   #PHP Manual Image functions imagecolorallocate imagecolorat

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                            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().
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