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 — Activa la opción de mezcla alfa para utilizar los efectos de libgd
Activa la opción de mezcla alfa para utilizar los efectos de libgd.
image
Un objeto GdImage, retornado por una de las funciones de creación de imágenes, como imagecreatetruecolor().
effect
Una de las constantes siguientes:
IMG_EFFECT_REPLACE
true
a la función imagealphablending())
IMG_EFFECT_ALPHABLEND
false
a la función imagealphablending())
IMG_EFFECT_NORMAL
IMG_EFFECT_ALPHABLEND
.
IMG_EFFECT_OVERLAY
IMG_EFFECT_MULTIPLY
Versión | Descripción |
---|---|
8.0.0 |
image expects a GdImage
instance now; previously, a valid gd resource was expected.
|
7.2.0 |
Añadida la constante IMG_EFFECT_MULTIPLY
(requiere la libgd del sistema >= 2.1.1 o la libgd integrada).
|
Ejemplo #1 Ejemplo con imagelayereffect()
<?php
// Creación de una imagen
$im = imagecreatetruecolor(100, 100);
// Define el fondo
imagefilledrectangle($im, 0, 0, 100, 100, imagecolorallocate($im, 220, 220, 220));
// Aplica el overlay
imagelayereffect($im, IMG_EFFECT_OVERLAY);
// Dibuja 2 elipses grises
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));
// Visualización
header('Content-type: image/png');
imagepng($im);
?>
Resultado del ejemplo anterior es similar a :
^^ 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 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.
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.