/* Copyright (c) 2006-2007 MetaCarta, Inc., published under a modified BSD license. * See http://svn.openlayers.org/trunk/openlayers/repository-license.txt * for the full text of the license. */ /** * @requires OpenLayers/Tile.js * * Class: OpenLayers.Tile.Image * Instances of OpenLayers.Tile.Image are used to manage the image tiles * used by various layers. Create a new image tile with the * constructor. * * Inherits from: * - */ OpenLayers.Tile.Image = OpenLayers.Class(OpenLayers.Tile, { /** * Property: url * {String} The URL of the image being requested. No default. Filled in by * layer.getURL() function. */ url: null, /** * Property: imgDiv * {DOMElement} The div element which wraps the image. */ imgDiv: null, /** * Property: frame * {DOMElement} The image element is appended to the frame. Any gutter on * the image will be hidden behind the frame. */ frame: null, /** TBD 3.0 - reorder the parameters to the init function to remove * URL. the getUrl() function on the layer gets called on * each draw(), so no need to specify it here. * * Constructor: OpenLayers.Tile.Image * Constructor for a new instance. * * Parameters: * layer - {} layer that the tile will go in. * position - {} * bounds - {} * url - {} Deprecated. Remove me in 3.0. * size - {} */ initialize: function(layer, position, bounds, url, size) { OpenLayers.Tile.prototype.initialize.apply(this, arguments); this.url = url; //deprecated remove me this.frame = document.createElement('div'); this.frame.style.overflow = 'hidden'; this.frame.style.position = 'absolute'; }, /** * APIMethod: destroy * nullify references to prevent circular references and memory leaks */ destroy: function() { if (this.imgDiv != null) { OpenLayers.Event.stopObservingElement(this.imgDiv.id); if (this.imgDiv.parentNode == this.frame) { this.frame.removeChild(this.imgDiv); this.imgDiv.map = null; } } this.imgDiv = null; if ((this.frame != null) && (this.frame.parentNode == this.layer.div)) { this.layer.div.removeChild(this.frame); } this.frame = null; OpenLayers.Tile.prototype.destroy.apply(this, arguments); }, /** * Method: draw * Check that a tile should be drawn, and draw it. * * Returns: * {Boolean} Always returns true. */ draw:function() { if (this.layer != this.layer.map.baseLayer && this.layer.reproject) { this.bounds = this.getBoundsFromBaseLayer(this.position); } if (!OpenLayers.Tile.prototype.draw.apply(this, arguments)) { return false; } if (this.isLoading) { //if we're already loading, send 'reload' instead of 'loadstart'. this.events.triggerEvent("reload"); } else { this.isLoading = true; this.events.triggerEvent("loadstart"); } if (this.imgDiv == null) { this.initImgDiv(); } this.imgDiv.viewRequestID = this.layer.map.viewRequestID; this.url = this.layer.getURL(this.bounds); // position the frame OpenLayers.Util.modifyDOMElement(this.frame, null, this.position, this.size); var imageSize = this.layer.getImageSize(); if (this.layer.alpha) { OpenLayers.Util.modifyAlphaImageDiv(this.imgDiv, null, null, imageSize, this.url); } else { this.imgDiv.src = this.url; OpenLayers.Util.modifyDOMElement(this.imgDiv, null, null, imageSize) ; } this.drawn = true; return true; }, /** * Method: clear * Clear the tile of any bounds/position-related data so that it can * be reused in a new location. */ clear: function() { OpenLayers.Tile.prototype.clear.apply(this, arguments); if(this.imgDiv) { this.imgDiv.style.display = "none"; } }, /** * Method: initImgDiv * Creates the imgDiv property on the tile. */ initImgDiv: function() { var offset = this.layer.imageOffset; var size = this.layer.getImageSize(); if (this.layer.alpha) { this.imgDiv = OpenLayers.Util.createAlphaImageDiv(null, offset, size, null, "relative", null, null, null, true); } else { this.imgDiv = OpenLayers.Util.createImage(null, offset, size, null, "relative", null, null, true); } this.imgDiv.className = 'olTileImage'; /* checkImgURL used to be used to called as a work around, but it ended up hiding problems instead of solving them and broke things like relative URLs. See discussion on the dev list: http://openlayers.org/pipermail/dev/2007-January/000205.html OpenLayers.Event.observe( this.imgDiv, "load", this.checkImgURL.bind(this) ); */ this.frame.appendChild(this.imgDiv); this.layer.div.appendChild(this.frame); if(this.layer.opacity != null) { OpenLayers.Util.modifyDOMElement(this.imgDiv, null, null, null, null, null, null, this.layer.opacity); } // we need this reference to check back the viewRequestID this.imgDiv.map = this.layer.map; //bind a listener to the onload of the image div so that we // can register when a tile has finished loading. var onload = function() { //normally isLoading should always be true here but there are some // right funky conditions where loading and then reloading a tile // with the same url *really*fast*. this check prevents sending // a 'loadend' if the msg has already been sent // if (this.isLoading) { this.isLoading = false; this.events.triggerEvent("loadend"); } } OpenLayers.Event.observe(this.imgDiv, 'load', onload.bind(this)); }, /** * Method: checkImgURL * Make sure that the image that just loaded is the one this tile is meant * to display, since panning/zooming might have changed the tile's URL in * the meantime. If the tile URL did change before the image loaded, set * the imgDiv display to 'none', as either (a) it will be reset to visible * when the new URL loads in the image, or (b) we don't want to display * this tile after all because its new bounds are outside our maxExtent. * * This function should no longer be neccesary with the improvements to * Grid.js in OpenLayers 2.3. The lack of a good isEquivilantURL function * caused problems in 2.2, but it's possible that with the improved * isEquivilant URL function, this might be neccesary at some point. * * See discussion in the thread at * http://openlayers.org/pipermail/dev/2007-January/000205.html */ checkImgURL: function () { // Sometimes our image will load after it has already been removed // from the map, in which case this check is not needed. if (this.layer) { var loaded = this.layer.alpha ? this.imgDiv.firstChild.src : this.imgDiv.src; if (!OpenLayers.Util.isEquivalentUrl(loaded, this.url)) { this.imgDiv.style.display = "none"; } } }, /** @final @type String */ CLASS_NAME: "OpenLayers.Tile.Image" } );