1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
|
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0">
<meta name="apple-mobile-web-app-capable" content="yes">
<title>OpenLayers Vector Styles</title>
<link rel="stylesheet" href="../theme/default/style.css" type="text/css">
<link rel="stylesheet" href="style.css" type="text/css">
<script src="../lib/OpenLayers.js"></script>
<script type="text/javascript">
var map;
function init(){
map = new OpenLayers.Map('map', {maxResolution:'auto'});
var wms = new OpenLayers.Layer.WMS( "OpenLayers WMS",
"http://vmap0.tiles.osgeo.org/wms/vmap0", {layers: 'basic'} );
map.addLayer(wms);
map.setCenter(new OpenLayers.LonLat(0, 0), 0);
// Strategy 1: Style features based on some attribute.
// create 50 random features in the northern hemisphere
// give them a "type" attribute that will be used to style
// them by size
var features = new Array(50);
for (var i=0; i<features.length; i++) {
features[i] = new OpenLayers.Feature.Vector(
new OpenLayers.Geometry.Point(
(360 * Math.random()) - 180, 90 * Math.random()
), {
type: 5 + parseInt(5 * Math.random())
}
);
}
// allow testing of specific renderers via "?renderer=Canvas", etc
var renderer = OpenLayers.Util.getParameters(window.location.href).renderer;
renderer = (renderer) ? [renderer] : OpenLayers.Layer.Vector.prototype.renderers;
// create the layer styleMap with a simple symbolizer template
var layer1 = new OpenLayers.Layer.Vector('Points', {
styleMap: new OpenLayers.StyleMap({
pointRadius: "${type}", // based on feature.attributes.type
fillColor: "#666666"
}),
renderers: renderer
});
layer1.addFeatures(features);
// Strategy 2: Style features based on something besides attributes.
// create 50 random features in the southern hemisphere
var features = new Array(50);
for (var i=0; i<features.length; i++) {
features[i] = new OpenLayers.Feature.Vector(
new OpenLayers.Geometry.Point(
(360 * Math.random()) - 180, -90 * Math.random()
), {
type: 5 + parseInt(5 * Math.random())
}
);
}
// create the layer styleMap by giving the default style a context
var colors = ["red", "green", "blue"];
var context = {
getColor: function(feature) {
var region = parseInt((feature.geometry.x + 180) / 120);
return colors[region];
},
getSize: function(feature) {
return feature.attributes["type"] / map.getResolution() * .703125;
}
};
var template = {
pointRadius: "${getSize}", // using context.getSize(feature)
fillColor: "${getColor}" // using context.getColor(feature)
};
var style = new OpenLayers.Style(template, {context: context});
var layer2 = new OpenLayers.Layer.Vector('Points', {
styleMap: new OpenLayers.StyleMap(style),
renderers: renderer
});
layer2.addFeatures(features);
map.addLayers([layer1, layer2]);
}
</script>
</head>
<body onload="init()">
<h1 id="title">Feature Styles Example</h1>
<div id="tags">
vector, feature, stylemap, light
</div>
<p id="shortdesc">
To style features with a custom function that evaluates each feature, use
the context option of an OpenLayers.Style object. If the context object
contains a function and this function is referenced in a symbolizer, the
function will be called with the feature as an argument..
</p>
<div id="map" class="smallmap"></div>
<div id="docs">
<p>Features in the northern hemisphere are styled according to their
"type" attribute. This is accomplished with a simple template that
is evaluated with the feature attributes as context.</p>
<p>Features in the sourthern hemisphere are styled according to a
combination of their attributes and non-attribute properties. This
is accomplished using an advanced template that calls functions
on the context object passed to the Style constructor.</p>
</div>
</body>
</html>
|
