Adding a BBOX strategy. This triggers requests for data within a bounding box. When the map bounds invalidate previous data bounds, another request is issued. Reads are triggered with a spatial filter, and protocols that understand how to deal with filters may serialize the filter to request a subset of the data collection. The HTTP protocol understands one filter - the bbox filter. So the BBOX strategy can be used in conjunction with the HTTP protocol to request data via http in a bounding box. Thanks for the collaboration and tests Eric. r=elemoine,crschmidt (#1731)
git-svn-id: http://svn.openlayers.org/trunk/openlayers@8000 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
This commit is contained in:
Tim Schaub
210
lib/OpenLayers/Strategy/BBOX.js
Normal file
210
lib/OpenLayers/Strategy/BBOX.js
Normal file
@@ -0,0 +1,210 @@
|
||||
/* Copyright (c) 2006-2008 MetaCarta, Inc., published under the Clear BSD
|
||||
* license. See http://svn.openlayers.org/trunk/openlayers/license.txt for the
|
||||
* full text of the license. */
|
||||
|
||||
/**
|
||||
* @requires OpenLayers/Strategy.js
|
||||
* @requires OpenLayers/Filter/Spatial.js
|
||||
*/
|
||||
|
||||
/**
|
||||
* Class: OpenLayers.Strategy.BBOX
|
||||
* A simple strategy that reads new features when the viewport invalidates
|
||||
* some bounds.
|
||||
*
|
||||
* Inherits from:
|
||||
* - <OpenLayers.Strategy>
|
||||
*/
|
||||
OpenLayers.Strategy.BBOX = OpenLayers.Class(OpenLayers.Strategy, {
|
||||
|
||||
/**
|
||||
* Property: bounds
|
||||
* {<OpenLayers.Bounds>} The current data bounds.
|
||||
*/
|
||||
bounds: null,
|
||||
|
||||
/**
|
||||
* Property: ratio
|
||||
* {Float} The ratio of the data bounds to the viewport bounds (in each
|
||||
* dimension).
|
||||
*/
|
||||
ratio: 2,
|
||||
|
||||
/**
|
||||
* Property: response
|
||||
* {<OpenLayers.Protocol.Response>} The protocol response object returned
|
||||
* by the layer protocol.
|
||||
*/
|
||||
response: null,
|
||||
|
||||
/**
|
||||
* Constructor: OpenLayers.Strategy.BBOX
|
||||
* Create a new BBOX strategy.
|
||||
*
|
||||
* Parameters:
|
||||
* options - {Object} Optional object whose properties will be set on the
|
||||
* instance.
|
||||
*/
|
||||
initialize: function(options) {
|
||||
OpenLayers.Strategy.prototype.initialize.apply(this, [options]);
|
||||
},
|
||||
|
||||
/**
|
||||
* Method: activate
|
||||
* Set up strategy with regard to reading new batches of remote data.
|
||||
*
|
||||
* Returns:
|
||||
* {Boolean} The strategy was successfully activated.
|
||||
*/
|
||||
activate: function() {
|
||||
var activated = OpenLayers.Strategy.prototype.activate.call(this);
|
||||
if(activated) {
|
||||
this.layer.events.on({
|
||||
"moveend": this.update,
|
||||
scope: this
|
||||
});
|
||||
this.layer.events.on({
|
||||
"refresh": this.update,
|
||||
scope: this
|
||||
});
|
||||
}
|
||||
return activated;
|
||||
},
|
||||
|
||||
/**
|
||||
* Method: deactivate
|
||||
* Tear down strategy with regard to reading new batches of remote data.
|
||||
*
|
||||
* Returns:
|
||||
* {Boolean} The strategy was successfully deactivated.
|
||||
*/
|
||||
deactivate: function() {
|
||||
var deactivated = OpenLayers.Strategy.prototype.deactivate.call(this);
|
||||
if(deactivated) {
|
||||
this.layer.events.un({
|
||||
"moveend": this.update,
|
||||
scope: this
|
||||
});
|
||||
this.layer.events.un({
|
||||
"refresh": this.update,
|
||||
scope: this
|
||||
});
|
||||
}
|
||||
return deactivated;
|
||||
},
|
||||
|
||||
/**
|
||||
* Method: update
|
||||
* Callback function called on "moveend" or "refresh" layer events.
|
||||
*
|
||||
* Parameters:
|
||||
* options - {Object} An object with a property named "force", this
|
||||
* property references a boolean value indicating if new data
|
||||
* must be incondtionally read.
|
||||
*/
|
||||
update: function(options) {
|
||||
var mapBounds = this.layer.map.getExtent();
|
||||
if ((options && options.force) || this.invalidBounds(mapBounds)) {
|
||||
this.calculateBounds(mapBounds);
|
||||
this.triggerRead();
|
||||
}
|
||||
},
|
||||
|
||||
/**
|
||||
* Method: invalidBounds
|
||||
*
|
||||
* Parameters:
|
||||
* mapBounds - {<OpenLayers.Bounds>} the current map extent, will be
|
||||
* retrieved from the map object if not provided
|
||||
*
|
||||
* Returns:
|
||||
* {Boolean}
|
||||
*/
|
||||
invalidBounds: function(mapBounds) {
|
||||
if(!mapBounds) {
|
||||
mapBounds = this.layer.map.getExtent();
|
||||
}
|
||||
return !this.bounds || !this.bounds.containsBounds(mapBounds);
|
||||
},
|
||||
|
||||
/**
|
||||
* Method: calculateBounds
|
||||
*
|
||||
* Parameters:
|
||||
* mapBounds - {<OpenLayers.Bounds>} the current map extent, will be
|
||||
* retrieved from the map object if not provided
|
||||
*/
|
||||
calculateBounds: function(mapBounds) {
|
||||
if(!mapBounds) {
|
||||
mapBounds = this.layer.map.getExtent();
|
||||
}
|
||||
var center = mapBounds.getCenterLonLat();
|
||||
var dataWidth = mapBounds.getWidth() * this.ratio;
|
||||
var dataHeight = mapBounds.getHeight() * this.ratio;
|
||||
this.bounds = new OpenLayers.Bounds(
|
||||
center.lon - (dataWidth / 2),
|
||||
center.lat - (dataHeight / 2),
|
||||
center.lon + (dataWidth / 2),
|
||||
center.lat + (dataHeight / 2)
|
||||
);
|
||||
},
|
||||
|
||||
/**
|
||||
* Method: triggerRead
|
||||
*
|
||||
* Returns:
|
||||
* {<OpenLayers.Protocol.Response>} The protocol response object
|
||||
* returned by the layer protocol.
|
||||
*/
|
||||
triggerRead: function() {
|
||||
var filter = this.createFilter();
|
||||
if (this.response && this.response.priv &&
|
||||
typeof this.response.priv.abort == "function") {
|
||||
this.response.priv.abort();
|
||||
}
|
||||
this.response = this.layer.protocol.read({
|
||||
filter: filter,
|
||||
callback: this.merge,
|
||||
scope: this
|
||||
});
|
||||
},
|
||||
|
||||
/**
|
||||
* Method: createFilter
|
||||
*
|
||||
* Returns
|
||||
* {<OpenLayers.Filter>} The filter object.
|
||||
*/
|
||||
createFilter: function() {
|
||||
var filter = new OpenLayers.Filter.Spatial({
|
||||
type: OpenLayers.Filter.Spatial.BBOX,
|
||||
value: this.bounds,
|
||||
projection: this.layer.projection
|
||||
});
|
||||
if (this.layer.filter) {
|
||||
filter = new OpenLayers.Filter.Logical({
|
||||
type: OpenLayers.Filter.Logical.AND,
|
||||
filters: [this.layer.filter, filter]
|
||||
});
|
||||
}
|
||||
return filter;
|
||||
},
|
||||
|
||||
/**
|
||||
* Method: merge
|
||||
* Given a list of features, determine which ones to add to the layer.
|
||||
*
|
||||
* Parameters:
|
||||
* resp - {<OpenLayers.Protocol.Response>} The response object passed
|
||||
* by the protocol.
|
||||
*/
|
||||
merge: function(resp) {
|
||||
this.layer.destroyFeatures();
|
||||
var features = resp.features;
|
||||
if(features && features.length > 0) {
|
||||
this.layer.addFeatures(features);
|
||||
}
|
||||
},
|
||||
|
||||
CLASS_NAME: "OpenLayers.Strategy.BBOX"
|
||||
});
|
||||
Reference in New Issue
Block a user