/* 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
*/
/**
* Class: OpenLayers.Control.Graticule
* The Graticule displays a grid of latitude/longitude lines reprojected on
* the map.
*
* Inherits from:
* - <OpenLayers.Control>
*
*/
OpenLayers.Control.Graticule = OpenLayers.Class(OpenLayers.Control, {
/**
* APIProperty: autoActivate
* {Boolean} Activate the control when it is added to a map. Default is
* true.
*/
autoActivate: true,
/**
* APIProperty: intervals
* {Array(Float)} A list of possible graticule widths in degrees.
*/
intervals: [ 45, 30, 20, 10, 5, 2, 1,
0.5, 0.2, 0.1, 0.05, 0.01,
0.005, 0.002, 0.001 ],
/**
* APIProperty: displayInLayerSwitcher
* {Boolean} Allows the Graticule control to be switched on and off by
* LayerSwitcher control. Defaults is true.
*/
displayInLayerSwitcher: true,
/**
* APIProperty: visible
* {Boolean} should the graticule be initially visible (default=true)
*/
visible: true,
/**
* APIProperty: numPoints
* {Integer} The number of points to use in each graticule line. Higher
* numbers result in a smoother curve for projected maps
*/
numPoints: 50,
/**
* APIProperty: targetSize
* {Integer} The maximum size of the grid in pixels on the map
*/
targetSize: 200,
/**
* APIProperty: layerName
* {String} The name to be displayed in the layer switcher, default is set
* by {<OpenLayers.Lang>}.
*/
layerName: null,
/**
* APIProperty: labelled
* {Boolean} Should the graticule lines be labelled?. default=true
*/
labelled: true,
/**
* APIProperty: labelFormat
* {String} the format of the labels, default = 'dm'. See
* <OpenLayers.Util.getFormattedLonLat> for other options.
*/
labelFormat: 'dm',
/**
* APIProperty: lineSymbolizer
* {symbolizer} the symbolizer used to render lines
*/
lineSymbolizer: {
strokeColor: "#333",
strokeWidth: 1,
strokeOpacity: 0.5
},
/**
* APIProperty: labelSymbolizer
* {symbolizer} the symbolizer used to render labels
*/
labelSymbolizer: {},
/**
* Property: gratLayer
* {OpenLayers.Layer.Vector} vector layer used to draw the graticule on
*/
gratLayer: null,
/**
* Constructor: OpenLayers.Control.Graticule
* Create a new graticule control to display a grid of latitude longitude
* lines.
*
* Parameters:
* options - {Object} An optional object whose properties will be used
* to extend the control.
*/
initialize: function(options) {
options = options || {};
options.layerName = options.layerName || OpenLayers.i18n("graticule");
OpenLayers.Control.prototype.initialize.apply(this, [options]);
this.labelSymbolizer.stroke = false;
this.labelSymbolizer.fill = false;
this.labelSymbolizer.label = "${label}";
this.labelSymbolizer.labelAlign = "${labelAlign}";
this.labelSymbolizer.labelXOffset = "${xOffset}";
this.labelSymbolizer.labelYOffset = "${yOffset}";
},
/**
* APIMethod: destroy
*/
destroy: function() {
this.deactivate();
OpenLayers.Control.prototype.destroy.apply(this, arguments);
if (this.gratLayer) {
this.gratLayer.destroy();
this.gratLayer = null;
}
},
/**
* Method: draw
*
* initializes the graticule layer and does the initial update
*
* Returns:
* {DOMElement}
*/
draw: function() {
OpenLayers.Control.prototype.draw.apply(this, arguments);
if (!this.gratLayer) {
var gratStyle = new OpenLayers.Style({},{
rules: [new OpenLayers.Rule({'symbolizer':
{"Point":this.labelSymbolizer,
"Line":this.lineSymbolizer}
})]
});
this.gratLayer = new OpenLayers.Layer.Vector(this.layerName, {
styleMap: new OpenLayers.StyleMap({'default':gratStyle}),
visibility: this.visible,
displayInLayerSwitcher: this.displayInLayerSwitcher
});
}
return this.div;
},
/**
* APIMethod: activate
*/
activate: function() {
if (OpenLayers.Control.prototype.activate.apply(this, arguments)) {
this.map.addLayer(this.gratLayer);
this.map.events.register('moveend', this, this.update);
this.update();
return true;
} else {
return false;
}
},
/**
* APIMethod: deactivate
*/
deactivate: function() {
if (OpenLayers.Control.prototype.deactivate.apply(this, arguments)) {
this.map.events.unregister('moveend', this, this.update);
this.map.removeLayer(this.gratLayer);
return true;
} else {
return false;
}
},
/**
* Method: update
*
* calculates the grid to be displayed and actually draws it
*
* Returns:
* {DOMElement}
*/
update: function() {
//wait for the map to be initialized before proceeding
var mapBounds = this.map.getExtent();
if (!mapBounds) {
return;
}
//clear out the old grid
this.gratLayer.destroyFeatures();
//get the projection objects required
var llProj = new OpenLayers.Projection("EPSG:4326");
var mapProj = this.map.getProjectionObject();
var mapRes = this.map.getResolution();
//if the map is in lon/lat, then the lines are straight and only one
//point is required
if (mapProj.proj && mapProj.proj.projName == "longlat") {
this.numPoints = 1;
}
//get the map center in EPSG:4326
var mapCenter = this.map.getCenter(); //lon and lat here are really map x and y
var mapCenterLL = new OpenLayers.Pixel(mapCenter.lon, mapCenter.lat);
OpenLayers.Projection.transform(mapCenterLL, mapProj, llProj);
/* This block of code determines the lon/lat interval to use for the
* grid by calculating the diagonal size of one grid cell at the map
* center. Iterates through the intervals array until the diagonal
* length is less than the targetSize option.
*/
//find lat/lon interval that results in a grid of less than the target size
var testSq = this.targetSize*mapRes;
testSq *= testSq; //compare squares rather than doing a square root to save time
var llInterval;
for (var i=0; i<this.intervals.length; ++i) {
llInterval = this.intervals[i]; //could do this for both x and y??
var delta = llInterval/2;
var p1 = mapCenterLL.offset(new OpenLayers.Pixel(-delta, -delta)); //test coords in EPSG:4326 space
var p2 = mapCenterLL.offset(new OpenLayers.Pixel( delta, delta));
OpenLayers.Projection.transform(p1, llProj, mapProj); // convert them back to map projection
OpenLayers.Projection.transform(p2, llProj, mapProj);
var distSq = (p1.x-p2.x)*(p1.x-p2.x) + (p1.y-p2.y)*(p1.y-p2.y);
if (distSq <= testSq) {
break;
}
}
//alert(llInterval);
//round the LL center to an even number based on the interval
mapCenterLL.x = Math.floor(mapCenterLL.x/llInterval)*llInterval;
mapCenterLL.y = Math.floor(mapCenterLL.y/llInterval)*llInterval;
//TODO adjust for minutses/seconds?
/* The following 2 blocks calculate the nodes of the grid along a
* line of constant longitude (then latitiude) running through the
* center of the map until it reaches the map edge. The calculation
* goes from the center in both directions to the edge.
*/
//get the central longitude line, increment the latitude
var iter = 0;
var centerLonPoints = [mapCenterLL.clone()];
var newPoint = mapCenterLL.clone();
var mapXY;
do {
newPoint = newPoint.offset(new OpenLayers.Pixel(0,llInterval));
mapXY = OpenLayers.Projection.transform(newPoint.clone(), llProj, mapProj);
centerLonPoints.unshift(newPoint);
} while (mapBounds.containsPixel(mapXY) && ++iter<1000);
newPoint = mapCenterLL.clone();
do {
newPoint = newPoint.offset(new OpenLayers.Pixel(0,-llInterval));
mapXY = OpenLayers.Projection.transform(newPoint.clone(), llProj, mapProj);
centerLonPoints.push(newPoint);
} while (mapBounds.containsPixel(mapXY) && ++iter<1000);
//get the central latitude line, increment the longitude
iter = 0;
var centerLatPoints = [mapCenterLL.clone()];
newPoint = mapCenterLL.clone();
do {
newPoint = newPoint.offset(new OpenLayers.Pixel(-llInterval, 0));
mapXY = OpenLayers.Projection.transform(newPoint.clone(), llProj, mapProj);
centerLatPoints.unshift(newPoint);
} while (mapBounds.containsPixel(mapXY) && ++iter<1000);
newPoint = mapCenterLL.clone();
do {
newPoint = newPoint.offset(new OpenLayers.Pixel(llInterval, 0));
mapXY = OpenLayers.Projection.transform(newPoint.clone(), llProj, mapProj);
centerLatPoints.push(newPoint);
} while (mapBounds.containsPixel(mapXY) && ++iter<1000);
//now generate a line for each node in the central lat and lon lines
//first loop over constant longitude
var lines = [];
for(var i=0; i < centerLatPoints.length; ++i) {
var lon = centerLatPoints[i].x;
var pointList = [];
var labelPoint = null;
var latEnd = Math.min(centerLonPoints[0].y, 90);
var latStart = Math.max(centerLonPoints[centerLonPoints.length - 1].y, -90);
var latDelta = (latEnd - latStart)/this.numPoints;
var lat = latStart;
for(var j=0; j<= this.numPoints; ++j) {
var gridPoint = new OpenLayers.Geometry.Point(lon,lat);
gridPoint.transform(llProj, mapProj);
pointList.push(gridPoint);
lat += latDelta;
if (gridPoint.y >= mapBounds.bottom && !labelPoint) {
labelPoint = gridPoint;
}
}
if (this.labelled) {
//keep track of when this grid line crosses the map bounds to set
//the label position
//labels along the bottom, add 10 pixel offset up into the map
//TODO add option for labels on top
var labelPos = new OpenLayers.Geometry.Point(labelPoint.x,mapBounds.bottom);
var labelAttrs = {
value: lon,
label: this.labelled?OpenLayers.Util.getFormattedLonLat(lon, "lon", this.labelFormat):"",
labelAlign: "cb",
xOffset: 0,
yOffset: 2
};
this.gratLayer.addFeatures(new OpenLayers.Feature.Vector(labelPos,labelAttrs));
}
var geom = new OpenLayers.Geometry.LineString(pointList);
lines.push(new OpenLayers.Feature.Vector(geom));
}
//now draw the lines of constant latitude
for (var j=0; j < centerLonPoints.length; ++j) {
lat = centerLonPoints[j].y;
if (lat<-90 || lat>90) { //latitudes only valid between -90 and 90
continue;
}
var pointList = [];
var lonStart = centerLatPoints[0].x;
var lonEnd = centerLatPoints[centerLatPoints.length - 1].x;
var lonDelta = (lonEnd - lonStart)/this.numPoints;
var lon = lonStart;
var labelPoint = null;
for(var i=0; i <= this.numPoints ; ++i) {
var gridPoint = new OpenLayers.Geometry.Point(lon,lat);
gridPoint.transform(llProj, mapProj);
pointList.push(gridPoint);
lon += lonDelta;
if (gridPoint.x < mapBounds.right) {
labelPoint = gridPoint;
}
}
if (this.labelled) {
//keep track of when this grid line crosses the map bounds to set
//the label position
//labels along the right, 30 pixel offset left into the map
//TODO add option for labels on left
var labelPos = new OpenLayers.Geometry.Point(mapBounds.right, labelPoint.y);
var labelAttrs = {
value: lat,
label: this.labelled?OpenLayers.Util.getFormattedLonLat(lat, "lat", this.labelFormat):"",
labelAlign: "rb",
xOffset: -2,
yOffset: 2
};
this.gratLayer.addFeatures(new OpenLayers.Feature.Vector(labelPos,labelAttrs));
}
var geom = new OpenLayers.Geometry.LineString(pointList);
lines.push(new OpenLayers.Feature.Vector(geom));
}
this.gratLayer.addFeatures(lines);
},
CLASS_NAME: "OpenLayers.Control.Graticule"
});