Dynamic SVG sizes for safe-svg WP plugin

dynamic-sizes.php

<?php

add_action('init', removeSafeSvgOnePixelFix');
function removeSafeSvgOnePixelFix()
{
    global $wp_filter;

    if (! class_exists('safe_svg')) {
        return;
    }

    if (! isset($wp_filter['wp_get_attachment_image_src']->callbacks[10])) {
        return;
    }

    $look_in = $wp_filter['wp_get_attachment_image_src']->callbacks[10];
    foreach ($look_in as $callback) {
        if (! is_array($callback['function'])) {
            continue;
        }

        $object = $callback['function'][0] ?? null;
        $method = $callback['function'][1] ?? null;
        if ($object instanceof \safe_svg && $method === 'one_pixel_fix') {
            remove_filter('wp_get_attachment_image_src', [$object, 'one_pixel_fix'], 10);
            return;
        }
    }
}

// Removes sizes in SVG metadata
add_filter('wp_generate_attachment_metadata', 'filterMetadata', 11, 2);

/**
 * Filters the generated attachment meta data.
 *
 * @param array<string,mixed> $metadata      An array of attachment meta data.
 * @param int   $attachment_id Current attachment ID.
 *
 * @return array<string,mixed> $metadata
 */
function filterMetadata(array $metadata, int $attachment_id): array
{
    $mime = get_post_mime_type($attachment_id);
    if ($mime === 'image/svg+xml') {
        // Removes unnecessary sizes for SVG (
        // Generates by safe_svg::skip_svg_regeneration();
        if (array_key_exists('sizes', $metadata)) {
            unset($metadata['sizes']);
        }
    }

    return $metadata;
}


// Generate size on request
add_filter('image_downsize', 'returnSvgSizes', 10, 3);

/**
 * Filters whether to preempt the output of image_downsize().
 *
 * Returning a truthy value from the filter will effectively short-circuit
 * down-sizing the image, returning that value instead.
 *
 * @param bool|array   $downsize Whether to short-circuit the image downsize.
 * @param int          $id       Attachment ID for image.
 * @param string|int[] $size     Requested image size. Can be any registered image size name, or
 *                               an array of width and height values in pixels (in that order).
 */
function returnSvgSizes($downsize, $id, $size)
{
    $mime = get_post_mime_type($id);
    if ($mime !== 'image/svg+xml') {
        return $downsize;
    }
    // This is where we need to get the dimensions. If they are not present, it will lead to unpredictable behavior.
    // For control, we can use a metadata filter.
    $meta = wp_get_attachment_metadata($id);
    if (! $meta) {
        return $downsize;
    }
    // 300x150 - Default size for <img>, <object>, <iframe> and inline <svg>
    $file_width  = $meta['width'] ?: 300;
    $file_height = $meta['height'] ?: 150;
    $file_url    = wp_get_attachment_url($id);
    // Custom handler for getting file url?
    if (! $file_url) {
        return $downsize;
    }
    $ratio = $file_width / $file_height;
    if (is_array($size)) {
        $width  = $size[0];
        $height = $size[1];
    } else {
        $additional_sizes = wp_get_additional_image_sizes();
        if (isset($additional_sizes[$size])) {
            $width  = $additional_sizes[$size]['width'];
            $height = $additional_sizes[$size]['height'];
        } else {
            $width  = $file_width;
            $height = $file_height;
        }
    }
    // Responsive: width or height are zero
    $width  = $width ?: $height * $ratio;
    $height = $height ?: $width / $ratio;
    // Zero size:  width and height are zero
    $width  = $width ?: $file_width;
    $height = $height ?: $file_height;
    
    $is_intermediate = ($size !== 'file');

    return [$file_url, $width, $height, $is_intermediate];
}