/**
 * Copyright (c) 2006-2015, JGraph Ltd
 * Copyright (c) 2006-2015, Gaudenz Alder
 */
/**
 * Class: mxImageBundle
 *
 * Maps from keys to base64 encoded images or file locations. All values must
 * be URLs or use the format data:image/format followed by a comma and the base64
 * encoded image data, eg. "data:image/gif,XYZ", where XYZ is the base64 encoded
 * image data.
 * 
 * To add a new image bundle to an existing graph, the following code is used:
 * 
 * (code)
 * var bundle = new mxImageBundle(alt);
 * bundle.putImage('myImage', 'data:image/gif,R0lGODlhEAAQAMIGAAAAAICAAICAgP' +
 *   '//AOzp2O3r2////////yH+FUNyZWF0ZWQgd2l0aCBUaGUgR0lNUAAh+QQBCgAHACwAAAAA' +
 *   'EAAQAAADTXi63AowynnAMDfjPUDlnAAJhmeBFxAEloliKltWmiYCQvfVr6lBPB1ggxN1hi' +
 *   'laSSASFQpIV5HJBDyHpqK2ejVRm2AAgZCdmCGO9CIBADs=', fallback);
 * bundle.putImage('mySvgImage', 'data:image/svg+xml,' + encodeURIComponent(
 *   '<svg xmlns="http://www.w3.org/2000/svg" width="100%" height="100%">' +
 *   '<linearGradient id="gradient"><stop offset="10%" stop-color="#F00"/>' +
 *   '<stop offset="90%" stop-color="#fcc"/></linearGradient>' +
 *   '<rect fill="url(#gradient)" width="100%" height="100%"/></svg>'), fallback);
 * graph.addImageBundle(bundle);
 * (end);
 * 
 * Alt is an optional boolean (default is false) that specifies if the value
 * or the fallback should be returned in <getImage>.
 * 
 * The image can then be referenced in any cell style using image=myImage.
 * If you are using mxOutline, you should use the same image bundles in the
 * graph that renders the outline.
 * 
 * The keys for images are resolved in <mxGraph.postProcessCellStyle> and
 * turned into a data URI if the returned value has a short data URI format
 * as specified above.
 * 
 * A typical value for the fallback is a MTHML link as defined in RFC 2557.
 * Note that this format requires a file to be dynamically created on the
 * server-side, or the page that contains the graph to be modified to contain
 * the resources, this can be done by adding a comment that contains the
 * resource in the HEAD section of the page after the title tag.
 * 
 * This type of fallback mechanism should be used in IE6 and IE7. IE8 does
 * support data URIs, but the maximum size is limited to 32 KB, which means
 * all data URIs should be limited to 32 KB.
 */
function mxImageBundle(alt)
{
	this.images = [];
	this.alt = (alt != null) ? alt : false;
};

/**
 * Variable: images
 * 
 * Maps from keys to images.
 */
mxImageBundle.prototype.images = null;

/**
 * Variable: alt
 * 
 * Specifies if the fallback representation should be returned.
 */
mxImageBundle.prototype.alt = null;

/**
 * Function: putImage
 * 
 * Adds the specified entry to the map. The entry is an object with a value and
 * fallback property as specified in the arguments.
 */
mxImageBundle.prototype.putImage = function(key, value, fallback)
{
	this.images[key] = {value: value, fallback: fallback};
};

/**
 * Function: getImage
 * 
 * Returns the value for the given key. This returns the value
 * or fallback, depending on <alt>. The fallback is returned if
 * <alt> is true, the value is returned otherwise.
 */
mxImageBundle.prototype.getImage = function(key)
{
	var result = null;
	
	if (key != null)
	{
		var img = this.images[key];
		
		if (img != null)
		{
			result = (this.alt) ? img.fallback : img.value;
		}
	}
	
	return result;
};