r, $g, $b) {
return hexdec(str_pad(dechex($r), 2, 0, STR_PAD_LEFT).str_pad(dechex($g), 2, 0, STR_PAD_LEFT).str_pad(dechex($b), 2, 0, STR_PAD_LEFT));
}
/* As said earlier, this function does the exact same thing as imagecolorallocate(), without needing an image resource. This means that the following two blocks of code result in the exact same thing: */
//Block 1
$color = colorcreate(105, 199, 204);
//Block 2
$img = imagecreatetruecolor(100, 100); //the arguments here don't really matter
$color = imagecolorallocate($img, 105, 199, 204);
imagedestroy($img);
?>
federicot at gmail dot com ¶
4 years ago
Little correction to marc-gutt's regural expression to validate hex color values. You can use this little function:
<?php
// Validate an hex color string. Return true if valid, false otherwise
function validateHexColor($color) {
$color = substr($color, 0, 7);
return preg_match('/#[0-9a-fA-F]{6}/', $color);
}
?>
djcassis at gmail dot com ¶
5 years ago
I also find the following useful when dealing with HTML hexadecimal colors :
<?php
$color = '#FFffFF';
print_r(sscanf($color, '#%2x%2x%2x'));
?>
outputs :
Array
(
[0] => 255
[1] => 255
[2] => 255
)
info at marc-gutt dot de Marc Gutt ¶
5 years ago
rgb from hex without creating a new function or using split features:
<?php
$color = 'FF9900';
$color = imagecolorallocate($im, hexdec('0x' . $color{0} . $color{1}), hexdec('0x' . $color{2} . $color{3}), hexdec('0x' . $color{4} . $color{5}));
?>
You can validate $color with preg_match('#[a-z0-9]{6}#i', $color) if necessary.