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16 years ago
With the following functions you can not only convert a 24 bit RGB integer to its corresponding red, green, and blue values, but also 32 bit RGBA integers to its corresponding red, green, blue, and ALPHA values.



Not only that, but I even threw in a function for converting those red, green, blue, and alpha values back into a 32 bit RGBA integer.



Sample usage:

<?php

$int = rgba2int(255, 255, 255, 16);

echo $int . "<br>";

$rgba = int2rgba($int);

print_r($rgba);

?>



What it should output:

285212671

Array

(

    [r] => 255

    [g] => 255

    [b] => 255

    [a] => 16

)



<?php

function rgba2int($r, $g, $b, $a=1) {

    /*

    This function builds a 32 bit integer from 4 values which must be 0-255 (8 bits)

    Example 32 bit integer: 00100000010001000000100000010000

    The first 8 bits define the alpha

    The next 8 bits define the blue

    The next 8 bits define the green

    The next 8 bits define the red

    */

    return ($a << 24) + ($b << 16) + ($g << 8) + $r;

}



function int2rgba($int) {

    $a = ($int >> 24) & 0xFF;

    $r = ($int >> 16) & 0xFF;

    $g = ($int >> 8) & 0xFF;

    $b = $int & 0xFF;

    return array('r'=>$r, 'g'=>$g, 'b'=>$b, 'a'=>$a);

}

?>
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