imagecolorallocatealpha

(PHP 4 >= 4.3.2, PHP 5)

imagecolorallocatealpha -- Allocate a color for an image

Beschreibung

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.

Parameter Liste

image

An image resource, returned by one of the image creation functions, such as imagecreatetruecolor().

red

Value of red component

green

Value of green component

blue

Value of blue component

alpha

A value between 0 and 127. 0 indicates completely opaque while 127 indicates completely transparent.

The colors parameters are integers between 0 and 255 or hexadecimals between 0x00 and 0xFF.

Rückgabewerte

A color identifier or FALSE if the allocation failed.

ChangeLog

VersionBeschreibung
Prior to 5.1.3 Returns -1 if the allocation failed.

Beispiele

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);
?>

Das oben gezeigte Beispiel erzeugt eine ähnliche Ausgabe wie:

Anmerkungen

Anmerkung: Diese Funktion setzt die GD Bibliothek in der Version 2.0.1 oder höher voraus.

Siehe auch

imagecolorallocate()
imagecolordeallocate()