Help with GD library

[JeremyCanada26]

I'm using the GD library to manipulate a png image and I'd like to know how to get access to a byte array of the data so that I can use a third party function that takes in a png bytearray and sends it off to a webservice for storage.

 

//fetch an image from the web
$image = imagecreatefrompng($url);

//I do other GD manipulations with the $image resource above so I need it to come in as an image resource
doOtherStrangeThings();

// where $width and $height are the dimensions of the final image
$final_img = imagecreate($width, $height);

//get access to the bytearray ????
$finalImageByteArray = imagepng($image, "0", PNG_NO_FILTER)

//save the new image to third party storage service, must be a png bytearray
$this->_saveImage($finalImageByteArray);

 

The above code generates an error message for me. imagepng(): Unable to open '0' for writing: Permission denied but i'm not trying to write the file, I want to get access to the image resource as a bytearray. It's already a png image so I suspect it has the png header already in tact, etc

[GoneNowBye]

the second paramater is for saving files

you need this:

 

function OutputImage($img) 
{
ob_start();
imagejpeg($img, null, 100);
$page = ob_get_contents();
ob_end_clean(); // use ob_end_clean if you don't want to display the image  
return $page;
}

[JeremyCanada26]

the second paramater is for saving files

you need this:

 

function OutputImage($img) 
{
ob_start();
imagejpeg($img, null, 100);
$page = ob_get_contents();
ob_end_clean(); // use ob_end_clean if you don't want to display the image  
return $page;
}

 

I will definitely try this when I get home. I actually require a png image so i'll probably try using the imagepng($img, null, PNG_NO_FILTER);

 

if that works, your a genius

 

[JeremyCanada26]

The third party storage service that I'm using is amazon s3 and I'm using this php class here, http://undesigned.org.za/2007/10/22/amazon-s3-php-class

 

I notice there is a putObject that can take an input resource. Maybe I can use that instead of the first method that takes in a bytearray?

[GoneNowBye]

i can't tell you sorry, never used it.

 

[JeremyCanada26]

The documentation for the s3 php class says it can take an input resource but it looks like it might be only for file resources and not image resources.

 

http://undesigned.org.za/2007/10/22/amazon-s3-php-class/documentation#inputResource

 

it says

 

 

inputResource (resource &$resource, integer $bufferSize, [string $md5sum = '']) Back to top

 

Create an input array for pubObject() with a resource

 

Example:

 

<?php

 

    $file = "file.txt";

    $input = $s3->inputResource(fopen($file, "rb"), filesize($file));

    if (S3::putObject($input, $bucket, $uri, S3::ACL_PUBLIC_READ)) {

        echo "File uploaded.";

    } else {

        echo "Failed to upload file.";

    }

 

?>

 

 

Does anyone know how to convert that code to use an image resource instead of a file resource?

[JeremyCanada26]

the second paramater is for saving files

you need this:

 

function OutputImage($img) 
{
ob_start();
imagejpeg($img, null, 100);
$page = ob_get_contents();
ob_end_clean(); // use ob_end_clean if you don't want to display the image  
return $page;
}

 

Ok, I finally got home to try this and now my image is not readable so something went wrong. I tried both with your imagejpeg($img, null, 100) as well as with imagepng($img, NULL, 4); and both produce unreadable png images that do not work.