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imagelayereffect

(PHP 4 >= 4.3.0, PHP 5)

imagelayereffectSet the alpha blending flag to use the bundled libgd layering effects

Descrizione

bool imagelayereffect ( resource $image , int $effect )

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

Elenco dei parametri

image

Una risorsa immagine, restituita da una delle funzioni di creazione immagine, come 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.

Valori restituiti

Restituisce TRUE in caso di successo, FALSE in caso di fallimento.

Esempi

Example #1 imagelayereffect() example

<?php
// Setup an image
$im imagecreatetruecolor(100100);

// Set a background
imagefilledrectangle($im00100100imagecolorallocate($im220220220));

// Apply the overlay alpha blending flag
imagelayereffect($imIMG_EFFECT_OVERLAY);

// Draw two grey ellipses
imagefilledellipse($im50504040imagecolorallocate($im100255100));
imagefilledellipse($im50505080imagecolorallocate($im100100255));
imagefilledellipse($im50508050imagecolorallocate($im255100100));

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

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

Il precedente esempio visualizzerĂ  qualcosa simile a:

Output of example : imagelayereffect()

Note

Nota: Questa funzione necessita di GD 2.0.1 o successivi (raccomandato 2.0.28 o successivi).

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User Contributed Notes 5 notes

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rx
29 days ago
IMG_EFFECT_OVERLAY doesn't work in PHP 5.6.0 with GD version: 2.1.0-alpha.
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0
andrew at iwebsolutions dot co dot uk
6 years ago
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.
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0
[myname] at mac dot com
6 years ago
^^ 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);

?>
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0
Remon
6 years ago
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.
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0
Anonymous
9 years ago
I assume, that the specific effects are similiar to those used in Adobe Photoshop for blending layers.
There might be things like IMG_EFFECT_MULTIPLY resulting of that.
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