I made a copy of the samples/leaflet sample and added support for a “route” property on the link data – an Array of { lat: …, long: … } pairs.
I also added support for allowing the user to reshape the link route interactively (by setting Link.reshapable and Link.resegmentable to true.
I think everything works well, but maybe I forgot to try some meaningful cases.
<!DOCTYPE html>
<html><body>
<script src="https://unpkg.com/gojs"></script>
<link rel="stylesheet" href="https://unpkg.com/leaflet@1.9.4/dist/leaflet.css" />
<script src="https://unpkg.com/leaflet@1.9.4/dist/leaflet.js"></script>
<style type="text/css">
/* CSS applied to the Leaflet map */
.mapDiagram {
border: solid 1px black;
width: 500px;
height: 500px;
}
#myDiagramDiv {
z-index: 701;
}
</style>
<script id="code">
function init() {
/* Leaflet init */
const defaultZoom = 6;
const defaultOrigin = [50.02185841773444, 0.15380859375];
myLeafletMap = L.map('map', {}).setView(defaultOrigin, defaultZoom);
L.tileLayer('https://api.mapbox.com/styles/v1/{id}/tiles/{z}/{x}/{y}?access_token={accessToken}', {
attribution: '© <a href="https://www.mapbox.com/about/maps/">Mapbox</a> © <a href="http://www.openstreetmap.org/copyright">OpenStreetMap</a>',
maxZoom: 18,
minZoom: 2,
tileSize: 512,
zoomOffset: -1,
id: 'mapbox/streets-v11',
// NOTE: use your own MapBox token
accessToken: 'pk.eyJ1IjoiZ29qcyIsImEiOiJjbHMyN3QxcnIwZ2ZoMmxvMzVvNGg3MTRrIn0.8u9prGrtYU2zmuFhxsr76g',
}).addTo(myLeafletMap);
myLeafletMap.on('zoomend', updateNodes);
myLeafletMap.on('move', updatePosition);
myLeafletMap.on('moveend', updatePosition);
let myUpdatingGoJS = false; // prevent modifying data.latlong properties upon Leaflet "move" events
function updateNodes() {
// called when zoom level has changed
myUpdatingGoJS = true;
myDiagram.commit((diag) => {
diag.nodes.each((n) => n.updateTargetBindings('latlong')); // without virtualization this can be slow if there are many nodes
diag.links.each(l => l.updateTargetBindings("route"));
}, null);
myUpdatingGoJS = false;
}
function updatePosition() {
// called when map has been panned (i.e. top-left corner is at a different latlong)
const mapb = myLeafletMap.getBounds();
const pos = myLeafletMap.project([mapb.getNorth(), mapb.getWest()], myLeafletMap.getZoom());
myDiagram.position = new go.Point(pos.x, pos.y);
}
/* GoJS init */
// Since 2.2 you can also author concise templates with method chaining instead of GraphObject.make
// For details, see https://gojs.net/latest/intro/buildingObjects.html
const $ = go.GraphObject.make;
myDiagram = new go.Diagram('myDiagramDiv', {
InitialLayoutCompleted: (e) => updatePosition(),
'dragSelectingTool.isEnabled': false,
'animationManager.isEnabled': false,
scrollMode: go.ScrollMode.Infinite,
allowZoom: false,
allowHorizontalScroll: false,
allowVerticalScroll: false,
hasHorizontalScrollbar: false,
hasVerticalScrollbar: false,
padding: 0,
defaultCursor: 'default',
'toolManager.hoverDelay': 100, // how quickly tooltips are shown
'undoManager.isEnabled': true,
ModelChanged: (e) => {
if (e.change === go.ChangeType.Transaction && (e.propertyName === 'FinishedUndo' || e.propertyName === 'FinishedRedo')) {
setTimeout(() => updateNodes());
}
},
});
// the node template describes how each Node should be constructed
myDiagram.nodeTemplate = $(go.Node,
'Auto',
{
locationSpot: go.Spot.Center,
cursor: 'pointer',
toolTip: $('ToolTip',
$(go.TextBlock,
{ margin: 4, textAlign: 'center' },
new go.Binding('text', '', (d) => `${d.key}\n[${d.latlong[0].toFixed(6)}, ${d.latlong[1].toFixed(6)}]`)
)
),
},
$(go.Shape, 'Circle', {
fill: 'rgba(0, 255, 0, .4)',
stroke: '#082D47',
strokeWidth: 1,
width: 7,
height: 7,
}),
// A two-way data binding with an Array of latitude,longitude numbers.
// We have to explicitly avoid updating the source data Array
// when myUpdatingGoJS is true; otherwise there would be accumulating errors.
new go.Binding('location', 'latlong', (data) => {
const pos = myLeafletMap.project(data, myLeafletMap.getZoom());
return new go.Point(pos.x, pos.y);
}).makeTwoWay((pt, data) => {
if (myUpdatingGoJS) {
return data.latlong; // no-op
} else {
const ll = myLeafletMap.unproject(L.point(pt.x, pt.y), myLeafletMap.getZoom());
return [ll.lat, ll.lng];
}
})
);
function convertRouteToPoints(route, link) {
const points = new go.List();
route.forEach(p => {
const pos = myLeafletMap.project([p.lat, p.long], myLeafletMap.getZoom());
points.add(new go.Point(pos.x, pos.y));
});
return points;
}
function convertPointsToRoute(points, data, model) {
if (myUpdatingGoJS) {
return data.route; // no-op
} else {
const route = [];
points.each(p => {
const ll = myLeafletMap.unproject(L.point(p.x, p.y), myLeafletMap.getZoom());
route.push({ lat: ll.lat, long: ll.lng });
});
model.set(data, "route", route);
return route;
}
}
myDiagram.linkTemplate = $(go.Link,
{
layerName: 'Background',
adjusting: go.Link.Stretch,
//curve: go.Curve.Bezier, curviness: 5,
reshapable: true, resegmentable: true,
toolTip: $('ToolTip', $(go.TextBlock, { margin: 4, textAlign: 'center' }, new go.Binding('text', '', (d) => `${d.from} -- ${d.to}`))),
},
new go.Binding("points", "route", convertRouteToPoints).makeTwoWay(convertPointsToRoute),
$(go.Shape, { strokeWidth: 3, stroke: 'rgba(100,100,255,.7)' })
);
// DraggingTool needs to disable panning of Leaflet map
myDiagram.toolManager.draggingTool.doActivate = function () {
// method override must be function, not =>
myLeafletMap.dragging.disable();
go.DraggingTool.prototype.doActivate.call(this);
};
myDiagram.toolManager.draggingTool.doDeactivate = function () {
// method override must be function, not =>
myLeafletMap.dragging.enable();
go.DraggingTool.prototype.doDeactivate.call(this);
};
// create the model data that will be represented by Nodes and Links
myDiagram.model = new go.GraphLinksModel(
[
// France
{ key: 'Paris', latlong: [48.876569, 2.359017] },
{ key: 'Brest', latlong: [48.387778, -4.479921] },
{ key: 'Rennes', latlong: [48.103375, -1.672809] },
{ key: 'Le Mans', latlong: [47.995562, 0.192413] },
{ key: 'Nantes', latlong: [47.217579, -1.541839] },
{ key: 'Tours', latlong: [47.388502, 0.6945] },
{ key: 'Le Havre', latlong: [49.492755, 0.125278] },
{ key: 'Rouen', latlong: [49.449031, 1.094128] },
{ key: 'Lille', latlong: [50.636379, 3.07062] },
// Belgium
{ key: 'Brussels', latlong: [50.836271, 4.333963] },
{ key: 'Antwerp', latlong: [51.217495, 4.421204] },
{ key: 'Liege', latlong: [50.624168, 5.566008] },
// UK
{ key: 'London', latlong: [51.531132, -0.125132] },
{ key: 'Bristol', latlong: [51.449541, -2.581118] },
{ key: 'Birmingham', latlong: [52.477405, -1.898494] },
{ key: 'Liverpool', latlong: [53.408396, -2.978809] },
{ key: 'Manchester', latlong: [53.476346, -2.229651] },
{ key: 'Leeds', latlong: [53.79548, -1.548345] },
{ key: 'Glasgow', latlong: [55.863287, -4.250989] },
],
[
{ from: 'Brest', to: 'Rennes' },
{ from: 'Rennes', to: 'Le Mans' },
{ from: 'Nantes', to: 'Le Mans' },
{ from: 'Le Mans', to: 'Paris' },
{ from: 'Tours', to: 'Paris' },
{ from: 'Le Havre', to: 'Rouen' },
{ from: 'Rouen', to: 'Paris' },
{ from: 'Lille', to: 'Paris', route: [
{ lat: 50.636379, long: 3.07062 },
{ lat: 50.5, long: 2.9 },
{ lat: 50.4, long: 2.8 },
{ lat: 50.3, long: 2.7 },
{ lat: 50.2, long: 2.6 },
{ lat: 50.1, long: 2.5 },
{ lat: 50.0, long: 2.4 },
{ lat: 49.9, long: 2.53 },
{ lat: 49.8, long: 2.2 },
{ lat: 49.7, long: 2.1 },
{ lat: 49.6, long: 2.0 },
{ lat: 49.5, long: 2.1 },
{ lat: 49.4, long: 2.2 },
{ lat: 49.3, long: 2.3 },
{ lat: 49.2, long: 2.4 },
{ lat: 49.1, long: 2.3 },
{ lat: 49.0, long: 2.32 },
{ lat: 48.876569, long: 2.359017 },
] },
{ from: 'London', to: 'Lille' },
{ from: 'Lille', to: 'Brussels' },
{ from: 'Brussels', to: 'Antwerp' },
{ from: 'Brussels', to: 'Liege' },
{ from: 'Bristol', to: 'London' },
{ from: 'Birmingham', to: 'London' },
{ from: 'Leeds', to: 'London' },
{ from: 'Liverpool', to: 'Birmingham' },
{ from: 'Manchester', to: 'Liverpool' },
{ from: 'Manchester', to: 'Leeds' },
{ from: 'Glasgow', to: 'Manchester' },
{ from: 'Glasgow', to: 'Leeds' },
]
);
} // end init
window.addEventListener('DOMContentLoaded', init);
</script>
<div id="sample">
<div id="map" class="mapDiagram">
<div id="myDiagramDiv" class="mapDiagram"></div>
</div>
<p>
This sample integrates GoJS as a layer in front of the <a href="https://leafletjs.com/">Leaflet mapping library</a>. This demonstrates how to use GoJS
within a GIS application by displaying a Diagram of nodes and links atop the map, using latitude and longitude for their coordinates.
</p>
<p>
You can pan and zoom with Leaflet, and select and drag with GoJS. The GoJS div is on top of the Leaflet map, but this sample selectively bubbles events to
leaflet by using a custom Tool. Dragged nodes will update their latitude and longitude data in the <a>Diagram.model</a>.
</p>
<p>
This diagram displays a few train stations and routes in France, Belgium, and the UK. The data is only meant as an example of using GoJS and is not meant to
be accurate.
</p>
<p>Note that the map is fetched through the <a href="https://mapbox.com/">Mapbox</a> API. Access tokens can expire, and you'll need to get your own token.</p>
</div>
</body></html>
