Replace GD resize function with Imagemagick.

I’m not 100% sure this is the solution, this essentially takes GD out of play, forcing ImageMagick to be used. If your function uses the editor object used by WP, this should work, but it’s not clear that is what’s happening. Easy enough to try and delete if it doesn’t work. Copy this code into a new empty PHP file and save it in wp-content/plugins/. Activate this “Force Imagick” plugin.

<?php
/**
 * Plugin Name: Force Imagick
 * Description: Stops GD image library from being used by default
 * Author: bcworkz
 * License: GPL2
 */
add_filter('wp_image_editors', 'fi_force_imagick');
function fi_force_imagick() {
   return array('WP_Image_Editor_Imagick');
}

Thank you bcworkz,

I will test this out. I hope it will work..

other than that if this does not work, can I switch out the “imagecopyresampled” function for imagicks resize function directly in plugin file.

From what I have been told, the resize function in imagick, does not strip away the exif of image. The code I posted uses imagecopyresampled, but I want it to use imagick:resize instead.

public function create_download_size( $size, $location=null ){

        $image_p = imagecreatetruecolor( $size['width'], $size['height'] );
        $image = imagecreatefromjpeg( $location );

        list( $current_image['width'], $current_image['height'] ) = getimagesize( $location );
        imagecopyresampled($image_p, $image, 0, 0, 0, 0, $size['width'], $size['height'], $current_image['width'], $current_image['height']);

        $destination_file = $this->tmp_dir . basename( $location );

        if ( ! file_exists( $destination_file ) ){
            wp_mkdir_p( dirname( $destination_file ) );
        }

Regards, mxfarsa

Looking at this code again, I really doubt the WP editor is being used, so my little plugin idea will not work. I’m not sure what you’re referring to by imagick:resize, perhaps Imagick::resizeImage()? That’s worth a try if your PHP installation has Imagck module loaded. Or try the WP version: WP_Image_Editor_Imagick::resize(). The parameters are different than imagecopyresampled(), some rearranging will be necessary.

Thank you for your answer bcworkz, and yes when I tried the plugin version it did not work.

So I need to alter the file to use imagemagick instead…. I′ll have to read up on php and these parts before i give it a try.

But right now the three parts i need to rewrite is

$image_p = imagecreatetruecolor( $size['width'], $size['height'] );
        $image = imagecreatefromjpeg( $location );

        list( $current_image['width'], $current_image['height'] ) = getimagesize( $location );
        imagecopyresampled($image_p, $image, 0, 0, 0, 0, $size['width'], $size['height'], $current_image['width'], $current_image['height']);

1. imagecreatetruecolor – need change
2. imagecreatefromjpeg – need change
3. imagecopyresampled – need change

these are all calling GD functions, but I need to read up on what functions I should call to use imagick instead.

The plugin gets the size variable from cart when a buyer selects one of three choices (large, medium, small) – upon checkout a resized copy of the image is created and put in a tmp dir, the original is not altered.

So the different sizes are only created temporaily when bought – not on upload, but how do I initate imagicks functions with the variables that are already in the file, because all the paths and locations will remain untouched.

The only function I need is to resize an exact copy of original in a smaller size, and make sure that the resized image still have all exif info unaltered.

Alot of questions here, and I am not in any way good with php code, but I will test after reading the php manual.

Or do you have some more information on how to initiate the imagick class and execute.

My webhotel has imagick installed so it should not be any problem on the server end.

I value your help bcworkz
Regards, mxfarsa

Your primary reference will be https://us2.php.net/manual/en/book.imagick.php, which you’ve probably found already, but just in case. There are examples of initiating the class and calling methods.

The snippet you posted looks like in may be from within a class definition, is this the case? I’m unsure how to use one class from within another. I’m sort of new to OOP, I know you are.

Somewhat of an issue is what ever changes you make would likely be lost when you upgrade this software. A proper approach will minimize what needs to be done to reinstate your modifications after an upgrade. It may be best to extend this class and override this one function. Maybe save that for later and first just do what’s easiest to confirm this is going to work at all.

I believe you should be able to simply substitute in the Imagick function you need, including the Imagick scope resolution (the Imagick:: part). Rearrange the parameters to work with the new function. I believe this is how to reference one class function from within another, but as I warned, OOP is new to me as well. You can’t always use class functions this way and I don’t know the reasoning of when you can and cannot. My best guess is it has to do with if this is used or not.

I’m pretty much up against the limits of my knowledge, but I will try to continue answering any questions you may have. In the mean time, happy learning, it will serve you well into the future.

Thank you bcworkz, I will read up on this at php manual – and I will test around to see if I get it to work…

I′ll post questions along the way ??

//mxfarsa