Add theme tweaks upgrader

core/modules/upgraders/themetweaks.js

@@ -0,0 +1,65 @@
+/*\
+title: $:/core/modules/upgraders/themetweaks.js
+type: application/javascript
+module-type: upgrader
+
+Upgrader module that handles the change in theme tweak storage introduced in 5.0.14-beta.
+
+Previously, theme tweaks were stored in two data tiddlers:
+
+* $:/themes/tiddlywiki/vanilla/metrics
+* $:/themes/tiddlywiki/vanilla/settings
+
+Now, each tweak is stored in its own separate tiddler.
+
+This upgrader copies any values from the old format to the new. The old data tiddlers are not deleted in case they have been used to store additional indexes.
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+var MAPPINGS = {
+	"$:/themes/tiddlywiki/vanilla/metrics": {
+		"fontsize": "$:/themes/tiddlywiki/vanilla/metrics/fontsize",
+		"lineheight": "$:/themes/tiddlywiki/vanilla/metrics/lineheight",
+		"storyleft": "$:/themes/tiddlywiki/vanilla/metrics/storyleft",
+		"storytop": "$:/themes/tiddlywiki/vanilla/metrics/storytop",
+		"storyright": "$:/themes/tiddlywiki/vanilla/metrics/storyright",
+		"storywidth": "$:/themes/tiddlywiki/vanilla/metrics/storywidth",
+		"tiddlerwidth": "$:/themes/tiddlywiki/vanilla/metrics/tiddlerwidth"
+	},
+	"$:/themes/tiddlywiki/vanilla/settings": {
+		"fontfamily": "$:/themes/tiddlywiki/vanilla/settings/fontfamily"
+	}
+};
+
+exports.upgrade = function(wiki,titles,tiddlers) {
+	var self = this,
+		messages = {};
+	// Check for tiddlers on our list
+	$tw.utils.each(titles,function(title) {
+		var mapping = MAPPINGS[title];
+		if(mapping) {
+			var tiddler = new $tw.Tiddler(tiddlers[title]),
+				tiddlerData = wiki.getTiddlerData(tiddler,{});
+			for(var index in mapping) {
+				var mappedTitle = mapping[index];
+				if(!tiddlers[mappedTitle] || tiddlers[mappedTitle].title !== mappedTitle) {
+					tiddlers[mappedTitle] = {
+						title: mappedTitle,
+						text: tiddlerData[index]
+					}
+					messages[mappedTitle] = $tw.language.getString("Import/Upgrader/ThemeTweaks/Created",{variables: {
+						from: title + "##" + index
+					}})
+				}
+			}
+		}
+	});
+	return messages;
+};
+
+})();