From d9b581653032a9d775a1b23c0bb03c8e26449965 Mon Sep 17 00:00:00 2001
From: Tom MacWright <tom@macwright.org>
Date: Sat, 9 Feb 2013 17:34:44 -0500
Subject: [PATCH] Store background setting in hash. Fixes #632

---
 js/id/id.js                  | 17 +++++++++++++----
 js/id/renderer/background.js | 13 +++++++++++++
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/js/id/id.js b/js/id/id.js
index 5e39e6b0e..544c66a12 100644
--- a/js/id/id.js
+++ b/js/id/id.js
@@ -92,10 +92,19 @@ window.iD = function () {
         return context;
     };
 
-    context.background()
-        .source(_.find(iD.layers, function(l) {
-            return l.data.name === 'Bing aerial imagery';
-        }));
+    var q = iD.util.stringQs(location.hash.substring(1));
+    if (q.layer) {
+        context.background()
+                .source(_.find(iD.layers, function(l) {
+                    return l.data.sourcetag === q.layer;
+                }));
+    }
+    if (!context.background()) {
+        context.background()
+            .source(_.find(iD.layers, function(l) {
+                return l.data.name === 'Bing aerial imagery';
+            }));
+    }
 
     return d3.rebind(context, dispatch, 'on');
 };
diff --git a/js/id/renderer/background.js b/js/id/renderer/background.js
index be4cc1927..8a14dc0f3 100644
--- a/js/id/renderer/background.js
+++ b/js/id/renderer/background.js
@@ -152,9 +152,22 @@ iD.Background = function() {
         return background;
     };
 
+    function setPermalink(source) {
+        var tag = source.data.sourcetag;
+        var q = iD.util.stringQs(location.hash.substring(1));
+        if (tag) {
+            location.replace('#' + iD.util.qsString(_.assign(q, {
+                layer: tag
+            }), true));
+        } else {
+            location.replace('#' + iD.util.qsString(_.omit(q, 'layer'), true));
+        }
+    }
+
     background.source = function(_) {
         if (!arguments.length) return source;
         source = _;
+        setPermalink(source);
         return background;
     };