IGN layer

Like this: https://www.randopitons.re/randonnee/1009-toboggans-fleurs-jaunes-bassin-roche-bras-rouge

Looks like there’s a plugin for it: https://github.com/mylen/leaflet.TileLayer.WMTS

As a rule, I’ve been avoiding adding plugins to my plugin (difficult to maintain, and I feel like I’d be taking credit for their work). But you should be able to customize your site with some amount of effort.

You could add a new shortcode :

add_shortcode('leaflet-wmts', array(&$this, 'wmts_shortcode'));

Register (and enqueue) the wmts js library:

wp_register_script('leaflet_wmts_js', '/leaflet-tilelayer-wmts.js', Array(), $version, true);

And basically copy/edit the map_shortcode script:

wp_enqueue_script('leaflet_wmts_js');

            $content = '<div id="leaflet-wordpress-map-'.$leaflet_map_count.'" class="leaflet-wordpress-map" style="height:'.$height.'; width:'.$width.';"></div>';
            $content .= "<script>
            WPLeafletMapPlugin.add(function () {
                var map,
                    baseURL = '{$tileurl}',
                    base = new L.TileLayer.WMTS( baseURL ,
                               {
                                   layer: 'GEOGRAPHICALGRIDSYSTEMS.MAPS.SCAN-EXPRESS.STANDARD',
                                   style: 'normal',
                                   tilematrixSet: 'PM',
                                   format: 'image/jpeg',
                                   attribution: '<a href=\'https://github.com/mylen/leaflet.TileLayer.WMTS\'>GitHub</a>&copy; <a href=\'https://www.ign.fr\'>IGN</a>'
                               }
                              );

                map = L.map('leaflet-wordpress-map-{$leaflet_map_count}',
                    {
                        layers: [base],
                        zoomControl: {$zoomcontrol},
                        scrollWheelZoom: {$scrollwheel}
                    }).setView([{$lat}, {$lng}], {$zoom});";

…etc.

Then your shortcode could be [leaflet-wmts tileurl="tile-url-here.com"].

Thank you for your answer.
An Idea for the result with another solution (my website)
https://www.slackline974.org/ti-slack7/

I’m a beginner in Js and php, but I learn to understand, and I will try to succeed with your indication.

Thank you again, I hope to be as good like you one day! ??