0ba7961df4
improvements in the form of reduced memory use and lower element creating costs, hopefully making the OpenLayers code more usable in internet explorer as well as less of a memory hog in Firefox and other browsers. Additionally, a buffer is available around the main map grid which allows tiles to be loaded outside of the viewing area for faster dragging. git-svn-id: http://svn.openlayers.org/trunk/openlayers@1137 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
444 lines
14 KiB
JavaScript
444 lines
14 KiB
JavaScript
/* Copyright (c) 2006 MetaCarta, Inc., published under the BSD license.
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* See http://svn.openlayers.org/trunk/openlayers/license.txt for the full
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* text of the license. */
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// @require: OpenLayers/Layer/HTTPRequest.js
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// @require: OpenLayers/Util.js
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/**
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* @class
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*/
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OpenLayers.Layer.Grid = Class.create();
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OpenLayers.Layer.Grid.prototype =
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Object.extend( new 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 Hash 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.alpha = 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. that should stay at null
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obj.grid = null;
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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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/**
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* @deprecated User should just set the 'tileSize' via options
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*
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* @param {OpenLayers.Size} size
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*/
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setTileSize: function (size) {
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if (size) {
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this.tileSize = size.clone();
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}
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},
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/**
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* @param {String} tileID
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*
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* @returns The OpenLayers.Tile with the corresponding ID from the grid.
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* if no tile is found, returns null
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* @type OpenLayers.Tile
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*/
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getTile: function(tileID) {
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var foundTile = null;
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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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var tile = row[iCol];
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if (tile.id == tileID) {
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foundTile = tile;
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}
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}
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}
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}
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return foundTile;
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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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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.getVisibility()) {
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if (zoomChanged) {
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// FIX ME FIX ME FIX ME -- should be this.hideGrid() basically
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}
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} else 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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while (true) {
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var topLeft = this.map.getViewPortPxFromLayerPx( this.grid[0][0].position );
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if (topLeft.x > -this.tileSize.w * (this.buffer - 1)) {
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this.shiftColumn(true);
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} else if (topLeft.x < -this.tileSize.w * this.buffer) {
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this.shiftColumn(false);
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} else if (topLeft.y > -this.tileSize.w * (this.buffer - 1)) {
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this.shiftRow(true);
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} else if (topLeft.y < -this.tileSize.h * this.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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}
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}
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},
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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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*
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*/
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_initTiles:function() {
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var viewSize = this.map.getSize();
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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 newGrid = (this.grid.length == 0);
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var rowidx = 0;
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do {
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var row;
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if (newGrid) {
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row = new Array();
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this.grid.push(row);
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} else {
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row = this.grid[rowidx++];
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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;
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if (newGrid) {
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tile = this.addTile(tileBounds, px);
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tile.draw();
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row.push(tile);
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} else {
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tile = row[colidx++];
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tile.moveTo(tileBounds, px);
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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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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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},
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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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/********************************************************/
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/* */
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/* Baselayer Functions */
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/* */
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/********************************************************/
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/**
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* @returns Degrees per Pixel
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* @type float
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*/
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getResolution: function() {
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var maxRes = this.map.getMaxResolution();
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var zoom = this.map.getZoom();
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return maxRes / Math.pow(2, zoom);
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},
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/** Calculates based on resolution, center, and mapsize
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*
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* @returns A Bounds object which represents the lon/lat bounds of the
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* current viewPort.
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* @type OpenLayers.Bounds
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*/
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getExtent: function () {
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var extent = null;
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var center = this.map.getCenter();
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if (center != null) {
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var res = this.getResolution();
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var size = this.map.getSize();
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var w_deg = size.w * res;
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var h_deg = size.h * res;
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extent = new OpenLayers.Bounds(center.lon - w_deg / 2,
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center.lat - h_deg / 2,
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center.lon + w_deg / 2,
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center.lat + h_deg / 2);
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}
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return extent;
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},
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/**
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* @param {OpenLayers.Bounds} bounds
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*
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* @return {int}
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*/
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getZoomForExtent: function (bounds) {
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var maxRes = this.map.getMaxResolution();
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var viewSize = this.map.getSize();
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var width = bounds.getWidth();
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var height = bounds.getHeight();
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var degPerPixel = (width > height) ? width / viewSize.w
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: height / viewSize.h;
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var zoom = Math.floor( (Math.log(maxRes/degPerPixel)) / Math.log(2) );
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var maxZoomLevel = this.map.getMaxZoomLevel();
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var minZoomLevel = this.map.getMinZoomLevel();
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//make sure zoom is within bounds
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zoom = Math.min( Math.max(zoom, minZoomLevel),
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maxZoomLevel );
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return zoom;
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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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while(this.grid.length > 0) {
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var row = this.grid[0];
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while(row.length > 0) {
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var tile = row[0];
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tile.destroy();
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row.remove(tile);
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}
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this.grid.remove(row);
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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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