Custom header images won’t appear when set to random

I’m using a custom theme, developed from Boilerplate (some time ago). I noticed that the header images work fine when set statically, but fail to appear when set to random. I tried switching themes, and realized the same issue happens with Boilerplate, as well as Twentytwelve. Twentyten worked though, so I copied its code to my theme, and STILL it doesn’t work!

My functions.php contains:

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    // The custom header business starts here.

$custom_header_support = array(
    // The default image to use.
    // The %s is a placeholder for the theme template directory URI.
    'default-image' => '%s/images/headers/starkers.png',
    // The height and width of our custom header.
    'width' => 760,
    'height' => 280,
    // Don't support text inside the header image.
    'header-text' => false,
    // Callback for styling the header preview in the admin.
    'admin-head-callback' => '',
);

add_theme_support( 'custom-header', $custom_header_support );

if ( ! function_exists( 'get_custom_header' ) ) {
    // This is all for compatibility with versions of WordPress prior to 3.4.
    define( 'HEADER_TEXTCOLOR', '' );
    define( 'NO_HEADER_TEXT', true );
    define( 'HEADER_IMAGE', $custom_header_support['default-image'] );
    define( 'HEADER_IMAGE_WIDTH', $custom_header_support['width'] );
    define( 'HEADER_IMAGE_HEIGHT', $custom_header_support['height'] );
    add_custom_image_header( '', $custom_header_support['admin-head-callback'] );
    add_custom_background();
}

// We'll be using post thumbnails for custom header images on posts and pages.
// We want them to be 940 pixels wide by 198 pixels tall.
// Larger images will be auto-cropped to fit, smaller ones will be ignored. See header.php.
set_post_thumbnail_size( $custom_header_support['width'], $custom_header_support['height'], true );

// ... and thus ends the custom header business.


// Default custom headers packaged with the theme. %s is a placeholder for the theme template directory URI.
register_default_headers( array(
    'berries' => array(
        'url' => '%s/images/headers/starkers.png',
        'thumbnail_url' => '%s/images/headers/starkers-thumbnail.png',
        /* translators: header image description */
        'description' => __( 'Boilerplate', 'boilerplate' )
    )
) );
}
endif;

Basically copied verbatim.

And my header.php:

<?php
    // The header image
    // Check if this is a post or page, if it has a thumbnail, and if it's a big one
    if ( is_singular() &&
            has_post_thumbnail( $post->ID ) &&
            ( /* $src, $width, $height */ $image = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), array( HEADER_IMAGE_WIDTH, HEADER_IMAGE_WIDTH ) ) ) &&
            $image[1] >= HEADER_IMAGE_WIDTH ) :
        // Houston, we have a new header image!
        echo get_the_post_thumbnail( $post->ID, 'post-thumbnail' );
    elseif (get_header_image()) : ?>
    <img src="<?php header_image(); ?>" width="<?php echo HEADER_IMAGE_WIDTH; ?>" height="<?php echo HEADER_IMAGE_HEIGHT; ?>" alt="" />
<?php endif; // end check for featured image or standard header 
?>

I’m JUST about out of my mind with it now—is there something I’m missing, maybe? Or a conflict I haven’t noticed?

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2 comments

  1. Checked the code and it looks like the random header image functionality is happening inside get_header_image(). So the issue could be one of the following:

    1. Your elseif never gets executed. In other words, the if condition always evaluates to true and get_the_post_thumbnail() takes care of generating the image.
    2. Your theme does not support enabled for either custom-header, default-image, or both.

    For a quick way to diagnose exactly what’s happening I would put debugging messages everywhere in your header.php to see what’s going on.

    Here’s the source code of get_header_image() for reference.

    function get_header_image() {
        $url = get_theme_mod( 'header_image', get_theme_support( 'custom-header', 'default-image' ) );
    
        if ( 'remove-header' == $url )
            return false;
    
        if ( is_random_header_image() )
            $url = get_random_header_image();
    
        return esc_url_raw( set_url_scheme( $url ) );
    }
    

    Edit: just found something. Try adding default-image param to your array for add_theme_support call, like so:

    $custom_header_support = array(
        // The default image to use.
        // The %s is a placeholder for the theme template directory URI.
        'default-image' => '%s/images/headers/starkers.png',
        // The height and width of our custom header.
        'width' => 760,
        'height' => 280,
        // Don't support text inside the header image.
        'header-text' => false,
        // Callback for styling the header preview in the admin.
        'admin-head-callback' => '',
        'random-default' => true
    );
    

    Note: This link was super-useful in understanding which parameter is responsible for enabling random images in themes.