PHP Australia Conference 2015

imagecreatefrompng

(PHP 4, PHP 5)

imagecreatefrompngCreează o imagine nouă din fișier sau din URL

Descrierea

resource imagecreatefrompng ( string $filename )

imagecreatefrompng() returns an image identifier representing the image obtained from the given filename.

Sfat

Un URL poate fi utilizat în calitate de denumire a fișierului în această funcție dacă învelișurile fopen au fost activate. Accesați fopen() pentru mai multe detalii despre modul de specificare a denumirii fișierului. Accesați Supported Protocols and Wrappers pentru referințe la informații despre posibilitățile pe care le oferă diferite învelișuri, note despre utilizarea lor și informații despre variabile predefinite pe care le oferă.

Parametri

filename

Path to the PNG image.

Valorile întoarse

Întoarce un identificator de resursă de tip imagine în cazul succesului, FALSE în caz de erori.

Exemple

Example #1 Example to handle an error during loading of a PNG

<?php
function LoadPNG($imgname)
{
    
/* Attempt to open */
    
$im = @imagecreatefrompng($imgname);

    
/* See if it failed */
    
if(!$im)
    {
        
/* Create a blank image */
        
$im  imagecreatetruecolor(15030);
        
$bgc imagecolorallocate($im255255255);
        
$tc  imagecolorallocate($im000);

        
imagefilledrectangle($im0015030$bgc);

        
/* Output an error message */
        
imagestring($im155'Error loading ' $imgname$tc);
    }

    return 
$im;
}

header('Content-Type: image/png');

$img LoadPNG('bogus.image');

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

Exemplul de mai sus va afișa ceva similar cu:

imagecreatefrompng() example

Note

Avertizare

Versiunile PHP pentru Windows până la PHP 4.3.0 nu susțin accesarea fișierelor la distanță prin intermediul acestei funcții, chiar dacă allow_url_fopen este activată.

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User Contributed Notes 4 notes

up
15
Anonymous
10 years ago
If you're trying to load a translucent png-24 image but are finding an absence of transparency (like it's black), you need to enable alpha channel AND save the setting. I'm new to GD and it took me almost two hours to figure this out.

<?php
$imgPng
= imageCreateFromPng($strImagePath);
imageAlphaBlending($imgPng, true);
imageSaveAlpha($imgPng, true);

/* Output image to browser */
header("Content-type: image/png");
imagePng($imgPng);
?>
up
9
marcos at assl-site dot net
7 years ago
I had the same problem as jboyd1189 at yahoo dot com but I solve d it allocating more memory dynamically.

Usually the memory_limit var on php.ini is set to 8M. Unfortunately, the required amount of memory to manage a PNG image about 1000x1000 could be bigger !

The approach I used to solve the problem is:

1-Calculate the memory required by the image
2-Set the new memory_limit value
3-Create the PNG image and thumbnail
4-Restore the original value

1-The following value works for me:
$required_memory = Round($width * $height * $size['bits']);

Note that for JPEG the requirements are not the same:
http://es2.php.net/manual/en/function.imagecreatefromjpeg.php#60241

2-Use somthing like:
$new_limit=memory_get_usage() + $required_memory;
ini_set("memory_limit", $new_limit);

4-ini_restore ("memory_limit");
up
1
admin at wdfa dot co dot uk
5 years ago
When using imagecreatepng with alpha blending you will lose the blending.

To over come this use something like the following
<?php
$dstimage
=imagecreatetruecolor($width,$height);
$srcimage=imagecreatefrompng($src);
imagecopyresampled($dstimage,$srcimage,0,0,0,0, $width,$height,$width,$height);
?>
Where $width and $height are the width and height of the $src image.

This will create a true colour image then copy the png image to this true colour image and retain alpha blending.
up
-1
jboyd1189 at yahoo dot com
8 years ago
I was having a terrible time with the imagecreatefrompng function as it was working perfectly for one image and not at all for another.  After many hours of frustration, I discovered that the problem was the image size (number of pixels).  It appears that the maximum number of pixels this function will process is 1,040,000.  So, be sure that the pixel resolution of the image (eg. 1040 x 1000) does not exceed this value.
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