(PHP 4 >= 4.0.6, PHP 5, PHP 7, PHP 8)
imagecolorexactalpha — Get the index of the specified color + alpha
Returns the index of the specified color+alpha in the palette of the image.
imageEin GdImage-Objekt, das von einer der Funktionen zur Bilderzeugung, z. B. imagecreatetruecolor(), zurückgegeben wurde.
redWert der Rotkomponente.
greenWert der Grünkomponente.
blueWert der Blaukomponente.
alpha
A value between 0 and 127.
0 indicates completely opaque while
127 indicates completely transparent.
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.
| Version | Beschreibung |
|---|---|
| 8.0.0 |
image erwartet nun eine
GdImage-Instanz; vorher wurde eine gültige
gd-Ressource erwartet.
|
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
)
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!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.