628978f894
If a load fails then we won't have any features, but we also won't try and load them again for any part of that area because the bounds tell us we have already loaded them. So clear the bounds in order that reloads will be triggered.
290 lines
9.4 KiB
JavaScript
290 lines
9.4 KiB
JavaScript
/* Copyright (c) 2006-2012 by OpenLayers Contributors (see authors.txt for
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* full list of contributors). Published under the 2-clause BSD license.
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* See license.txt in the OpenLayers distribution or repository for the
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* full text of the license. */
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/**
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* @requires OpenLayers/Strategy.js
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* @requires OpenLayers/Filter/Spatial.js
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*/
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/**
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* Class: OpenLayers.Strategy.BBOX
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* A simple strategy that reads new features when the viewport invalidates
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* some bounds.
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*
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* Inherits from:
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* - <OpenLayers.Strategy>
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*/
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OpenLayers.Strategy.BBOX = OpenLayers.Class(OpenLayers.Strategy, {
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/**
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* Property: bounds
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* {<OpenLayers.Bounds>} The current data bounds (in the same projection
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* as the layer - not always the same projection as the map).
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*/
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bounds: null,
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/**
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* Property: resolution
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* {Float} The current data resolution.
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*/
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resolution: null,
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/**
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* APIProperty: ratio
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* {Float} The ratio of the data bounds to the viewport bounds (in each
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* dimension). Default is 2.
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*/
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ratio: 2,
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/**
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* Property: resFactor
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* {Float} Optional factor used to determine when previously requested
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* features are invalid. If set, the resFactor will be compared to the
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* resolution of the previous request to the current map resolution.
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* If resFactor > (old / new) and 1/resFactor < (old / new). If you
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* set a resFactor of 1, data will be requested every time the
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* resolution changes. If you set a resFactor of 3, data will be
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* requested if the old resolution is 3 times the new, or if the new is
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* 3 times the old. If the old bounds do not contain the new bounds
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* new data will always be requested (with or without considering
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* resFactor).
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*/
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resFactor: null,
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/**
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* Property: response
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* {<OpenLayers.Protocol.Response>} The protocol response object returned
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* by the layer protocol.
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*/
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response: null,
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/**
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* Constructor: OpenLayers.Strategy.BBOX
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* Create a new BBOX strategy.
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*
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* Parameters:
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* options - {Object} Optional object whose properties will be set on the
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* instance.
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*/
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/**
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* Method: activate
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* Set up strategy with regard to reading new batches of remote data.
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*
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* Returns:
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* {Boolean} The strategy was successfully activated.
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*/
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activate: function() {
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var activated = OpenLayers.Strategy.prototype.activate.call(this);
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if(activated) {
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this.layer.events.on({
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"moveend": this.update,
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"refresh": this.update,
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"visibilitychanged": this.update,
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scope: this
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});
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this.update();
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}
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return activated;
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},
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/**
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* Method: deactivate
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* Tear down strategy with regard to reading new batches of remote data.
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*
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* Returns:
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* {Boolean} The strategy was successfully deactivated.
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*/
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deactivate: function() {
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var deactivated = OpenLayers.Strategy.prototype.deactivate.call(this);
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if(deactivated) {
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this.layer.events.un({
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"moveend": this.update,
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"refresh": this.update,
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"visibilitychanged": this.update,
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scope: this
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});
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}
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return deactivated;
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},
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/**
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* Method: update
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* Callback function called on "moveend" or "refresh" layer events.
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*
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* Parameters:
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* options - {Object} Optional object whose properties will determine
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* the behaviour of this Strategy
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*
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* Valid options include:
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* force - {Boolean} if true, new data must be unconditionally read.
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* noAbort - {Boolean} if true, do not abort previous requests.
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*/
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update: function(options) {
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var mapBounds = this.getMapBounds();
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if (mapBounds !== null && ((options && options.force) ||
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(this.layer.visibility && this.layer.calculateInRange() && this.invalidBounds(mapBounds)))) {
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this.calculateBounds(mapBounds);
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this.resolution = this.layer.map.getResolution();
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this.triggerRead(options);
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}
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},
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/**
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* Method: getMapBounds
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* Get the map bounds expressed in the same projection as this layer.
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*
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* Returns:
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* {<OpenLayers.Bounds>} Map bounds in the projection of the layer.
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*/
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getMapBounds: function() {
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if (this.layer.map === null) {
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return null;
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}
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var bounds = this.layer.map.getExtent();
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if(bounds && !this.layer.projection.equals(
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this.layer.map.getProjectionObject())) {
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bounds = bounds.clone().transform(
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this.layer.map.getProjectionObject(), this.layer.projection
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);
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}
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return bounds;
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},
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/**
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* Method: invalidBounds
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* Determine whether the previously requested set of features is invalid.
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* This occurs when the new map bounds do not contain the previously
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* requested bounds. In addition, if <resFactor> is set, it will be
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* considered.
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*
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* Parameters:
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* mapBounds - {<OpenLayers.Bounds>} the current map extent, will be
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* retrieved from the map object if not provided
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*
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* Returns:
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* {Boolean}
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*/
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invalidBounds: function(mapBounds) {
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if(!mapBounds) {
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mapBounds = this.getMapBounds();
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}
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var invalid = !this.bounds || !this.bounds.containsBounds(mapBounds);
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if(!invalid && this.resFactor) {
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var ratio = this.resolution / this.layer.map.getResolution();
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invalid = (ratio >= this.resFactor || ratio <= (1 / this.resFactor));
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}
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return invalid;
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},
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/**
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* Method: calculateBounds
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*
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* Parameters:
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* mapBounds - {<OpenLayers.Bounds>} the current map extent, will be
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* retrieved from the map object if not provided
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*/
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calculateBounds: function(mapBounds) {
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if(!mapBounds) {
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mapBounds = this.getMapBounds();
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}
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var center = mapBounds.getCenterLonLat();
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var dataWidth = mapBounds.getWidth() * this.ratio;
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var dataHeight = mapBounds.getHeight() * this.ratio;
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this.bounds = new OpenLayers.Bounds(
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center.lon - (dataWidth / 2),
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center.lat - (dataHeight / 2),
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center.lon + (dataWidth / 2),
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center.lat + (dataHeight / 2)
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);
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},
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/**
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* Method: triggerRead
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*
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* Parameters:
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* options - {Object} Additional options for the protocol's read method
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* (optional)
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*
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* Returns:
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* {<OpenLayers.Protocol.Response>} The protocol response object
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* returned by the layer protocol.
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*/
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triggerRead: function(options) {
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if (this.response && !(options && options.noAbort === true)) {
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this.layer.protocol.abort(this.response);
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this.layer.events.triggerEvent("loadend");
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}
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this.layer.events.triggerEvent("loadstart");
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this.response = this.layer.protocol.read(
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OpenLayers.Util.applyDefaults({
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filter: this.createFilter(),
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callback: this.merge,
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scope: this
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}, options));
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},
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/**
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* Method: createFilter
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* Creates a spatial BBOX filter. If the layer that this strategy belongs
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* to has a filter property, this filter will be combined with the BBOX
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* filter.
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*
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* Returns
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* {<OpenLayers.Filter>} The filter object.
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*/
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createFilter: function() {
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var filter = new OpenLayers.Filter.Spatial({
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type: OpenLayers.Filter.Spatial.BBOX,
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value: this.bounds,
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projection: this.layer.projection
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});
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if (this.layer.filter) {
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filter = new OpenLayers.Filter.Logical({
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type: OpenLayers.Filter.Logical.AND,
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filters: [this.layer.filter, filter]
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});
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}
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return filter;
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},
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/**
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* Method: merge
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* Given a list of features, determine which ones to add to the layer.
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* If the layer projection differs from the map projection, features
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* will be transformed from the layer projection to the map projection.
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*
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* Parameters:
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* resp - {<OpenLayers.Protocol.Response>} The response object passed
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* by the protocol.
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*/
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merge: function(resp) {
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this.layer.destroyFeatures();
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if (resp.success()) {
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var features = resp.features;
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if(features && features.length > 0) {
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var remote = this.layer.projection;
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var local = this.layer.map.getProjectionObject();
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if(!local.equals(remote)) {
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var geom;
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for(var i=0, len=features.length; i<len; ++i) {
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geom = features[i].geometry;
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if(geom) {
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geom.transform(remote, local);
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}
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}
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}
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this.layer.addFeatures(features);
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}
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} else {
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this.bounds = null;
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}
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this.response = null;
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this.layer.events.triggerEvent("loadend", {response: resp});
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},
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CLASS_NAME: "OpenLayers.Strategy.BBOX"
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});
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