Markdown Renderer for GitHub Hooks Reference

This reference lists the public WordPress hooks exposed by Markdown Renderer for GitHub. Use these hooks from a theme, site-specific plugin, or add-on plugin when you need to customize rendering, multilingual behavior, asset loading, SEO output, settings, metadata, or performance features without editing the plugin.

Hook callbacks should keep WordPress conventions: return the same type documented by the filter, escape output when you generate markup, and keep expensive work out of high-frequency rendering hooks.

Quick Reference

Rendering and Output

Hook	Type	Signature	Purpose
`gfmr_pre_render_markdown`	Filter	`string $content, array $context`	Modify Markdown before the renderer builds HTML.
`gfmr_render_markdown`	Filter	`string $output, string $content, array $context`	Modify final shortcode/content-rendered HTML.
`gfmr_after_render`	Action	`string $output, string $content, array $context`	Run side effects after Markdown rendering completes.
`gfmr_block_attributes`	Filter	`array $attributes`	Adjust block attributes before block rendering.
`gfmr_block_render_output`	Filter	`string $output, array $attributes, string $content`	Modify rendered block HTML.
`gfmr_iframe_safe_mode`	Filter	`bool $enabled`	Enable or disable iframe safe mode in block configuration.

Diagrams, Syntax Highlighting, and Performance

Hook	Type	Signature	Purpose
`gfmr_chart_image_ssr_enabled`	Filter	`bool $enabled`	Enable or disable front-end Chart.js image baking.
`gfmr_use_prerendered_diagrams`	Filter	`bool $use_prerendered, array $attributes`	Force or bypass baked diagram HTML for a block.
`gfmr_shiki_languages`	Filter	`array $languages`	Extend the list of Shiki languages.
`gfmr_shiki_themes`	Filter	`array $themes`	Extend available Shiki themes.
`gfmr_worker_line_threshold`	Filter	`int $threshold`	Set the minimum code line count for Worker rendering.
`gfmr_worker_config`	Filter	`array $worker_config`	Modify Worker Manager settings.
`gfmr_enable_workers`	Filter	`bool $enabled`	Enable or disable Web Workers for syntax highlighting.
`gfmr_enable_service_worker`	Filter	`bool $enabled`	Enable or disable the vendor-caching Service Worker.
`gfmr_exclude_heavy_pages_from_prerender`	Filter	`bool $enabled`	Exclude heavy diagram pages from browser prerender rules.
`gfmr_compression_health_assets`	Filter	`array $assets`	Customize bundles checked by the compression Site Health test.

Multilingual and Language Switcher

Hook	Type	Signature	Purpose
`gfmr_multilingual_enabled`	Filter	`bool $enabled`	Enable or disable multilingual features.
`gfmr_multilingual_enqueue_assets`	Filter	`bool $enqueue`	Control multilingual asset loading.
`gfmr_multilingual_url_enabled`	Filter	`bool $enabled`	Enable or disable path-based multilingual URL rewriting.
`gfmr_multilingual_taxonomy_current_language`	Filter	`string $language, int $post_id, array $settings`	Override current language detection for multilingual taxonomy logic.
`gfmr_language_switcher_enabled`	Filter	`bool $enabled, string $context, array $args`	Disable the language switcher before HTML is generated.
`gfmr_language_flag_map`	Filter	`array $map`	Customize language-code to flag mapping.
`gfmr_language_name_map`	Filter	`array $names`	Customize language-code to display-name mapping.
`gfmr_featured_image_post_types`	Filter	`array $post_types`	Select post types that support per-language featured images.
`gfmr_featured_image_thirdparty_multilingual_active`	Filter	`bool $active`	Override third-party multilingual plugin detection for featured images.

SEO and Schema

Hook	Type	Signature	Purpose
`gfmr_meta_description_enabled`	Filter	`bool $enabled`	Enable or disable per-language meta descriptions.
`gfmr_meta_description_post_types`	Filter	`array $post_types`	Select post types that support per-language descriptions.
`gfmr_meta_description`	Filter	`string $description, WP_Post $post, string $lang`	Modify the resolved meta description.
`gfmr_meta_description_fallback_to_default`	Filter	`bool $fallback`	Control fallback to the default language description.
`gfmr_meta_description_output_og`	Filter	`bool $output`	Control `og:description` output.
`gfmr_meta_description_output_twitter`	Filter	`bool $output`	Control `twitter:description` output.
`gfmr_meta_description_thirdparty_multilingual_active`	Filter	`bool $active`	Override third-party multilingual plugin detection.
`gfmr_meta_description_seo_plugin_active`	Filter	`bool $active`	Override SEO plugin conflict detection.
`gfmr_meta_description_theme_handles`	Filter	`bool $active`	Override theme-level meta description detection.
`gfmr_schema_data`	Filter	`array $schema, WP_Post $post`	Modify generated structured data.
`gfmr_breadcrumb_schema`	Filter	`array $list, WP_Post $post`	Modify generated breadcrumb schema.

Settings, Extensions, Metadata, and Licensing

Hook	Type	Signature	Purpose
`gfmr_loaded`	Action	`string $version`	Initialize add-ons after the plugin loads.
`gfmr_registered_addons`	Filter	`array $addons`	Register add-ons with the extension API.
`gfmr_feature_flags`	Filter	`array $flags`	Register or override feature flags.
`gfmr_frontend_config`	Filter	`array $config_data`	Extend localized front-end configuration.
`gfmr_enqueue_assets`	Action	`string $context`	Enqueue add-on assets for `frontend` or `admin`.
`gfmr_settings_tabs_list`	Filter	`array $tabs`	Add or modify settings tabs.
`gfmr_settings_tabs`	Action	`string $page_slug, array $tabs`	Render settings tab UI.
`gfmr_settings_sections`	Action	`string $page_slug, string $tab_id`	Render custom settings sections for a tab.
`gfmr_post_list_column_post_types`	Filter	`array $post_types`	Choose post types that receive the GFMR language column.
`gfmr_metadata_saved`	Action	`int $post_id, array $metadata`	React after code block metadata is saved.
`gfmr_metadata_get_metadata`	Filter	`array $metadata, int $post_id`	Modify stored code block metadata when read.
`gfmr_is_pro_active`	Filter	`bool $active`	Tell free-version code that Pro features are active.
`gfmr_pro_feature_registered`	Action	`string $feature_id, array $feature`	React when a Pro feature is registered.
`gfmr_pro_feature_unregistered`	Action	`string $feature_id`	React when a Pro feature is removed.
`gfmr_pro_license_changed`	Action	No parameters	React after Pro license state changes.

Common Examples

Disable the Language Switcher

This filter runs before language-switcher HTML is generated, so it avoids unnecessary rendering work.

php

add_filter(
    'gfmr_language_switcher_enabled',
    function ( bool $enabled, string $context, array $args ): bool {
        if ( is_singular( 'docs' ) && 'header' === $context ) {
            return false;
        }

        return $enabled;
    },
    10,
    3
);

Customize Mermaid or Chart Output

Use the block output filter when you need to add wrapper attributes around rendered diagram content. Always return sanitized HTML.

php

add_filter(
    'gfmr_block_render_output',
    function ( string $output, array $attributes, string $content ): string {
        if ( false === strpos( $content, '```mermaid' ) ) {
            return $output;
        }

        return '<div class="docs-diagram-frame">' . $output . '</div>';
    },
    10,
    3
);

To bypass baked diagram HTML for a particular block, use gfmr_use_prerendered_diagrams.

php

add_filter(
    'gfmr_use_prerendered_diagrams',
    function ( bool $use_prerendered, array $attributes ): bool {
        if ( ! empty( $attributes['forceLiveDiagramRender'] ) ) {
            return false;
        }

        return $use_prerendered;
    },
    10,
    2
);

Register a Shiki Language or Theme

php

add_filter(
    'gfmr_shiki_languages',
    function ( array $languages ): array {
        $languages[] = 'toml';
        return array_values( array_unique( $languages ) );
    }
);

add_filter(
    'gfmr_shiki_themes',
    function ( array $themes ): array {
        $themes['docs-dark'] = 'github-dark-dimmed';
        return $themes;
    }
);

Tune Worker-Based Syntax Highlighting

The Worker threshold controls when long code blocks move off the main thread.

php

add_filter(
    'gfmr_worker_line_threshold',
    function (): int {
        return 12;
    }
);

Filter Rendered Markdown Output

php

add_filter(
    'gfmr_render_markdown',
    function ( string $output, string $content, array $context ): string {
        if ( empty( $context['post_id'] ) ) {
            return $output;
        }

        return str_replace(
            'class="gfmr-markdown-container"',
            'class="gfmr-markdown-container docs-rendered-markdown"',
            $output
        );
    },
    10,
    3
);

Add Schema Metadata

php

add_filter(
    'gfmr_schema_data',
    function ( array $schema, WP_Post $post ): array {
        if ( has_term( 'reference', 'category', $post ) ) {
            $schema['about'] = 'Developer documentation';
        }

        return $schema;
    },
    10,
    2
);

Register an Add-On

php

add_filter(
    'gfmr_registered_addons',
    function ( array $addons ): array {
        $addons['my-company-docs'] = array(
            'name'    => 'My Company Docs Enhancer',
            'version' => '1.0.0',
            'author'  => 'My Company',
        );

        return $addons;
    }
);

Markdown Renderer for GitHub Hooks Reference ​

Quick Reference ​

Rendering and Output ​

Diagrams, Syntax Highlighting, and Performance ​

Multilingual and Language Switcher ​

SEO and Schema ​

Settings, Extensions, Metadata, and Licensing ​

Common Examples ​

Disable the Language Switcher ​

Customize Mermaid or Chart Output ​

Register a Shiki Language or Theme ​

Tune Worker-Based Syntax Highlighting ​

Filter Rendered Markdown Output ​

Add Schema Metadata ​

Register an Add-On ​