Hooks & filters

Ultimate Watermark exposes actions and filters across both plugins so you can add behaviour without forking. This page lists the most useful ones with file:line references.

Some marketing-mentioned hooks are subscribed but never fired in the current build. Those are flagged below as dead.

Bootstrap & lifecycle

Hook	Type	Args	When	File:line
ultimate_watermark_init	action	$plugin	After textdomain & migration.	Plugin.php:240
ultimate_watermark_admin_init	action	$plugin	Admin bootstrap.	Plugin.php:254
ultimate_watermark_enqueue_assets	action	$plugin	Inside enqueue cycle.	Plugin.php:268
ultimate_watermark_deactivate	action	$plugin	Plugin deactivation.	Plugin.php:285

add_action( 'ultimate_watermark_init', function ( $plugin ) {
    // Register custom watermark types or dynamic placeholders.
} );

Settings

Hook	Type	Use
ultimate_watermark_settings_config	filter	Modify settings field config rendered on the Settings page.
ultimate_watermark_settings_tabs	filter	Add tabs to the Settings page.
ultimate_watermark_load_frontend_assets	filter	Decide whether to enqueue right-click protection JS.

add_filter( 'ultimate_watermark_settings_config', function ( $config ) {
    $config['general']['my_extra_field'] = [
        'label'   => 'My extra field',
        'type'    => 'checkbox',
        'default' => '0',
    ];
    return $config;
} );

ultimate_watermark_settings_fields (subscribed in ProAdminManager.php:29) is dead — Free SettingsPage doesn't apply it. Use ultimate_watermark_settings_config instead.

Watermark builder form

Hook	Type	Use	File:line
ultimate_watermark_type_options	filter	Add new watermark types (beyond text/image).	AddWatermarkPage.php:645
ultimate_watermark_text_settings_fields	filter	Add fields to the text-watermark Appearance tab.	:665
ultimate_watermark_add_form_sections	filter	Add a new section to the Add Watermark form.	:994
ultimate_watermark_rules_sections	filter	Add to the Rules tab.	:1000
ultimate_watermark_form_tabs	filter	Add a new tab to the builder.	:1006
ultimate_watermark_after_textarea_field	action	Render extra HTML after a textarea field (Pro uses for placeholder helper).	:418

// Add a "Stamp profile" watermark type alongside text/image.
add_filter( 'ultimate_watermark_type_options', function ( $types ) {
    $types['stamp_profile'] = 'Stamp profile';
    return $types;
} );

Rules evaluator

Hook	Type	Args	Use	File:line
uwm_condition_types	filter	$types	Register a custom rule type.	AddWatermarkPage.php:1082
uwm_evaluate_condition	filter	$matches, $rule, $context	Evaluate a rule for a given image context.	RulesEvaluator.php:135
uwm_condition_context_value	filter	$value, $rule, $context	Override the value pulled from context for a rule.	:246
uwm_compare_values	filter	$matches, $left, $operator, $right	Override comparison logic for a rule.	:278

See Conditional rules → Custom rule types via filter for a full example.

Watermark data resolver

Hook	Type	Use	File:line
ultimate_watermark_sanitize_type	filter	Sanitize the type value during save.	WatermarkDataResolver.php:95
ultimate_watermark_before_normalize_data	filter	Modify raw data before normalisation.	:131
ultimate_watermark_after_normalize_data	filter	Modify normalised data before persistence.	:198
ultimate_watermark_sanitized_data	filter	Final sanitization pass.	WatermarkAjaxHandler.php:210

Save lifecycle

Hook	Type	Args	When
ultimate_watermark_saved	action	$watermark_id, $data	After save (WatermarkAjaxHandler.php:574).
ultimate_watermark_security_violation	action	$type, $context	Security guard tripped.

add_action( 'ultimate_watermark_saved', function ( $id, $data ) {
    // Sync watermark to a CDN edge config.
}, 10, 2 );

Processors

Hook	Type	Args	Use	File:line
ultimate_watermark_apply_custom_type	action	$image, $watermarkData, $type	Apply a custom raster type that GD/Imagick processors don't know.	GDWatermarkProcessor.php:294
ultimate_watermark_handle_custom_type	filter	$result, $image, $data, $type	Return a non-false value to short-circuit and supply your own rendered image.	:279

add_filter( 'ultimate_watermark_handle_custom_type', function ( $result, $image, $data, $type ) {
    if ( $type !== 'qr' ) return $result;
    // ... render QR onto $image, return modified GD/Imagick handle ...
    return $image;
}, 10, 4 );

Frontend / data

Hook	Type	Use	File:line
ultimate_watermark_load_frontend_assets	filter (bool)	Whether to load right-click / drag-protection JS.	AssetManager.php:130
ultimate_watermark_build_data	filter	Tweak the data passed to the frontend (e.g. extra image URLs).	WatermarkHelper.php:168
ultimate_watermark_statistics	filter	Modify stats for the Analytics page.	WatermarkHelper.php:873

Pro: dynamic content

Hook	Type	Args	Use
ultimate_watermark_pro_register_dynamic_types	action	$manager	Register additional placeholder types.
ultimate_watermark_pro_resolve_placeholder	filter	($value, $placeholder, $data)	Replace what a placeholder renders.

add_filter( 'ultimate_watermark_pro_resolve_placeholder', function ( $value, $placeholder, $data ) {
    if ( $placeholder === 'order_id' && ! empty( $data['post_id'] ) ) {
        return get_post_meta( $data['post_id'], '_order_id', true );
    }
    return $value;
}, 10, 3 );

License updater (Pro)

Hook	Type	Use
in_plugin_update_message-{$file}	action	Custom update message row (WP core).
edd_sl_api_request_verify_ssl	filter	SSL verify for EDD updater.
https_local_ssl_verify	filter	License HTTP SSL switch.

Hooks that look like hooks but aren't

The following are subscribed in code but never fired — flagged for documentation honesty:

Hook	Reason
ultimate_watermark_before_apply	Pro DynamicWatermarkProcessor.php:22 subscribes; no do_action exists in either plugin. Treat as no-op.
ultimate_watermark_admin_enqueue_scripts	Pro ProPlugin.php:117 subscribes; never fired. The real admin enqueue is ProAdminManager::enqueueAssets.
ultimate_watermark_settings_fields	Pro ProAdminManager.php:29 subscribes; the free SettingsPage doesn't apply it. Use ultimate_watermark_settings_config instead.

Tip: discover all hooks at runtime

Drop this in wp-content/mu-plugins/uw-hook-trace.php:

<?php
add_action( 'all', function ( $hook_name ) {
    if ( strpos( $hook_name, 'ultimate_watermark' ) === 0
      || strpos( $hook_name, 'uwm_' ) === 0 ) {
        error_log( "[Ultimate Watermark hook] $hook_name" );
    }
} );

This logs every plugin hook that fires during a request.

Where to go next

• 🎯 Conditional rules — custom rule type recipes.
• ⚙️ Global settings — settings filter usage.
• 🔌 REST & WP integration — how the plugin hooks WP core.