A filter for wp_get_attachment_image() html output

[prionkor]

The function wp_get_attachment_image() is used to output image tags in WP sites. Currently it has a filter for attr but not filter on html output of the function. I am proposing a filter so plugin developers can modify its output.

An example use case:

Output of <picture> tag instead of <img> for supporting multiple format of images (jpeg, webp).

<picture>
   <source type="image/jpeg" src="foo.jpg" />
   <img src="foo.webp" alt="Bar" />
</picture>

Add wp_get_attachment_image filter in output of wp_get_attachment_image() Trac ticket https://core.trac.wordpress.org/ticket/50801

Trac ticket:

[prionkor]

Relevant discussion ​https://wordpress.stackexchange.com/questions/371881/how-to-host-different-file-formats-types-for-a-media-attachment-without-creating

Return a filter in wp_get_attachment_image(). Props to @prionkor for ​https://github.com/WordPress/wordpress-develop/pull/440. I initialized $attachment, add unit test, and filter docs.

Trac ticket: https://core.trac.wordpress.org/ticket/50801

@donmhico Thank you! Appreciate it!

[audrasjb]

patch refreshed against trunk

[Mista-Flo]

Patch looks good, unit tests are passing, thanks for the refresh @audrasjb

[antpb]

In the recent Media component meeting all agreed this is commit candidate. Marking commit so we don't forget. :)

[antpb]

I made some changes to the patch that I'd like to get some outside looks at. I've been talking this through with @garrett-eclipse and we landed on the below proposed patch. I've removed the @since in the parent function's doc block because we are covering the documentation in the new filter.

I've also matched the passed attributes for the parent function in the new filter so folks can override any of them. Happy to hear any feedback on that.

I'm removing commit only because I don't want it to be committed before we all agree this approach is best. I'm also blocked at the moment by some local tests failing due to an unrelated change here: https://core.trac.wordpress.org/ticket/49558#comment:12

[antpb]

50801 - 2

[Mista-Flo]

Patch looks good to me, slightly better hook

[audrasjb]

This new approach looks good to me as well, thanks @antpb 👍

[hellofromTonya]

The new approach looks good. My only suggestion is to remove the added $attachment = '' as it's no longer used outside of the if block or by the new filter.

<?php
function wp_get_attachment_image( $attachment_id, $size = 'thumbnail', $icon = false, $attr = '' ) {
        $attachment = '';

But this can be done when committing this patch.

[SergeyBiryukov]

In 49234:

Media: Introduce a filter for wp_get_attachment_image() HTML output.

Props prionkor, antpb, donmhico, audrasjb, Mista-Flo, hellofromTonya.
Fixes #50801.

Merged into WP Core in https://core.trac.wordpress.org/changeset/49234

Merged into WP Core in https://core.trac.wordpress.org/changeset/49234

[daisyo]

Dev note published: ​https://make.wordpress.org/core/2020/11/23/wordpress-and-php-8-0/