imagecolorexactalpha

(PHP 4 >= 4.0.6, PHP 5)

imagecolorexactalpha — Get the index of the specified color + alpha

Beschreibung

int imagecolorexactalpha ( resource $image , int $red , int $green , int $blue , int $alpha )

Returns the index of the specified color+alpha in the palette of the image.

Parameter-Liste

image: Eine von den verschiedenen Erzeugungsfunktionen wie imagecreatetruecolor() gelieferte Grafikressource.
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

Returns the index of the specified color+alpha in the palette of the image, or -1 if the color does not exist in the image's palette.

Beispiele

Beispiel #1 Get colors from the GD logo


<?php

// Setup an image
$im = imagecreatefrompng('./gdlogo.png');

$colors   = Array();
$colors[] = imagecolorexactalpha($im, 255, 0, 0, 0);
$colors[] = imagecolorexactalpha($im, 0, 0, 0, 127);
$colors[] = imagecolorexactalpha($im, 255, 255, 255, 55);
$colors[] = imagecolorexactalpha($im, 100, 255, 52, 20);

print_r($colors);

// Free from memory
imagedestroy($im);
?>

Das oben gezeigte Beispiel erzeugt eine ähnliche Ausgabe wie:

Array
(
    [0] => 16711680
    [1] => 2130706432
    [2] => 939524095
    [3] => 342163252
)

Anmerkungen

Hinweis: Diese Funktion setzt die GD-Bibliothek in der Version 2.0.1 oder höher (empfohlen wird mindestens 2.0.28) voraus.

Siehe auch

imagecolorclosestalpha() - Get the index of the closest color to the specified color + alpha

2 BenutzerBeiträge:
- Beiträge aktualisieren...

matt at matt-darby dot com
12.07.2005 3:09


Note that a color allocated with imagecolorexactalpha won't show alpha (it will be opaque) when used with imageline(). Use imagerectangle() set to your normal start and end points instead.



Ensure that the image is created via imagecreatetruecolor() as well!

phpdoc-comment at aditus dot nu
8.11.2002 19:01


What might be misleading in the docs is that if the specified color + alpha channel does not exist it will be created. So if you like to use an alpha channel in your image enable alpha blending and then create you color using this method.