/* Copyright (c) 2006-2010 by OpenLayers Contributors (see authors.txt for
* full list of contributors). Published under the Clear BSD license.
* See http://svn.openlayers.org/trunk/openlayers/license.txt for the
* full text of the license. */
/**
* @requires OpenLayers/Control.js
* @requires OpenLayers/Layer/Vector.js
*/
/**
* Class: OpenLayers.Control.Snapping
* Acts as a snapping agent while editing vector features.
*
* Inherits from:
* - <OpenLayers.Control>
*/
OpenLayers.Control.Snapping = OpenLayers.Class(OpenLayers.Control, {
/**
* Constant: EVENT_TYPES
* {Array(String)} Supported application event types. Register a listener
* for a particular event with the following syntax:
* (code)
* control.events.register(type, obj, listener);
* (end)
*
* Listeners will be called with a reference to an event object. The
* properties of this event depends on exactly what happened.
*
* Supported control event types (in addition to those from <OpenLayers.Control>):
* beforesnap - Triggered before a snap occurs. Listeners receive an
* event object with *point*, *x*, *y*, *distance*, *layer*, and
* *snapType* properties. The point property will be original point
* geometry considered for snapping. The x and y properties represent
* coordinates the point will receive. The distance is the distance
* of the snap. The layer is the target layer. The snapType property
* will be one of "node", "vertex", or "edge". Return false to stop
* snapping from occurring.
* snap - Triggered when a snap occurs. Listeners receive an event with
* *point*, *snapType*, *layer*, and *distance* properties. The point
* will be the location snapped to. The snapType will be one of "node",
* "vertex", or "edge". The layer will be the target layer. The
* distance will be the distance of the snap in map units.
* unsnap - Triggered when a vertex is unsnapped. Listeners receive an
* event with a *point* property.
*/
EVENT_TYPES: ["beforesnap", "snap", "unsnap"],
/**
* CONSTANT: DEFAULTS
* Default target properties.
*/
DEFAULTS: {
tolerance: 10,
node: true,
edge: true,
vertex: true
},
/**
* Property: greedy
* {Boolean} Snap to closest feature in first layer with an eligible
* feature. Default is true.
*/
greedy: true,
/**
* Property: precedence
* {Array} List representing precedence of different snapping types.
* Default is "node", "vertex", "edge".
*/
precedence: ["node", "vertex", "edge"],
/**
* Property: resolution
* {Float} The map resolution for the previously considered snap.
*/
resolution: null,
/**
* Property: geoToleranceCache
* {Object} A cache of geo-tolerances. Tolerance values (in map units) are
* calculated when the map resolution changes.
*/
geoToleranceCache: null,
/**
* Property: layer
* {<OpenLayers.Layer.Vector>} The current editable layer. Set at
* construction or after construction with <setLayer>.
*/
layer: null,
/**
* Property: feature
* {<OpenLayers.Feature.Vector>} The current editable feature.
*/
feature: null,
/**
* Property: point
* {<OpenLayers.Geometry.Point>} The currently snapped vertex.
*/
point: null,
/**
* Constructor: OpenLayers.Control.Snapping
* Creates a new snapping control. A control is constructed with an editable
* layer and a set of configuration objects for target layers. While the
* control is active, dragging vertices while drawing new features or
* modifying existing features on the editable layer will engage
* snapping to features on the target layers. Whether a vertex snaps to
* a feature on a target layer depends on the target layer configuration.
*
* Parameters:
* options - {Object} An object containing all configuration properties for
* the control.
*
* Valid options:
* layer - {OpenLayers.Layer.Vector} The editable layer. Features from this
* layer that are digitized or modified may have vertices snapped to
* features from any of the target layers.
* targets - {Array(Object | OpenLayers.Layer.Vector)} A list of objects for
* configuring target layers. See valid properties of the target
* objects below. If the items in the targets list are vector layers
* (instead of configuration objects), the defaults from the <defaults>
* property will apply. The editable layer itself may be a target
* layer - allowing newly created or edited features to be snapped to
* existing features from the same layer. If no targets are provided
* the layer given in the constructor (as <layer>) will become the
* initial target.
* defaults - {Object} An object with default properties to be applied
* to all target objects.
* greedy - {Boolean} Snap to closest feature in first target layer that
* applies. Default is true. If false, all features in all target
* layers will be checked and the closest feature in all target layers
* will be chosen. The greedy property determines if the order of the
* target layers is significant. By default, the order of the target
* layers is significant where layers earlier in the target layer list
* have precedence over layers later in the list. Within a single
* layer, the closest feature is always chosen for snapping. This
* property only determines whether the search for a closer feature
* continues after an eligible feature is found in a target layer.
*
* Valid target properties:
* layer - {OpenLayers.Layer.Vector} A target layer. Features from this
* layer will be eligible to act as snapping target for the editable
* layer.
* tolerance - {Float} The distance (in pixels) at which snapping may occur.
* Default is 10.
* node - {Boolean} Snap to nodes (first or last point in a geometry) in
* target layer. Default is true.
* nodeTolerance - {Float} Optional distance at which snapping may occur
* for nodes specifically. If none is provided, <tolerance> will be
* used.
* vertex - {Boolean} Snap to vertices in target layer. Default is true.
* vertexTolerance - {Float} Optional distance at which snapping may occur
* for vertices specifically. If none is provided, <tolerance> will be
* used.
* edge - {Boolean} Snap to edges in target layer. Default is true.
* edgeTolerance - {Float} Optional distance at which snapping may occur
* for edges specifically. If none is provided, <tolerance> will be
* used.
* filter - {OpenLayers.Filter} Optional filter to evaluate to determine if
* feature is eligible for snapping. If filter evaluates to true for a
* target feature a vertex may be snapped to the feature.
*/
initialize: function(options) {
// concatenate events specific to measure with those from the base
Array.prototype.push.apply(
this.EVENT_TYPES, OpenLayers.Control.prototype.EVENT_TYPES
);
OpenLayers.Control.prototype.initialize.apply(this, [options]);
this.options = options || {}; // TODO: this could be done by the super
// set the editable layer if provided
if(this.options.layer) {
this.setLayer(this.options.layer);
}
// configure target layers
var defaults = OpenLayers.Util.extend({}, this.options.defaults);
this.defaults = OpenLayers.Util.applyDefaults(defaults, this.DEFAULTS);
this.setTargets(this.options.targets);
if(this.targets.length === 0 && this.layer) {
this.addTargetLayer(this.layer);
}
this.geoToleranceCache = {};
},
/**
* APIMethod: setLayer
* Set the editable layer. Call the setLayer method if the editable layer
* changes and the same control should be used on a new editable layer.
* If the control is already active, it will be active after the new
* layer is set.
*
* Parameters:
* layer - {OpenLayers.Layer.Vector} The new editable layer.
*/
setLayer: function(layer) {
if(this.active) {
this.deactivate();
this.layer = layer;
this.activate();
} else {
this.layer = layer;
}
},
/**
* Method: setTargets
* Set the targets for the snapping agent.
*
* Parameters:
* targets - {Array} An array of target configs or target layers.
*/
setTargets: function(targets) {
this.targets = [];
if(targets && targets.length) {
var target;
for(var i=0, len=targets.length; i<len; ++i) {
target = targets[i];
if(target instanceof OpenLayers.Layer.Vector) {
this.addTargetLayer(target);
} else {
this.addTarget(target);
}
}
}
},
/**
* Method: addTargetLayer
* Add a target layer with the default target config.
*
* Parameters:
* layer - {<OpenLayers.Layer.Vector>} A target layer.
*/
addTargetLayer: function(layer) {
this.addTarget({layer: layer});
},
/**
* Method: addTarget
* Add a configured target layer.
*
* Parameters:
* target - {Object} A target config.
*/
addTarget: function(target) {
target = OpenLayers.Util.applyDefaults(target, this.defaults);
target.nodeTolerance = target.nodeTolerance || target.tolerance;
target.vertexTolerance = target.vertexTolerance || target.tolerance;
target.edgeTolerance = target.edgeTolerance || target.tolerance;
this.targets.push(target);
},
/**
* Method: removeTargetLayer
* Remove a target layer.
*
* Parameters:
* layer - {<OpenLayers.Layer.Vector>} The target layer to remove.
*/
removeTargetLayer: function(layer) {
var target;
for(var i=this.targets.length-1; i>=0; --i) {
target = this.targets[i];
if(target.layer === layer) {
this.removeTarget(target);
}
}
},
/**
* Method: removeTarget
* Remove a target.
*
* Parameters:
* target - {Object} A target config.
*
* Returns:
* {Array} The targets array.
*/
removeTarget: function(target) {
return OpenLayers.Util.removeItem(this.targets, target);
},
/**
* APIMethod: activate
* Activate the control. Activating the control registers listeners for
* editing related events so that during feature creation and
* modification, moving vertices will trigger snapping.
*/
activate: function() {
var activated = OpenLayers.Control.prototype.activate.call(this);
if(activated) {
if(this.layer && this.layer.events) {
this.layer.events.on({
sketchstarted: this.onSketchModified,
sketchmodified: this.onSketchModified,
vertexmodified: this.onVertexModified,
scope: this
});
}
}
return activated;
},
/**
* APIMethod: deactivate
* Deactivate the control. Deactivating the control unregisters listeners
* so feature editing may proceed without engaging the snapping agent.
*/
deactivate: function() {
var deactivated = OpenLayers.Control.prototype.deactivate.call(this);
if(deactivated) {
if(this.layer && this.layer.events) {
this.layer.events.un({
sketchstarted: this.onSketchModified,
sketchmodified: this.onSketchModified,
vertexmodified: this.onVertexModified,
scope: this
});
}
}
this.feature = null;
this.point = null;
return deactivated;
},
/**
* Method: onSketchModified
* Registered as a listener for the sketchmodified event on the editable
* layer.
*
* Parameters:
* event - {Object} The sketch modified event.
*/
onSketchModified: function(event) {
this.feature = event.feature;
this.considerSnapping(event.vertex, event.vertex);
},
/**
* Method: onVertexModified
* Registered as a listener for the vertexmodified event on the editable
* layer.
*
* Parameters:
* event - {Object} The vertex modified event.
*/
onVertexModified: function(event) {
this.feature = event.feature;
var loc = this.layer.map.getLonLatFromViewPortPx(event.pixel);
this.considerSnapping(
event.vertex, new OpenLayers.Geometry.Point(loc.lon, loc.lat)
);
},
/**
* Method: considerSnapping
*
* Parameters:
* point - {<OpenLayers.Geometry.Point}} The vertex to be snapped (or
* unsnapped).
* loc - {<OpenLayers.Geometry.Point>} The location of the mouse in map
* coords.
*/
considerSnapping: function(point, loc) {
var best = {
rank: Number.POSITIVE_INFINITY,
dist: Number.POSITIVE_INFINITY,
x: null, y: null
};
var snapped = false;
var result, target;
for(var i=0, len=this.targets.length; i<len; ++i) {
target = this.targets[i];
result = this.testTarget(target, loc);
if(result) {
if(this.greedy) {
best = result;
best.target = target;
snapped = true;
break;
} else {
if((result.rank < best.rank) ||
(result.rank === best.rank && result.dist < best.dist)) {
best = result;
best.target = target;
snapped = true;
}
}
}
}
if(snapped) {
var proceed = this.events.triggerEvent("beforesnap", {
point: point, x: best.x, y: best.y, distance: best.dist,
layer: best.target.layer, snapType: this.precedence[best.rank]
});
if(proceed !== false) {
point.x = best.x;
point.y = best.y;
this.point = point;
this.events.triggerEvent("snap", {
point: point,
snapType: this.precedence[best.rank],
layer: best.target.layer,
distance: best.dist
});
} else {
snapped = false;
}
}
if(this.point && !snapped) {
point.x = loc.x;
point.y = loc.y;
this.point = null;
this.events.triggerEvent("unsnap", {point: point});
}
},
/**
* Method: testTarget
*
* Parameters:
* target - {Object} Object with target layer configuration.
* loc - {<OpenLayers.Geometry.Point>} The location of the mouse in map
* coords.
*
* Returns:
* {Object} A result object with rank, dist, x, and y properties.
* Returns null if candidate is not eligible for snapping.
*/
testTarget: function(target, loc) {
var tolerance = {
node: this.getGeoTolerance(target.nodeTolerance),
vertex: this.getGeoTolerance(target.vertexTolerance),
edge: this.getGeoTolerance(target.edgeTolerance)
};
// this could be cached if we don't support setting tolerance values directly
var maxTolerance = Math.max(
tolerance.node, tolerance.vertex, tolerance.edge
);
var result = {
rank: Number.POSITIVE_INFINITY, dist: Number.POSITIVE_INFINITY
};
var eligible = false;
var features = target.layer.features;
var feature, type, vertices, vertex, closest, dist, found;
var numTypes = this.precedence.length;
var ll = new OpenLayers.LonLat(loc.x, loc.y);
for(var i=0, len=features.length; i<len; ++i) {
feature = features[i];
if(feature !== this.feature && !feature._sketch &&
feature.state !== OpenLayers.State.DELETE &&
(!target.filter || target.filter.evaluate(feature.attributes))) {
if(feature.atPoint(ll, maxTolerance, maxTolerance)) {
for(var j=0, stop=Math.min(result.rank+1, numTypes); j<stop; ++j) {
type = this.precedence[j];
if(target[type]) {
if(type === "edge") {
closest = feature.geometry.distanceTo(loc, {details: true});
dist = closest.distance;
if(dist <= tolerance[type] && dist < result.dist) {
result = {
rank: j, dist: dist,
x: closest.x0, y: closest.y0 // closest coords on feature
};
eligible = true;
// don't look for lower precedence types for this feature
break;
}
} else {
// look for nodes or vertices
vertices = feature.geometry.getVertices(type === "node");
found = false;
for(var k=0, klen=vertices.length; k<klen; ++k) {
vertex = vertices[k];
dist = vertex.distanceTo(loc);
if(dist <= tolerance[type] &&
(j < result.rank || (j === result.rank && dist < result.dist))) {
result = {
rank: j, dist: dist,
x: vertex.x, y: vertex.y
};
eligible = true;
found = true;
}
}
if(found) {
// don't look for lower precedence types for this feature
break;
}
}
}
}
}
}
}
return eligible ? result : null;
},
/**
* Method: getGeoTolerance
* Calculate a tolerance in map units given a tolerance in pixels. This
* takes advantage of the <geoToleranceCache> when the map resolution
* has not changed.
*
* Parameters:
* tolerance - {Number} A tolerance value in pixels.
*
* Returns:
* {Number} A tolerance value in map units.
*/
getGeoTolerance: function(tolerance) {
var resolution = this.layer.map.getResolution();
if(resolution !== this.resolution) {
this.resolution = resolution;
this.geoToleranceCache = {};
}
var geoTolerance = this.geoToleranceCache[tolerance];
if(geoTolerance === undefined) {
geoTolerance = tolerance * resolution;
this.geoToleranceCache[tolerance] = geoTolerance;
}
return geoTolerance;
},
/**
* Method: destroy
* Clean up the control.
*/
destroy: function() {
if(this.active) {
this.deactivate(); // TODO: this should be handled by the super
}
delete this.layer;
delete this.targets;
OpenLayers.Control.prototype.destroy.call(this);
},
CLASS_NAME: "OpenLayers.Control.Snapping"
});