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/* Copyright (c) 2006-2013 by OpenLayers Contributors (see authors.txt for
* full list of contributors). Published under the 2-clause BSD license.
* See license.txt in the OpenLayers distribution or repository for the
* full text of the license. */
/**
* @requires OpenLayers/Layer/Vector.js
* @requires OpenLayers/Geometry/Polygon.js
*/
/**
* Class: OpenLayers.Layer.PointGrid
* A point grid layer dynamically generates a regularly spaced grid of point
* features. This is a specialty layer for cases where an application needs
* a regular grid of points. It can be used, for example, in an editing
* environment to snap to a grid.
*
* Create a new vector layer with the <OpenLayers.Layer.PointGrid> constructor.
* (code)
* // create a grid with points spaced at 10 map units
* var points = new OpenLayers.Layer.PointGrid({dx: 10, dy: 10});
*
* // create a grid with different x/y spacing rotated 15 degrees clockwise.
* var points = new OpenLayers.Layer.PointGrid({dx: 5, dy: 10, rotation: 15});
* (end)
*
* Inherits from:
* - <OpenLayers.Layer.Vector>
*/
OpenLayers.Layer.PointGrid = OpenLayers.Class(OpenLayers.Layer.Vector, {
/**
* APIProperty: dx
* {Number} Point grid spacing in the x-axis direction (map units).
* Read-only. Use the <setSpacing> method to modify this value.
*/
dx: null,
/**
* APIProperty: dy
* {Number} Point grid spacing in the y-axis direction (map units).
* Read-only. Use the <setSpacing> method to modify this value.
*/
dy: null,
/**
* APIProperty: ratio
* {Number} Ratio of the desired grid size to the map viewport size.
* Default is 1.5. Larger ratios mean the grid is recalculated less often
* while panning. The <maxFeatures> setting has precedence when determining
* grid size. Read-only. Use the <setRatio> method to modify this value.
*/
ratio: 1.5,
/**
* APIProperty: maxFeatures
* {Number} The maximum number of points to generate in the grid. Default
* is 250. Read-only. Use the <setMaxFeatures> method to modify this value.
*/
maxFeatures: 250,
/**
* APIProperty: rotation
* {Number} Grid rotation (in degrees clockwise from the positive x-axis).
* Default is 0. Read-only. Use the <setRotation> method to modify this
* value.
*/
rotation: 0,
/**
* APIProperty: origin
* {<OpenLayers.LonLat>} Grid origin. The grid lattice will be aligned with
* the origin. If not set at construction, the center of the map's maximum
* extent is used. Read-only. Use the <setOrigin> method to modify this
* value.
*/
origin: null,
/**
* Property: gridBounds
* {<OpenLayers.Bounds>} Internally cached grid bounds (with optional
* rotation applied).
*/
gridBounds: null,
/**
* Constructor: OpenLayers.Layer.PointGrid
* Creates a new point grid layer.
*
* Parameters:
* config - {Object} An object containing all configuration properties for
* the layer. The <dx> and <dy> properties are required to be set at
* construction. Any other layer properties may be set in this object.
*/
initialize: function(config) {
config = config || {};
OpenLayers.Layer.Vector.prototype.initialize.apply(this, [config.name, config]);
},
/**
* Method: setMap
* The layer has been added to the map.
*
* Parameters:
* map - {<OpenLayers.Map>}
*/
setMap: function(map) {
OpenLayers.Layer.Vector.prototype.setMap.apply(this, arguments);
map.events.register("moveend", this, this.onMoveEnd);
},
/**
* Method: removeMap
* The layer has been removed from the map.
*
* Parameters:
* map - {<OpenLayers.Map>}
*/
removeMap: function(map) {
map.events.unregister("moveend", this, this.onMoveEnd);
OpenLayers.Layer.Vector.prototype.removeMap.apply(this, arguments);
},
/**
* APIMethod: setRatio
* Set the grid <ratio> property and update the grid. Can only be called
* after the layer has been added to a map with a center/extent.
*
* Parameters:
* ratio - {Number}
*/
setRatio: function(ratio) {
this.ratio = ratio;
this.updateGrid(true);
},
/**
* APIMethod: setMaxFeatures
* Set the grid <maxFeatures> property and update the grid. Can only be
* called after the layer has been added to a map with a center/extent.
*
* Parameters:
* maxFeatures - {Number}
*/
setMaxFeatures: function(maxFeatures) {
this.maxFeatures = maxFeatures;
this.updateGrid(true);
},
/**
* APIMethod: setSpacing
* Set the grid <dx> and <dy> properties and update the grid. If only one
* argument is provided, it will be set as <dx> and <dy>. Can only be
* called after the layer has been added to a map with a center/extent.
*
* Parameters:
* dx - {Number}
* dy - {Number}
*/
setSpacing: function(dx, dy) {
this.dx = dx;
this.dy = dy || dx;
this.updateGrid(true);
},
/**
* APIMethod: setOrigin
* Set the grid <origin> property and update the grid. Can only be called
* after the layer has been added to a map with a center/extent.
*
* Parameters:
* origin - {<OpenLayers.LonLat>}
*/
setOrigin: function(origin) {
this.origin = origin;
this.updateGrid(true);
},
/**
* APIMethod: getOrigin
* Get the grid <origin> property.
*
* Returns:
* {<OpenLayers.LonLat>} The grid origin.
*/
getOrigin: function() {
if (!this.origin) {
this.origin = this.map.getExtent().getCenterLonLat();
}
return this.origin;
},
/**
* APIMethod: setRotation
* Set the grid <rotation> property and update the grid. Rotation values
* are in degrees clockwise from the positive x-axis (negative values
* for counter-clockwise rotation). Can only be called after the layer
* has been added to a map with a center/extent.
*
* Parameters:
* rotation - {Number} Degrees clockwise from the positive x-axis.
*/
setRotation: function(rotation) {
this.rotation = rotation;
this.updateGrid(true);
},
/**
* Method: onMoveEnd
* Listener for map "moveend" events.
*/
onMoveEnd: function() {
this.updateGrid();
},
/**
* Method: getViewBounds
* Gets the (potentially rotated) view bounds for grid calculations.
*
* Returns:
* {<OpenLayers.Bounds>}
*/
getViewBounds: function() {
var bounds = this.map.getExtent();
if (this.rotation) {
var origin = this.getOrigin();
var rotationOrigin = new OpenLayers.Geometry.Point(origin.lon, origin.lat);
var rect = bounds.toGeometry();
rect.rotate(-this.rotation, rotationOrigin);
bounds = rect.getBounds();
}
return bounds;
},
/**
* Method: updateGrid
* Update the grid.
*
* Parameters:
* force - {Boolean} Update the grid even if the previous bounds are still
* valid.
*/
updateGrid: function(force) {
if (force || this.invalidBounds()) {
var viewBounds = this.getViewBounds();
var origin = this.getOrigin();
var rotationOrigin = new OpenLayers.Geometry.Point(origin.lon, origin.lat);
var viewBoundsWidth = viewBounds.getWidth();
var viewBoundsHeight = viewBounds.getHeight();
var aspectRatio = viewBoundsWidth / viewBoundsHeight;
var maxHeight = Math.sqrt(this.dx * this.dy * this.maxFeatures / aspectRatio);
var maxWidth = maxHeight * aspectRatio;
var gridWidth = Math.min(viewBoundsWidth * this.ratio, maxWidth);
var gridHeight = Math.min(viewBoundsHeight * this.ratio, maxHeight);
var center = viewBounds.getCenterLonLat();
this.gridBounds = new OpenLayers.Bounds(
center.lon - (gridWidth / 2),
center.lat - (gridHeight / 2),
center.lon + (gridWidth / 2),
center.lat + (gridHeight / 2)
);
var rows = Math.floor(gridHeight / this.dy);
var cols = Math.floor(gridWidth / this.dx);
var gridLeft = origin.lon + (this.dx * Math.ceil((this.gridBounds.left - origin.lon) / this.dx));
var gridBottom = origin.lat + (this.dy * Math.ceil((this.gridBounds.bottom - origin.lat) / this.dy));
var features = new Array(rows * cols);
var x, y, point;
for (var i=0; i<cols; ++i) {
x = gridLeft + (i * this.dx);
for (var j=0; j<rows; ++j) {
y = gridBottom + (j * this.dy);
point = new OpenLayers.Geometry.Point(x, y);
if (this.rotation) {
point.rotate(this.rotation, rotationOrigin);
}
features[(i*rows)+j] = new OpenLayers.Feature.Vector(point);
}
}
this.destroyFeatures(this.features, {silent: true});
this.addFeatures(features, {silent: true});
}
},
/**
* Method: invalidBounds
* Determine whether the previously generated point grid is invalid.
* This occurs when the map bounds extends beyond the previously
* generated grid bounds.
*
* Returns:
* {Boolean}
*/
invalidBounds: function() {
return !this.gridBounds || !this.gridBounds.containsBounds(this.getViewBounds());
},
CLASS_NAME: "OpenLayers.Layer.PointGrid"
});
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