IMG_EFFECT_OVERLAY doesn't work in PHP 5.6.0 with GD version: 2.1.0-alpha.imagelayereffect
(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)
imagelayereffect — Set the alpha blending flag to use layering effects
Description
Set the alpha blending flag to use layering effects.
Parameters
-
image A GdImage object, 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
trueto imagealphablending()) IMG_EFFECT_ALPHABLEND-
Use normal pixel blending (equivalent of passing
falseto 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.
IMG_EFFECT_MULTIPLY- Overlays with a multiply effect.
Changelog
| Version | Description |
|---|---|
| 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).
|
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:
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User Contributed Notes 4 notes
andrew at iwebsolutions dot co dot uk ¶
16 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.
[myname] at mac dot com ¶
16 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);
?>
Remon ¶
16 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.