PHP Dokumentation: Function imagecolorallocatealpha
12. Januar 2010 von werner
imagecolorallocatealpha
(PHP 4 >= 4.3.2, PHP 5)
imagecolorallocatealpha — Allocate a color for an image
Beschreibung
imagecolorallocatealpha() behaves identically to imagecolorallocate() with the addition of the transparency parameter alpha.
Parameter-Liste
- image
Eine von den verschiedenen Erzeugungsfunktionen wieimagecreatetruecolor() gelieferteGrafikressource.
- 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 0×00 and 0xFF.
Rückgabewerte
A color identifier or FALSE if the allocation failed.
Changelog
| Version | Beschreibung |
|---|---|
| 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 erzeugteine ähnliche Ausgabe wie:
Anmerkungen
Hinweis: Diese Funktion setzt die GD-Bibliothek inder Version 2.0.1 oder höher (empfohlen wird mindestens 2.0.28) voraus.
Siehe auch
- imagecolorallocate() – Bestimmt die Farbe einer Grafik
- imagecolordeallocate() – Löscht eine Farbdefinition
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