PHP Manual: Set the alpha blending flag to use the bundled libgd layering effects

Description

bool imagelayereffect ( resource $image , int $effect )

Set the alpha blending flag to use the bundled libgd layering effects.

Parameters

image

An image resource, returned by one of the image creation functions, such as imagecreatetruecolor.

effect

One of the following constants:

IMG_EFFECT_REPLACE: Use pixel replacement (equivalent of passing TRUE to imagealphablending)
IMG_EFFECT_ALPHABLEND: Use normal pixel blending (equivalent of passing FALSE to imagealphablending)
IMG_EFFECT_NORMAL: Same as IMG_EFFECT_ALPHABLEND.
IMG_EFFECT_OVERLAY: Overlay has the effect that black background pixels will remain black, white background pixels will remain white, but grey background pixels will take the colour of the foreground pixel.

Return Values

Returns TRUE on success or FALSE on failure.

Examples

Example #1 imagelayereffect example


<?php
// Setup an image
$im = imagecreatetruecolor(100, 100);

// Set a background
imagefilledrectangle($im, 0, 0, 100, 100, imagecolorallocate($im, 220, 220, 220));

// Apply the overlay alpha blending flag
imagelayereffect($im, IMG_EFFECT_OVERLAY);

// Draw two grey ellipses
imagefilledellipse($im, 50, 50, 40, 40, imagecolorallocate($im, 100, 255, 100));
imagefilledellipse($im, 50, 50, 50, 80, imagecolorallocate($im, 100, 100, 255));
imagefilledellipse($im, 50, 50, 80, 50, imagecolorallocate($im, 255, 100, 100));

// Output
header('Content-type: image/png');

imagepng($im);
imagedestroy($im);
?>

The above example will output something similar to:

Notes

Note: This function requires GD 2.0.1 or later (2.0.28 or later is recommended).