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/* Copyright (c) 2006-2011 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/Tile/Image.js
*/
/**
* Constant: OpenLayers.Tile.Image.IFrame
* Mixin for tiles that use form-encoded POST requests to get images from
* remote services. Images will be loaded using HTTP-POST into an IFrame.
*
* This mixin will be applied to <OpenLayers.Tile.Image> instances
* configured with <OpenLayers.Tile.Image.allowPost> or
* <OpenLayers.Tile.Image.enforcePost> set to true.
*
* Inherits from:
* - <OpenLayers.Tile.Image>
*/
OpenLayers.Tile.Image.IFrame = {
/**
* Property: useIFrame
* {Boolean} true if we are currently using an IFrame to render POST
* responses, false if we are using an img element to render GET responses.
*/
useIFrame: null,
/**
* Method: clear
* Removes the iframe from DOM (avoids back-button problems).
*/
clear: function() {
if (this.useIFrame) {
if (this.imgDiv) {
var iFrame = this.imgDiv.firstChild;
OpenLayers.Event.stopObservingElement(iFrame);
this.imgDiv.removeChild(iFrame);
delete iFrame;
}
} else {
OpenLayers.Tile.Image.prototype.clear.apply(this, arguments);
}
},
/**
* Method: renderTile
*/
renderTile: function() {
if (OpenLayers.Tile.Image.prototype.renderTile.apply(this, arguments) &&
this.useIFrame) {
// create a html form and add it temporary to the layer div
var form = this.createRequestForm();
this.imgDiv.appendChild(form);
// submit the form (means fetching the image)
form.submit();
this.imgDiv.removeChild(form);
delete form;
}
return true;
},
/**
* Method: initImgDiv
* Creates the imgDiv property on the tile.
*/
initImgDiv: function() {
this.useIFrame = this.maxGetUrlLength !== null && !this.layer.async &&
this.url.length > this.maxGetUrlLength;
if (this.imgDiv != null) {
var nodeName = this.imgDiv.nodeName.toLowerCase();
if ((this.useIFrame && nodeName == "img") ||
(!this.useIFrame && nodeName == "div")) {
// switch between get and post
this.removeImgDiv();
this.imgDiv = null;
}
}
if (this.useIFrame) {
if (this.imgDiv == null) {
var eventPane = document.createElement("div");
if(OpenLayers.BROWSER_NAME == "msie") {
// IE cannot handle events on elements without backgroundcolor.
// So we use this little hack to make elements transparent
eventPane.style.backgroundColor = '#FFFFFF';
eventPane.style.filter = 'chroma(color=#FFFFFF)';
}
OpenLayers.Util.modifyDOMElement(eventPane, null,
new OpenLayers.Pixel(0,0), this.layer.getImageSize(), "absolute");
this.imgDiv = document.createElement("div");
this.imgDiv.appendChild(eventPane);
OpenLayers.Util.modifyDOMElement(this.imgDiv, this.id, null,
this.layer.getImageSize(), "relative");
this.imgDiv.className = 'olTileImage';
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;
}
this.imgDiv.viewRequestID = this.layer.map.viewRequestID;
} else {
OpenLayers.Tile.Image.prototype.initImgDiv.apply(this, arguments);
}
},
/**
* Method: createIFrame
* Create the IFrame which shows the image.
*
* Returns:
* {DOMElement} Iframe
*/
createIFrame: function() {
var id = this.id+'_iFrame';
var iframe;
if(OpenLayers.BROWSER_NAME == "msie") {
// InternetExplorer does not set the name attribute of an iFrame
// properly via DOM manipulation, so we need to do it on our own with
// this hack.
iframe = document.createElement('<iframe name="'+id+'">');
// IFrames in InternetExplorer are not transparent, if you set the
// backgroundColor transparent. This is a workarround to get
// transparent iframes.
iframe.style.backgroundColor = '#FFFFFF';
iframe.style.filter = 'chroma(color=#FFFFFF)';
}
else {
iframe = document.createElement('iframe');
iframe.style.backgroundColor = 'transparent';
// iframe.name needs to be an unique id, otherwise it
// could happen that other iframes are overwritten.
iframe.name = id;
}
iframe.id = id;
// some special properties to avoid scaling the images and scrollbars
// in the iframe
iframe.scrolling = 'no';
iframe.marginWidth = '0px';
iframe.marginHeight = '0px';
iframe.frameBorder = '0';
OpenLayers.Util.modifyDOMElement(iframe, id,
new OpenLayers.Pixel(0,0), this.layer.getImageSize(), "absolute");
//bind a listener to the onload of the iframe 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(iframe, 'load',
OpenLayers.Function.bind(onload, this));
return iframe;
},
/**
* Method: createRequestForm
* Create the html <form> element with width, height, bbox and all
* parameters specified in the layer params.
*
* Returns:
* {DOMElement} The form element which sends the HTTP-POST request to the
* WMS.
*/
createRequestForm: function() {
// creation of the form element
var form = document.createElement('form');
form.method = 'POST';
var cacheId = this.layer.params["_OLSALT"];
cacheId = (cacheId ? cacheId + "_" : "") + this.bounds.toBBOX();
form.action = OpenLayers.Util.urlAppend(this.layer.url, cacheId);
// insert the iframe, which has been removed to avoid back-button
// problems
this.imgDiv.insertBefore(this.createIFrame(), this.imgDiv.firstChild);
form.target = this.id+'_iFrame';
// adding all parameters in layer params as hidden fields to the html
// form element
var imageSize = this.layer.getImageSize();
var params = OpenLayers.Util.getParameters(this.url);
for(var par in params) {
var field = document.createElement('input');
field.type = 'hidden';
field.name = par;
field.value = params[par];
form.appendChild(field);
}
return form;
}
};
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