Develop Reference

Openlayer load GEOJSON from a variable instead of url

I've a map rapresentation, I want to add a layer based on a GEOJSON, but I don't want to read it directly from a GEOJSON file, instead I've a variable that contain the exact string of GEOJSON that I require, is possible to load it from a variable instead of an url?
var map = new ol.Map({
target: 'map',
layers: [
new ol.layer.Tile({
source: new ol.source.OSM()
}),
new ol.layer.Vector({
title: 'bikesRented',
source: new ol.source.Vector({
url: !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
format: new ol.format.GeoJSON()
}),
style: bikeStyle2
})
],
view: new ol.View({
center: ol.proj.fromLonLat([11.341868,44.494949]),
zoom: 14
})
});

You could read the features from your string and add them to the source
var source = new ol.source.Vector();
var map = new ol.Map({
target: 'map',
layers: [
new ol.layer.Tile({
source: new ol.source.OSM()
}),
new ol.layer.Vector({
title: 'bikesRented',
source: source,
style: bikeStyle2
})
],
view: new ol.View({
center: ol.proj.fromLonLat([11.341868,44.494949]),
zoom: 14
})
});
source.addFeatures(
new ol.format.GeoJSON().readFeatures(geojsonstring, {
dataProjection: 'EPSG:4326',
featureProjection: map.getView().getProjection()
})
);
or you could use a data url and let OpenLayers load that
var map = new ol.Map({
target: 'map',
layers: [
new ol.layer.Tile({
source: new ol.source.OSM()
}),
new ol.layer.Vector({
title: 'bikesRented',
source: new ol.source.Vector({
url: 'data:,' + encodeURIComponent(geojsonstring),
format: new ol.format.GeoJSON()
}),
style: bikeStyle2
})
],
view: new ol.View({
center: ol.proj.fromLonLat([11.341868,44.494949]),
zoom: 14
})
});

Reprojection WFS GeoJSON

I need to display my layer from geoserver on the map. I have problems with the projection system (EPSG:7749). I can't change the projection system with proj4 in my vector layer. I chose GeoJSON format because I will need to build a filter for the feature of my layer. Someone can help me?
`
proj4.defs('EPSG:7749', '+proj=aea +lat_1=34.0733 +lat_2=34.3833 +lat_0=34.2283 +lon_0=-112.7915 +x_0=0 +y_0=0 +ellps=GRS80 +datum=NAD83 +units=m +no_defs');
ol.proj.proj4.register(proj4);
console.log("Console: " + ol.proj.get('EPSG:7749'));
var test = ol.proj.get('EPSG:7749');
var urltest = 'http://myGeoserverIP/geoserver/ows?service=WFS&version=1.1.0&request=GetFeature&typeName=myworkspace:201910081246140571_Perimeters&outputFormat=application%2Fjson';
var vectorSource = new ol.source.Vector({
format: new ol.format.GeoJSON(),
projection: test,
url: urltest,
});
var vector = new ol.layer.Vector({
source: vectorSource,
});
var raster = new ol.layer.Tile({
source: new ol.source.OSM()
});
var map = new ol.Map({
layers: [raster, vector],
target: 'map',
view: new ol.View({
projection: test,
center: [-8908887.277395891, 5381918.072437216],
maxZoom: 19,
zoom: 3
})
});
`

OpenLayers 5.3 : Why doesn't draw my poligon?

This is the code :
drawPoligon : function (vertices) {
debugger;
var map = peaMap;
var feature = new ol.Feature({
geometry: new ol.geom.Polygon([vertices])
});
var vectorSource= new ol.source.Vector({
features: [feature ]
});
var vectorLayer = new ol.layer.Vector({
source: vectorSource
});
map.addLayer(vectorLayer);
}
vertices = [1253906.08982072, 5430790.35506443, 1253935.16019819, 5430769.74133789, 1253951.90741865, 5430793.82802342, 1253955.42311216........]
Format of my coordinates array:
[
[1253906.08982072,5430790.35506443],
[1253935.16019819,5430769.74133789],
[1253951.90741865,5430793.82802342],
[1253955.42311216,5430798.88815272],
[1253953.91064413,5430800.28580152],
[1253952.03520923,5430801.40886153],
[1253945.88800332,5430791.50307534],
[1253936.62615957,5430797.3914173]
]
...The coordinates list isnt full. Only part of it for exposure.

The format [ [lon, lat], … ] is the correct one. With a bigger zoom you can see the result:
var osmLayer = new ol.layer.Tile({
source: new ol.source.OSM()
});
var vertices = [
[1253906.08982072, 5430790.35506443],
[1253935.16019819, 5430769.74133789],
[1253951.90741865, 5430793.82802342],
[1253955.42311216, 5430798.88815272],
[1253953.91064413, 5430800.28580152],
[1253952.03520923, 5430801.40886153],
[1253945.88800332, 5430791.50307534],
[1253936.62615957, 5430797.3914173]
];
var feature = new ol.Feature({
geometry: new ol.geom.Polygon([vertices])
});
var vectorSource = new ol.source.Vector({
features: [feature]
});
var vectorLayer = new ol.layer.Vector({
source: vectorSource,
style: new ol.style.Style({
stroke: new ol.style.Stroke({
width: 2,
color: [255, 0, 0]
})
})
});
var map = new ol.Map({
layers: [osmLayer, vectorLayer],
target: document.getElementById("map"),
view: new ol.View({
center: [1253950, 5430800],
zoom: 20
})
});

How to change a open layer tile source?

I need to change the layer source for openlayer (using open weather api). Currently I am using the following code with no success.
let layer = this.map.getLayers().getArray()[2]
layer.setSource(forecastLayer)
Could you tell me what I am doing wrong?
What is the correct way to update the data source?
renderMapOpenLayer () {
let geo = this.props.geo
// render marker vector
let markerFeature = new ol.Feature({
geometry: new ol.geom.Point(ol.proj.transform([-72.0704, 46.678], 'EPSG:4326', 'EPSG:3857')) // TODO // take lat long from openweather api which should be sotred in the state
})
let markerSource = new ol.source.Vector({
features: [markerFeature]
})
let markerStyle = new ol.style.Style({
image: new ol.style.Icon(({
anchor: [0, 0],
anchorXUnits: 'fraction',
anchorYUnits: 'pixels',
opacity: 0.75,
src: 'assets/pin.svg'
}))
})
let markerLayer = new ol.layer.Vector({
source: markerSource,
style: markerStyle
})
// render OpenStreetMap tile server
var tileLayer = new ol.layer.Tile({
source: new ol.source.OSM()
}, new ol.layer.Vector({
source: new ol.source.Vector({ features: [], projection: 'EPSG:4326' })
}))
// render cloud tile
let cloudLayer = new ol.layer.Tile({
source: new ol.source.XYZ({
url: api.mapTemperature()
})
})
let forecastLayer = new ol.layer.Tile({
source: new ol.source.XYZ({
url: api.forecast()
})
})
setTimeout(function () {
let layer = this.map.getLayers().getArray()[2]
layer.setSource(forecastLayer)
}.bind(this), 3000)
// create map
this.map = new ol.Map({
target: 'map',
layers: [
tileLayer,
markerLayer,
cloudLayer
],
view: new ol.View({
center: ol.proj.transform(geo, 'EPSG:4326', 'EPSG:3857'),
zoom: 4
})
})
}

layer.setSource should do the trick.
function onClick() {
layer.setSource(xyz2);
}
var xyz1 = new ol.source.XYZ({
url: 'https://server.arcgisonline.com/ArcGIS/rest/services/' +
'Demographics/USA_Percent_Over_64/MapServer/tile/{z}/{y}/{x}'
})
var xyz2 = new ol.source.XYZ({
url: 'https://server.arcgisonline.com/ArcGIS/rest/services/' +
'Demographics/USA_Percent_Under_18/MapServer/tile/{z}/{y}/{x}'
})
var layer = new ol.layer.Tile({
source: xyz1
});
var map = new ol.Map({
layers: [
new ol.layer.Tile({
source: new ol.source.OSM()
}),
layer
],
target: 'map',
view: new ol.View({
center: ol.proj.fromLonLat([0, 0]),
zoom: 3
})
});
Here is a working example:
layer.setSource Example

Openlayers 3 circles from geojson not working with layer tile source different from TileWMS

I am working with openlayers 3 with a layer from mapbox or openstreetmap and I need to draw some circles on it.
I am able to print the circles with a view with a projection EPSG:4326, but then I have no map. Changing the projection with a transform the map is displayed, but the points are all together. The only way I am made it work is using TileWMS as a source, but I am not able to use it in production environment
Here is my code:
version 1: working with TileWMS
var source = new ol.source.GeoJSON({
url: 'geojson url'
});
var pointsLayer = new ol.layer.Vector({
source: source,
style: new ol.style.Style({
image: new ol.style.Circle({
radius: 15,
fill: new ol.style.Fill({color: 'rgba(170,33,33, 0.8)'}),
stroke: new ol.style.Stroke({color: 'rgba(170,33,33, 0.3)', width: 8})
})
})
});
var map = new ol.Map({
target: 'map',
layers: [
new ol.layer.Tile({
title: "Global Imagery",
source: new ol.source.TileWMS({
url: 'http://maps.opengeo.org/geowebcache/service/wms',
params: {LAYERS: 'bluemarble', VERSION: '1.1.1'}
})
}),
pointsSource
],
view: new ol.View({
projection: 'EPSG:4326',
center: [-82.3, -10.65],
zoom: 3
})
});
This is the result
Using mapbox or osm, failing:
var map = new ol.Map({
target: 'map',
layers: [
new ol.layer.Tile({
source: new ol.source.XYZ({
url: 'http://api.tiles.mapbox.com/v4/XXXXX.kcp9cpdn/{z}/{x}/{y}.png?access_token=token'
})
}),
/*
new ol.layer.Tile({
source: new ol.source.OSM()
}),*/
pointsSource
],
view: new ol.View({
projection: 'EPSG:4326',
center: [-82.3, -10.65],
zoom: 3
})
});
This is the result
And finally, changing the view the map is displayed but the circles
var map = new ol.Map({
target: 'map',
layers: [
new ol.layer.Tile({
source: new ol.source.XYZ({
url: 'http://api.tiles.mapbox.com/v4/XXXXX.kcp9cpdn/{z}/{x}/{y}.png?access_token=token'
})
}),
/*
new ol.layer.Tile({
source: new ol.source.OSM()
}),*/
pointsSource
],
view: new ol.View({
center: ol.proj.transform([-82.3, -10.65], 'EPSG:4326', 'EPSG:3857'),
zoom: 3
})
});
And the result
Is there a way to make this work?
Thanks in advance.

I found the solution, here it is for it is helping anyone
Following this answer in gis stackexchange https://gis.stackexchange.com/a/118818/42868 There is an unstable option for the ol.source.GeoJSON object, so adding it in this way made it work
var source = new ol.source.GeoJSON({
url: 'geojson url',
projection: 'EPSG:3857'
});