606991fc0d
git-svn-id: http://svn.openlayers.org/tags/openlayers/release-2.3-rc1@2106 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
440 lines
15 KiB
JavaScript
440 lines
15 KiB
JavaScript
/* Copyright (c) 2006 MetaCarta, Inc., published under the BSD license.
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* See http://svn.openlayers.org/trunk/openlayers/release-license.txt
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* for the full text of the license. */
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/**
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* @class
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*
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* @requires OpenLayers/Layer/HTTPRequest.js
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*/
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OpenLayers.Layer.Grid = OpenLayers.Class.create();
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OpenLayers.Layer.Grid.prototype =
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OpenLayers.Class.inherit( OpenLayers.Layer.HTTPRequest, {
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/** @type OpenLayers.Size */
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tileSize: null,
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/** this is an array of rows, each row is an array of tiles
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*
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* @type Array(Array) */
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grid: null,
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/** @type Integer */
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buffer: 2,
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/**
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* @constructor
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*
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* @param {String} name
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* @param {String} url
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* @param {Object} params
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* @param {Object} options Hashtable of extra options to tag onto the layer
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*/
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initialize: function(name, url, params, options) {
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OpenLayers.Layer.HTTPRequest.prototype.initialize.apply(this,
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arguments);
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this.grid = new Array();
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},
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/** on destroy, clear the grid.
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*
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*/
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destroy: function() {
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this.clearGrid();
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this.grid = null;
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this.tileSize = null;
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OpenLayers.Layer.HTTPRequest.prototype.destroy.apply(this, arguments);
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},
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/**
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* @param {Object} obj
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*
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* @returns An exact clone of this OpenLayers.Layer.Grid
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* @type OpenLayers.Layer.Grid
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*/
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clone: function (obj) {
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if (obj == null) {
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obj = new OpenLayers.Layer.Grid(this.name,
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this.url,
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this.params,
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this.options);
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}
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//get all additions from superclasses
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obj = OpenLayers.Layer.HTTPRequest.prototype.clone.apply(this, [obj]);
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// copy/set any non-init, non-simple values here
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if (this.tileSize != null) {
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obj.tileSize = this.tileSize.clone();
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}
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// we do not want to copy reference to grid, so we make a new array
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obj.grid = new Array();
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return obj;
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},
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/** When the layer is added to a map, then we can ask the map for
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* its default tile size
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*
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* @param {OpenLayers.Map} map
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*/
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setMap: function(map) {
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OpenLayers.Layer.HTTPRequest.prototype.setMap.apply(this, arguments);
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if (this.tileSize == null) {
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this.tileSize = this.map.getTileSize();
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}
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},
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/** This function is called whenever the map is moved. All the moving
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* of actual 'tiles' is done by the map, but moveTo's role is to accept
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* a bounds and make sure the data that that bounds requires is pre-loaded.
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*
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* @param {OpenLayers.Bounds} bounds
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* @param {Boolean} zoomChanged
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* @param {Boolean} dragging
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*/
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moveTo:function(bounds, zoomChanged, dragging) {
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OpenLayers.Layer.HTTPRequest.prototype.moveTo.apply(this, arguments);
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if (bounds == null) {
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bounds = this.map.getExtent();
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}
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if (bounds != null) {
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if (!this.grid.length || zoomChanged
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|| !this.getGridBounds().containsBounds(bounds, true)) {
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this._initTiles();
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} else {
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var buffer = (this.buffer) ? this.buffer*1.5 : 1;
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while (true) {
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var tlLayer = this.grid[0][0].position;
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var tlViewPort =
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this.map.getViewPortPxFromLayerPx(tlLayer);
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if (tlViewPort.x > -this.tileSize.w * (buffer - 1)) {
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this.shiftColumn(true);
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} else if (tlViewPort.x < -this.tileSize.w * buffer) {
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this.shiftColumn(false);
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} else if (tlViewPort.y > -this.tileSize.h * (buffer - 1)) {
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this.shiftRow(true);
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} else if (tlViewPort.y < -this.tileSize.h * buffer) {
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this.shiftRow(false);
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} else {
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break;
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}
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};
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if (this.buffer == 0) {
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for (var r=0, rl=this.grid.length; r<rl; r++) {
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var row = this.grid[r];
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for (var c=0, cl=row.length; c<cl; c++) {
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var tile = row[c];
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if (!tile.drawn && tile.bounds.intersectsBounds(bounds, false)) {
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tile.draw();
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}
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}
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}
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}
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}
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}
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},
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/**
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* @private
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*
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* @returns A Bounds object representing the bounds of all the currently
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* loaded tiles (including those partially or not at all seen
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* onscreen)
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* @type OpenLayers.Bounds
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*/
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getGridBounds:function() {
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var bottom = this.grid.length - 1;
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var bottomLeftTile = this.grid[bottom][0];
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var right = this.grid[0].length - 1;
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var topRightTile = this.grid[0][right];
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return new OpenLayers.Bounds(bottomLeftTile.bounds.left,
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bottomLeftTile.bounds.bottom,
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topRightTile.bounds.right,
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topRightTile.bounds.top);
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},
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/**
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* @private
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*/
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_initTiles:function() {
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// work out mininum number of rows and columns; this is the number of
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// tiles required to cover the viewport plus one for panning
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var viewSize = this.map.getSize();
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var minRows = Math.ceil(viewSize.h/this.tileSize.h) + 1;
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var minCols = Math.ceil(viewSize.w/this.tileSize.w) + 1;
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var bounds = this.map.getExtent();
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var extent = this.map.getMaxExtent();
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var resolution = this.map.getResolution();
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var tilelon = resolution * this.tileSize.w;
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var tilelat = resolution * this.tileSize.h;
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var offsetlon = bounds.left - extent.left;
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var tilecol = Math.floor(offsetlon/tilelon) - this.buffer;
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var tilecolremain = offsetlon/tilelon - tilecol;
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var tileoffsetx = -tilecolremain * this.tileSize.w;
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var tileoffsetlon = extent.left + tilecol * tilelon;
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var offsetlat = bounds.top - (extent.bottom + tilelat);
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var tilerow = Math.ceil(offsetlat/tilelat) + this.buffer;
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var tilerowremain = tilerow - offsetlat/tilelat;
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var tileoffsety = -tilerowremain * this.tileSize.h;
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var tileoffsetlat = extent.bottom + tilerow * tilelat;
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tileoffsetx = Math.round(tileoffsetx); // heaven help us
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tileoffsety = Math.round(tileoffsety);
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this.origin = new OpenLayers.Pixel(tileoffsetx, tileoffsety);
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var startX = tileoffsetx;
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var startLon = tileoffsetlon;
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var rowidx = 0;
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do {
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var row = this.grid[rowidx++];
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if (!row) {
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row = new Array();
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this.grid.push(row);
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}
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tileoffsetlon = startLon;
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tileoffsetx = startX;
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var colidx = 0;
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do {
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var tileBounds = new OpenLayers.Bounds(tileoffsetlon,
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tileoffsetlat,
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tileoffsetlon + tilelon,
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tileoffsetlat + tilelat);
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var x = tileoffsetx;
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x -= parseInt(this.map.layerContainerDiv.style.left);
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var y = tileoffsety;
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y -= parseInt(this.map.layerContainerDiv.style.top);
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var px = new OpenLayers.Pixel(x, y);
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var tile = row[colidx++];
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if (!tile) {
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tile = this.addTile(tileBounds, px);
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row.push(tile);
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} else {
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tile.moveTo(tileBounds, px, false);
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}
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tileoffsetlon += tilelon;
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tileoffsetx += this.tileSize.w;
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} while ((tileoffsetlon <= bounds.right + tilelon * this.buffer)
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|| colidx < minCols)
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tileoffsetlat -= tilelat;
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tileoffsety += this.tileSize.h;
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} while((tileoffsetlat >= bounds.bottom - tilelat * this.buffer)
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|| rowidx < minRows)
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// remove extra rows
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while (this.grid.length > rowidx) {
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var row = this.grid.pop();
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for (var i=0, l=row.length; i<l; i++) {
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row[i].destroy();
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}
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}
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// remove extra columns
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while (this.grid[0].length > colidx) {
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for (var i=0, l=this.grid.length; i<l; i++) {
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var row = this.grid[i];
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var tile = row.pop();
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tile.destroy();
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}
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}
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//now actually draw the tiles
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this.spiralTileLoad();
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},
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/**
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* @private
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*
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* Starts at the top right corner of the grid and proceeds in a spiral
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* towards the center, adding tiles one at a time to the beginning of a
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* queue.
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*
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* Once all the grid's tiles have been added to the queue, we go back
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* and iterate through the queue (thus reversing the spiral order from
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* outside-in to inside-out), calling draw() on each tile.
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*/
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spiralTileLoad: function() {
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var tileQueue = new Array();
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var directions = ["right", "down", "left", "up"];
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var iRow = 0;
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var iCell = -1;
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var direction = OpenLayers.Util.indexOf(directions, "right");
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var directionsTried = 0;
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while( directionsTried < directions.length) {
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var testRow = iRow;
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var testCell = iCell;
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switch (directions[direction]) {
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case "right":
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testCell++;
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break;
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case "down":
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testRow++;
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break;
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case "left":
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testCell--;
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break;
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case "up":
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testRow--;
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break;
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}
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// if the test grid coordinates are within the bounds of the
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// grid, get a reference to the tile.
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var tile = null;
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if ((testRow < this.grid.length) && (testRow >= 0) &&
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(testCell < this.grid[0].length) && (testCell >= 0)) {
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tile = this.grid[testRow][testCell];
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}
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if ((tile != null) && (!tile.queued)) {
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//add tile to beginning of queue, mark it as queued.
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tileQueue.unshift(tile);
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tile.queued = true;
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//restart the directions counter and take on the new coords
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directionsTried = 0;
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iRow = testRow;
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iCell = testCell;
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} else {
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//need to try to load a tile in a different direction
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direction = (direction + 1) % 4;
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directionsTried++;
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}
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}
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// now we go through and draw the tiles in forward order
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for(var i=0; i < tileQueue.length; i++) {
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var tile = tileQueue[i]
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tile.draw();
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//mark tile as unqueued for the next time (since tiles are reused)
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tile.queued = false;
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}
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},
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/**
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* addTile gives subclasses of Grid the opportunity to create an
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* OpenLayer.Tile of their choosing. The implementer should initialize
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* the new tile and take whatever steps necessary to display it.
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*
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* @param {OpenLayers.Bounds} bounds
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*
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* @returns The added OpenLayers.Tile
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* @type OpenLayers.Tile
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*/
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addTile:function(bounds, position) {
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// Should be implemented by subclasses
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},
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/** go through and remove all tiles from the grid, calling
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* destroy() on each of them to kill circular references
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*
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* @private
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*/
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clearGrid:function() {
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if (this.grid) {
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for(var iRow=0; iRow < this.grid.length; iRow++) {
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var row = this.grid[iRow];
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for(var iCol=0; iCol < row.length; iCol++) {
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row[iCol].destroy();
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}
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this.grid = [];
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}
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}
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},
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/**
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* @private
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*
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* @param {Boolean} prepend if true, prepend to beginning.
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* if false, then append to end
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*/
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shiftRow:function(prepend) {
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var modelRowIndex = (prepend) ? 0 : (this.grid.length - 1);
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var modelRow = this.grid[modelRowIndex];
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var resolution = this.map.getResolution();
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var deltaY = (prepend) ? -this.tileSize.h : this.tileSize.h;
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var deltaLat = resolution * -deltaY;
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var row = (prepend) ? this.grid.pop() : this.grid.shift();
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for (var i=0; i < modelRow.length; i++) {
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var modelTile = modelRow[i];
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var bounds = modelTile.bounds.clone();
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var position = modelTile.position.clone();
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bounds.bottom = bounds.bottom + deltaLat;
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bounds.top = bounds.top + deltaLat;
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position.y = position.y + deltaY;
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row[i].moveTo(bounds, position);
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}
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if (prepend) {
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this.grid.unshift(row);
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} else {
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this.grid.push(row);
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}
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},
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/**
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* @private
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*
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* @param {Boolean} prepend if true, prepend to beginning.
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* if false, then append to end
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*/
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shiftColumn: function(prepend) {
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var deltaX = (prepend) ? -this.tileSize.w : this.tileSize.w;
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var resolution = this.map.getResolution();
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var deltaLon = resolution * deltaX;
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for (var i=0; i<this.grid.length; i++) {
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var row = this.grid[i];
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var modelTileIndex = (prepend) ? 0 : (row.length - 1);
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var modelTile = row[modelTileIndex];
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var bounds = modelTile.bounds.clone();
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var position = modelTile.position.clone();
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bounds.left = bounds.left + deltaLon;
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bounds.right = bounds.right + deltaLon;
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position.x = position.x + deltaX;
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var tile = prepend ? this.grid[i].pop() : this.grid[i].shift()
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tile.moveTo(bounds, position);
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if (prepend) {
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this.grid[i].unshift(tile);
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} else {
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this.grid[i].push(tile);
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}
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}
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},
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/** @final @type String */
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CLASS_NAME: "OpenLayers.Layer.Grid"
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});
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