From e9244159dc94b5192c22d73b5fd3a0f211ad2f15 Mon Sep 17 00:00:00 2001
From: Ansis Brammanis <ansis.brammanis@gmail.com>
Date: Thu, 28 Mar 2013 18:30:10 -0400
Subject: [PATCH] fix midpoint redrawing

Midpoints weren't being redrawn when the way was deleted
but both edge nodes still existed in other ways.
---
 js/id/renderer/map.js  | 23 ++++++++++++++++++-----
 js/id/svg/midpoints.js |  3 ++-
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/js/id/renderer/map.js b/js/id/renderer/map.js
index 07fbcf5d2..0ca898165 100644
--- a/js/id/renderer/map.js
+++ b/js/id/renderer/map.js
@@ -71,11 +71,24 @@ iD.Map = function(context) {
             all = _.compact(_.values(complete));
             filter = function(d) {
                 if (d.type === 'midpoint') {
-                    var a = graph.entity(d.edge[0]),
-                        b = graph.entity(d.edge[1]);
-                    return !a || !b ||
-                        _.intersection(graph.parentWays(a), all).length ||
-                        _.intersection(graph.parentWays(b), all).length;
+
+                    var a = d.edge[0],
+                        b = d.edge[1];
+
+                    // redraw a midpoint if it needs to be
+                    // - moved (either edge node moved)
+                    // - deleted (edge nodes not consecutive in any parent way)
+                    if (a in complete || b in complete) return true;
+
+                    var parentsWays = graph.parentWays({ id: a });
+                    for (var i = 0; i < parentsWays.length; i++) {
+                        var nodes = parentsWays[i].nodes;
+                        for (var n = 0; n < nodes.length; n++) {
+                            if (nodes[n] === a && (nodes[n - 1] === b || nodes[n + 1] === b)) return false;
+                        }
+                    }
+                    return true;
+
                 } else {
                     return d.id in complete;
                 }
diff --git a/js/id/svg/midpoints.js b/js/id/svg/midpoints.js
index 9c81b44fe..4c263ecad 100644
--- a/js/id/svg/midpoints.js
+++ b/js/id/svg/midpoints.js
@@ -19,7 +19,8 @@ iD.svg.Midpoints = function(projection) {
                     b = nodes[j + 1],
                     id = [a.id, b.id].sort().join('-');
 
-                if (!midpoints[id]) {
+                // If neither of the nodes changed, no need to redraw midpoint
+                if (!midpoints[id] && (filter(a) || filter(b))) {
                     var loc = iD.geo.interp(a.loc, b.loc, 0.5);
                     if (extent.intersects(loc) && iD.geo.dist(projection(a.loc), projection(b.loc)) > 40) {
                         midpoints[id] = {