imagecolorallocatealpha
(PHP 4 >= 4.3.2)
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.
Example 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);
?>
See also imagecolorallocate() and imagecolordeallocate().
