imagesavealpha
(PHP 4 >= 4.3.2, PHP 5, PHP 7, PHP 8)
imagesavealpha — Whether to retain full alpha channel information when saving PNG images
Description
imagesavealpha() sets the flag which determines whether to retain full alpha channel information (as opposed to single-color transparency) when saving PNG images.
Alphablending has to be disabled (imagealphablending($im, false))
to retain the alpha-channel in the first place.
Parameters
-
image -
A GdImage object, returned by one of the image creation functions, such as imagecreatetruecolor().
-
enable -
Whether to save the alpha channel or not. Defaults to
false.
Return Values
Returns true on success or false on failure.
Changelog
| Version | Description |
|---|---|
| 8.0.0 |
image expects a GdImage
instance now; previously, a resource was expected.
|
Examples
Example #1 Basic imagesavealpha() Usage
<?php
// Load a png image with alpha channel
$png = imagecreatefrompng('./alphachannel_example.png');
// Turn off alpha blending
imagealphablending($png, false);
// Do desired operations
// Set alpha flag
imagesavealpha($png, true);
// Output image to browser
header('Content-Type: image/png');
imagepng($png);
imagedestroy($png);
?>
See Also
- imagealphablending() - Set the blending mode for an image
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