Most Referenced Functions
  » google_pagerank()
  » preg_replace()
  » imagecreatefrompng()
  » site_pageranks()
  » imagepng()
  » imagestring()
  » imagedestroy()
  » htmlentities()
  » imagecolorallocate()
  » fopen()
  » preg_match()
  » header()
  » getimagesize()
  » session_start()
  » ob_start()
  » preg_match_all()
  » strstr()
  » ob_flush()
  » flush()
  » htmlspecialchars()
  » str_replace()
  » strpos()
  » array2vars()
  » nl2br()
  » setcookie()
  » urlencode()
  » preg_split()
  » ereg()
  » ereg_replace()
  » var_dump()

Become a sponsor for $15/month. Link is sitewide - PR5 homepage, 20+ PR4 pages, 90+ PR3 pages. Email dave[AT]icemelon[D0T]c0m.

PHP Functions

Function: 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.

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);
?>

Note: This function requires GD 2.0.1 or later.

Related Function(s)

  • imagecolorallocate()
  • imagecolordeallocate()
  • Icemelon -- PHP, CSS, Javascript Tutorials, & More!
      © 2005-2010 Icemelon.com   Email: dave[AT]icemelon[D0T]c0m