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var map, navigationControl, queryControl;
function init(){
map = new OpenLayers.Map('map', {controls: []});
var layer = new OpenLayers.Layer.WMS(
"OpenLayers WMS",
"http://vmap0.tiles.osgeo.org/wms/vmap0",
{layers: 'basic'}
);
map.addLayers([layer]);
navigationControl = new OpenLayers.Control.KeyboardDefaults({
observeElement: 'map'
});
map.addControl(navigationControl);
queryControl = new OpenLayers.Control.KeyboardClick({
observeElement: 'map'
});
map.addControl(queryControl);
map.zoomToMaxExtent();
}
/**
* Class: OpenLayers.Control.KeyboardClick
*
* A custom control that (a) adds a vector point that can be moved using the
* arrow keys of the keyboard, and (b) displays a browser alert window when the
* RETURN key is pressed. The control can be activated/deactivated using the
* "i" key. When activated the control deactivates any KeyboardDefaults control
* in the map so that the map is not moved when the arrow keys are pressed.
*
* This control relies on the OpenLayers.Handler.KeyboardPoint custom handler.
*/
OpenLayers.Control.KeyboardClick = OpenLayers.Class(OpenLayers.Control, {
initialize: function(options) {
OpenLayers.Control.prototype.initialize.apply(this, [options]);
var observeElement = this.observeElement || document;
this.handler = new OpenLayers.Handler.KeyboardPoint(this, {
done: this.onClick,
cancel: this.deactivate
}, {
observeElement: observeElement
});
OpenLayers.Event.observe(
observeElement,
"keydown",
OpenLayers.Function.bindAsEventListener(
function(evt) {
if (evt.keyCode == 73) { // "i"
if (this.active) {
this.deactivate();
} else {
this.activate();
}
}
},
this
)
);
},
onClick: function(geometry) {
alert("You clicked near " + geometry.x + " N, " +
geometry.y + " E");
},
activate: function() {
if(!OpenLayers.Control.prototype.activate.apply(this, arguments)) {
return false;
}
// deactivate any KeyboardDefaults control
var keyboardDefaults = this.map.getControlsByClass(
'OpenLayers.Control.KeyboardDefaults')[0];
if (keyboardDefaults) {
keyboardDefaults.deactivate();
}
return true;
},
deactivate: function() {
if(!OpenLayers.Control.prototype.deactivate.apply(this, arguments)) {
return false;
}
// reactivate any KeyboardDefaults control
var keyboardDefaults = this.map.getControlsByClass(
'OpenLayers.Control.KeyboardDefaults')[0];
if (keyboardDefaults) {
keyboardDefaults.activate();
}
return true;
}
});
/**
* Class: OpenLayers.Handler.KeyboardPoint
*
* A custom handler that displays a vector point that can be moved
* using the arrow keys of the keyboard.
*/
OpenLayers.Handler.KeyboardPoint = OpenLayers.Class(OpenLayers.Handler, {
KEY_EVENTS: ["keydown"],
initialize: function(control, callbacks, options) {
OpenLayers.Handler.prototype.initialize.apply(this, arguments);
// cache the bound event listener method so it can be unobserved later
this.eventListener = OpenLayers.Function.bindAsEventListener(
this.handleKeyEvent, this
);
},
activate: function() {
if(!OpenLayers.Handler.prototype.activate.apply(this, arguments)) {
return false;
}
this.layer = new OpenLayers.Layer.Vector(this.CLASS_NAME);
this.map.addLayer(this.layer);
this.observeElement = this.observeElement || document;
for (var i=0, len=this.KEY_EVENTS.length; i<len; i++) {
OpenLayers.Event.observe(
this.observeElement, this.KEY_EVENTS[i], this.eventListener);
}
if(!this.point) {
this.createFeature();
}
return true;
},
deactivate: function() {
if (!OpenLayers.Handler.prototype.deactivate.apply(this, arguments)) {
return false;
}
for (var i=0, len=this.KEY_EVENTS.length; i<len; i++) {
OpenLayers.Event.stopObserving(
this.observeElement, this.KEY_EVENTS[i], this.eventListener);
}
this.map.removeLayer(this.layer);
this.destroyFeature();
return true;
},
handleKeyEvent: function (evt) {
switch(evt.keyCode) {
case OpenLayers.Event.KEY_LEFT:
this.modifyFeature(-3, 0);
break;
case OpenLayers.Event.KEY_RIGHT:
this.modifyFeature(3, 0);
break;
case OpenLayers.Event.KEY_UP:
this.modifyFeature(0, 3);
break;
case OpenLayers.Event.KEY_DOWN:
this.modifyFeature(0, -3);
break;
case OpenLayers.Event.KEY_RETURN:
this.callback('done', [this.point.geometry.clone()]);
break;
case OpenLayers.Event.KEY_ESC:
this.callback('cancel');
break;
}
},
modifyFeature: function(lon, lat) {
if(!this.point) {
this.createFeature();
}
var resolution = this.map.getResolution();
this.point.geometry.x = this.point.geometry.x + lon * resolution;
this.point.geometry.y = this.point.geometry.y + lat * resolution;
this.callback("modify", [this.point.geometry, this.point, false]);
this.point.geometry.clearBounds();
this.drawFeature();
},
createFeature: function() {
var center = this.map.getCenter();
var geometry = new OpenLayers.Geometry.Point(
center.lon, center.lat
);
this.point = new OpenLayers.Feature.Vector(geometry);
this.callback("create", [this.point.geometry, this.point]);
this.point.geometry.clearBounds();
this.layer.addFeatures([this.point], {silent: true});
},
destroyFeature: function() {
this.layer.destroyFeatures([this.point]);
this.point = null;
},
drawFeature: function() {
this.layer.drawFeature(this.point, this.style);
}
});
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