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imagecolorallocatealpha

(PHP 4 >= 4.3.2, PHP 5)

imagecolorallocatealpha -- Allocate a color for an image

Description

int imagecolorallocatealpha ( resource image, int red, int green, int blue, int alpha)

imagecolorallocatealpha() behaves identically to imagecolorallocate() with the addition of the transparency parameter alpha which may have a value between 0 and 127. 0 indicates completely opaque while 127 indicates completely transparent.

Returns FALSE if the allocation failed.

Beispiel 1. Example of using imagecolorallocatealpha()

<?php

                $size = 300;
$image=imagecreatetruecolor($size, $size);

                
// something to get a white background with black border
$back = imagecolorallocate($image, 255, 255, 255);
$border = imagecolorallocate($image, 0, 0, 0);
imagefilledrectangle($image, 0, 0, $size - 1, $size - 1, $back);
imagerectangle($image, 0, 0, $size - 1, $size -
                1, $border);

                
$yellow_x = 100;
$yellow_y = 75;
$red_x    = 120;
$red_y    = 165;
 $blue_x   = 187;
$blue_y   = 125;
 $radius   =
                150;

                
// allocate colors with alpha values
$yellow = imagecolorallocatealpha($image, 255, 255, 0, 75);
$red    = imagecolorallocatealpha($image, 255, 0, 0, 75);
$blue   = imagecolorallocatealpha($image, 0, 0, 255, 75);

                
// drawing 3 overlapped circle
imagefilledellipse($image, $yellow_x, $yellow_y, $radius, $radius, $yellow);
imagefilledellipse($image, $red_x, $red_y, $radius, $radius, $red);   
imagefilledellipse($image, $blue_x, $blue_y, $radius, $radius, $blue);

                
// don't forget to output a correct header!
header('Content-type: image/png');

                
// and finally, output the result
imagepng($image);
imagedestroy($image);
?>

Anmerkung: This function requires GD 2.0.1 or later.

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