Add a datauri widget

Used in stylesheets to get a data URI for a font or bitmap

core/modules/widgets/datauri.js

@@ -0,0 +1,48 @@
+/*\
+title: $:/core/modules/widgets/datauri.js
+type: application/javascript
+module-type: widget
+
+The datauri widget displays the contents of a tiddler as a data URI.
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+var DataUriWidget = function(renderer) {
+	// Save state
+	this.renderer = renderer;
+	// Generate child nodes
+	this.generate();
+};
+
+DataUriWidget.prototype.generate = function() {
+	// Get parameters from our attributes
+	this.tiddlerTitle = this.renderer.getAttribute("tiddler",this.renderer.tiddlerTitle);
+	// Compose the data URI
+	var tiddler = this.renderer.renderTree.wiki.getTiddler(this.tiddlerTitle),
+		uri = "";
+	if(tiddler) {
+		var type = tiddler.fields.type || "text/vnd.tiddlywiki",
+			typeInfo = $tw.config.contentTypeInfo[type],
+			isBase64 = typeInfo && typeInfo.encoding === "base64";
+		uri = "data:" + type + (isBase64 ? ";base64" : "") + "," + tiddler.fields.text;
+	}
+	// Set the element
+	this.tag = "pre";
+	this.attributes = {
+		"class": "tw-data-uri"
+	};
+	// Create the renderers for the wrapper and the children
+	this.children = this.renderer.renderTree.createRenderers(this.renderer,[{
+		type: "text",
+		text: uri
+	}]);
+};
+
+exports.datauri = DataUriWidget;
+
+})();