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    imagelayereffect

    (PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)

    imagelayereffect — Set the alpha blending flag to use layering effects

    Beschreibung

    imagelayereffect(GdImage $image, int $effect): bool

    Set the alpha blending flag to use layering effects.

    Parameter-Liste

    image

    Ein GdImage-Objekt, das von einer der Funktionen zur Bilderzeugung, z. B. imagecreatetruecolor(), zurückgegeben wurde.

    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.
    IMG_EFFECT_MULTIPLY
    Overlays with a multiply effect.

    Rückgabewerte

    Gibt bei Erfolg true zurück. Bei einem Fehler wird false zurückgegeben.

    Changelog

    Version Beschreibung
    8.0.0 image erwartet nun eine GdImage-Instanz; vorher wurde eine gültige gd-Ressource erwartet.
    7.2.0 Added IMG_EFFECT_MULTIPLY (requires system libgd >= 2.1.1 or the bundled libgd).

    Beispiele

    Beispiel #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);
    ?>

    Das oben gezeigte Beispiel erzeugt eine ähnliche Ausgabe wie:

    Output of example : imagelayereffect()
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    User Contributed Notes 4 notes

    up
    1
    rx
    10 years ago
    IMG_EFFECT_OVERLAY doesn't work in PHP 5.6.0 with GD version: 2.1.0-alpha.
    up
    0
    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.
    up
    -1
    [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);

    ?>
    up
    -1
    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.
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