Custom header "Hide image" button not displayed when randomizing images via theme setup

[webmandesign]

DESCRIPTION

When registering multiple ​custom header images via theme code, and setting them to randomize (by enabling random-default custom header attribute), there is no "Hide image" button displayed. But the image should be displayed even in this case.

The only way to enable "Hide image" button is to set default-image attribute during custom header registration in the theme code. But this actually effectively disables images randomization...

---

HOW TO TEST/REPRODUCE

Append this code to Twenty Nineteen theme's functions.php file (without opening <?php) to test - see the code comments for more details:

<?php

function test_custom_header_hide_button() {

        /**
         * Registering custom header support.
         *
         * The issue description:
         * ======================
         * When 'default-image' is set, there is "Hide image" button
         * displayed in "Header Image" section of customizer. But now
         * the 'random-default' does not work.
         * On the other side, if 'default-image' is not set, "Hide image"
         * button is not displayed in "Header Image" section of customizer
         * when we have 'random-default' enabled.
         * In both cases the "Hide image" button should be available.
         *
         * How to test:
         * ============
         * Simply (un)comment the 'default-image' to see the difference
         * in "Header Image" section of customizer.
         * But do not save/publish your customizer as we are testing
         * how the theme code is treated in customizer!
         */
        add_theme_support( 'custom-header', array(
                // 'default-image' => 'https://via.placeholder.com/1000x200/000099/ffffff?text=Image+default',
                'random-default' => true,

                // Irrelevant, but required options:
                'height' => 200,
                'width'  => 1000,
        ) );

        // Registering some images to randomize from:
        register_default_headers( array(
                'image-1' => array(
                        'url'           => 'https://via.placeholder.com/1000x200/990000/ffffff?text=Image+1',
                        'thumbnail_url' => 'https://via.placeholder.com/250x50/990000/ffffff?text=Image+1',
                        'description'   => 'Image 1',
                ),
                'image-2' => array(
                        'url'           => 'https://via.placeholder.com/1000x200/009900/ffffff?text=Image+2',
                        'thumbnail_url' => 'https://via.placeholder.com/250x50/009900/ffffff?text=Image+2',
                        'description'   => 'Image 2',
                ),
        ) );

}
add_action( 'after_setup_theme', 'test_custom_header_hide_button' );
// Display the custom header in theme footer for preview:
add_action( 'wp_footer', 'the_custom_header_markup' );

---

SCREENSHOT

[webmandesign]

Preview of the issue with custom header registration in customizer

[dlh]

Hi @webmandesign, and (belated) thanks for this report.

The custom header API is far from my expertise. But, by my reckoning, the default for the header_image setting needs to be modified so that it returns random-default-image when random header images are going to be used. 46128.diff​ has that change. Would you be able to test the patch?

From my reading of the code and testing, the patch should respect themes that set random-image to false.

I don't think there needs to be a case where the default is random-uploaded-image, because is_random_header_image() won't return an uploaded image as a fallback, but my unfamiliarity could be misleading me about this point.