From d2f3d161e5863be2d0ebe6efd3d5bee8b5058e62 Mon Sep 17 00:00:00 2001
From: John Firebaugh <john.firebaugh@gmail.com>
Date: Wed, 27 Mar 2013 14:24:59 -0700
Subject: [PATCH] Eliminate attribution flashing (fixes #1134)

---
 js/id/ui/attribution.js | 63 +++++++++++++++++++++++++++--------------
 1 file changed, 41 insertions(+), 22 deletions(-)

diff --git a/js/id/ui/attribution.js b/js/id/ui/attribution.js
index 9c4ecb7a7..eb3182e46 100644
--- a/js/id/ui/attribution.js
+++ b/js/id/ui/attribution.js
@@ -2,34 +2,53 @@ iD.ui.Attribution = function(context) {
     var selection;
 
     function update() {
-        var d = context.background().source();
+        if (!context.background().source()) {
+            selection.html('');
+            return
+        }
 
-        var provided_by = selection
-            .html('')
+        var attribution = selection.selectAll('.provided-by')
+            .data([context.background().source()], function(d) { return d.data.name; });
+
+        attribution.enter()
             .append('span')
-            .attr('class', 'provided-by');
+            .attr('class', 'provided-by')
+            .each(function(d) {
+                var source = d.data.sourcetag || d.data.name;
 
-        if (!d) return;
+                if (d.data.logo) {
+                    source = '<img class="source-image" src="img/' + d.data.logo + '">';
+                }
 
-        var source = d.data.sourcetag || d.data.name;
-        if (d.data.logo) {
-            source = '<img class="source-image" src="img/' + d.data.logo + '">';
-        }
+                if (d.data.terms_url) {
+                    d3.select(this)
+                        .append('a')
+                        .attr('href', d.data.terms_url)
+                        .attr('target', '_blank')
+                        .html(source);
+                } else {
+                    d3.select(this)
+                        .text(source);
+                }
+            });
 
-        if (d.data.terms_url) {
-            provided_by.append('a')
-                .attr('href', d.data.terms_url)
-                .attr('target', '_blank')
-                .html(source);
-        } else {
-            provided_by.text(source);
-        }
+        attribution.exit()
+            .remove();
 
-        var copyright = d.copyrightNotices(context.map().zoom(), context.map().extent());
-        if (copyright) {
-            provided_by.append('span')
-                .text(copyright);
-        }
+        var copyright = attribution.selectAll('.copyright-notice')
+            .data(function(d) {
+                var notice = d.copyrightNotices(context.map().zoom(), context.map().extent());
+                return notice ? [notice] : [];
+            });
+
+        copyright.enter()
+            .append('span')
+            .attr('class', 'copyright-notice');
+
+        copyright.text(String);
+
+        copyright.exit()
+            .remove();
     }
 
     return function(select) {