PHP: imagecolorexactalpha - Manual (original) (raw)

(PHP 4 >= 4.0.6, PHP 5, PHP 7, PHP 8)

imagecolorexactalpha — Get the index of the specified color + alpha

Parameters

image

A GdImage object, 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.

alpha

A value between 0 and 127.0 indicates completely opaque while 127 indicates completely transparent.

The colors parameters are integers between 0 and 255 or hexadecimals between 0x00 and 0xFF.

Return Values

Returns the index of the specified color+alpha in the palette of the image, or -1 if the color does not exist in the image's palette.

Changelog

Version	Description
8.0.0	image expects a GdImage instance now; previously, a valid gd resource was expected.

Examples

Example #1 Get colors from the GD logo

<?php

// Setup an image
$im = imagecreatefrompng('./gdlogo.png');

$colors   = Array(); <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>c</mi><mi>o</mi><mi>l</mi><mi>o</mi><mi>r</mi><mi>s</mi><mo stretchy="false">[</mo><mo stretchy="false">]</mo><mo>=</mo><mi>i</mi><mi>m</mi><mi>a</mi><mi>g</mi><mi>e</mi><mi>c</mi><mi>o</mi><mi>l</mi><mi>o</mi><mi>r</mi><mi>e</mi><mi>x</mi><mi>a</mi><mi>c</mi><mi>t</mi><mi>a</mi><mi>l</mi><mi>p</mi><mi>h</mi><mi>a</mi><mo stretchy="false">(</mo></mrow><annotation encoding="application/x-tex">colors[] = imagecolorexactalpha(</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal">co</span><span class="mord mathnormal" style="margin-right:0.01968em;">l</span><span class="mord mathnormal">ors</span><span class="mopen">[</span><span class="mclose">]</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal">ima</span><span class="mord mathnormal" style="margin-right:0.03588em;">g</span><span class="mord mathnormal">eco</span><span class="mord mathnormal" style="margin-right:0.01968em;">l</span><span class="mord mathnormal">ore</span><span class="mord mathnormal">x</span><span class="mord mathnormal">a</span><span class="mord mathnormal">c</span><span class="mord mathnormal">t</span><span class="mord mathnormal">a</span><span class="mord mathnormal">lp</span><span class="mord mathnormal">ha</span><span class="mopen">(</span></span></span></span>im, 255, 0, 0, 0); <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>c</mi><mi>o</mi><mi>l</mi><mi>o</mi><mi>r</mi><mi>s</mi><mo stretchy="false">[</mo><mo stretchy="false">]</mo><mo>=</mo><mi>i</mi><mi>m</mi><mi>a</mi><mi>g</mi><mi>e</mi><mi>c</mi><mi>o</mi><mi>l</mi><mi>o</mi><mi>r</mi><mi>e</mi><mi>x</mi><mi>a</mi><mi>c</mi><mi>t</mi><mi>a</mi><mi>l</mi><mi>p</mi><mi>h</mi><mi>a</mi><mo stretchy="false">(</mo></mrow><annotation encoding="application/x-tex">colors[] = imagecolorexactalpha(</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal">co</span><span class="mord mathnormal" style="margin-right:0.01968em;">l</span><span class="mord mathnormal">ors</span><span class="mopen">[</span><span class="mclose">]</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal">ima</span><span class="mord mathnormal" style="margin-right:0.03588em;">g</span><span class="mord mathnormal">eco</span><span class="mord mathnormal" style="margin-right:0.01968em;">l</span><span class="mord mathnormal">ore</span><span class="mord mathnormal">x</span><span class="mord mathnormal">a</span><span class="mord mathnormal">c</span><span class="mord mathnormal">t</span><span class="mord mathnormal">a</span><span class="mord mathnormal">lp</span><span class="mord mathnormal">ha</span><span class="mopen">(</span></span></span></span>im, 0, 0, 0, 127); <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>c</mi><mi>o</mi><mi>l</mi><mi>o</mi><mi>r</mi><mi>s</mi><mo stretchy="false">[</mo><mo stretchy="false">]</mo><mo>=</mo><mi>i</mi><mi>m</mi><mi>a</mi><mi>g</mi><mi>e</mi><mi>c</mi><mi>o</mi><mi>l</mi><mi>o</mi><mi>r</mi><mi>e</mi><mi>x</mi><mi>a</mi><mi>c</mi><mi>t</mi><mi>a</mi><mi>l</mi><mi>p</mi><mi>h</mi><mi>a</mi><mo stretchy="false">(</mo></mrow><annotation encoding="application/x-tex">colors[] = imagecolorexactalpha(</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal">co</span><span class="mord mathnormal" style="margin-right:0.01968em;">l</span><span class="mord mathnormal">ors</span><span class="mopen">[</span><span class="mclose">]</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal">ima</span><span class="mord mathnormal" style="margin-right:0.03588em;">g</span><span class="mord mathnormal">eco</span><span class="mord mathnormal" style="margin-right:0.01968em;">l</span><span class="mord mathnormal">ore</span><span class="mord mathnormal">x</span><span class="mord mathnormal">a</span><span class="mord mathnormal">c</span><span class="mord mathnormal">t</span><span class="mord mathnormal">a</span><span class="mord mathnormal">lp</span><span class="mord mathnormal">ha</span><span class="mopen">(</span></span></span></span>im, 255, 255, 255, 55); <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>c</mi><mi>o</mi><mi>l</mi><mi>o</mi><mi>r</mi><mi>s</mi><mo stretchy="false">[</mo><mo stretchy="false">]</mo><mo>=</mo><mi>i</mi><mi>m</mi><mi>a</mi><mi>g</mi><mi>e</mi><mi>c</mi><mi>o</mi><mi>l</mi><mi>o</mi><mi>r</mi><mi>e</mi><mi>x</mi><mi>a</mi><mi>c</mi><mi>t</mi><mi>a</mi><mi>l</mi><mi>p</mi><mi>h</mi><mi>a</mi><mo stretchy="false">(</mo></mrow><annotation encoding="application/x-tex">colors[] = imagecolorexactalpha(</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal">co</span><span class="mord mathnormal" style="margin-right:0.01968em;">l</span><span class="mord mathnormal">ors</span><span class="mopen">[</span><span class="mclose">]</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal">ima</span><span class="mord mathnormal" style="margin-right:0.03588em;">g</span><span class="mord mathnormal">eco</span><span class="mord mathnormal" style="margin-right:0.01968em;">l</span><span class="mord mathnormal">ore</span><span class="mord mathnormal">x</span><span class="mord mathnormal">a</span><span class="mord mathnormal">c</span><span class="mord mathnormal">t</span><span class="mord mathnormal">a</span><span class="mord mathnormal">lp</span><span class="mord mathnormal">ha</span><span class="mopen">(</span></span></span></span>im, 100, 255, 52, 20);

print_r($colors);
?>

The above example will output something similar to:

Array ( [0] => 16711680 [1] => 2130706432 [2] => 939524095 [3] => 342163252 )

Found A Problem?

matt at matt-darby dot com ¶

20 years ago

Note that a color allocated with imagecolorexactalpha won't show alpha (it will be opaque) when used with imageline(). Use imagerectangle() set to your normal start and end points instead.

Ensure that the image is created via imagecreatetruecolor() as well!

phpdoc-comment at aditus dot nu ¶

23 years ago