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Customize requestSuccess to limit number of features actually drawn on the map

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Christopher Schmidt 2008-04-22 11:14:58 +00:00
parent d3314fee0f
commit 98be40a312
1 changed files with 49 additions and 1 deletions
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50
app/views/browse/start.rjs
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@ -2,7 +2,7 @@ page.replace_html :sidebar_title, 'Browse'
page.replace_html :sidebar_content, :partial => 'start'
page << <<EOJ
var gml, sf, objList, currentFeature;
var gml, sf, objList, currentFeature, featureList;
OpenLayers.Feature.Vector.style['default'].strokeWidth = 3;
OpenLayers.Feature.Vector.style['default'].cursor = "pointer";
@ -59,7 +59,52 @@ page << <<EOJ
getData(bounds);
$("drag_box").innerHTML = "Manually select a different area";
}
function displayFeatureWarning() {
var div = document.createElement("div");
var p = document.createElement("p");
p.appendChild(document.createTextNode("You have loaded an area which contains " + featureList.length + " features. In general, some browsers may not cope well with displaying this quantity of data. Generally, browsers work best at displaying less than 100 features at a time: doing anything else may make your browser slow/unresponsive. If you are sure you want to display this data, you may do so by clicking the button below."));
div.appendChild(p);
var input = document.createElement("input");
input.type = "submit";
input.value = "Load Data";
input.onclick = loadFeatureList;
div.appendChild(input);
$("object").innerHTML="";
$("object").appendChild(div);
}
function loadFeatureList() {
gml.addFeatures(featureList);
gml.events.triggerEvent("loadend");
}
function customDataLoader(request) {
var doc = request.responseXML;
if (!doc || !doc.documentElement) {
doc = request.responseText;
}
var options = {};
OpenLayers.Util.extend(options, this.formatOptions);
if (this.map && !this.projection.equals(this.map.getProjectionObject())) {
options.externalProjection = this.projection;
options.internalProjection = this.map.getProjectionObject();
}
var gml = this.format ? new this.format(options) : new OpenLayers.Format.GML(options);
var features = gml.read(doc);
if (!this.maxFeatures || features.length <= this.maxFeatures) {
this.addFeatures(features);
this.events.triggerEvent("loadend");
featureList = [];
} else {
featureList = features;
displayFeatureWarning();
}
}
function getData(bounds) {
$("status").innerHTML = "Loading...";
@ -78,6 +123,7 @@ page << <<EOJ
)]);
gml = new OpenLayers.Layer.GML("Data",url,
{format: OpenLayers.Format.OSM, formatOptions: {checkTags: true},
maxFeatures: 100, requestSuccess: customDataLoader,
styleMap: new OpenLayers.StyleMap({'default': style, 'select': {'strokeColor': '#0000ff'}})
}
);
@ -90,6 +136,8 @@ page << <<EOJ
} else {
gml.setUrl(url);
}
currentFeature = null;
}
function dataLoaded() {