Add iD.Map#redrawEnable to enable/disable redraws

js/id/id.js

@@ -267,6 +267,7 @@ window.iD = function () {
     context.zoomOut = map.zoomOut;
     context.zoomInFurther = map.zoomInFurther;
     context.zoomOutFurther = map.zoomOutFurther;
+    context.redrawEnable = map.redrawEnable;
 
     context.surfaceRect = function() {
         // Work around a bug in Firefox.

js/id/renderer/map.js

@@ -8,6 +8,7 @@ iD.Map = function(context) {
             .scaleExtent([1024, 256 * Math.pow(2, 24)])
             .on('zoom', zoomPan),
         dblclickEnabled = true,
+        redrawEnabled = true,
         transformStart,
         transformed = false,
         minzoom = 0,
@@ -186,7 +187,7 @@ iD.Map = function(context) {
     }
 
     function redraw(difference, extent) {
-        if (!surface) return;
+        if (!surface || !redrawEnabled) return;
 
         clearTimeout(timeoutId);
 
@@ -255,6 +256,12 @@ iD.Map = function(context) {
         return map;
     };
 
+    map.redrawEnable = function(_) {
+        if (!arguments.length) return redrawEnabled;
+        redrawEnabled = _;
+        return map;
+    };
+
     function interpolateZoom(_) {
         var k = projection.scale(),
             t = projection.translate();