imagecolortransparent

(PHP 4, PHP 5)

imagecolortransparent — Define a color as transparent

Descrizione

int imagecolortransparent ( resource $image [, int $color ] )

Sets the transparent color in the given image.

Elenco dei parametri

image: Una risorsa immagine, restituita da una delle funzioni di creazione immagine, come imagecreatetruecolor().
color: A color identifier created with imagecolorallocate().

Valori restituiti

The identifier of the new (or current, if none is specified) transparent color is returned. If color is not specified, and the image has no transparent color, the returned identifier will be -1.

Esempi

Example #1 imagecolortransparent() example


<?php
// Create a 55x30 image
$im = imagecreatetruecolor(55, 30);
$red = imagecolorallocate($im, 255, 0, 0);
$black = imagecolorallocate($im, 0, 0, 0);

// Make the background transparent
imagecolortransparent($im, $black);

// Draw a red rectangle
imagefilledrectangle($im, 4, 4, 50, 25, $red);

// Save the image
imagepng($im, './imagecolortransparent.png');
imagedestroy($im);
?>

Il precedente esempio visualizzerà qualcosa simile a:

Note

Nota:
Transparency is copied only with imagecopymerge() and true color images, not with imagecopy() or pallete images.

Nota:
The transparent color is a property of the image, transparency is not a property of the color. Once you have set a color to be the transparent color, any regions of the image in that color that were drawn previously will be transparent.