From d6fa8c1e26aecede955ba1dcfe4ce0b45571cfcf Mon Sep 17 00:00:00 2001
From: John Firebaugh <john.firebaugh@gmail.com>
Date: Fri, 21 Mar 2014 17:43:54 -0700
Subject: [PATCH] Support quartile scheme for any imagery source (fixes #2112)

---
 js/id/renderer/background_source.js | 32 ++++++++++++-----------------
 1 file changed, 13 insertions(+), 19 deletions(-)

diff --git a/js/id/renderer/background_source.js b/js/id/renderer/background_source.js
index e0a0cb9c5..444082dc1 100644
--- a/js/id/renderer/background_source.js
+++ b/js/id/renderer/background_source.js
@@ -35,6 +35,17 @@ iD.BackgroundSource = function(data) {
             .replace(/\{switch:([^}]+)\}/, function(s, r) {
                 var subdomains = r.split(',');
                 return subdomains[(coord[0] + coord[1]) % subdomains.length];
+            })
+            .replace('{u}', function() {
+                var u = '';
+                for (var zoom = coord[2]; zoom > 0; zoom--) {
+                    var b = 0;
+                    var mask = 1 << (zoom - 1);
+                    if ((coord[0] & mask) !== 0) b++;
+                    if ((coord[1] & mask) !== 0) b += 2;
+                    u += b.toString();
+                }
+                return u;
             });
     };
 
@@ -63,6 +74,8 @@ iD.BackgroundSource.Bing = function(data, dispatch) {
     // http://msdn.microsoft.com/en-us/library/ff701716.aspx
     // http://msdn.microsoft.com/en-us/library/ff701701.aspx
 
+    data.template = 'https://ecn.t{switch:0,1,2,3}.tiles.virtualearth.net/tiles/a{u}.jpeg?g=587&mkt=en-gb&n=z';
+
     var bing = iD.BackgroundSource(data),
         key = 'Arzdiw4nlOJzRwOz__qailc8NiR31Tt51dN2D7cm57NrnceZnCpgOkmJhNpGoppU', // Same as P2 and JOSM
         url = 'https://dev.virtualearth.net/REST/v1/Imagery/Metadata/Aerial?include=ImageryProviders&key=' +
@@ -84,25 +97,6 @@ iD.BackgroundSource.Bing = function(data, dispatch) {
         dispatch.change();
     });
 
-    var template = 'https://ecn.t{t}.tiles.virtualearth.net/tiles/a{u}.jpeg?g=587&mkt=en-gb&n=z',
-        subdomains = [0, 1, 2, 3];
-
-    bing.url = function(coord) {
-        var u = '';
-
-        for (var zoom = coord[2]; zoom > 0; zoom--) {
-            var b = 0;
-            var mask = 1 << (zoom - 1);
-            if ((coord[0] & mask) !== 0) b++;
-            if ((coord[1] & mask) !== 0) b += 2;
-            u += b.toString();
-        }
-
-        return template
-            .replace('{t}', subdomains[(coord[0] + coord[1]) % 4])
-            .replace('{u}', u);
-    };
-
     bing.copyrightNotices = function(zoom, extent) {
         zoom = Math.min(zoom, 21);
         return providers.filter(function(provider) {