stream_preview_image() should stream with right mime type, if filter _load_image_to_edit_path change file with different mime type

[Hrohh]

Hi, im working on allowing image editor for PDF thumnbails https://core.trac.wordpress.org/ticket/62712.

in functiion stream_preview_image() in wp-admin/includes/image-edit.php - line 766
is function with filter

<?php
_load_image_to_edit_path( $post_id )

we can change filepath, but for example if we change to

metadata['sizes']['full']

which has mimetype image/jpg, function stream_preview_image() dont send image to browser. Bug is in

<?php
return wp_stream_image( $img, $post->post_mime_type, $post_id );

should be

<?php
return wp_stream_image( $img, $img['mime-type'], $attachment_id );

Trac ticket: https://core.trac.wordpress.org/ticket/62729

Introduced detailed PHPUnit tests for AJAX image cropping preview functionality. Made get_mime_type a public method and adjusted MIME type handling in stream_preview_image for better compatibility with image editors. These changes ensure more robustness in image handling and testing.

Trac ticket: [](https://core.trac.wordpress.org/ticket/62729)

[pbearne]

I have added some test but I was not able to test the header change in this ticket as the test suit does not seem to allow this
maybe someone else can help testing

Paul

[Hrohh]

I have nasty fix

<?php
// bug in wp_stream_image in image-edit.php, bad mime type
add_filter( 'image_editor_save_pre', 'core_thumbnail_generator_image_editor_save_pre', 10, 2 );
function core_thumbnail_generator_image_editor_save_pre( $image, $attachment_id ) {

    if ( did_action( 'wp_ajax_imgedit-preview' ) ) {
        if ( is_wp_error( $image->stream() ) ) {
            wp_die( -1 );
        } else {
            wp_die();
        }    
    }
}

[Hrohh]

Same bug is in

<?php
    function wp_save_image( $post_id ) {
        $post    = get_post( $post_id );
        $img     = wp_get_image_editor( _load_image_to_edit_path( $post_id, 'full' ) );
        $saved_image = wp_save_image_file( $new_path, $img, $post->post_mime_type, $post_id ); 

Cannot change mime_type.

[pbearne]

Replying to Hrohh:

Same bug is in

<?php
    function wp_save_image( $post_id ) {
        $post    = get_post( $post_id );
        $img     = wp_get_image_editor( _load_image_to_edit_path( $post_id, 'full' ) );
        $saved_image = wp_save_image_file( $new_path, $img, $post->post_mime_type, $post_id ); 

Cannot change mime_type.

OK we will need to add a filter where in the function should put this?

[pbearne]

I have moved the get_mine_type to after the filter returns so this should solve the problem stream_preview_image

[Hrohh]

Hi sir, sorry for long delay.

function wp_save_image is here =>
​https://github.com/WordPress/wordpress-develop/blob/626d9af280566d008ccf501952f119fb0ce61662/src/wp-admin/includes/image-edit.php#L904

relevant code is

<?php
   $post    = get_post( $post_id );
   $img     = wp_get_image_editor( _load_image_to_edit_path( $post_id, 'full' ) );
   $saved_image = wp_save_image_file( $new_path, $img, $post->post_mime_type, $post_id ); 

so with your patch is should be

<?php
   $post      = get_post( $post_id );
   $img       = wp_get_image_editor( _load_image_to_edit_path( $post_id, 'full' ) );
   $mime_type = $post->post_mime_type;
   if ( method_exists( $img, 'get_mime_type' ) ) {
       $mime_type = $img->get_mime_type();
   }

   $saved_image = wp_save_image_file( $new_path, $img, $mime_type, $post_id ); 

Thank you.

[pbearne]

@Hrohh the patch doesn't match the current code so I am confused as what you are trying to do

I can't see the filter that would change the mine type

can provide more info?

Paul

[Hrohh]

@pbearne If I change target image in filter in function _load_image_to_edit_path from jpg to avif for example
in wp_save_image_file this is not taken into account
$saved_image = wp_save_image_file( $new_path, $img, $post->post_mime_type, $post_id )

Thank you.

[pbearne]

@Hrohh can you provide an example of the filter that breaks the mine type

I am having problems recreating

Paul

[Hrohh]

@pbearne Hi Paul, like this

<?php
add_filter( 'load_image_to_edit_path', 'avif_load_image_to_edit_path', 10, 3 );
function avif_load_image_to_edit_path( $filepath, $attachment_id, $size ) {
    return str_replace( '.jpg', '.avif', $filepath );
}

wp_stream_image function will send image/jpeg instead image/avif.

Thank you.