IMG_EFFECT_OVERLAY doesn't work in PHP 5.6.0 with GD version: 2.1.0-alpha.
(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)
imagelayereffect — Set the alpha blending flag to use layering effects
Set the alpha blending flag to use layering effects.
image
Una risorsa immagine, restituita da una delle funzioni di creazione immagine, come imagecreatetruecolor().
effect
One of the following constants:
IMG_EFFECT_REPLACE
true
to
imagealphablending())
IMG_EFFECT_ALPHABLEND
false
to
imagealphablending())
IMG_EFFECT_NORMAL
IMG_EFFECT_ALPHABLEND
.
IMG_EFFECT_OVERLAY
IMG_EFFECT_MULTIPLY
Versione | Descrizione |
---|---|
8.0.0 |
image expects a GdImage
instance now; previously, a valid gd resource was expected.
|
7.2.0 |
Added IMG_EFFECT_MULTIPLY (requires system libgd >=
2.1.1 or the bundled libgd).
|
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);
?>
Il precedente esempio visualizzerà qualcosa simile a:
I have been getting a fatal error:
Fatal error: Call to undefined function imagelayereffect()
This doesn't work with Ubuntu server (8.04 lts) and the php5-gd package. If you need this you will have to recompile PHP with GD built-in.
^^ my name is coreyward ^^
imagelayereffect needs to be applied to the destination image, not the source image. As noted, the only useful "effect" as of this time is IMG_EFFECT_OVERLAY since the others are merely another way of setting the alpha blending flag.
You can also use imagecopymerge with a lower pct argument to blend two images with more control over the opacity at which the top image is blended.
<?
// overlays $im_src onto $im_dst properly (assuming same dims)
imagelayereffect($im_dst, IMG_EFFECT_OVERLAY);
imagecopy($im_dst, $im_src, 0, 0, 0, 0, $im_dst_x, $im_dst_y);
?>
I found the following example on a Chinese site and translated and adjusted it. It creates a portrait from the sample picture.
<?php
// Portrait image
$im = imagecreatefromjpeg( "sample.jpg");
// Get width and height
$w = imagesx($im);
$h = imagesy($im);
// Non-through
$c_visible = 0x007F7F7F;
// Background (black)
$c_bg = 0x00000000;
// Create mask
$im_mask = imagecreatetruecolor($w,$h);
imageFilledRectangle($im_mask, 0,0, $w,$h, $c_bg);
imageFilledEllipse ($im_mask, $w/2,$h/2, $w*.9,$h*.9, $c_visible);
// Only overlay seems to something useful
imagelayereffect($im_mask, IMG_EFFECT_OVERLAY);
imagecopy($im_mask, $im, 0,0, 0,0, $w,$h);
imagedestroy($im);
imagepng($im_mask);
imagedestroy($im_mask);
?>
Try removing the 'create mask' code and just add another image with 'createimagefromjpeg' to see 'normal' overlay. It blends the colors like different layers in Photoshop.