imagecolorallocatealpha (PHP 4 >= 4.3.2, PHP 5) imagecolorallocatealpha -- Allocate a color for an image Descriptionint 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); ?>
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Note: This function requires GD 2.0.1 or later.
See also imagecolorallocate() and
imagecolordeallocate().
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