I'm trying to make a LineString which has arrows in the end of each line to show direction of the route. I use an example from the official site: https://openlayers.org/en/latest/examples/line-arrows.html The example code creates arrows by user's drawing, but I need arrows for given LineString. My code contains icons for end and finish of the route. When I use
'route': new ol.style.Style({
stroke: new ol.style.Stroke({
width: 6, color: [23, 120, 22, 0.6]
})
}),
in styles, my code works. But when I put style for Linestring from the example, it gives me an error saying "Uncaught TypeError: c.Y is not a function".
Here is my code:
var points = [
[76.8412, 43.2245], [76.8405, 43.2210], [76.8479, 43.2200], [76.8512, 43.2220]
];
var route = new ol.geom.LineString(points);
route.transform('EPSG:4326', 'EPSG:3857');
var routeFeature = new ol.Feature({
type: 'route',
geometry: route
});
var startMarker = new ol.Feature({
type: 'icon-a',
geometry: new ol.geom.Point(ol.proj.fromLonLat(points[0]))
});
var endMarker = new ol.Feature({
type: 'icon-b',
geometry: new ol.geom.Point(ol.proj.fromLonLat(points[points.length - 1]))
});
var styles = {
'route': function(feature) {
var geometry = feature.getGeometry();
var styles = [
// linestring
new ol.style.Style({
stroke: new ol.style.Stroke({
color: '#ffcc33',
width: 2
}),
image: new ol.style.Icon({
anchor: [0.5, 1],
src: 'img/icon-a.png'
})
})
];
geometry.forEachSegment(function(start, end) {
var dx = end[0] - start[0];
var dy = end[1] - start[1];
var rotation = Math.atan2(dy, dx);
// arrows
styles.push(new ol.style.Style({
geometry: new ol.geom.Point(end),
image: new ol.style.Icon({
src: 'https://openlayers.org/en/v4.6.3/examples/data/arrow.png',
anchor: [0.75, 0.5],
rotateWithView: true,
rotation: -rotation
})
}));
});
return styles;
},
'icon-a': new ol.style.Style({
image: new ol.style.Icon({
anchor: [0.5, 1],
src: 'img/icon-a.png'
})
}),
'icon-b': new ol.style.Style({
image: new ol.style.Icon({
anchor: [0.5, 1],
src: 'img/icon-b.png'
})
})
};
var vectorLayer = new ol.layer.Vector({
source: new ol.source.Vector({
features: [routeFeature, startMarker, endMarker]
}),
style: function(feature) {
return styles[feature.get('type')];
}
});
var center = ol.proj.fromLonLat([76.8512, 43.2220]);
var map = new ol.Map({
target: document.getElementById('map'),
view: new ol.View({
center: center,
zoom: 15,
minZoom: 2,
maxZoom: 19
}),
layers: [
new ol.layer.Tile({
source: new ol.source.OSM()
}),
vectorLayer
]
});#map {
/* just for testing purposes */
width: 100%;
min-width: 100px;
max-width: 500px;
margin-top: 50px;
height: 50px;
}<link href="https://openlayers.org/en/v4.6.4/css/ol.css" rel="stylesheet"/>
<script src="https://openlayers.org/en/v4.6.4/build/ol-debug.js"></script>
<div id="map"></div>Firstly, you can use ol-debug.js instead of ol.js, which is uncompressed and helps debugging. The exception you get is
TypeError: style.getImage is not a function (Line 30443)
You get that error because your styles object is mixed: some styles are functions, some are plain Style objects.
You might think that OL can handle both, and you are normally right. However, you provide a function to vectorLayer, so OL detects that you provided a function and calls it. The return value of that function is expected to be a style object. But for route, that returns a function instead!
So when OL calls
style: function(feature) {
return styles[feature.get('type')];
}
It gets styles for the types icon-a, icon-b, but an function for route. You need to enhance your style function to handle that special case:
style: function(feature) {
const myStyle = stylesMap[feature.get('type')];
if (myStyle instanceof Function) {
return myStyle(feature);
}
return myStyle;
}
PS: Using the same name for a variable twice (styles) is bad practice and can lead to weird bugs.
Here is the runnable example:
var points = [
[76.8412, 43.2245],
[76.8405, 43.2210],
[76.8479, 43.2200],
[76.8512, 43.2220]
];
var route = new ol.geom.LineString(points);
route.transform('EPSG:4326', 'EPSG:3857');
var routeFeature = new ol.Feature({
type: 'route',
geometry: route
});
var startMarker = new ol.Feature({
type: 'icon-a',
geometry: new ol.geom.Point(ol.proj.fromLonLat(points[0]))
});
var endMarker = new ol.Feature({
type: 'icon-b',
geometry: new ol.geom.Point(ol.proj.fromLonLat(points[points.length - 1]))
});
var stylesMap = {
'route': function(feature) {
var geometry = feature.getGeometry();
var styles = [
// linestring
new ol.style.Style({
stroke: new ol.style.Stroke({
color: '#ffcc33',
width: 2
}),
image: new ol.style.Icon({
anchor: [0.5, 1],
src: 'img/icon-a.png'
})
})
];
geometry.forEachSegment(function(start, end) {
var dx = end[0] - start[0];
var dy = end[1] - start[1];
var rotation = Math.atan2(dy, dx);
// arrows
styles.push(new ol.style.Style({
geometry: new ol.geom.Point(end),
image: new ol.style.Icon({
src: 'https://openlayers.org/en/v4.6.5/examples/data/arrow.png',
anchor: [0.75, 0.5],
rotateWithView: true,
rotation: -rotation
})
}));
});
return styles;
},
'icon-a': new ol.style.Style({
image: new ol.style.Icon({
anchor: [0.5, 1],
src: 'img/icon-a.png'
})
}),
'icon-b': new ol.style.Style({
image: new ol.style.Icon({
anchor: [0.5, 1],
src: 'img/icon-b.png'
})
})
};
var vectorLayer = new ol.layer.Vector({
source: new ol.source.Vector({
features: [routeFeature, startMarker, endMarker]
}),
style: function(feature) {
const myStyle = stylesMap[feature.get('type')];
if (myStyle instanceof Function) {
return myStyle(feature);
}
return myStyle;
}
});
var center = ol.proj.fromLonLat([76.8512, 43.2220]);
var map = new ol.Map({
target: document.getElementById('map'),
view: new ol.View({
center: center,
zoom: 15,
minZoom: 2,
maxZoom: 19
}),
layers: [
new ol.layer.Tile({
source: new ol.source.OSM()
}),
vectorLayer
]
});html,
body {
width: 100%;
height: 100%;
padding: 0px;
margin: 0px;
}
#map {
/* just for testing purposes */
width: 100%;
height: 100%;
}<link href="https://openlayers.org/en/v4.6.5/css/ol.css" rel="stylesheet" />
<script src="https://openlayers.org/en/v4.6.5/build/ol-debug.js"></script>
<div id="map"></div>