Created
April 28, 2018 21:08
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Use ol.source.Raster to mask only 2 layers instead of playing between full canvas and a particular layer
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<!DOCTYPE html> | |
<html> | |
<head> | |
<meta charset=utf-8> | |
<meta name=description content=""> | |
<meta name=viewport content="width=device-width, initial-scale=1"> | |
<title>Simple Map with mask between 2 layers</title> | |
<link rel="stylesheet" href="https://openlayers.org/en/v4.6.5/css/ol.css" type="text/css"> | |
<!-- The line below is only needed for old environments like Internet Explorer and Android 4.x --> | |
<script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL"></script> | |
<script src="https://openlayers.org/en/v4.6.5/build/ol.js"></script> | |
</head> | |
<body> | |
<div id="map" class="map"></div> | |
<select id="filtercountry"></select> | |
<script> | |
var initialCenter = [0, 0]; | |
var initialZoom = 2; | |
var view = new ol.View({ | |
center: initialCenter, | |
zoom: initialZoom | |
}); | |
var map = new ol.Map({ | |
layers: [ | |
new ol.layer.Tile({ | |
source: new ol.source.OSM() | |
}) | |
], | |
target: 'map', | |
view: view | |
}); | |
var style = new ol.style.Style({ | |
fill: new ol.style.Fill({ | |
color: [0, 0, 0, 1] | |
}) | |
}); | |
var geoJSONFormat = new ol.format.GeoJSON(); | |
var vectorSource = new ol.source.Vector(); | |
var features; | |
fetch('http://openlayers.org/en/v4.6.5/examples/data/geojson/countries.geojson') | |
.then(response => response.json()) | |
.then(json => { | |
features = geoJSONFormat.readFeatures(json, { | |
dataProjection: 'EPSG:4326', | |
featureProjection: 'EPSG:3857' | |
}); | |
vectorSource.addFeatures(features); | |
var rasterSource = new ol.source.ImageVector({ | |
source: vectorSource, | |
style: style | |
}); | |
var clipLayer = new ol.layer.Image({ | |
source: rasterSource | |
}); | |
var raster = new ol.source.Raster({ | |
sources: [ | |
new ol.source.Stamen({ | |
layer: 'watercolor', | |
transition: 0 | |
}), | |
rasterSource | |
], | |
operation: function(pixels, data) { | |
if (pixels[1][3] == 0) { | |
return [0, 0, 0, 1]; | |
} else { | |
return pixels[0]; | |
} | |
} | |
}); | |
var rasterLayer = new ol.layer.Image({ | |
source: raster | |
}); | |
map.addLayer(rasterLayer); | |
var filterCountry = document.getElementById('filtercountry'); | |
var options = [ | |
['', 'Unfiltered'], | |
...features.map(feature => { | |
return [feature.getId(), feature.get('name')]; | |
}) | |
].reduce((acc, curr) => { | |
var option = document.createElement('option'); | |
option.text = curr[1]; | |
option.value = curr[0]; | |
acc.appendChild(option); | |
return acc; | |
}, document.createDocumentFragment()); | |
filterCountry.appendChild(options); | |
filterCountry.addEventListener("change", function() { | |
if(filterCountry.value.length > 0) { | |
console.log('One country', filterCountry.options[filterCountry.selectedIndex].text); | |
vectorSource.clear(); | |
vectorSource.addFeature(features.find(el => el.getId() === filterCountry.options[filterCountry.selectedIndex].value)); | |
map.getView().fit(vectorSource.getExtent()); | |
} else { | |
console.log('Unfiltered', filterCountry.options[filterCountry.selectedIndex].text); | |
vectorSource.clear(); | |
vectorSource.addFeatures(features); | |
map.getView().setCenter([0, 0]); | |
map.getView().setZoom(2); | |
} | |
raster.changed(); | |
}); | |
}); | |
</script> | |
</body> | |
</html> |
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