Add `[is[image]]` filter operator

boot/boot.js

@@ -371,10 +371,11 @@ $tw.utils.checkVersions = function(versionStringA,versionStringB) {
 
 /*
 Register file type information
+flags: "image" for image types
 */
-$tw.utils.registerFileType = function(type,encoding,extension) {
+$tw.utils.registerFileType = function(type,encoding,extension,flags) {
 	$tw.config.fileExtensionInfo[extension] = {type: type};
-	$tw.config.contentTypeInfo[type] = {encoding: encoding, extension: extension};
+	$tw.config.contentTypeInfo[type] = {encoding: encoding, extension: extension, flags: flags || []};
 };
 
 /*
@@ -1459,12 +1460,12 @@ $tw.boot.startup = function(options) {
 	$tw.utils.registerFileType("text/html","utf8",".html");
 	$tw.utils.registerFileType("application/javascript","utf8",".js");
 	$tw.utils.registerFileType("application/json","utf8",".json");
-	$tw.utils.registerFileType("application/pdf","base64",".pdf");
-	$tw.utils.registerFileType("image/jpeg","base64",".jpg");
-	$tw.utils.registerFileType("image/png","base64",".png");
-	$tw.utils.registerFileType("image/gif","base64",".gif");
-	$tw.utils.registerFileType("image/svg+xml","utf8",".svg");
-	$tw.utils.registerFileType("image/x-icon","base64",".ico");
+	$tw.utils.registerFileType("application/pdf","base64",".pdf",["image"]);
+	$tw.utils.registerFileType("image/jpeg","base64",".jpg",["image"]);
+	$tw.utils.registerFileType("image/png","base64",".png",["image"]);
+	$tw.utils.registerFileType("image/gif","base64",".gif",["image"]);
+	$tw.utils.registerFileType("image/svg+xml","utf8",".svg",["image"]);
+	$tw.utils.registerFileType("image/x-icon","base64",".ico",["image"]);
 	$tw.utils.registerFileType("application/font-woff","base64",".woff");
 	// Create the wiki store for the app
 	$tw.wiki = new $tw.Wiki();

core/modules/filters/is/image.js

@@ -0,0 +1,43 @@
+/*\
+title: $:/core/modules/filters/is/image.js
+type: application/javascript
+module-type: isfilteroperator
+
+Filter function for [is[image]]
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+/*
+Export our filter function
+*/
+exports.image = function(source,prefix,options) {
+	var results = [];
+	// Function to check a tiddler
+	function checkTiddler(title) {
+		var match = options.wiki.isImageTiddler(title);
+		if(prefix === "!") {
+			match = !match;
+		}
+		if(match) {
+			results.push(title);
+		}
+	};
+	// Iterate through the source tiddlers
+	if($tw.utils.isArray(source)) {
+		$tw.utils.each(source,function(title) {
+			checkTiddler(title);
+		});
+	} else {
+		$tw.utils.each(source,function(element,title) {
+			checkTiddler(title);
+		});
+	}
+	return results;
+};
+
+})();

core/modules/wiki.js

@@ -196,6 +196,16 @@ exports.isShadowTiddler = function(title) {
 	return $tw.utils.hop(this.shadowTiddlers,title);
 };
 
+exports.isImageTiddler = function(title) {
+	var tiddler = this.getTiddler(title);
+	if(tiddler) {		
+		var contentTypeInfo = $tw.config.contentTypeInfo[tiddler.fields.type || "text/vnd.tiddlywiki"];
+		return !!contentTypeInfo && contentTypeInfo.flags.indexOf("image") !== -1;
+	} else {
+		return null;
+	}
+};
+
 exports.addTiddler = function(tiddler) {
 	// Check if we're passed a fields hashmap instead of a tiddler
 	if(!(tiddler instanceof $tw.Tiddler)) {