Fix theme supports for themes without theme.json

[oandregal]

Fixes #34931
Fixes https://wordpress.org/support/topic/gutenberg-plugin-over-rides-custom-editor-color-palette/

#34334 introduced a bug by which settings provided via theme supports were not passed to the editor for themes without theme.json supports. This resulted in bugs like the palette of the theme not showing in the editor (it was shown the core palette instead) or that a plugin could not enable the custom-line-height support.

Tests

Activate TT1-blocks: a theme with theme.json support.

• Visit the front end. Check the content of global-styles-inline-css is: both core & theme presets (classes and variables), the block gap styles (see), the theme styles.
• Visit the editor and verify that the editor palette is the theme palette.

Activate the TwentyTwentyOne theme: a theme without theme.json but with experimental-link-color support.

• Visit the front end. Check the content of global-styles-inline-css is both core & theme presets (classes and variables).
• Visit the editor and verify that the editor palette is the theme palette.

Activate the TwentyTwenty theme: a theme without theme.json and no experimental-link-color support.

• Visit the front end. Check the content of global-styles-inline-css is the core presets (classes & variables).
• Visit the editor and verify that the editor palette is the theme palette.
• Enable the custom-line-height and verify the control is shown in the editor. See full instructions or paste the following code in the global-styles.php file:

function test_modify_theme_support() {
	add_theme_support( 'custom-line-height' );
}
add_action( 'after_setup_theme', 'test_modify_theme_support', 11 );

[oandregal]

With this PR the stylesheet would contain the theme presets as well, which is not the expected behavior #34334

Themes without theme.json and no experimental-link-color support either: the stylesheet contains the core presets.

I'm looking at alternatives.

[oandregal]

Pushed the necessary changes to make it work in all scenarios.

[youknowriad]

Are we adding more complexity to the caller by adding new options here instead of absorbing the logic inside the class? Maybe this is not the right level of abstraction I'm looking for. When I want the stylesheet of a theme, why should I need to specify a "type" (meaning do we have dedicated use case to retrieve two different stylesheets for the same theme) or "origins"

[oandregal]

meaning do we have a dedicated use case to retrieve two different stylesheets for the same theme

Yeah, we have. The front enqueues a single stylesheet with all styles but the block editor needs two different stylesheets: one with the block styles that will be wrapped by .editor-styes-wrapper and the other with the CSS Custom Properties that won't be wrapped so they're available to the UI controls in the sidebar.

[oandregal]

I'm troubled about the origins as well. However, this is the result of having added them to the existing format for each preset. We still have use cases when we only want one preset (stylesheet for themes without theme.json support, settings from the theme, etc).

I'll continue with the explorations at #34843 to create a higher-level API for consumers.

[youknowriad]

How can we test this to avoid regressions?

[youknowriad]

the block gap styles (see)

The block gap styles are not there but I think it's the right thing since now they are opt-in.

[youknowriad]

This is working as advertised (testing instructions).

A think some documentation or effort to clarify the backend APIs for themes would be great. #34843 is a good start in that aspect.

[chad1008]

Being newer to the code base, I won't speak to the specifics of how the change is implemented, but it does test well, and fixes the issue raised with theme_support declarations on themes without a theme.json. 👍

Thanks @oandregal!

[oandregal]

This has been cherry-picked to the release/11.5 branch.

[dennisheiden]

Thanks folks, this really saved us hours of overtime and helps planning for theme.json implementation in our theme.

[oandregal]

How can we test this to avoid regressions?

I'm adding tests for this at #34998