imagecolorexactalpha

(PHP 4 >= 4.0.6, PHP 5)

imagecolorexactalpha — Get the index of the specified color + alpha

Descrizione

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.

Elenco dei parametri

image: Una risorsa immagine, restituita da una delle funzioni di creazione immagine, come imagecreatetruecolor().
red: Valore della componente rossa.
green: Valore della componente verde.
blue: Valore della componente blu.
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.

Valori restituiti

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.

Esempi

Example #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);
?>

Il precedente esempio visualizzerà qualcosa simile a:

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

Note

Nota: Questa funzione necessita di GD 2.0.1 o successivi (raccomandato 2.0.28 o successivi).

Vedere anche:

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