grinat / leaflet-simple-map-screenshoter

Leaflet plugin which take screenshot of map
MIT License
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'Cannot read properties of undefined' error when exporting updated map image after AJAX statement #33

Open RafaelSLopes opened 2 years ago

RafaelSLopes commented 2 years ago

(by Google Translator) I have a page that generates the first map with the default filters and the user can also apply filters to update the map. The problem is that when I update my map via AJAX instruction, I get an error alert

TypeError: Cannot read properties of undefined (reading 'style')

and which increases the amount of alerts as the user applies new filters. Images are generated normally even with the error. How can I solve this problem? Despite the problem, I really liked this library. It's quite flexible and effective.

My code below:

function generateMyMap(zoom, centerMap, title, dataSource, collectionDate, user) {
    // checks for authenticated user and applies temporary map name
    if (user) {
        mapUrl = "../assets/js/temp-geojson/" + user + "|geojson.js";
    } else {
        mapUrl = "../assets/js/temp-geojson/geojson.js";
    }

    // delete the old map before applying the new map with selected filters
    if (map && map.remove) {
        map.off();
        map.remove();
    }

    // generate map attributes
    map = L.map('map').setView(centerMap, zoom);
    map.spin(true);

    L.tileLayer('http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
        minZoom: 3,
        maxZoom: 18,
        attribution: '&copy; <a href="http://openstreetmap.org">OpenStreetMap</a> contributors',
        id: 'mapbox/light-v9',
        tileSize: 512,
        zoomOffset: -1
    }).addTo(map);

    // control that shows state info on hover
    var info = L.control();

    info.onAdd = function (map) {
        this._div = L.DomUtil.create('div', 'info');
        this.update();
        return this._div;
    };

    info.update = function (props) {
        this._div.innerHTML = '<h6><b>' + title + '</b></h6>' + (props ?
            '<b>' + props.local + '</b>: ' +
            '<br>' + props.values.toLocaleString() + '%'
            : '<span>Mouse over the desired location</span>');
    };

    info.addTo(map);

    // get color depending on selection value
    function getColor(d) {
        return d > 30 ? '#33C009' :
            d > 20 ? '#73D50B' :
                d > 10 ? '#ABEC08' :
                    d > 0 ? '#E1EB09' :
                        d > -10 ? '#F3BC01' :
                            d > -20 ? '#F3A201' :
                                d > -30 ? '#F36401' :
                                    '#F30101';
    }

    function style(feature) {
        return {
            weight: 2,
            opacity: 1,
            color: 'white',
            dashArray: '3',
            fillOpacity: 0.7,
            fillColor: getColor(feature.properties.values)
        };
    }

    function highlightFeature(e) {
        var layer = e.target;

        layer.setStyle({
            weight: 5,
            color: '#666',
            dashArray: '',
            fillOpacity: 0.7
        });

        if (!L.Browser.ie && !L.Browser.opera && !L.Browser.edge) {
            layer.bringToFront();
        }

        info.update(layer.feature.properties);
    }

    // generate map from a GeoJSON file
    var geojson;

    function resetHighlight(e) {
        geojson.resetStyle(e.target);
        info.update();
    }

    function zoomToFeature(e) {
        map.fitBounds(e.target.getBounds());
    }

    function onEachFeature(feature, layer) {
        layer.on({
            mouseover: highlightFeature,
            mouseout: resetHighlight,
            click: function () {
                layer.bindPopup('<b>' + feature.properties.local + '</b>' +
                    '<br>' + feature.properties.values.toLocaleString() + '%').openPopup()
            }
        });
    }

    geojson = new L.GeoJSON.AJAX(mapUrl, {
        style: style,
        onEachFeature: onEachFeature
    });
    geojson.addTo(map);

    collectionDate = collectionDate.split("-");
    collectionDate = collectionDate[0];
    map.attributionControl.addAttribution();
    $('#data-source-chart').html('Data Source: ' + dataSource + ' (' + collectionDate + ')');

    var legend = L.control({position: 'bottomright'});

    legend.onAdd = function (map) {

        var div = L.DomUtil.create('div', 'info legend'),
            grades = [-30, -20, -10, 0, 10, 20, 30, 40],
            labels = [],
            from, to;

        for (var i = 0; i < grades.length; i++) {
            from = grades[i];
            to = grades[i + 1];

            labels.push(
                '<i style="background:' + getColor(from) + '"></i> ' +
                from + (to ? '% &ndash; ' + to + '%' : '%+'));
        }

        div.innerHTML = labels.join('<br>');
        return div;
    };

    legend.addTo(map);

    map.spin(false);

    /************** Export map to image ****************/
    // init plugin
    var simpleMapScreenshoter = L.simpleMapScreenshoter({
            hidden: true, // hide screen btn on map
            hideElementsWithSelectors: ['.leaflet-control-zoom', '.leaflet-control span']
        }).addTo(map);

    // return as blob
    document.getElementById('btn-download-chart').addEventListener('click', function () {
        simpleMapScreenshoter.takeScreen('blob', {}).then(blob => {
            saveAs(blob, 'my-map.png')
        }).catch(e => {
            alert(e.toString())
        })
    })

    // listen on fired error or catch error in prev promise
    map.on('simpleMapScreenshoter.error', function (event) {
        var el = document.createElement('div')
        el.classList.add('create-screen-error')
        el.innerHTML = event.e.toString()
        document.getElementById('screens').appendChild(el)
    })
    /******************* ***************************/

    // deletes the GeoJSON file after generating the map 
    geojson.on("data:loaded", function () {
        deleteTempGeoJSON();
    });
}