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: Wert der Rotkomponente.
green: Wert der Grünkomponente.
blue: Wert der Blaukomponente.
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

add a note User Contributed Notes imagecolorexactalpha - [2 notes]

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matt at matt-darby dot com ¶

7 years ago


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!

down

phpdoc-comment at aditus dot nu ¶

10 years ago


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.

add a note