Use options callback to get supported layers and providers.

src/Listener/Dca/LayerDcaListener.php

@@ -112,6 +112,26 @@ class LayerDcaListener extends AbstractListener
         $this->labelRenderer = $labelRenderer;
     }
 
+    /**
+     * Get layer options.
+     *
+     * @return array
+     */
+    public function getLayerOptions(): array
+    {
+        return array_keys($this->layers);
+    }
+
+    /**
+     * Get tile provider options.
+     *
+     * @return array
+     */
+    public function getProviderOptions(): array
+    {
+        return array_keys($this->tileProviders);
+    }
+
     /**
      * Get variants of the tile provider.
      *

src/Resources/contao/dca/tl_leaflet_layer.php

@@ -286,7 +286,7 @@ $GLOBALS['TL_DCA']['tl_leaflet_layer'] = [
                 'chosen'             => true,
                 'helpwizard'         => true,
             ],
-            'options'   => array_keys($GLOBALS['LEAFLET_LAYERS']),
+            'options_callback'   => ['netzmacht.contao_leaflet_maps.listeners.dca.layer', 'getLayerOptions'],
             'reference' => &$GLOBALS['TL_LANG']['leaflet_layer'],
             'sql'       => "varchar(32) NOT NULL default ''",
         ],
@@ -312,7 +312,7 @@ $GLOBALS['TL_DCA']['tl_leaflet_layer'] = [
                 'submitOnChange'     => true,
                 'chosen'             => true,
             ],
-            'options'   => array_keys($GLOBALS['LEAFLET_TILE_PROVIDERS']),
+            'options_callback' => ['netzmacht.contao_leaflet_maps.listeners.dca.layer', 'getProviderOptions'],
             'sql'       => "varchar(32) NOT NULL default ''",
         ],
         'tile_provider_variant'          => [